MOLECULAR CHARACTERIZATION OF Triticum durum – Aegilops speltoides INTROGRESSION LINES AND EVALUATION FOR THERMO–TOLERANCE AND ITS COMPONENTS
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Date
2013
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PAU Ludhiana
Abstract
Backcross introgression lines (BILs) developed from crosses of Triticum durum –Aegilops speltoides were used to identify quantitative trait loci (QTLs) associated with heat tolerance.Three hundred lines in the first season and 100 selected lines in two consecutive cropping seasons were grown under normal sown and late sown conditions. Membrane thermostability, chlorophyll content (CH), canopy temperature and triphenyl tetrazolium chloride (TTC) tests have been used for identifying genetic variability within genotypes.Yield and yield related traits were also recorded. In all the traits variations between BILs in both normal sown and late sown conditions have been observed. Early maturity, shorter height and reduced tillering were recorded in late sown conditions which could be due to terminal heat stress. Out of 386 markers tested, 76 markers (19.7%) showed polymorphism between the parental lines. These polymorphic markers were used to genotype 100 selected BILs. Graphical genotyping showed introgressed regions in all 14 chromosomes of the recipient parent with overall 14.2% introgression.Single marker analysis (SMA) revealed that six markers (Xgwm293, Xgwm565, Xgwm148, Xwmc269, Xgwm299 and Xwmc603) were significantly associated with spikelets/spike at LOD values ranging from 6.1-10.3 and phenotypic contribution of 18.5-44.3%.Similarly, markers Xgwm293,Xwmc269, Xgwm565, Xgwm471, Xgwm148, Xgwm299, Xwmc603, Xwmc31, Xcfd6 and Xcfa2278 were linked to thousand grain weight. One marker Xcfd60 revealed association to TTC in normal sown BILs with LOD value of 3.1 and PVE of 16.1%. Four markers Xgwm293,Xgwm148, Xcfd60 and Xwmc269 showed linkage with CH with varying LOD score and PVE%. SMA also identified eight markers (Xgwm293, Xgwm565, Xgwm471, Xgwm148, Xgwm299, Xwmc603, Xcfd6 and Xwmc269) linked to days to flowering and four markers viz, Xgwm293, Xgwm471, Xgwm299 and Xwmc603 showed association to days to maturity with LOD value higher than the threshold. Plant height was also linked to four marker loci (Xgwm471, Xgwm148, Xgwm565 and Xwmc603) in average environment and stay green trait was linked to Xgwm148, Xwmc269, Xgwm471 and Xwmc269 with LOD score in the range of2.6 -3.4 and PVE of 12.6-15.9%. Additive QTL analysis identified that most of the traits were contributed from the donor parent and a number of markers identified in SMA were validated in additive QTL analysis also.
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