Browsing by Author "Arun Chacko"

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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.
Genotype x environment interaction in hedge lucerne (desmanthus virgatus (L.) willd.) for yield and quality
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2018) Arun Chacko; Mareen Abraham
The present work on “Genotype×Environment interaction in hedge lucerne (Desmanthus virgatus (L.) Willd.) for yield and quality” was carried out across four locations in Kerala viz., College of Agriculture, Vellayani, College of Horticulture, Thrissur, Krishi Vigyan Kendra, Kottarakkara and Regional Agricultural Research Station, Ambalavayal, Wayanad, during 2016-2018 with an objective to identify stable genotypes of Desmanthus virgatus in varied environments with respect to yield and quality. The eight genotypes of hedge lucerne viz., T1 (IC 345276), T2 (IC 343710), T3 (IC 89910), T4 (IC 261839), T5 (IC 90934), T6 (IC 421199), T7 (TNDV 1) and T8 (Thumburmuzhi local) were evaluated in a Randomized Block Design (RBD) with four replications over four locations during 2017-2018. Eberhart and Russell model (1966) was used to analyze the stability and adaptability of yield and yield related characters of these genotypes. Based on the environmental indices, COA, Vellayani and RARS, Ambalavayal was found most favourable for all of the characters, while COH, Thrissur was unfavourable for all the characters studied. In the pooled analysis of variance for evaluation of hedge lucerne over locations, significant differences among the genotypes and environments were noticed for all the characters studied, suggesting that genotypes interacted significantly with environments. Stability analysis revealed that the genotype T1 (IC 345276) was stable over all locations for different characters such as plant height, number of branches, green fodder yield, dry fodder yield, dry matter production and crude fibre. The genotype T4 (IC 261839) was stable for the characters number of branches, leaf to stem ratio and crude protein across the locations. The genotype T6 (IC 421199) was stable over locations for the characters viz., plant height, length of branches and number of leaves, while the genotype T7 (TNDV 1) was stable for leaf to stem ratio, number of pods and crude fibre. The genotypes T2 (IC 343710) and T8 (Thumburmuzhi local) were identified as stable genotypes for favourable environments. The genotype T2 (IC 343710) showed stable performance for the characters such as leaf to stem ratio, green fodder yield, dry fodder yield and crude fibre. The genotype T8 (Thumburmuzhi local) was stable in favourable environment for length of branches, green fodder yield, dry fodder yield and dry matter production. The genotype T5 (IC 90934) was found to be stable for the characters plant height and crude fibre in unfavourable environments. The present study revealed that the genotypes T1 (IC 345276), T4 (IC 261839), T6 (IC 421199) and T7 (TNDV 1) were stable over the four different locations viz., College of Agriculture, Vellayani, College of Horticulture, Thrissur, Krishi Vigyan Kendra, Kottarakkara and Regional Agricultural Research Station, Ambalavayal, Wayanad. The genotypes T2 (IC 343710) and T8 (Thumburmuzhi local) showed stable performance under favourable environments viz., College of Agriculture, Vellayani and Regional Agricultural Research Station, Ambalavayal, Wayanad, while the genotype T5 (IC 90934) was suitable for unfavourable environment i.e., College of Horticulture, Thrissur.