Browsing by Author "V K, Vikas"

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GENETIC DIVERGENCE OF BREAD WHEAT GENOTYPES BASED ON CLUSTER AND PRINCIPAL COMPONENT ANALYSIS FOR BREEDING STRATEGIES
(2015-08-16) P, Shajitha; M, Sivasamy; K, Gajalakshmi; K, Baghyalakshmi; V K, Vikas
The genetic divergence study was conducted to estimate the nature and magnitude of diversity in Lr19+ and Lr19-lines of bread wheat. The divergence analysis including Tocher's, canonical (vector) and Principal component analysis(PCA) for yield and its nine contributing characters were studied. The twenty two wheat genotypes were grouped into four clusters by both Tocher's method of divergence study. The result of PCA revealed that all the 4 principal components (PC1, PC2, PC3 and PC 4) contributed 93.35% of the total variability. The first PC assigned 60% and the second PC assigned 16% and of total variation between traits. The first PC was more related to days to heading, plant height, tillers per lant, spikelets per spike, grain yield per spike and peduncle length. Therefore, selection based on first component is helpful for a good hybridization breeding program. The information obtained from this study can be used to plan crosses and maximized the use of genetic diversity and expression of heterosis from alien translocation.
MARKER AIDED INTROGRESSION OF STEM RUST RESISTANCE GENES TO DEVELOP DURABLE WHEAT VARIETIES
(Innovative Farming, 2019-12-27) R, Nisha; M, Sivasamy; K, Gajalakshmi; P, Shajitha; John Peter; E, Punniakotti; V K, Vikas
Wheat is one of the most important cereal crops for food security and rust diseases continually pose a threat to wheat production at national and international level. Resistant cultivars are the economical, most reliable, environmentally safest and sustainable way to manage the rust diseases. Most of the rust resistance genes are all stage resistance (ASR) and therefore succumb to new variants of the respective pathogen soon after their deployment. Deployment of ASR genes does not often provide durable resistance, whereas adult plant resistance (APR) genes have small to intermediate effects when present alone. Same time, high and durable rust resistance could be achieved by combining the APR and ASR genes together. Selection of two or more genes in a single genotype can be difficult using conventional selection system. In such a scenario, phenotype neutral selection based on marker-trait association becomes inevitable. Stem rust has been a major threat to wheat production in the recent days. Sr2, a minor stem rust resistance gene was introgressed together with a major stem rust resistance gene Sr36 in the background of two popular wheat varieties, ‘Lok-1’ and ‘Raj 4083’. As the minor gene Sr2 alone cannot provide adequate resistance to stem rusts, major gene Sr36 was pyramided along with it. Marker assisted selection using microsatellite markers gwm533 and stm773-2 linked to Sr2 and Sr36 were performed in the BC1F1, BC1F2 and BC1F3 generations for the successful pyramiding of these genes. The microsatellite markers eased the process of identification of lines carrying the introgressed genes. Both phenotype and genotype data confirmed the co-presence of Sr2 and Sr36 genes. These lines with the two highly effective genes should be more useful for developing durable stem rust resistant wheat cultivars.
PROTEIN MARKER AS AN EASY TOOL TO DETECT SECALE CEREAL - DERIVED LINKED GENES SR31, LR26, YR9 AND PM8 IN WHEAT
(Diva Enterprises pvt ltd, 2014-12-18) R, Nisha; M, Sivasamy; K, Gajalakshmi; V K, Vikas; Kumar Jagdish; P, Jayaprakash; P, Shajitha; N, Senthil
The high yielding potential associated with IRS.IBL translocation involving the short arm of rye chromosome 1R and the long arm of wheat chromosome 1B were well exploited world over for developing disease resistant and high yielding wheat varieties. This was due to the translocation of the effective disease resistance linked genes Sr31 for resistance to stem rust (P. graminis f. sp. tritici), Lr26 for resistance to leaf rust (caused by Puccinia triticinia), Yr9 for resistance to stripe rust (P. striiformis f. sp. tritici), Pm8 for resistance against powdery mildew (caused by Erisiphe graminis f. sp. tritici) along with useful agronomic traits. However now virulent pathotypes have been reported which has overcome these rust resistance genes. The Sr31 gene complex has close linkage with the genes controlling secalins (Sec-1). Thus Sec-1 acts as a marker for the identification of Sr31, Lr26, Yr9 and Pm8 genes. SDS - PAGE was used to examine the presence of 1BL.1RS translocation in six Indian wheat genotypes viz., HP 1205, HD 2329, HD 2285, WH 147, Lok-1 and J 24 introgressed with Sr31+ gene complex with the aim to eliminate the lines carrying these genes, since it is tightly linked to poor baking quality. The SDS - PAGE results showed that all the lines carry Sec-l band and are therefore likely to carry the IBL.IRS translocation and the linked genes Sr31, Lr26, Yr9 and Pm8. This technique could be well exploited to detect the presence of linked genes Sr31, Lr26, Yr9 and Pm8 in wheat cultivars as it is an easy, efficient, faster and economical tool to eliminate the lines with 1BL.1RS translocation and developing wheat varieties for better end use quality and reducing the risk to Ug99 stem rust race threat