Genetic Dissection of the Major Quantitative Trait Locus (qSE11), and Its Validation As the Major Influence on the Rate of Stigma Exsertion in Rice (Oryza sativa L.).

Md Habibur Rahman,Aamir Riaz,Yingxing Zhang,Shihua Cheng,Liyong Cao,Yuyu Chen,Weixun Wu,Hirendra N Barman,Keqin Zhang,Md Sazzadur Rahman,Xiaodeng Zhan

doi:10.3389/fpls.2017.01818

Md Habibur Rahman, Aamir Riaz + Show 9 more

Open Access

https://doi.org/10.3389/fpls.2017.01818

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Abstract

The rate of stigma exsertion (SE) is an important trait in rice breeding because the efficiency of hybrid rice seed production can be improved by increasing the percentage of stigmas that exsert. In this study, we developed a near isogenic line (NIL) from two parents, XieqingzaoB (XQZB) and Zhonghoi9308 (ZH9308), which have high and low SE rates in that order. In our previous study, we employed 75 chromosome segment substitution lines (CSSLs) and analyzed quantitative trait loci (QTLs) for their influence on SE rate. The single gene QTL (qSE11), which is located on chromosome 11, was responsible for this trait. In this study, we focused on one of the CSSLs (C65), namely, the NIL (qSE11XB). It contains an introgression segment of XQZB in the genetic background of ZH9308, and exhibits a significantly higher SE rate than that of the parents. We demonstrated that qSE11 regulated both the single and the dual SE rates. They both contribute to the total SE rate. Genetic analysis revealed that qSE11 acted as a single Mendelian factor and that the allele from XQZB increased the SE rate. The validity of our conclusions was established when C65 was used to develop secondary F2 (BC5F2) and F2:3 (BC5F2:3) populations by backcrossing to ZH9308, with subsequent selfing. We entered 3600 plants from the F2 population and 3200 from the F2:3 populations into a genetic dissection program and dissected the major QTL qSE11 to a 350.7-kb region located on chromosome 11. This study will contribute to the future isolation of candidate genes of SE and will play a vital role in future hybrid rice seed production programs.

Highlights

Rice (Oryza sativa L.) is a major cereal grains contributing approximately 60% of the daily dietary requirement, fulfilling about 20 and 14% of the calorie and protein requirement, respectively, of the world’s population (Mahalingam et al, 2013)
The phenotypic data and analyses of this study indicated that XQZB, C65, ZH9308, and near isogenic line (NIL) were significantly different in the single, dual, and total stigma exsertion (TSE) rates in the same row (Table 2), but the differences in the stigma exsertion (SSE) and dual stigma exsertion (DSE) between C65 and NIL were not significant
The NIL phenotypic data (Table 2) showed that qSE11 increased the percentage of exserted stigmas by 27, 5, and 32% in the SSE, DSE, and TSE, compared with ZH9308 on the basis of phenotypic evaluation

Summary

Introduction

Rice (Oryza sativa L.) is a major cereal grains contributing approximately 60% of the daily dietary requirement, fulfilling about 20 and 14% of the calorie and protein requirement, respectively, of the world’s population (Mahalingam et al, 2013). The use of hybrid varieties along with better cultivation and management package would contribute to the increase of rice about 6 tons per hectare. These increases in rice production contributed to the China’s total production and accomplished self-sufficiency and continued to the food supply (Cheng et al, 2007). With an increase in the frequency of stigma exsertion (SE) in female lines of hybrid rice, the seed-setting rate in hybrid seed production and yield of hybrid seed both increased (Zetian and Yanrong, 2011). Several phenotypic traits contribute to the seed production efficiency of hybrid rice, and SE is especially emphasized as major component in increasing pollination and seed set (Kato and Nimai, 1987). The exserted stigmas remained viable for approximately 4 days and could continue to accept pollination (Long and Shu, 2000; Tian et al, 2004)

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