Browsing by Author "Veena Vighneswaran"

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Exploitation of male sterility in sesame (Sesamum indicum L.)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellanikkara, 2001) Veena Vighneswaran; Kumaran, K
Molecular screening of rice genotypes for submergence tolerance
(Department of Plant Biotechnology, College of Agriculture, Vellayani, 2018) Aryalekshmi, A S; Veena Vighneswaran
Rice (Oryza sativa L.) is the most important staple food crop that providing food to about half of the population. One of the major constraints in rice cultivation worldwide is submergence stress. This mainly affects flood prone areas like kuttanadu Pokkali as well as low lying paddy fields in Kerala. Sub1 is a major quatitative trait locus (QTL) representing a cluster of three ethylene responsive factor (ERF) genes: Sub1A, Sub1B and Sub1C that confers submergence tolerance to rice genotype. Submergence tolerant rice variety is credited with maintaining energy and alcoholic fermentation which require high levels of carbohydrates. Sub1 locus contain Sub1A, Sub1B and Sub1C, all of which are encode ethylene responsive factor and are up regulated under submergence, but only Sub1A is responsible for the flash flood tolerance. The near isogenic lines generated by the introgression of the Sub1 from FR13A into to susceptible cultivar shows restricted shoot elongation similar to FR13A. Submergence tolerant plants suppress the expression of gene encoding α- amylase and sucrose synthase, which are involved in sucrose metabolism. Sub1 A enhance the expression of genes encoding SLENDER RICE -1 (SLR1) and SLR1 like 1(SLRL1), which are key repressor of gibberellins (GA) signalling in rice; it also negatively regulate s the GA response in order to restrict shoot elongation under submergence. Rice varieties with the Sub1 gene were shown higher survival rate with better yield even after 2 weeks of submergence stress. The advancement of marker assisted selection (MAS) have striking impacts on developing improved Sub1 varieties that can meet the increasing demands of consumers along with population hike. In the present study, two rice genotypes were observed with Sub1 QTL using SSR markers through molecular characterization in order to find out the best submergence tolerant lines. Moreover this finding lays the foundation for further researches with sub 1 QTL for crop improvement.
Performance analysis of Sub 1 pyramided F5 population in rice
(Department of Plant Breeding and Genetics, College of Agriculture , Vellayani, 2023-04-10) Aravind Krishnan ,P S.; Veena Vighneswaran
Rice (Oryza sativa L.) is the most important primary food crop that provides food to about half of the population. The cultivated species of rice are semi aquatic plants of normal height ranging from 0.90m – 1.8m, but some can grow up to 5 metres in deep water. In lowlands and deep-water rice field, over 16 million hectares of the world’s rice lands are unfavourably impacted by floods due to total submergence and one of the major constraints in rice cultivation worldwide is submergence stress. This mainly affects flood prone areas like kuttanadu, pokkali as well as low lying paddy fields in Kerala. Even though hundreds of high yielding varieties were developed in the nation, they are not suitable for cultivation in the problematic areas affected by various abiotic stresses. The easiest way is to incorporate the abiotic stress tolerant (Quantitative Trait Loci) QTLs into the already bred high yielding varieties without altering any of the characters through molecular breeding. Sub1 is a major quantitative trait locus (QTL) representing a cluster of three ethylene responsive factor (ERF) genes: Sub1 A, Sub1B and Sub1C that confers submergence tolerance to rice genotype. Submergence tolerant rice variety is credited with maintaining energy and alcoholic fermentation which require high levels of carbohydrates. Sub1 locus contain Sub1A, Sub1B and Sub1C, all of which encode ethylene responsive factor and are up regulated under submergence, but only Sub1A is responsible for flash flood tolerance. The near isogenic lines generated by the introgression of the Sub1 from FR13A into to susceptible cultivar shows restricted shoot elongation similar to FR13A. The present study was undertaken for the performance assessment of Sub 1 QTL in the BC3F5 progenies of submergence susceptible rice varieties Jaya, Jyothi and Uma. The research was conducted in the Department of Plant Breeding and Genetics, Rice Research Station, Vyttila during the period 2021-2022. The experimental material used for the study included 50 accessions of BC3F5 progenies of Jaya, Jyothi and Uma obtained from Rice Research Station, Vyttila. 47 SSR markers distributed across the rice genome were used for polymorphism survey between recurrent parents Jaya, Jyothi and Uma and Swarna Sub-1 96 Progenies of BC3F5 was evaluated in the field to assess the submergence tolerance of Sub-1 introgressed lines. In-vitro screening of BC3F5 progenies were performed by pot culture experiment. 14 days old seedlings were subjected to complete submergence and the pots were desubmerged after 14 days. The survival percentage and elongation percentage were scored based on the observation. Most of the selected lines have shown good recovery percentage resembling its Sub-1 donor Swarna Sub-1. Rice varieties with the Sub1 gene were shown higher survival rate with better yield even after 2 weeks of submergence stress. The advancement of marker assisted selection (MAS) have striking impacts on developing improved Sub1 varieties that can meet the increasing demands of consumers along with the population hike. In this present study, 31 rice genotypes were observed with the Sub1 QTL using SSR markers through molecular characterisation in order to find out the best submergence tolerant lines. More over this finding lays the foundation for further researches with Sub1 QTL for crop improvement. 2 SSR markers ART-5 and Sub1BC2 were used as foreground markers to identify the Sub-1 QTL. Background markers are used to identify the recurrent parent marker allele. A total of 45 polymorphic background markers were used for background screening. 9
Physiological, biochemical and molecular characterization of saline tolerant genotypes of rice
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2022-03-11) Bindhya Mathew; Veena Vighneswaran
The study entitled “Physiological, biochemical and molecular characterization of saline tolerant genotypes of rice” was conducted at Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, during 2019-21 to screen saline tolerant rice genotypes of Kerala for the presence of Saltol QTL and to assess various physiological and biochemical parameters of salt tolerance under different stress levels. Twenty rice varieties, including one susceptible check were grown in nutrient media and soil whose electrical conductivity was maintained at three different levels viz, 6 dS m-1, 9 dS m-1 and 12 dS m-1. Experiment was conducted in two parts. Visual scoring and molecular screening were done on the genotypes in the first part and physiological and biochemical characterization of their saline tolerance were performed in the second part. For visual scoring, rice seedlings were grown hydroponically in seedling floats containing salinized Yoshida nutrient medium, for 21 days. Molecular screening was done using 20 SSR markers linked to the Saltol QTL of rice. For physiological and biochemical characterization, the genotypes were grown in pots, with soil maintained at EC of 6 dS m-1, 9 dS m-1 and 12 dS m-1. Various morphological, biometrical, physiological and biochemical parameters of salt tolerance were studied. Observations were taken at 5 stages- 21st day (seedling stage), 40th day (active tillering), 60th day (panicle initiation), at flowering and at harvest stage. On analysis of the binary marker data in NTSYSpc for genetic distance, it was found that the genotypes were diverse in terms of marker alleles and they clustered into 4 groups. The released varieties and the traditional saline tolerant landraces of Kerala are highly related and got clustered under one group. The CSR varieties were more related to FL 478, than the varieties from Kerala. Jyothi, was very unrelated to other varieties and formed a separate group. All tolerant varieties except CSR 10 and CSR 27 were polymorphic with FL 478 for atleast one of the three important markers linked to Saltol - RM1287, RM493 and RM10748, revealing that a salt tolerance mechanism other than that controlled by Saltol QTL might be in action within them. The morphological, physiological and biochemical parameters under study showed a significant variation among genotypes and treatments. The interaction between genotypes and salinity levels was significant for the observations on number of tillers per hill, grain yield, plant height, root length, fresh weight of shoot and root, dry weight of shoot and also for all biochemical parameters- chlorophyll content, sodium content, potassium content, Na+: K+ ratio, proline content and activities of catalase, peroxidase and superoxide dismutase. For all these parameters the susceptible variety showed significantly high/low values compared to the tolerant varieties except in plant height at 12 dS m-1, root length at 9 dS m-1 and 12 dS m-1, and chlorophyll content in all treatments on 21st day, 40th day and in 6 dS m-1at 60th day. Cluster analysis revealed that the genotypes clustered in a similar fashion based on the biochemical observations from 21st and 40th day, but a much different clustering was observed in 60th day, opening the possibility for a different kind of tolerance mechanism working at reproductive stage. As observed from the results of principal component analysis, at seedling stage and active tillering stage, Na+: K+ ratio had the greatest contribution to salt tolerance but at panicle initiation stage, it was the peroxidase activity. The percentage contribution of Na+ and K+ contents on the principal component 1 of salinity tolerance had reduced and that of peroxidase activity and superoxide dismutase activity increased, as the plants transitioned from seedling and tillering stage to the panicle initiation stage. Combining this observation with the polymorphism of genotypes for the important markers of Saltol, it was concluded that there could be an alternate mechanism and a genomic region, possibly a QTL, providing reproductive stage salinity tolerance to genotypes.