Oryza sativa and O. latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, interspecific hybrids of these species were obtained using the embryo rescue technique. Hybrid panicle traits, such as long awns, small grain, exoteric large purple stigma, grain shattering and dispersed panicles, resemble that of the paternal parent, O. latifolia, whereas there is obvious heterosis in such respects as plant height, tillering ability and vegetative vigor. Chromosome pairing and the genomic components of the hybrid were subsequently investigated using genomic in situ hybridization (GISH) and fluorescent in situ hybridization (FISH) analysis. Based on the mitotic metaphase chromosome numbers of the root tips investigated, the hybrid is a triploid with 36 chromosomes. The genomic constitution of the hybrid is ACD. In the meiotic metaphase I of the hybrid pollen mother cell, poor chro- mosome pairing was identified and most of the chromosomes were univalent, which resulted in com- plete male sterility in the hybrid.
YI ChuanDeng TANG ShuZhu ZHOU Yong LIANG GuoHua GONG ZhiYun GU MingHong
From the progenies of a telotrisomic of chromosome 9 short arm of an indica rice variety, Zhongxian 3037, a phenotypical variant was selected. The variant plant had rolled leaves, dispersed plant type, as well as a low seed-setting rate. Cytological and molecular cytological investigations revealed two extra chromosomes, which were the shortest in somatic cells of the variant. Fluorescent in situ hybridization (FISH) analysis using a rice centromere specific DNA (RCS2) and a DNA sequence specific for chromosome 9 on premetaphase and pachytene chromosomes showed that these two chromosomes were the short arms of chromosome 9. That is to say, the variant was a telotetrasomic of chromosome 9. Among the 25 pachytene cells, the two telosomic chromosomes paired each other to form a bivalent and didn't pair with other normal chromosome 9 as multivalents in 96% cells. However, the bivalent was easy to disassociate in advance.
GONG Zhi-yun GAO Qing-song Yu Heng-xiu YI Chuan-deng Gu Ming-hong
将亚洲栽培稻(Oryza sativa,染色体组型为AA)与宽叶野生稻(O. latifolia,染色体组型为CCDD)进行杂交,结合胚拯救手段,获得了这两个种的种间杂交种.杂种F1在株高、分蘖力、生长繁茂性等方面表现明显的杂种优势,穗部性状明显偏向于父本宽叶野生稻的特征,表现为长芒、小粒、大而外露的紫色柱头极易落粒.根尖细胞染色体鉴定证明杂种染色体数为2n=36.进一步利用基因组原位杂交(genomic in situ hybridization,GISH)和荧光原位杂交(fluorescent in situ hybridization,FISH)技术,鉴定了杂种F1的染色体组成及其在减数分裂中的配对行为.结果表明,杂种染色体的组成为ACD,在减数分裂中,绝大部分染色体以单价体形式存在,很少有配对现象发生,因而杂种表现完全雄性不育。
The centromere of eukaryotic chromosomes is the crucial locus responsible for sister chromatid cohesion and for correct segregation of chromosomes to daughter cells during cell division. In the structural genomics era, centromeres represent the last frontiers of higher eukaryotic genomes because of their densely methylated, highly repetitive and, heterochromatic DNA (Hall et al., 2004). Although these functions are conserved among all eukaryotes, centromeric DNA sequences are evolving rapidly (Jiang et al., 2003).
依据水稻端粒酶基因的相关生物学信息,构建了含有水稻端粒酶序列RNA干扰结构的植物表达载体pC am 23A-1-2,并利用农杆菌介导法将目的基因导入到粳稻品种日本晴中,获得了78个独立转化子,共165棵转基因植株。通过PCR和Southern杂交分析,证明RNA干扰结构已整合进水稻基因组中;应用染色体末端限制性片段分析法,显示在转基因水稻中端粒DNA序列长度有逐代缩短的趋势,初步证明这些转基因水稻中端粒酶亚基已失活,但是T0和T1代转基因水稻植株的主要农艺性状没有发生明显变化。