Mapping of QTLs for heat tolerance in hot pepper (Capsicum annuum L.).

The investigation entitled, "Mapping of QTLs for heat tolerance in hot pepper (Capsicum annuum L.)" was undertaken at the research farm of Division of Vegetable Science, ICAR-IARI, New Delhi, India. F1 was derived by crossing DLS-161-1 (heat tolerant) and DChBL-240 (heat susceptible) and selfed to generate the F2 Phenotypic evaluation of parents revealed that DLS-161-1 performed significantly better for various morphological, physiological and biochemical parameters which are affected due to heat stress such as plant height, number of fruits per plant, average fruit length, canopy temperature depression , membrane stability index, pollen viability, photosynthetic rate and activities of different antioxidant enzymes indicating thereby that DLS-161-1 was able to adapt high temperature conditions by regulating various morphological, physiological, and biochemical mechanisms.A wide range of variation was observed in the F2 population for all the studied traits in high temperature conditions indicating the quantitative nature of heat tolerance. Genotyping of F2 population was done through genotyping by sequencing (GBS) using Illumina Hiseq platform and 67.21 Gb raw sequencing data generated was aligned against reference genome (Capsicum annnum). Variant calling with UGBS- GATK pipeline resulted in identification of 5806 polymorphic SNP markers which were grouped into 12 linkage groups. QTL analysis with composite interval mapping revealed a total of 165 QTLs for 24 different traits studied out of which all the QTLs having either very minor LOD score or which explained very little phenotypic variance were eliminated, and only 64 QTLs were retained. The LOD values of selected 64 QTLs ranged from 2.517-11.170 and PVE (Phenotypic Variance Explained) from 4.05 to 19.39.