MOLECULAR MAPPING OF QUANTITATIVE TRAIT LOCI FOR DROUGHT TOLERANCE AND YIELD TRAITS IN LENTIL

Abstract

newline ABSTRACT newlineLentil (Lens culinaris Medik subsp. culinaris) is an autogamous diploid (2n=2x=14), cool season food legume crop cultivated globally. Genomic resources in lentil are limited in comparison to other food legumes, primarily due to large genome size and lack of genetic variation. Further, lentil production is hampered due to various biotic and abiotic stresses worldwide. Among abiotic stresses, drought is one the major production constraints causing up to 70 per cent yield losses in lentil. In order to dissect the complex nature of drought tolerance and to use genomics tools for enhancing yield of lentil under drought stress conditions, intraspecific RIL mapping population (L830 x Precoz) segregating for drought tolerance and yield related traits was used. Twelve hundred and twenty-nine SSR markers (including previously published anchor markers) were screened for parental polymorphism and 293 (23.84 %) were found to be polymorphic among the parents. Of these, 291 were mapped on seven linkage groups at LOD 4.0 spanning 1199.0 cM with an average marker density of 4.8 cM. The study reported assigning of 46 new SSRs on the linkage map. newlineAnalysis of variance revealed significant differences for all the 27 measured traits between the drought tolerant L830 and the susceptible cultivar Precoz . The ANOVA of 126 RILs revealed significant differences for almost all the traits except RFW, RDW, CAR and CHL evaluated under the drought stress conditions. Significant effect of environment was also observed for all the traits measured, except DTF, RP, DTM and SS. Phenotypic data from the RILs were used to identify QTLs for drought tolerance and yield traits by composite interval mapping (CIM). A total of 75 QTLs (LOD and#8805; 2.5) were detected across the three environments (control, drought stress and cylinder culture) and QTLs were detected across all the linkage groups. Among these, 13 were stable across locations/environments, 12 were found to be consistent across the seasons and 27 were drought specific. Phenotypic variation explained (PVE) by QTLs ranged from 5.4 to 45.9 per cent. The highest phenotypic variation (45.9 %) was explained by the QTLs for 100-seed weight. newlineIn conclusion, it is envisaged that the present linkage map, fortified with 291 SSR markers and 75 QTLs for drought tolerance and yield-related traits would provide genomics tools to breeders for further genetic enhancement of this crop species. Thus, the current study would serve as a strong foundation for further validation and fine mapping of QTLs for utilization in lentil breeding programs. newline