QSE7 is a major quantitative trait locus (QTL) influencing stigma exsertion rate in rice (Oryza sativa L.)

Keqin Zhang,Md Habibur Rahman,Galal Bakr Anis,Weixun Wu,Aamir Riaz,Xiaodeng Zhan,Qinqin Yang,Liyong Cao,Shihua Cheng,Yingxin Zhang,Lianping Sun,Yongbo Hong,Yongrun Cao,Aike Zhu,Zhengfu Yang

doi:10.1038/s41598-018-32629-2

Keqin Zhang, Md Habibur Rahman + Show 13 more

Open Access

https://doi.org/10.1038/s41598-018-32629-2

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Abstract

Stigma exsertion is a key determinant to increase the efficiency of commercial hybrid rice seed production. The major quantitative trait locus (QTL) qSE7 for stigma exsertion rate was previously detected on the chromosome 7 using 75 Chromosome Segment Substitution Lines (CSSLs) derived from a cross between the high stigma exsertion indica maintainer XieqingzaoB (XQZB) and low stigma exsertion indica restorer Zhonghui9308 (ZH9308). The C51 line, a CSSL population with an introgression from XQZB, was backcrossed with ZH9308 to produce the secondary F2 (BC5F2) and F2:3 (BC5F2:3) populations. As a result, the Near Isogenic Line (NIL qSE7XB) was developed. Analysis indicated qSE7 acted as a single Mendelian factor and decreased the stigma exsertion. We hypothesized qSE7 regulates single, dual, and total stigma exsertion rate, provided experimental support. qSE7 was mapped and localized between RM5436 and RM5499 markers, within a physical distance of 1000-kb. With use of new insertion-deletion (InDel) markers and analysis of the heterozygous and phenotypic data, it was ultimately dissected to a 322.9-kb region between InDel SER4-1 and RM5436. The results are useful for additional identification and isolation of this candidate gene controlling stigma exsertion rate, and provide a basis for further fine mapping, gene cloning, and Marker Assisted Selection (MAS) breeding later.

Highlights

Stigma exsertion is a key determinant to increase the efficiency of commercial hybrid rice seed production
Using the Chromosome Segment Substitution Lines (CSSLs) populations, the primary quantitative trait locus (QTL) qSE7 was detected in the interval between Simple Sequence Repeat (SSR) markers RM5436 and RM5875 of chromosome 7 and was validated in the secondary F2 population derived from the cross between C51 and ZH9308
The C51 and secondary F2 populations were used for validation and narrowing of the major QTL qSE7, while the F2:3 population was used for genetic validation and dissection

Summary

Introduction

Stigma exsertion is a key determinant to increase the efficiency of commercial hybrid rice seed production. Stigma exsertion, including that of single and dual stigmas, together with other floral traits, plays an important role in hybrid seed production, and receives consistent attention from rice breeders and researchers[8,9,10,11]. Hybrid rice breeders select pollen parents which show traits associated with high yield, whereas the female parents require the trait of male sterility. This has been achieved in rice using cytoplasmic male sterility[15], which results from mutations in mitochondria, or by genetic male sterility, which occurs from nuclear mutations and www.nature.com/scientificreports/. By using the recombinant inbred lines (RILs) derived from a cross between the indica cultivar, pei-kuh, and the wild accession W1944 (Oryza rufipogon), two QTLs for stigma exsertion were found on chromosomes 5 and 1018

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