野生稻在中国有 3种 :普通野生稻 (OryzarufipogonGriff.)、药用野生稻 (O .officinalisWatt.etWatt)和疣粒野生稻 (O .meyerianaBaill.)。主要分布在热带亚热带的江河流域。多项研究表明 ,野生稻对多种害虫有较强的抗性 ,利用野生稻的...野生稻在中国有 3种 :普通野生稻 (OryzarufipogonGriff.)、药用野生稻 (O .officinalisWatt.etWatt)和疣粒野生稻 (O .meyerianaBaill.)。主要分布在热带亚热带的江河流域。多项研究表明 ,野生稻对多种害虫有较强的抗性 ,利用野生稻的优良特性采用杂交技术选育出新的抗虫品种 。展开更多
The rice disease resistance （R） gene Xa3/Xa26 （having also been named Xa3 and Xa26） against Xanthomonas oryzae pv. oryzae （Xoo）, which causes bacterial blight disease, belongs to a multiple gene family clustered...The rice disease resistance （R） gene Xa3/Xa26 （having also been named Xa3 and Xa26） against Xanthomonas oryzae pv. oryzae （Xoo）, which causes bacterial blight disease, belongs to a multiple gene family clustered in chromosome 11 and is from an AA genome rice cultivar （Oryza sativa L.）. This family encodes leucine-rich repeat （LRR） receptor kinase- type proteins, Here, we show that the orthologs （alleles） of Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3, from wild Oryza spe- cies O. officinalis （CC genome） and O. minuta （BBCC genome）, respectively, were also R genes against Xoo. Xa3/Xa26-2 and Xa3/Xa26-3 conferred resistance to 16 of the 18 Xoo strains examined. Comparative sequence analysis of the Xa3/Xa26 families in the two wild Oryza species showed that Xa3/Xa26-3 appeared to have originated from the CC genome of O. minuta. The predicted proteins encoded by Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3 share 91-99% sequence identity and 94-99% sequence similarity. Transgenic plants carrying a single copy of Xa3/Xa26, Xa3/Xa26-2, or Xa3PXa26-3, in the same genetic background, showed a similar resistance spectrum to a set of Xoo strains, although plants carrying Xa3/Xa26-2 or Xa3/Xa26-3 showed lower resistance levels than the plants carrying Xa3/Xa26. These results suggest that the Xa3/Xa26 locus predates the speciation of A and C genome, which is approximately 7.5 million years ago. Thus, the resistance spec- ificity of this locus has been conserved for a long time.展开更多
Oryza officinalis is one of the important wild species in the tertiary gene pool of Oryza sativa. It has a number of elite genes for rice breeding in resistance or tolerance. However, breeding barriers are so serious ...Oryza officinalis is one of the important wild species in the tertiary gene pool of Oryza sativa. It has a number of elite genes for rice breeding in resistance or tolerance. However, breeding barriers are so serious that the gene transfer is much difficult by sexual cross method between O. sativa and O. officinalis. Characteristics of the breeding barriers were systemically studied in this paper. When both the diploid （AA, 2n=2x=24） and autotetraploid （AAAA, 2n=4x=48） cultivated rice were crossed as maternal parents with O. officinalis （CC, 2n=2x=24）, none F1 hybrid seeds were obtained. The young hybrid ovaries aborted at 13-16 d after pollinations （DAP）. By rescuing hybrid embryos, in vitro F1 plantlets were obtained in 2x×2x combinations with the crossabilities lower than 0.5%. Lower rates of double-fertilization and abnormal development of hybrid embryo and endosperm were mainly observed in both combinations of 2x×2x and 4x×2x. Free endosperm nuclei in hybrid degenerated early at 1 DAP in a large scale. Almost no normal endosperm cells formed at 3 DAP. Development of a lot of embryos ceased at globularor pear-shaped stage as well as some degenerated gradually. The hybrid plantlets were both male and female sterility. Due to the abnormal development, a diversity of abnormal embryo sacs formed in hybrids, and hybrid pollen grains were typically abortive. It showed that conflicts of genome A and C in hybrid induced abnormal meioses of meiocytes.展开更多
Comparative analyses of genome structure and sequence of closely related species have yielded insights into the evolution and function of plant genomes. A total of 103,844 BAC end sequences delegated -73.8 Mb of O. of...Comparative analyses of genome structure and sequence of closely related species have yielded insights into the evolution and function of plant genomes. A total of 103,844 BAC end sequences delegated -73.8 Mb of O. officinalis that belongs to the CC genome type of the rice genus Oryza were obtained and compared with the genome sequences office cultivar, O. sativa ssp.japonica cv. Nipponbare. We found that more than 45% of O. officinalis genome consists of repeat sequences, which is higher than that of Nipponbare cultivar. To further investigate the evolutionary divergence of AA and CC genomes, two BAC-contigs of O. officinalis were compared with the collinear genomic regions of Nipponbare. Of 57 genes predicted in the AA genome orthologous regions, 39 had orthologs in the regions of the CC genome. Alignment of the orthologous regions indicated that the CC genome has undergone expansion in both genic and intergenic regions through primarily retroelement insertion. Particularly, the density of RNA transposable elements was 17.95% and 1.78% in O. officinalis and O. sativa, respectively. This explains why the orthologous region is about 100 kb longer in the CC genome in comparison to the AA genome.展开更多
As maternal parents, diploid （L202-2x） and autotetraploid （L202-4x） of Oryza sativa cv. L2O2 were crossed with O. officinalis. Embryo development and fertilization in these two crosses were comparatively studied. ...As maternal parents, diploid （L202-2x） and autotetraploid （L202-4x） of Oryza sativa cv. L2O2 were crossed with O. officinalis. Embryo development and fertilization in these two crosses were comparatively studied. There were no mature hybrid seeds obtained because all the hybridized spikelets died 30 days after pollination. The main reasons for no seed set were abnormal fertilization and development of the embryos and endosperms in the interspecific hybrids. There were doublefertilization, egg cell single-fertilization and non-fertilization in these crosses. Although 59.45% and 54.87% of hybrid embryos produced in the crosses of L202-2x/O. officinalis and L202-4x/O. officinalis, respectively, hybrid embryos ceased to develop or degenerated and plenty of free endosperm nuclei were in disaggregating state without developing cellular endosperms three days after pollination. Besides, some embryological differences in these two crosses were found, that is, the rate of double-fertilization and total rate of doubleand single-fertilization in L202-2x/O. officinalis were higher than those in L202-4x/O. officinalis. The embryo and endosperm of hybrids developed more slowly, and embryos and free endosperm nuclei were more severely degenerated in L202-4x/O. officinalis than in L202-2x/O. officinalis. Five days after pollination, a few of embryos in L202-2x/O. officinalis developed into pear-shaped ones, however, embryos in L202-4x/O. officinalis were all degenerated. Therefore, it is more difficult to obtain interspecific hybrids by wide crosses between autotetraploid of O. sativa and O. officinalis.展开更多
基金This work was supported by grants from the National Program on the Development of Basic Research in China，the National Natural Science Foundation of China
文摘The rice disease resistance （R） gene Xa3/Xa26 （having also been named Xa3 and Xa26） against Xanthomonas oryzae pv. oryzae （Xoo）, which causes bacterial blight disease, belongs to a multiple gene family clustered in chromosome 11 and is from an AA genome rice cultivar （Oryza sativa L.）. This family encodes leucine-rich repeat （LRR） receptor kinase- type proteins, Here, we show that the orthologs （alleles） of Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3, from wild Oryza spe- cies O. officinalis （CC genome） and O. minuta （BBCC genome）, respectively, were also R genes against Xoo. Xa3/Xa26-2 and Xa3/Xa26-3 conferred resistance to 16 of the 18 Xoo strains examined. Comparative sequence analysis of the Xa3/Xa26 families in the two wild Oryza species showed that Xa3/Xa26-3 appeared to have originated from the CC genome of O. minuta. The predicted proteins encoded by Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3 share 91-99% sequence identity and 94-99% sequence similarity. Transgenic plants carrying a single copy of Xa3/Xa26, Xa3/Xa26-2, or Xa3PXa26-3, in the same genetic background, showed a similar resistance spectrum to a set of Xoo strains, although plants carrying Xa3/Xa26-2 or Xa3/Xa26-3 showed lower resistance levels than the plants carrying Xa3/Xa26. These results suggest that the Xa3/Xa26 locus predates the speciation of A and C genome, which is approximately 7.5 million years ago. Thus, the resistance spec- ificity of this locus has been conserved for a long time.
基金supported by the Key Project of the Natural Science Foundation of Guangdong Province, China (021037)the Natural Science Foundation of Guangdong Province, China (9151064201000067)+1 种基金the Special Fund for Agro-Scientific Research in the Public Interest, China (201003021)the Joint Fund of the National Natural Science Foundation of China-Guangdong Province (U0631003)
文摘Oryza officinalis is one of the important wild species in the tertiary gene pool of Oryza sativa. It has a number of elite genes for rice breeding in resistance or tolerance. However, breeding barriers are so serious that the gene transfer is much difficult by sexual cross method between O. sativa and O. officinalis. Characteristics of the breeding barriers were systemically studied in this paper. When both the diploid （AA, 2n=2x=24） and autotetraploid （AAAA, 2n=4x=48） cultivated rice were crossed as maternal parents with O. officinalis （CC, 2n=2x=24）, none F1 hybrid seeds were obtained. The young hybrid ovaries aborted at 13-16 d after pollinations （DAP）. By rescuing hybrid embryos, in vitro F1 plantlets were obtained in 2x×2x combinations with the crossabilities lower than 0.5%. Lower rates of double-fertilization and abnormal development of hybrid embryo and endosperm were mainly observed in both combinations of 2x×2x and 4x×2x. Free endosperm nuclei in hybrid degenerated early at 1 DAP in a large scale. Almost no normal endosperm cells formed at 3 DAP. Development of a lot of embryos ceased at globularor pear-shaped stage as well as some degenerated gradually. The hybrid plantlets were both male and female sterility. Due to the abnormal development, a diversity of abnormal embryo sacs formed in hybrids, and hybrid pollen grains were typically abortive. It showed that conflicts of genome A and C in hybrid induced abnormal meioses of meiocytes.
基金supported by the grants from the Ministry of Science and Technology of China (the China Rice Functional Genomics Programs, No. 2006AA10A102 and 2005CB120805)the Chinese Academy of Sciences (No. KSCX2-YWN-024)the Shanghai Municipal Commission of Science and Technology
文摘Comparative analyses of genome structure and sequence of closely related species have yielded insights into the evolution and function of plant genomes. A total of 103,844 BAC end sequences delegated -73.8 Mb of O. officinalis that belongs to the CC genome type of the rice genus Oryza were obtained and compared with the genome sequences office cultivar, O. sativa ssp.japonica cv. Nipponbare. We found that more than 45% of O. officinalis genome consists of repeat sequences, which is higher than that of Nipponbare cultivar. To further investigate the evolutionary divergence of AA and CC genomes, two BAC-contigs of O. officinalis were compared with the collinear genomic regions of Nipponbare. Of 57 genes predicted in the AA genome orthologous regions, 39 had orthologs in the regions of the CC genome. Alignment of the orthologous regions indicated that the CC genome has undergone expansion in both genic and intergenic regions through primarily retroelement insertion. Particularly, the density of RNA transposable elements was 17.95% and 1.78% in O. officinalis and O. sativa, respectively. This explains why the orthologous region is about 100 kb longer in the CC genome in comparison to the AA genome.
基金supported by the Guangdong Provincial Key Project of Natural Science Foundation, China (Grant No. 021037)Guangdong Province Natural Science Foundation, China (Grant No. 7301008)+1 种基金South China Agricultural University President Foundation, China (Grant No. 2007K036)The Confocal Laser Scanning Microscope was provided by the Testing Center of South China Agricultural University, Guangzhou, China
文摘As maternal parents, diploid （L202-2x） and autotetraploid （L202-4x） of Oryza sativa cv. L2O2 were crossed with O. officinalis. Embryo development and fertilization in these two crosses were comparatively studied. There were no mature hybrid seeds obtained because all the hybridized spikelets died 30 days after pollination. The main reasons for no seed set were abnormal fertilization and development of the embryos and endosperms in the interspecific hybrids. There were doublefertilization, egg cell single-fertilization and non-fertilization in these crosses. Although 59.45% and 54.87% of hybrid embryos produced in the crosses of L202-2x/O. officinalis and L202-4x/O. officinalis, respectively, hybrid embryos ceased to develop or degenerated and plenty of free endosperm nuclei were in disaggregating state without developing cellular endosperms three days after pollination. Besides, some embryological differences in these two crosses were found, that is, the rate of double-fertilization and total rate of doubleand single-fertilization in L202-2x/O. officinalis were higher than those in L202-4x/O. officinalis. The embryo and endosperm of hybrids developed more slowly, and embryos and free endosperm nuclei were more severely degenerated in L202-4x/O. officinalis than in L202-2x/O. officinalis. Five days after pollination, a few of embryos in L202-2x/O. officinalis developed into pear-shaped ones, however, embryos in L202-4x/O. officinalis were all degenerated. Therefore, it is more difficult to obtain interspecific hybrids by wide crosses between autotetraploid of O. sativa and O. officinalis.
