Abstract

BackgroundLimited genetic resource in the cultivated rice may hinder further yield improvement. Some valuable genes that contribute to rice yield may be lost or lacked in the cultivated rice. Identification of the quantitative trait locus (QTL) for yield-related traits such as thousand-grain weight (TGW) from wild rice speices is desired for rice yield improvement.ResultsIn this study, sixteen TGW QTL were identified from a recombinant inbred line (RIL) population derived from the cross between the introgression line K1561 of Oryza minuta and the rice cultivar G1025. TGW12, One of most effective QTL was mapped to the region of 204.12 kb between the marker 2,768,345 and marker 2,853,491 of the specific locus amplified fragment (SLAF). The origin of TGW12 was tested using three markers nearby or within the TGW12 region, but not clarified yet. Our data indicated thirty-two open reading fragments (ORFs) were present in the region. RT-PCR analysis and sequence alignment showed that the coding domain sequences of ORF12, one MADS-box gene, in G1025 and K1561 were different due to alternative slicing, which caused premature transcription termination. The MADS-box gene was considered as a candidate of TGW12.ConclusionThe effective QTL, TGW12, was mapped to a segment of 204.12 kb using RILs population and a MADS-box gene was identified among several candidate genes in the segment. The region of TGW12 should be further narrowed and creation of transgenic lines will reveal the gene function. TGW12 could be applied for improvement of TGW in breeding program.

Highlights

  • Limited genetic resource in the cultivated rice may hinder further yield improvement

  • quantitative trait locus (QTL) mapping of thousand-grain weight (TGW) by simple sequence repeats (SSR) TGW QTLs were preliminarily detected by 300 SSR markers evenly distributed on the 12 chromosomes

  • The population were F6, F7 recombinant inbred line (RIL) derived from the cross of G1025 and K1561 planted in NN in 2013, 2014

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Summary

Introduction

Limited genetic resource in the cultivated rice may hinder further yield improvement. GNS4 [22], the otubain-like protease WTG1 (WIDE AND THICK GRAIN 1) [23], the 16-kDa α-amylase/trypsin inhibitor RAG2 [24], the GSK3/SHAGGY-Like Kinase qTGW3 [25]. Some genes such as GW2, WTG1, OsCKX2, TGW3, TGW6, qSW5/GW5qSW5/GW5, GS3, DEP1, qGL3/ OsPPKL1,and OsSNB negatively regulate grain weight, while others like GW6a/OsglHAT1, GNS4, GS5/qTGW5a, OsAGSW1, RAG2, and GW8 (OsSPL16) function as positive regulator of grain weight. Wild rice species should contain many valuable genes that can be used for genetic improvements of cultivated rice [26]. It would be an effective way to widen the genetic basis of cultivated rice by introduction and application of favorable wild rice genes

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