Analysis of segregation distortion and its relationship to hybrid barriers in rice.

Reflinur Reflinur,Joong Hyoun Chin,Sun Mi Jang,Md Babul Akter,Backki Kim,Yogendra Bordiya,Hee-Jong Koh,Joohyun Lee,Sang-Ho Chu

doi:10.1186/s12284-014-0003-8

Abstract

BackgroundSegregation distortion (SD) is a frequently observed occurrence in mapping populations generated from crosses involving divergent genotypes. In the present study, ten genetic linkage maps constructed from reciprocal F2 and BC1F1 mapping populations derived from the parents Dasanbyeo (indica) and Ilpumbyeo (japonica) were used to identify the distribution, effect, and magnitude of the genetic factors underlying the mechanisms of SD between the two subspecies.ResultsSD loci detected in the present study were affected by male function, female function, and zygotic selection. The most pronounced SD loci were mapped to chromosome 3 (transmitted through male gametes), chromosome 5 (transmitted through male gametes), and chromosome 6 (transmitted through female gametes). The level of SD in BC1F1 populations which defined by chi-square value independence multiple tests was relatively low in comparison to F2 populations. Dasanbyeo alleles were transmitted at a higher frequency in both F2 and BC1F1 populations, suggesting that indic a alleles are strongly favored in inter-subspecific crosses in rice. SD loci in the present study corresponded to previously reported loci for reproductive barriers. In addition, new SD loci were detected on chromosomes 2 and 12.ConclusionThe identification of the distribution of SD and the effect of genetic factors causing SD in genetic mapping populations provides an opportunity to survey the whole genome for new SD loci and their relationships to reproductive barriers. This provides a basis for future research on the elucidation of the genetic mechanisms underlying SD in rice, and will be useful in molecular breeding programs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-014-0003-8) contains supplementary material, which is available to authorized users.

Highlights

Segregation distortion (SD) is a frequently observed occurrence in mapping populations generated from crosses involving divergent genotypes
Construction of linkage maps in two F2 and eight BC1F1 populations Total map length, average distance between adjacent markers, and the linkage map coverage of the genome constructed from reciprocal F2 and BC1F1 populations was variable in the different mapping populations (Table 1)
Map lengths in female-segregating populations (BC1F1 populations in which F1 was used as a female parent) were generally longer than those in malesegregating population (BC1F1 populations in which F1 was used as a male parent) (Table 1)

Summary

Introduction

Segregation distortion (SD) is a frequently observed occurrence in mapping populations generated from crosses involving divergent genotypes. Ten genetic linkage maps constructed from reciprocal F2 and BC1F1 mapping populations derived from the parents Dasanbyeo (indica) and Ilpumbyeo (japonica) were used to identify the distribution, effect, and magnitude of the genetic factors underlying the mechanisms of SD between the two subspecies. Previous studies detected loci linked with SD in both single and multiple crosses (Harushima et al 2001, 2002; Wang et al 2009). Use of abundant DNA markers allowed development of high-density linkage maps for rice, and these were used to survey the whole genome for SD loci (Causse et al 1994; Harushima et al 1996; Yano et al 1998). Most of the barriers were mapped at different loci and demonstrated to have formed after japonica–indica differentiation (Harushima et al 2001, 2002)

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