Genetic mapping of the three-pistil gene Pis1 in an F2 population derived from a synthetic hexaploid wheat using multiple molecular marker systems

The wheat spike mutant 'three-pistil' (TP) exhibits normal external morphology but produces two additional pistils per floret. Much attention has been paid to this natural mutation because elucidation of its genetic foundation potentially paves a way to increase the number of grains per spike for breeding. Our previous studies roughly mapped the causal locus of TP on chromosome 2D. In this study, we performed genetic mapping of the three-pistil gene Pis1 in an F2 population derived from a cross of TP and synthetic hexaploid wheat of which chromosome 2D was from Aegilops tauschii. Segregation analysis in the F2 population confirmed the dominance of the Pis1 locus. Bulked segregant analysis with three DNA marker systems revealed a total of 18 markers genetically linked with Pis1. Successive genetic linkage analysis of the F2 individuals using the 18 markers identified two sequence-related amplified polymorphisms markers, Me5-eM33 and Me26-eM33, flanked the Pis1 locus at distances of 0.6 and 1.7 cM, respectively. Integration of the genetic linkage and previously discovered DNA markers associated with Pis1 revealed a potential location of the Pis1 locus between Me5-eM33 and a KASP marker M75. Thus, the constructed partial genetic linkage map is useful for the isolation of Pis1 and marker-assisted breeding in wheat.