Abstract
Detecting quantity trait locus (QTLs) and elite alleles that are associated with grain-filling rate (GFR) in rice is essential for promoting the utilization of hybrid japonica rice and improving rice yield. Ninety-five varieties including 58 landraces and 37 elite varieties from the core germplasm collection were genotyped with 263 simple sequence repeat (SSR) markers. The GFR of the 95 varieties was evaluated at five stages, 7, 14, 21, 28 and 35 days after flowering (DAF) both in 2011 and 2012. We found abundant phenotypic and genetic diversity in the studied population. A population structure analysis identified seven subpopulations. A linkage disequilibrium (LD) analysis indicated that the levels of LD ranged from 60.3 cM to 84.8 cM and artificial selection had enhanced the LD. A time-course association analysis detected 31 marker-GFR associations involving 24 SSR markers located on chromosomes 1, 2, 3, 4, 5, 6, 8, 9, 11 and 12 of rice at five stages. The elite alleles for high GFR at each stage were detected. Fifteen excellent parental combinations were predicted, and the best parental combination ‘Nannongjing62401×Laolaihong’ could theoretically increase 4.086 mg grain-1 d-1 at the five stages. Our results demonstrate that the time-course association mapping for GFR in rice could detect elite alleles at different filling stages and that these elite alleles could be used to improve the GFR via pyramiding breeding.
Highlights
Rice (Oryza sativa L.) is a globally important cereal crop and is grown on 132 million hectares annually [1]
In 2011, the variety Yangguang200 headed on August 12, which was the earliest heading date (HD), and the varieties Huangshanshi and Manyedao headed on September 13, which was the latest HD
The daily average temperatures during the rice grain-filling were between 18°C and 30°C, which were under the normal climate conditions for rice grain-filling [51]
Summary
Rice (Oryza sativa L.) is a globally important cereal crop and is grown on 132 million hectares annually [1]. The rice yield trait consists of several key components, including grain weight, grain size, grain number, panicle number, and days to heading [5]. A few QTLs and genes of rice yield related, such as GS3, GS5, GW2, GW5, GW8, GL3, Gdh, and DTH7 were isolated recently [6,7,8,9,10,11,12,13,14,15,16,17]. Among all rice yield related traits, grain-filling is a complicated and dynamic process determining the final grain yield [18]. In China, hybrid rice has made great contributions to increasing yield since 1976. The yield of hybrid rice can increase up to 20% [19]. The acreage of PLOS ONE | DOI:10.1371/journal.pone.0119959 March 19, 2015
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
