Rice yield and heading date are two distinct traits controlled by quantitative trait loci （QTLs）. The dissection of molecular mechanisms underlying rice yield traits is important for developing high-yielding rice va...Rice yield and heading date are two distinct traits controlled by quantitative trait loci （QTLs）. The dissection of molecular mechanisms underlying rice yield traits is important for developing high-yielding rice varieties. Here, we report the cloning and characterization of Ghd8, a major QTL with pleiotropic effects on grain yield, heading date, and plant height. Two sets of near isogenic line populations were developed for the cloning of GhdS. Ghd8 was narrowed down to a 20-kb region containing two putative genes, of which one encodes the OsHAP3 subunit of a CCAAT-box binding protein （HAP complex）; this gene was regarded as the Ghd8 candidate. A complementary test confirmed the identity and pleiotropic effects of the gene; interestingly, the genetic effect of Ghd8 was dependent on its genetic background. By regulating Ehdl, RFT1, and Hd3a, Ghd8 delayed flowering under long-day conditions, but promoted flowering under short-day conditions. Ghd8 up-regulated MOC1, a key gene controlling tillering and branching; this increased the number of tillers, primary and secondary branches, thus producing 50% more grains per plant. The ectopic expression of Ghd8 in Arabidopsis caused early flowering by 10 d-a situation similar to the one observed by its homolog AtHAP3b, when compared to wild-type under long-day conditions; these findings indicate the conserved function of Ghd8 and AtHAP3b in flowering in Arabidopsis. Our results demonstrated the important roles of Ghd8 in rice yield formation and flowering, as well as its opposite functions in flowering between rice and Arabidopsis under long-day conditions.展开更多
Flowering at suitable time is very important for plants to adapt to complicated environments and produce their seeds successfully for reproduction. In rice （Oryza rufipogon Griff.） photoperiod regulation is one of t...Flowering at suitable time is very important for plants to adapt to complicated environments and produce their seeds successfully for reproduction. In rice （Oryza rufipogon Griff.） photoperiod regulation is one of the important factors for controlling heading date. Common wild rice, the ancestor of cultivated rice, exhibits a late heading date and a more sensitive photoperiodic response than cultivated rice. Here, through map-based cloning, we identified a major quantitative trait loci （QTL） LHD1 （Late Heading Date 1）, an allele of DTH8/Ghd8, which controls the late heading date of wild rice and encodes a putative HAP3/NF-YB/CBF-A subunit of the CCAAT-box-binding transcription factor. Sequence analysis revealed that several variants in the coding region of LHD1 were correlated with a late heading date, and a further complementary study successfully rescued the phenotype. These results suggest that a functional site for LHD1 could be among those variants present in the coding region. We also found that LHD1 could down-regulate the expression of several floral transition activators such as Ehdl, Hd3a and RFT1 under long-day conditions, but not under short-day conditions. This indicates that LHD1 may delay flowering by repressing the expression of Ehdl, Hd3a and RFT1 under long-day conditions.展开更多
文摘Rice yield and heading date are two distinct traits controlled by quantitative trait loci （QTLs）. The dissection of molecular mechanisms underlying rice yield traits is important for developing high-yielding rice varieties. Here, we report the cloning and characterization of Ghd8, a major QTL with pleiotropic effects on grain yield, heading date, and plant height. Two sets of near isogenic line populations were developed for the cloning of GhdS. Ghd8 was narrowed down to a 20-kb region containing two putative genes, of which one encodes the OsHAP3 subunit of a CCAAT-box binding protein （HAP complex）; this gene was regarded as the Ghd8 candidate. A complementary test confirmed the identity and pleiotropic effects of the gene; interestingly, the genetic effect of Ghd8 was dependent on its genetic background. By regulating Ehdl, RFT1, and Hd3a, Ghd8 delayed flowering under long-day conditions, but promoted flowering under short-day conditions. Ghd8 up-regulated MOC1, a key gene controlling tillering and branching; this increased the number of tillers, primary and secondary branches, thus producing 50% more grains per plant. The ectopic expression of Ghd8 in Arabidopsis caused early flowering by 10 d-a situation similar to the one observed by its homolog AtHAP3b, when compared to wild-type under long-day conditions; these findings indicate the conserved function of Ghd8 and AtHAP3b in flowering in Arabidopsis. Our results demonstrated the important roles of Ghd8 in rice yield formation and flowering, as well as its opposite functions in flowering between rice and Arabidopsis under long-day conditions.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest(201003021)the Project of Conservation and Utilization of Agricultural Wild Plants of the Ministry of Agriculture of Chinathe National High-Tech Research and Development(863)Program of China(2012AA101103)
文摘Flowering at suitable time is very important for plants to adapt to complicated environments and produce their seeds successfully for reproduction. In rice （Oryza rufipogon Griff.） photoperiod regulation is one of the important factors for controlling heading date. Common wild rice, the ancestor of cultivated rice, exhibits a late heading date and a more sensitive photoperiodic response than cultivated rice. Here, through map-based cloning, we identified a major quantitative trait loci （QTL） LHD1 （Late Heading Date 1）, an allele of DTH8/Ghd8, which controls the late heading date of wild rice and encodes a putative HAP3/NF-YB/CBF-A subunit of the CCAAT-box-binding transcription factor. Sequence analysis revealed that several variants in the coding region of LHD1 were correlated with a late heading date, and a further complementary study successfully rescued the phenotype. These results suggest that a functional site for LHD1 could be among those variants present in the coding region. We also found that LHD1 could down-regulate the expression of several floral transition activators such as Ehdl, Hd3a and RFT1 under long-day conditions, but not under short-day conditions. This indicates that LHD1 may delay flowering by repressing the expression of Ehdl, Hd3a and RFT1 under long-day conditions.
