Browsing by Author "Jayalekshmy, V G"

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Assessment of recurrent parent genome in the two/three R genes phyramided lines of the rice variety aiswarya through genome wide marker assay
(Department of Plant Biotechnology, College of Agriculture, ,Vellayani, 2022-03-14) Aiswarya Mohandas; Jayalekshmy, V G
Bacterial leaf blight (BLB) in rice caused by Xanthomonas oryzae pv. oryzae(Xoo) is one of the most destructive epidemic of rice throughout the world and widespread in Asia, especially in South East Asian countries like India. Durable and effective resistance against BLB can be attained by pyramiding resistance genes into the genetic background of BLB susceptible popular rice cultivars. In the present study entitled “Assessment of recurrent parent genome in the two/ three R genes pyramided lines of the rice variety Aiswarya through genome wide marker assay.” was undertaken at the Department of Seed Science and Technology, College of Agriculture, Vellayani, Thiruvananthapuram to estimate the recurrent parent genome recovery in BC2F4lines pyramided with BLB resistance genes, viz., Xa21, xa13 and xa5 from the donor variety Improved Samba Mahsuri (ISM) in to the genetic background of rice variety ‘Aiswarya’. DNA markers, pTA248, xa13pro and xa5FM tightly linked to the BLB resistance genes Xa21, xa13 and xa5 respectively were used for the selection of lines with two or three resistance gene combination in the BC2F4 lines in foreground screening. The comparison of allele sizes of amplicons of these markers in BC2F4 lines with that of both the parents confirmed the presence or absence of the marker associated with respective gene of resistance. Foreground selection was performed initially on 50 BC2F4 plants to identify the presence of the three R genes for BLB resistance. Xa21 gene was shown to be fixed in all the plants. A total of five plants were found to be homozygous for xa13 gene and another five was shown to be heterozygous for the gene. One BC2F4 line had the three genes xa5, xa13 and Xa21 in homozygous condition. Background screening was done in four plants (Ai- 543- 7- 10- 11, Ai- 543- 7- 10- 16, Ai- 543- 7- 10- 18 and Ai- 543- 7- 10- 24) with the homozygous two gene combination of Xa21 and xa13 and the one plant (Ai- 543- 7- 10- 10) with homozygous three gene combination. 150 genome wide SSR markers specific to Aiswarya had been identified in the previous studies. In BC2F2 generation, 140 out of 150 had been fixed in homozygous condition. The remaining 10 markers (RM4B, RM110, RM190, RM214, RM271, RM277, RM313, RM447, RM502 and RM517) were used in this study. The percentage of recurrent parent genome (RPG) recovery was calculated based on the results of background screening. The highest recurrent parent genome recovery of 96% was observed in the lines Ai-543-7-10-16 and Ai-543-7-10-24. The line Ai-543-7 10-10 with three gene combination showed 95.67% recovery of genome as in the rest of the lines screened (Ai-543-7-10-11 and Ai-543-7-10-18). The present could study identify BC2F4 lines Ai-543-7-10-16 and Ai-543-7-10-24 plants with homozygous two and three R gene combination with more than 95% recurrent parent genome recovery. These lines can be forwarded by self pollination and with stringent screening on the morphological traits of the recurrent parent to develop Essentially Derived Variety for Aiswarya with durable resistance to BLB.
Development of breeding lines in rice(Oryza sativa L.) Pyramided with R genese for resistance to brown plant hopper (BPH) by marker assisted selection.
(Department of plant breeding and genetics, college of agriculture, Vellayani, 2023-07-21) Arun Chacko; Jayalekshmy, V G
The present study ‘Development of breeding lines in rice (Oryza sativa L.) pyramided with R genes for resistance to Brown Plant Hopper (BPH) by markerassisted selection’ was conducted in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani and Regional Agricultural Research Station, Pattambi, during the year 2019-2022, with an objective to introgress R genes for resistance to BPH in the background of the elite variety Jyothi using marker-assisted selection. The study comprised of two main experiments. Experiment-I aimed at the BPH bioassay, assessment of morphological and biochemical characters linked to BPH resistance in the donor and recipient parents followed by the validation of the presence of genes for resistance using specific molecular markers. Recipient parent (Jyothi) and probable donors for BPH resistance from the results of a concluded project in the Department of Plant Breeding and Genetics, COA, Vellayani, and other R gene introgressed lines from IRRI were selected for screening. The BPH bioassay was done using the modified seedbox screening test (MSST) developed by Velusamy (1986). BPH-affected seedling survival rate was calculated based on the Standard Evaluation System (SES) scale of 0-9 (IRRI, 2013). Among the twelve rice genotypes screened, PTB-33, PTB-21, and IR7103-121-15-B were classified as highly resistant and the genotypes IR65482-7-216-1-2 and RP2068-18-3-5 were classified as resistant to BPH infestation. The japonica variety Kinandang Patong was moderately resistant to BPH. The recipient parent Jyothi and five other genotypes viz., Manu Ratna, White Ponni, Wayrarem, Vandana, and APO were classified as highly susceptible to BPH infestation. Five genotypes, Jyothi (recipient parent), PTB-33, IR7103-121-15-B, IR65482-7-216-1-2, and RP2068-18-3-5 were forwarded for studying the BPH resistance reaction. The antibiosis and tolerance mechanisms of BPH resistance were explored in terms of nymphal survival rate, honey-dew test, functional plant loss index (FPLI), and tolerance index (TI). The recipient parent, ‘Jyothi’ turned out to be highly susceptible, and ‘PTB-33’ showed high resistance to BPH feeding among the rice genotypes screened. Other genotypes, IR65482-7-216-1-2 RP206818-3-5, and IR7103-121-15-B showed intermediate values compared to PTB-33 and the highly susceptible variety ‘Jyothi’. The morphological characters and biochemical parameters linked with BPH resistance of five genotypes were assessed in a completely randomized design (CRD) with four replications. The results revealed that BPH feeding, survival, functional plant loss index, and disease score were positively correlated with protein content and negatively correlated with phenol and ascorbic acid content. Reducing sugar content in plants did not show much effect on BPH resistance. The genetic parameters, phenotypic and genotypic coefficient of variation were higher in seven characters, and moderate in six characters indicating high variability among the parents. High heritability and genetic advance in the characters except for the number of productive tillers, and culm thickness and grain length respectively indicated the presence of additive gene action. The characters, culm thickness, 1000 grain weight, and protein content showed a significant positive correlation with the functional plant loss index (FPLI). Path analysis of morphological and biochemical characters with FPLI as the dependent variable showed the direct positive effect of the number of productive tillers, panicle length, number of grains per panicle, grain breadth, LB ratio, and phenol content on FPLI. The validation of the presence or absence of genes for BPH resistance in donor and recipient parents was done using SSR markers RM589 for the Bph-3 gene, RM3331 for Bph-18, RM8213 for Bph-20, and RM28561 for Bph-21. Distinguishable polymorphic bands were obtained in SSR markers RM589 (200 bp for resistance and 180 bp for susceptibility) and RM3331 (110 bp for resistance and 130 bp for susceptibility). Based on BPH screening, resistant reaction study, and gene validation, the KAU released variety ‘PTB-33’ and IRRI introgression line IR65482-7-216-1-2 were selected as the donors for Bph-3 and Bph-18 gene respectively in the marker-assisted breeding program. The second experiment was marker-assisted backcrossing to introgress the R genes (Bph-3 and Bph-18) into the background of elite high-yielding but susceptible variety Jyothi. The donors PTB-33 and IR65482-7-216-1-2 were crossed independently with Jyothi to obtain the F1 generation followed by backcrossing with Jyothi to develop the BC1F1 generation. Phenotyping for ten morphological characters and genotyping using gene-specific SSR markers were carried out in all the backcross generations. Genotyping of 63 BC1F1 lines derived from the PTB-33 donor parent with RM589 marker identified 28 plants with the Bph-3 gene in heterozygous condition. Genotyping of 78 BC1F1 lines derived from the IR65482-7-216-1-2 donor parent with RM3331 marker identified 36 plants with Bph-18 gene in heterozygous condition. The goodness of fit test (χ2 test) in BC1F1 lines with genotypic data showed that the genes Bph-3 and Bph-18 followed the ratio of simple dominance. Intercrossing of BC1F1 lines involved two crosses viz., the PTB-33 derived BC1F1 lines with Bph-3 in heterozygous condition as the female parent and IR65482-7-216-1-2 derived BC1F1 lines with Bph-18 in heterozygous condition as male parent denoted as ‘ICAB’ and the reciprocal cross denoted as ‘ICBA’. Among the twenty-two ICAB progenies, three plants showed both genes (Bph-3 and Bph18) in heterozygous condition, and among the eighteen ICBA progenies, five plants were obtained with both genes (Bph-3 and Bph-18) in heterozygous condition. The Euclidean Distance of intercrossed BC1F1 lines from the recipient parent Jyothi using proximity dissimilarity matrix analysis was calculated to select the intercrossed BC1F1 lines more similar to the recipient parent. Eight intercrossed BC1F1 lines with Jyothi-specific characters and both genes in heterozygous condition were backcrossed with Jyothi to develop BC2F1 lines. In the genotypic evaluation of twenty-six BC2F1 lines, five lines showed the presence of both genes (Bph-3 and Bph-18) in heterozygous condition. The five BC2F1 lines with maximum similarity in proximity dissimilarity matrix analysis were selfed and three-hundred and twenty BC2F2 lines were forwarded to BPH bioassay in the seedling stage at RARS, Pattambi, and COA, Vellayani. Eighty-nine BC2F2 lines showed different levels of resistance in the BPH bioassay. Genotyping of these lines showed the presence of both genes (Bph-3 and Bph-18) in homozygous resistant condition in four lines namely, ICAB-1/3/6, ICAB-1/3/7, ICAB-1/6/2, and ICAB-1/6/10. The similarity percentage of these four lines with the recipient parent in proximity dissimilarity matrix analysis was obtained as 84.51 per cent in ICAB-1/3/6, 89.27 per cent in ICAB-1/6/10, 91.15 per cent in ICAB-1/6/2, and 91.6 per cent in ICAB-1/3/7. The developed breeding lines, possessing pyramided R genes for BPH resistance in the background of Jyothi, can be used to develop essentially derived varieties from Jyothi with BPH resistance. This will offer an improved and sustainable solution for combating BPH infestations, reducing reliance on chemical insecticides, and enhancing the stability of rice production.
Development of cytoplasmic male sterile line in an identified rice variety of Kerala through marker assisted back crossing
(Department of Plant Breeding & Genetics, College of Agriculture, Vellayani, 2019) Tejashree Shivaputra Lachyan; Jayalekshmy, V G
Development of near isogenic lines of rice variety 'uma' for blast resistance genes through molecular marker assisted backcross breeding
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Harikrishnan, P J; Jayalekshmy, V G
Evaluation of CMS based rice hybrids developed from rice varieties of Kerala identified as restorers
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Nayana Jyothibas; Jayalekshmy, V G
Gene recombination for resistance to bacterial wilt and yield components in brinjal
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1988) Jayalekshmy, V G; Gopinathan Nair, V
Brinjal (solanum melongena) is an important vegetable crop of India. It's cultivation is threatened by the bacterial wilt disease caused by Psuedomonas solanacaarum in many places. The cultivation of resistant high yielding varieties is the only effective method of controlling the disease. But the assocation of bacterial wilt resistance with poor yield has obstructed conventional breeding approaches aimed at, deriving useful' recombinations. The present study explores the possibility of developing a resistant high yielding variety by selection in the segregating generation of inter varietal crosses. The plants of the crosses between three resistant varieties, SM-6, SMI-10 and Pusa purple cluster with the susceptable variety Pusa purple long as the male parent, were selfed. The seeds were sown and seedlings raised under two environments, (i) in the field where there is chance for natural incidence of bacterial wilt. (2) in pots with sterilised soil under healthy condition, in both the experiments, mean, variance and correlation coefficients of yield and yield contributing characters were estimated. Study of f2 variability has revealed that, the characters plant height number of fruits per plant and weight of fruit are governed by polygenes. The characters, number of days to first harvest, number of days to final harvest and weight of fruits per plant were governed by major genes with late bearing and low yield dominant over early bearing and high yield respectively. Comparison of means and variances under healthy and infected condition gave an insight into the influence of selection on the expression of these characters. Natural selection for resistance eliminated the early bearers and high yielders leading to directional selection in favour of late bearers and poor yieldes.
Genetic diversity analysis of indigenous rice varieties in Kerala using molecular markers
(Department of Plant Pathology, College of Agriculture, Vellayani, 2019) Ajith, M K; Jayalekshmy, V G
The present study entitled “Genetic diversity analysis of indigenous rice varieties in Kerala using molecular markers “was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram during 2017-2018. The study was conducted with the objective to analyze the genetic diversity of traditional rice varieties in four agro climatic zones of Kerala using RAPD and SSR markers. Five varieties were collected from the each agro climatic zones viz., hill areas of Wayanad, rice growing tract of Palakkad, saline soils of Pokkali and Kuttanad soils. The DNA was isolated and RAPD analysis with 10 Operon primers and SSR analysis was done with ten RM primers. In the RAPD analysis the ten operon primers produced 88 amplicons with an average polymorphism 82%. Resolving power OPC-07 (15.4) had the highest value but its Polymorphism Information Content and Effective Multiplication Ratio (EMR) were considerably low. Considering all the three parameters together primer OPF-06 is found to be the best RAPD primer with considerably high polymorphism information content, resolving power and effective multiplication ratio. The dendrogram constructed based on the RAPD scoring showed that varieties Pokkali and VTL-2 had maximum similarity. These two were from Pokkali rice tract. PTB 12 from Pattambi was found to be unique and it clustered with others only at 30% similarity.The clustering of the genotypes did not show any correlation with the geographic origin. ABL 12 and VTL- 2 showed 70 % similarity but those two were from Wayanad Hills and Pokkali tract respectively. Vellakuttadan from Moncombu clustered with PTB 2 from pattambi at 72% a similarity. Kochuvith and Vellakuttadan from Moncombu clustered at 67 %. All the SSR markers produced two alleles except RM 210 and RM 204 which produced four alleles and one allele respectively. All the alleles of all the markers were polymorphic except that of primer RM204. The polymorphism information content of the SSR primers used in the study ranged from 0 to 0.88. In this study the highest PIC value of 0.88 was reported by RM 210 followed by RM 567 (0.85). The resolving power and EMR was also highest for RM 210. The dendrogram constructed based on the SSR markers could give a clustering of genotypes more correlated with the geographic origin. Genotypes Kochuvithu and Vellakuttadan showed 100 % similarity both where from Kuttanad. But Karavalakochuvith, T.virippu, and PTB 2 also showed 100% similarity but these three were from Moncompu, Pokkali and Palakkad respectively. At around 90 % similarity AMB 14, AMB 22 from Wayanad, Pokkali andVTL-2 from Pokkali, PTB 13 and PTB 8 from Palakkad clustered showing more correlation to the Geographic origin. SSR markers being sequence specific and flanking the repeat sequence which has more role in evolution, are more reliable in predicting the Genetic diversity based on origin. Since both of them could not give a clear-cut clustering based on geographic origin an analysis using both the markers together was done. This gave a better picture of the clustering as it involved more number of variables. But here also the varieties from Wayanad A1 to A5 were scattered in different clusters. Only A 14 and A15 (AMB 14 and AMB 5) clustered at 60 percentage similarity. The accessions from moncompu (A6-A10) clustered at around 50 % similarity. In the accession from Pokkali tract (A11-A15) only T.virippu to VTL-2 clustered at 78 % similarity. Accession from central zone Pattambi (A16-A20) was scattered into different clusters. PTB 12 was unique from other accessions. This molecular diversity analysis of the traditional rice genotypes from four different agro climatic zones could find that the maximum similarity was 78% and that too only between two accessions. The diversity among the genotypes was 64% as all the genotypes clustered at 36% similarity. The clustering of the genotypes did not show any correlation with the geographic origin. Exchange of varieties between the farmers and some amount of natural crossing would have led to the mixture of populations of rice genotypes in different agro climatic zones.
Genome analysis of traditional rice varieties of Kerala using ISSR and RAPD markers
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2006) Reshmi Manohar; Jayalekshmy, V G
The research project “Genome analysis of traditional rice varieties of Kerala using ISSR and RAPD markers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram during 2004-2006. The major objectives of the study were to characterize indigenous rice collection of Kerala on the basis of two molecular markers viz. ISSR and RAPD and to assess the genetic diversity using molecular marker technique. The study using RAPD markers produced 222 amplicons of which 182 were polymorphic thus giving a polymorphism of 81.98 per cent. Twenty primers were used for the study. Of these the primer OPF-04 gave maximum number of polymorphic products and also produced two unique positive products in the accession Cheruvirippu (size between 1.0 kb and 1.5 kb) and in the accession Njavara yellow (size of less than 0.5 kb). The amplification products had size ranging from 2.0 kb to less than 0.5 kb. The analysis produced nine unique positive products and seven unique negative products. Clustering based on Jaccard’s similarity coefficient revealed the highest similarity between the accessions Chettivirippu and Pokkali 3 (0.825). The least similarity index of 0.451 was between the accessions Cheeravithu and Vellakkoli. The Njavara group of accessions, Njavara yellow and Njavara black, clustered at a similarity value of 0.707. The primer OPB-05 and OPF-01 could distinguish the Njavara accessions from others. OPB-05 produced unique product with a size of less than 1.0 kb and OPF-01 produced product at size of less than 0.5 kb. ISSR analysis was carried out using two primers. The amplification using the two primers produced 19 amplicons of which 16 were polymorphic giving 84.21 per cent polymorphism. The amplification products had size ranging from 0.2 kb to more than 1.0 kb. A unique negative marker was amplified by the primer (GA) 8T in the accession Karuthacheera with a size of nearly 0.6 kb. The UPGMA clustering was done using Jaccard’s similarity coefficient values. The highest similarity of 1.00 was shown by the accessions, Athikiramundakan and Veluthakattamodan and by Vellamundakan and Chettivirippu. The least similarity was between the accessions Karuthacheera and Pandivella (0.230). The accession Karuthacheera was unique and formed a single cluster at similarity value of 0.420. The pattern of clustering for the individual marker systems did not show any congruence with each other. However the cluster analysis of combination of the two marker systems produced a better picture of the genetic relationship. The present study using the two dominant DNA markers, RAPD and ISSR, showed that both the DNA markers are effective and promising for detecting genetic variation. It has been observed that ISSR is superior to RAPD in terms of polymorphism detected.
Genotyping of Rf (restoring fertility) loci of rice varieties of Kerala using molecular markers
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Rajib Das; Jayalekshmy, V G
Identification of potential donors for superior fruit quality traits and genes for resistance to tomato leaf curl virus (ToLCV) In tomato and allied species
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2017) Nadkarni Siddhesh Raghvehdra; Jayalekshmy, V G
Identification of the donors for blast resistance from traditional rice varieties of Kerala using functional markers
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2014) Henry Nickolas; Jayalekshmy, V G
The research project entitled “Identification of the donors for blast resistance from traditional rice varieties of Kerala using functional markers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram and farmer’s field at Pattambi, Palakkad district during 2012 - 2014. The major objectives of the study were to identify the traditional rice varieties with blast resistance genes (Pi 1, Pi 2, Pi kh) using associated functional markers and the field scoring of the lines under disease stress condition. In the present study, thirty traditional rice varieties of Kerala were taken for resistance gene source identification and field level evaluation. The selected rice varieties were screened for the presence of the reported blast resistance genes Pi 1, Pi 2 and Pi kh using three SSR (Simple Sequence Repeat) markers RM224, RM527 and RM206 respectively. C101Lac (Pi 1), C101A51 (Pi 2) and Tetep (Pi kh) from DRR, Hyderabad were taken as the resistant gene source check. Functional marker analysis showed the presence of gene Pi 1 in nine varieties. Twenty varieties showed the presence of gene Pi 2 and six varieties showed the presence of gene Pi kh. Among these, three varieties were having a gene combination of Pi 1 and Pi 2. Three varieties were having genes Pi 2 and Pi kh and two varieties had Pi 1 and Pi kh gene combination. Five varieties did not show the presence of molecular marker linked to any of the genes under study. Field screening was done for scoring the varieties for blast disease resistance by growing in the disease prone farmer’s field at Pattambi. From screening, ten varieties were found to be moderately resistant and fifteen varieties displayed moderately susceptible response. Analysis of variance of the infection index calculated from disease score showed that, nine varieties were having low index and they were on par. All the remaining varieties showed susceptible response. None of the varieties were immune or resistant. Popular rice varieties Uma and Jyothi showed a high infection index. Comparing the disease score and the presence of genes, it was inferred that, genes Pi 1 and Pi kh in combination, imparted moderate resistance under Kerala condition. Varieties Parambuvattan and Kavunginpoothala having these two genes showed low infection index in the field screening. Considering single gene effect, gene Pi 1 imparted moderate resistance. Varieties Thekkan chitteni and Njavara from Kunnathoor are having this gene showed a low infection index. Pyramiding of genes Pi 1 and Pi kh can impart durable resistance to rice varieties of Kerala. Parambuvattan and Kavunginpoothala having these two genes in combination can be used as donors for the genes.
Identifying donors for gall midge resistance from traditional rice varieities by functional markers
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2016) Asha A Nair; Jayalekshmy, V G
Irradiation and seed coating for enhancing storage life of grain cowpea (Vigna unguiculata (L.) Walp.)
(Department of Seed Science and Technology, College of Agriculture, Vellayani, 2021) Jayashri, S; Jayalekshmy, V G
The present study entitled “Irradiation and seed coating for enhancing storage life of grain cowpea (Vigna unguiculata (L.) Walp.)” was carried out in the Department of Seed Science and Technology, College of Agriculture, Vellayani during 2020-2021, with an objective to standardize the dose of gamma rays for irradiation and concentration of chitosan for seed coating for enhancing the storage life of grain cowpea. The study was divided into two experiments which were conducted in Completely Randomized Block Design (CRD) with three replications. The first experiment was irradiation of cowpea seeds with gamma rays and the second experiment was seed coating of cowpea seeds with chitosan. The seeds were irradiated with five different doses (100 Gy to 500 Gy) at Indian Institute of Horticultural Research (IIHR), Bangalore. Another set of seeds were coated with chitosan at five different concentrations (1 % to 5 %) at two different quantities for each concentration as 1ml 50g-1 of seeds and 5ml 50g-1 of seeds. Coated seeds were then shade dried and packed in polythene bags and stored for six months along with control. In the first experiment, the cowpea seeds irradiated with 300 Gy, 400 Gy and 500 Gy gamma rays were not affected by pulse beetle infestation till the end of six months of storage. However, in control, the seed damage was observed which varied from 0.333% in first month to 56.333% in sixth month of storage with a seed weight loss of 28.182 per cent. The damage percentage recorded was 2.667 percent and 0.667 per cent in treatment T1 (100 Gy) and T2 (200 Gy) respectively in the sixth month of storage. Thus the gamma ray irradiation in all doses proved to be effective in controlling pulse beetle infestation. Germination parameters were studied in the undamaged seeds to study the effect of irradiation in seed aging. Among the different doses of gamma irradiation, T2 (200 Gy) recorded the highest seed germination percentage (84.33%), speed of germination (32.13 days), seedling shoot length (11.83 cm), seedling dry weight (0.703 g) and seedling vigour index I (2130.49) and II (59.29). All the germination parameters showed increased value at lower doses of gamma rays (100 Gy and 200 Gy) and declined at higher doses (300 Gy, 400 Gy, and 500 Gy) compared to control. Morphological evaluation of gamma irradiated seeds grown in field showed that the morphological parameters did not vary significantly from the control in treatments with gamma doses 100 Gy and 200 Gy. Gamma irradiation at 300 Gy also did not show variation in morphological parameters compared to control except for field germination percentage. But progressive decrease in all morphological parameters was observed for the treatments with gamma doses 400 Gy and 500 Gy. Reduction in germination percentage, plant height, number of pods plant-1 , number of seeds pod-1 and 100 seed test weight was observed when compared to control. Few crinkled leaves were observed in 400 Gy and 500 Gy irradiated treatments at earlier stages. No significant variation was observed in 100 Gy, 200 Gy and control. In the second experiment, among the different chitosan treatments, no seeds were observed with insects upto four months of storage. Although insect eggs and infestation were noticed in treatments such as T1 (1% 1 ml 50g-1 ), T2 (1% @ 5 ml 50g-1 ), T3 (2% @ 1 ml 50g1 ) and T5 (3% @ 1 ml 50g-1 ) at the end of storage period, the percentage of infestation decreased with an increase in concentration and quantity of chitosan used. The grain cowpea seeds coated with different concentrations of chitosan from lower to higher (1% to 5%) have different degrees of improvement in germination parameters compared to control. Among the different treatments of chitosan, T10 (5 % @ 5 ml 50g-1 ) recorded the highest seed germination percentage (89.37 %), maximum speed of germination (36.83), seedling shoot length (14.90 cm), seedling root length (17.53 cm), seedling dry weight (0.747 g). seedling vigour index I (2898.28) and II (66.79). In this study Gamma irradiation proved to be an effective method for controlling pulse beetle infestation during storage in grain cowpea. However the treatment with higher doses 400 Gy and 500 Gy affected the germination parameters negatively and produced some abnormalities in the progeny. Thus, the gamma irradiation at 200Gy and 300 Gy can be recommended for safe storage of grain cowpea seeds. Chitosan at 5% @ 5 ml 50g-1 exhibited higher values for seed germination parameters and showed no pulse beetle infestation till the end of the storage period of six months. Chitosan treatment at 5% @ 5 ml 50g-1 can be recommended for safe storage of grain cowpea seeds. Both gamma irradiation and chitosan seed coating maintained the longevity of seeds during storage and were effective in controlling the storage pests. Seed coating with chitosan had an additional advantage of substantial improvement of seed germination parameters. Gamma irradiation and chitosan seed coating are eco-friendly methods in enhancing the storage life of grain cowpea. Since gamma irradiation requires special facilities for seed treatment, chitosan seed coating will be a better technology for small scale farmers.
Locating donors for genes for biotic stress resistance in tomato through molecular marker assisted selection
(Department of Plant Biotechnology, College of Agriculture, Vellayani, 2022-01-17) Krishnendu, M R; Jayalekshmy, V G
The study entitled “Locating donors for genes for biotic stress resistance in tomato through molecular marker assisted selection” was conducted at the Department of Seed Science and Technology, College of Agriculture, Vellayani, Thiruvananthapuram during 2020-2021. The primary objective of the study was to identify donors for genes for resistance to different biotic stresses viz., Tomato Yellow Leaf Curl Virus (TYLCV), verticillium wilt, fusarium wilt, late blight and root knot nematodes from tomato varieties and elite wild species through marker assisted selection using gene specific markers. The study was conducted in 30 tomato genotypes, collected from inside and outside of Kerala which included wild species as well cultivated varieties. The genotypes were screened for the presence of genes for resistance to various biotic stress inducing diseases like Tomato Yellow Leaf Curl Virus (TYLCV), verticillium wilt, fusarium wilt, late blight and root knot using tightly linked gene specific SCAR and CAPS markers. The genotypes resistant to Tomato Yellow Leaf Curl Virus (TYLCV) were screened for the presence of gene Ty2 located on chromosome 11 using the SCAR marker TG0302/TY2R1 which amplified a band of size 600 bp for genotypes with Ty2/Ty2 alleles and 450 bp for susceptible genotypes. None of the 30 genotypes screened for Ty2 gene were identified to consist the Ty2/Ty2 alleles. Another gene for resistance to TYLCV, ie, Ty3 located on chromosome 6, was screened using the SCAR marker FLUW25, which amplified the genotypes carrying Ty3/Ty3 alleles with a band of size 640 bp and 480 bp for genotypes corresponding to ty3/ty3 alleles. Presence of Ty3 gene was not found in any of the genotypes screened in the study. Verticillium wilt resistance in genotypes was screened for the presence of two closely linked genes, Ve1 and Ve2 of Ve locus. Ve1 specific CAPS marker Ve1 XbaI, distinguished the genotypes of Ve1/Ve1 alleles with restriction digested fragments of size 410bp and 332bp from the susceptible genotypes of restriction digested fragments 410bp, 310bp and 22bp. Ve2 specific CAPS marker V2LeO3F/V2LeO3R generated restriction digested products, 601 bp and 428 bp for Ve2/Ve2 alleles and undigested product of 1029bp for ve2/ve2 alleles. Among the 30 genotypes screened in the study, IIHR 2374 and Kashi Vishesh were identified for the presence of Ve1 and Ve2 genes and PNR 7 for Ve2 gene alone. The genotypes resistant to Fusarium wilt were screened for the presence of the genes I3 located on chromosome 7 and I7 located on chromosome 8. The gene I3 specific SCAR marker P743DF1/R1 amplified a band of size 1270bp for genotypes with I3/I3 alleles and 1060 bp for genotypes with i3/i3 alleles. None of the genotypes screened in the study were identified for the presence of I3 gene. The CAPS marker CAPS7774 specific to I7 gene generated restriction digested fragments of size 612bp and 196bp for genotypes of I7/I7 alleles and undigested fragment of 808 bp for susceptible genotypes. The genotypes IIHR 2205, IIHR 2374 and Vellayani Vijai were identified for the presence of I7/I7 alleles from the study. The genotypes resistant to Late blight were screened for the presence of the genes Ph3 located on chromosome 9 and Ph2 located on chromosome 10. The SCAR marker Ph3-SCAR amplified the genotypes of Ph3/Ph3 alleles with a band of size 176bp and 154 bp for the genotypes of ph3/ph3 alleles. Presence of the gene Ph3 was identified in the genotypes Pusa Ruby, CA 22053, Hisar Lalit, PKM-1 and Arka Vikas from the study. The CAPS marker dtG63 differentiated the genotypes of Ph2/Ph2 alleles with a restriction digested fragment of band size 245 bp from 221 bp of susceptible genotypes. In the study, the genotypes Shakthi, Pusa Ruby, Nenmara local, CA 22053, Manulakshmi, IIHR 2204, PNR 7 and Solanum torvum were identified for the presence of Ph2/Ph2 alleles. Resistance to Root knot in genotypes were screened for the presence of gene Mi1.2 using the SCAR marker Mi23, which amplified a band of size 380 bp for Mi/Mi alleles and 430 bp for mi/mi alleles. From the study it was confirmed that, none of the genotypes screened for the presence of Mi 1.2 gene were resistant to root knot. In accordance with the findings from the study, phenotypic analysis of the genotypes identified as donors for genes for resistan ce can be carried out, in order to ensure the disease resistance in field conditions as well as the credibility of the molecular markers used in the study. The genes for resistance to the diseases studied, located in the 30 genotypes, screened from the study could indicate the donors for tomato resistance breeding programs.
Marker assisted selection for bacterial leaf blight resistance genes in the backcross progenies of prathyasa variety of rice(oryza sativa L)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2019) Govinda Rai Sarma; Jayalekshmy, V G
Marker assisted selection in black cross progenies of prathyasa and aiswarya pyramided with 2 R genes against BLB in rice(Oryza sativa L.)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2023-03-09) Arya Gopinath, M P; Jayalekshmy, V G
Bacterial leaf blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most devastating diseases of rice in the world. Major rice-growing countries are affected by this disease leading to losses of up to 80% in susceptible cultivars. The exploitation of host plant resistance is the most suitable practical strategy for disease management in an eco-friendly manner. To date, about 42 BLB resistance genes, conferring resistance against various strains of Xoo, have been identified from the rice germplasm collections worldwide. So, the present study entitled “Markerassisted selection in back cross progenies of Prathyasa and Aiswarya pyramided with 2 R genes against resistance to bacterial leaf blight in rice (Oryza sativa L.)” was undertaken at the College of Agriculture, Vellayani during 2018-2022 to develop and evaluate BC3F1 and BC3F2 progenies of Prathyasa and Aiswarya pyramided with two R genes (xa13 and Xa21) from the donor ISM (Improved samba Mahsuri). The morphometric traits of pyramided lines and recurrent parents were almost similar and yield contributing characteristics such as panicle length, the number of productive tillers per plant, and other traits were improved in the lines. Aiswarya and Prathyasa are the two high-yielding varieties of the major rice-growing regions Palakkad and Kuttanad. Hence the lines developed in the background of these varieties will overcome the susceptibility to BLB and can be cultivated in the tracts prone to the incidence of BLB. The pyramided lines are having high recovery of recurrent parent genome and they can be released as essentially derived varieties or can be incorporated as donor parents in the breeding programs
Molecular analysis of coconut (Cocos nucifera L.) segregants
(Department of Plant Biotechnology,College of Agriculture, Vellayani, 2016) Rennya, P R; Jayalekshmy, V G
Morphological, biochemical and molecular markers for the genetic analysis of cashew (Anacardium occidentale L.)
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2003) Usha Vani, D; Jayalekshmy, V G
The research project ‘ Morphological, biochemical and molecular markers for the genetic analysis of cashew’ was carried out in the College of Horticulture, Vellanikkara, Thrissur during the period 2000-2002. The major objectives of the study were to fingerprint cashew genotypes based on genetic analysis carried out and the genetic relationship deduced between the morphological, biochemical and molecular parameters studied and also to identify genetically diverse genotypes among those selected for the study to be used in breeding programmes. The study revealed that among the fourteen characters selected i.e., tree height, tree girth, number of primary branches, number of secondary branches, canopy spread, leaf area, number of panicles m*, number of nuts m‘ , number of perfect flowers m ', apple weight, nut weight, kernel weight, shelling percentage and nut yield, all showed significant variation except number of primary branches. Number of perfect flowers 2 2 m' , number of nuts m ', apple weight, nut weight and kernel weight provide a clear seperation of the genotypes. Correlation and path studies revealed tree height and number of nuts m'2 had significant positive correlation and direct effect on yield. Tree girth showed positive correlation but significant negative direct effect on yield. Number of primary branches showed significant positive direct effect but a significant negative correlation with yield. Apple weight showed significant negative correlation and significant negative direct effect with yield. Genetic divergence studied using Mahalanobis D2 analysis revealed H-1593 to be the most divergent genotype. Cluster analysis could group them into four clusters. The members of Cluster I (Sulabha, Priyanka and P-3-2) and Cluster II (Mdk-I, AKM-1 and K-22-1) were found to be best suited for hybrdisation being the farthest. Biochemical studies on phenol and tannin content could group the twelve genotypes into those with high and low contents. The genotype H-1593 had the lowest phenol content. Seed storage protein studies could distinguish K-22-1 from all others by a single unique band. Isozyme analysis in cashew showed only high initial rate of reaction. Further studies to standardise the protocol for isozyme studies needs to be done. Molecular studies involved RAPD analysis using four primers which gave 44 amplification products out of which 30 (68.19 per cent) were found to be polymorphic. Two primers OPP-5 and OPP-10 could distinguish varieties Mdk-2 and Mdk-1 with amplicons 22 and 25 respectively. Dendrogram constructed based on the study grouped together Kanaka and Dharasree; Mdk-1 and Mdk-2 and H-1600 and P-3-2 with the latter two being the closest of all. On comparative study, H-1600 (Damodar) was tied to Dharasree in biochemical studies and with P-3-2 in molecular studies. In morphological studies also, it was placed close to P-3-2 indicating the proximity of Indian accessions with those of South America. Kanaka and Dharasree were tied together both in morphological and molecular studies but both were diverse by pedigree. Similarly, AKM-1 and Dhana were placed close together in the three studies both of which were diverse by pedigree, H-1593 and H-1591 were found to be close in molecular and morphological studies. AKM-1 and Mdk-1,Bapatla accessions and early flowering varieties, were closer in both morphological and molecular studies. It can be said that pedigree is not completely answerable to variability.' The study had revealed a similar trend for morphological and molecular markers in deducing the genetic divergence, Biochemical markers need more refinement so as to get as precise information as has been obtained for the characterisation of the genotypes through molecular studies.
Morphological, biochemical and molecular markers for the genetic analysis of cashew(Anacardium occidentale L.)
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2003) Usha Vani, D; Jayalekshmy, V G
The research project' Morphological, biochemical and molecular markers for the genetic analysis of cashew' was carried out in the College of Horticulture, Vellanikkara, Thrissur during the period 2000-2002. The major objectives of the study were to fingerprint cashew genotypes based on genetic analysis carried out and the genetic relationship deduced between the morphological, biochemical and molecular parameters studied and also to identify genetically diverse genotypes among those selected for the study to be used in breeding programmes. The study revealed that among the fourteen characters selected i.e., tree height, tree girth, number of primary branches, number of secondary branches, canopy spread, leaf area, number of panicles m", number of nuts m", number of perfect flowers m", apple weight, nut weight, kernel weight, shelling percentage and nut yield, all showed significant variation except number of primary branches. Number of perfect flowers m", number of nuts m", apple weight, nut weight and kernel weight provide a clear seperation of the genotypes. Correlation and path studies revealed tree height and number of nuts m" had significant positive correlation and direct effect on yield. Tree girth showed positive correlation but significant negative direct effect on yield. Number of primary branches showed significant positive direct effect but a significant negative correlation with yield. Apple weight showed significant negative correlation and significant negative direct effect with yield. Genetic divergence studied using Mahalanobis D2 analysis revealed H-1593 to be the most divergent genotype. Cluster' analysis could group them into four clusters. The members of Cluster I (Sulabha, Priyanka and P-3-2) and Cluster II (Mdk-L, AKM-l and K~22-1) were found to be best suited for hybrdisation being the farthest. Biochemical studies on phenol and tannin content could group the twelve genotypes into those with high and low .contents. The genotype H-1593 had the lowest phenol content. Seed storage protein studies could distinguish K-22-1 from all others by a single unique band. Isozyme analysis in cashew showed only high initial rate of reaction. Further studies to standardise the protocol for isozyme studies needs to be done. Molecular studies involved RAPD analysis using four primers which gave 44 amplification products out of which 30 (68.19 per cent) were found to be polymorphic. Two primers OPP-5 and OPP-IO could distinguish varieties Mdk-2 and Mdk-l with amplicons 22 and 25 respectively. Dendrogram constructed based on the study grouped together Kanaka and Dharasree; Mdk-l and Mdk-2 and H-1600 and P-3-2 with the latter two being the closest of all. On comparative study, H-1600 (Damodar) was tied to Dharasree in biochemical studies and with P-3-2 in molecular studies. In morphological studies also, it was placed close to P-3-2 indicating the proximity of Indian accessions with those of South America. Kanaka and Dharasree were tied together both in morphological and molecular studies but both were diverse by pedigree. Similarly, AKM-l and Dhana were placed close together in the three studies both of which were diverse by pedigree. H-1593 and H-1591 were found to be close in molecular and morphological studies. AKM-l and Mdk-l,Bapatla accessions and early flowering varieties, were closer in both morphological and molecular studies. It can be said that pedigree is not completely answerable to variability. The study had revealed a similar trend for morphological and molecular markers in deducing the genetic divergence. Biochemical markers need more refinement so as to get as precise information as has been obtained for the characterisation of the genotypes through molecular studies.
Nanoparticulate seed invigoration in cowpea (Vigna unguiculata (L.) Walp.)
(Department of Seed Science and Technology, College of Agriculture, Vellayani, 2023-02-27) Dinesh Sai, S; Jayalekshmy, V G
The present study entitled "Nanoparticulate Seed Invigoration in Cowpea (Vigna unguiculata (L.) Walp.)" was undertaken with the objective of assessing the effect of nanopriming on seed germination, seedling vigour, plant growth, and yield in cowpea. Seeds of the cowpea variety "Kanakamony" were primed with nano ZnO and nano MgO (30 nm), which were taken in different doses of 100 (D1), 200 (D2), 400 (D3), and 600 (D4) mg L-1 with different durations of soaking 6 (S1), 8 (S2), and 10 (S3) hours. Laboratory evaluation on the effect of nano ZnO and nano MgO were done in two separate experiments in a completely randomized design (CRD), with different concentrations of nanoparticles as the first factor and the duration of soaking as the second factor and replicated three times. The results of the first experiment (nanopriming with ZnO) showed a significant difference from the control for seedling and germination parameters except for mean germination time (MGT). Of all the doses D3 (400 mg L-1) was found to be effective in improving the germination and seedling parameters. In seed priming with nano ZnO duration of soaking 6h was found to be effective. Priming with nano ZnO @ 400 mg L-1 and soaking duration of 6h recorded the highest values for the length of the seedling (39.64 cm), root length of the seedlings (17.46 cm), shoot length of the seedlings (22.17 cm), fresh weight of the seedlings (11.30 g), catalase activity (659.26 n moles of H2O2 used min-1 g weight of sample -1), peroxidase activity (2.39 units min -1mg of protein -1), Mean Germination Time (MGT) (4.87 days), Mean Daily Germination (MDG) (20.68 number day -1), Vigour Index-Ⅰ (VI-Ⅰ) (3514.23), Vigour Index-ⅠⅠ (VI-ⅠⅠ) (66.15). But, nano priming with ZnO @ 400 mg L-1, soaking duration 8h gave significantly higher values for dry weight of the seedling (0.68 g), gemination percentage (GP) (97.00), speed of germination (SG) (19.83), Germination Index (GI) (670.00), Germination Rate Index (GRI) (1931.96), Coefficient of Rate of Germination (CRG) (107.54). The results of the second experiment too (nanopriming with MgO) showed significant differences from the control for all the parameters except for MGT. Of all the doses tested, D4 (600 mg L-1) and D3 (400 mg L-1), were found to be effective in improving the germination and seedling parameters. Priming with nano MgO @ 400 mg L-1, soaking duration of 8h recorded highest values for the length of the seedlings (39.41cm), root length of the seedlings (15.93 cm), shoot length of the seedlings (23.48 cm), fresh weight of the seedlings (13.16 g), dry weight (0.58 g), catalase activity (626.94 n moles of H2O2 used min-1 g weight of sample -1), peroxidase activity (2.40 units min - 1mg of protein-1), GP (93.33), MDG (23.08 number days-1), VI-Ⅰ (3640.17), VI-ⅠⅠ (53.88), SG (19.72), GI (660. 67), GRI (1972.06), CRG (92.33) and nano MgO @ 400 mg L-1, soaking duration 6h recorded least MGT (4.75 days). Six treatments (three best from each experiments) with control (hydropriming, duration of soaking 10h) were included for field evaluation using RBD (Randomized Block Design) with three replications. In the nano ZnO treatments, d3s1 (nano ZnO @ 400 mg L-1, soaking duration 6h), d3s2 (nano ZnO @ 400 mg L-1, soaking duration 8h), d4s1 (nano ZnO @ 600 mg L-1, soaking duration 6h) were the three best treatments with scores of 19, 24, 39 respectively. In the nano MgO treatments, d3s2 (nano MgO @ 400 mg L-1, soaking duration 8h), d4s2 (nano MgO @ 600 mg L-1, soaking duration 8h), d4s1 (nano MgO @ 600 mg L-1, soaking duration 6h) were the three best treatments with the scores of 15, 23, 31 respectively. Nanoparticulate seed invigoration (nano ZnO and nano MgO) treatments showed significant positive influence on all the parameters except for plant height, 100 seed weight, days to 50% flowering in the field experiment. T1 (nano ZnO @ 400 mg L-1, soaking duration 6h ) recorded highest value for plant height (68.28 cm), number of branches per plant (13.00), pods per plant (19.73), number of seeds per pod (16.93), 100 seed weight (11.80), days taken to 50% flowering (36.33), pod yield per plant (19.41 g), seed yield per plant (21.79 g) in and T7 (control hydopriming, soaking duration of 10h) recorded least value (58.33 cm, 6.40, 12.47, 10.47, 10.07 g, 45.33, 10.38 g, 11. 09 g) respectively. With regarding to Zn content in seed, treatments T1 (nano ZnO @ 400 mg L-1, soaking duration 6h), T2 (nano ZnO @ 600 mg L-1, soaking duration 6h), and T3 (nano ZnO @ 400 mg L-1, soaking duration 8h) were on par and significantly different from T4 (nano MgO @ 600 mg L-1, soaking duration 6h), T5 (nano MgO @ 400 mg L-1, soaking duration 8h ), T6 (nano MgO @ 600 mg L-1, soaking duration 8h), and T7 (control hydopriming, Soaking duration 10h). Priming with all the doses of nano MgO showed significantly higher content of Mg in seed in comparison with other treatments. This study to evaluate the effect of seed nano priming with ZnO and MgO in cowpea clearly indicated that seed nano priming can be advocated as a seed enhancement tool in cowpea to produce superior seedling traits, crop growth, and yield. All the doses evaluated in this study did not produce any phytotoxic effect on the plant. Seed nanopriming with both ZnO and MgO had significant positive effect on germination and seedling parameters. In nano priming with ZnO d3s1 (nano ZnO @ 400 mg L-1 soaking duration 6h) can be recommended as the best and in nanopriming with MgO d3s2 (nano MgO @ 400 mg L-1 soaking duration 8h) can be recommended as the best for superior germination and seedling traits. Considering the effect on crop growth and yield seed nano priming with dose nano ZnO @ 400 mg L-1, soaking duration of 6h can be recommended for adoption by the farmer.