AUTHOR=Xue Pao , Chen Yu-yu , Wen Xiao-xia , Wang Bei-fang , Yang Qin-qin , Gong Ke , Kang Yi-wei , Sun Lian-ping , Yu Ping , Cao Li-yong , Zhang Ying-xin , Zhan Xiao-deng , Cheng Shi-hua 

TITLE=Dissection of Closely Linked Quantitative Trait Locis Controlling Grain Size in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.804444

DOI=10.3389/fpls.2021.804444

ISSN=1664-462X

ABSTRACT=<p>Grain size is a key constituent of grain weight and appearance in rice. However, insufficient attention has been paid to the small-effect quantitative trait loci (QTLs) on the grain size. In the present study, residual heterozygous populations were developed for mapping two genetically linked small-effect QTLs for grain size. After the genotyping and the phenotyping of five successive generations, <italic>qGS7.1</italic> was dissected into three QTLs and two were selected for further analysis. The <italic>qTGW7.2a</italic> was finally mapped into a 21.10 kb interval containing four annotated candidate genes. Transcript levels assay showed that the expression of the candidates <italic>LOC_Os07g39490</italic> and the <italic>LOC_Os07g39500</italic> were significantly reduced in the NIL-<italic>qTGW7.2a<sup>BG1</sup></italic>. The cytological observation indicated that <italic>qTGW7.2a</italic> regulated the grain width through controlling the cell expansion. Using the same strategy, <italic>qTGW7.2b</italic> was fine-mapped into a 52.71 kb interval containing eight annotated candidate genes, showing a significant effect on the grain length and width with opposite allelic directions, but little on the grain weight. Our study provides new genetic resources for yield improvement and for fine-tuning of grain size in rice.</p>