Progress in research and development on hybrid rice: a super-domesticate in China.
BACKGROUND
China has been successful in breeding hybrid rice strains, but is now facing challenges to develop new hybrids with high-yielding potential, better grain quality, and tolerance to biotic and abiotic stresses. This paper reviews the most significant advances in hybrid rice breeding in China, and presents a recent study on fine-mapping quantitative trait loci (QTLs) for yield traits.


METHODS
By exploiting new types of male sterility, hybrid rice production in China has become more diversified. The use of inter-subspecies crosses has made an additional contribution to broadening the genetic diversity of hybrid rice and played an important role in the breeding of super rice hybrids in China. With the development and application of indica-inclined and japonica-inclined parental lines, new rice hybrids with super high-yielding potential have been developed and are being grown on a large scale. DNA markers for subspecies differentiation have been identified and applied, and marker-assisted selection performed for the development of restorer lines carrying disease resistance genes. The genetic basis of heterosis in highly heterotic hybrids has been studied, but data from these studies are insufficient to draw sound conclusions. In a QTL study using stepwise residual heterozygous lines, two linked intervals harbouring QTLs for yield traits were resolved, one of which was delimited to a 125-kb region.


CONCLUSIONS
Advances in rice genomic research have shed new light on the genetic study and germplasm utilization in rice. Molecular marker-assisted selection is a powerful tool to increase breeding efficiency, but much work remains to be done before this technique can be extended from major genes to QTLs.
Cheng
Shi-Hua
SH
Chinese National Center for Rice Improvement and State Key Laboratory of Rice Biology, China National Rice Research Institute (CNRRI), Hangzhou 310006, China. shcheng@mail.hz.zj.cn
Zhuang
Jie-Yun
JY
Fan
Ye-Yang
YY
Du
Jing-Hong
JH
Cao
Li-Yong
LY
D000383:Agriculture / Q000639:trends*; D002681:China; D002874:Chromosome Mapping; D018556:Crops, Agricultural / Q000235:genetics*; D005819:Genetic Markers; D006824:Hybridization, Genetic; D012275:Oryza / Q000235:genetics*; D051479:Plant Infertility; D040641:Quantitative Trait Loci
D005819:Genetic Markers
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