Genetic Enhancement for Drought Tolerance and Durable Blast Resistance in Rainfed Rice (Oryza Sativa L.)
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Date
2013
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UAS Dharwad
Abstract
The primary objective of this study include screening introgressed population (Swarna
x WAB 450 BILs) for physiological and yield component traits under upland condition to
identify QTL linked to drought and blast disease, identify top performing BILs tolerant to
drought and resistant to blast disease and carry out G x E analysis of selected superior BILs
under rainfed condition. One hundred and eighty eight BILs along with 10 checks were
screened in pots and on the field in a randomized block design with two replications. Drought
stress was imposed at the onset of the reproductive growth phase until grain filling stage by
withholding irrigation from the treatment plot until severe leaf rolling was observed. BILs
were genotyped with 58 polymorphic SSR markers and marker data were used for the
construction of linkage map using QTL IciMapping software.
Analysis of variance indicated highly significant differences among BILs for most of
the traits under both water stress and non-stressed conditions except harvest index that was
significant at 0.05 level of probability. Fifteen QTL were detected for various traits based on
composite interval mapping under water stress and non-stress condition with significant
contribution from the donor parent, WAB 450. In this study, 10 QTL were detected for
physiological, productivity related traits under water stress, whereas, 5 QTL were identified
under non stress condition. All identified QTL under water stress for various traits exhibited
high phenotypic variance except leaf temperature. WAB 450 contributed all the alleles that
enhance drought resistance for all QTL identified in this study except two QTL identified for
relative water content and spikelet fertility. Reaction to blast was assayed over the period of
two seasons from which 10 BILs were identified as resistant to both leaf and neck blast.
WAB 450, BILs No 48, 183 and 188 were identified in the two consecutive seasons as
promising lines that were resistant to leaf and neck blast. A number of BILs better than the
parents and checks in drought tolerance, blast resistance and G x E interaction were identified
as promising for upland ecosystem.