Mapping of QTLs affecting stigma exsertion rate of Huhan 1B as a CMS maintainer of upland hybrid rice.

To clarify the genetic mechanism of percentage of stigma exsertion in rice(Oryza sativa L.) and improve stigma exsertion rate of a drought tolerant CMS maintainer Huhan 1B,QTL analysis was conducted in a F2 population of 190 plants derived from a cross between Huhan 1B and Ⅱ-32B.Ten QTLs of rice stigma exsertion rate were identified on four chromosomes.Three QTLs of percentage of single exserted stigma(PSES) were mapped on chromosomes 3、7 and 9 with accumulated contribution of 21.44%;Two QTLs of percentage of dual exserted stigma(PDES) were detected on chromosomes 3 and 9 with accumulated contribution of 15.98%; Five QTLs of percentage of total exserted stigma(PES) were mapped on chromosome 3,4,7,9,including 2 QTLs on chromosome 3,whose contribution rates varied from 6.86% to 9.73% and the total contribution rates of the five QTLs was 39.42%.Totally,seven QTLs pairs had significant epistatic effect on the percentage of stigma exsertion rate and accounted for 67.39% of the phenotypic variation.Most of them were additive×additive epistatic effects,and some of major QTLs were involved in the interactions.The identification of the QTLs markers may be important for improvement of Huhan 1B in stigma exsertion rate.