Mapping main and epistatic QTL and their interaction with environment for traits related to spike characteristics in recombinant inbred lines of spring wheat

In order to mapping additive and epistatic QTL and their interaction with environment for traits related to spike characteristics using a RILs population of wheat, comprising 148 recombinant inbred lines derived from a cross between two winter wheat cultivars, ‘YecoraRojo’ and ‘No. 49’, was evaluated in two locations in Iran (Miandoab and Mahabad) during 2014-2016. A linkage map including 177 microsatellite and 51 retrotransposon markers was used in this study. Quantitative trait loci (QTL) were determined using QTL Network 2.0 software based on the CIM and mixed-linear method. In the present study, the highest broad (58.31%) and narrow-sense (29.15%) heritability was measured for spikelet number per spike and the lowest broad (51.28%) and narrow-sense (25.64%) heritability was detected for spike length. Results of QTL analysis showed that in normal condition, one QTL (R2A= 1.54%), one QTL×E (R2AE= 4.40%), 2 additive × additive epistatic effects (R2AA= 0.44- 0.4%) and 6 QTL × QTL×E interactions (R2AAE= 8.24-9.7%) were significant. In water deficit condition, 1 additive × additive interactions (R2AA= 4%) and 3 QTL × QTL × E interactions (R2AAE= 6.98%) were identified. In average of two conditions, two QTL (R2A= 0.78%), 1 QTL×E (R2AE= 5.15%), 10 additive × additive epistatic effects (R2AA= 0.02-7.9%) and 14 QTL × QTL × E interactions (R2AAE= 0.86-8.92%), were significant which can be due to the high number of QTLs with low effects and also environmental effects.