Progress in Research and Development on Hybrid Rice: A Super-domesticate in China

Abstract

BackgroundChina 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.ScopeBy 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.ConclusionsAdvances 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.

Multi-step formation, evolution, and functionalization of new cytoplasmic male sterility genes in the plant mitochondrial genomes

“…The CMS-WA system, which is most widely used for hybrid rice production since 1970s, was developed by successive backcrossing to introduce the CMS cytoplasm of a male sterile O. rufipogon plant into the nuclear backgrounds of rice cultivars [8,9]. We previously identified the CMS-WA gene WA352 (here renamed WA352c, see below) and revealed that WA352c causes CMS by interaction with the nucleus-encoded, highly conserved mitochondrial protein COX11, leading to premature programmed cell death in the anther tapetum and defective pollen development.…”

Changes in Grain Yield and Root Morphology and Physiology of Mid-Season Rice in the Yangtze River Basin of China During the Last 60 Years

“…The genetic improvement (GI) in rice plays a crucial role in the yield increase in China and even in the world (Cheng et al, 2007;Zhang et al, 2007). As an integral part of plant organs, plant roots are involved in acquisition of water and nutrients, synthesis of plant hormones, organic acids and amino acids, and anchorage of plants (Fitter et al, 2002;Inukai et al, 2004).…”

RNase ZS1 processes UbL40 mRNAs and controls thermosensitive genic male sterility in rice

“…Rice is strictly selfpollinating; therefore, hybrid varieties are bred using male-sterile maternal lines that fail to produce viable pollen, thus preventing self-pollination. Hybrid rice breeding uses the well-developed three-line and two-line systems 4,5 . The three-line system uses a cytoplasmic male-sterile (CMS) line, a restorer line and a CMS maintainer line to produce F 1 hybrid seeds and maintain the CMS line [6][7][8] .…”

“…The three-line system uses a cytoplasmic male-sterile (CMS) line, a restorer line and a CMS maintainer line to produce F 1 hybrid seeds and maintain the CMS line [6][7][8] . Three-line hybrid rice has been grown since the 1970s and is a major type of hybrid rice 1,4,9 . However, the limited germplasm resources of restorer lines and the genetic diversity between CMS and restorer lines have limited further improvements in three-line breeding 10 .…”