棉花细胞核雄性不育两用系差异表达基因分析

应用cDNA-AFLP对棉花ms5ms6双隐性核雄性不育两用系的不育株和可育株花粉发育的3个时期—造孢细胞时期、花粉母细胞时期和花粉粒时期进行对比分析,共得到17个差异表达片段,它们分别属于11种表达模式,其中14个片段可以在NCBI数据库中找到同源序列,功能分析表明这些片段所编码的基因可能参与了信号转导、转录、能量代谢、细胞壁发育等相关过程。Northern杂交结果证明检测片段的表达模式与cDNA-AFLP结果吻合。同时还在可育花药中发现了与玉米T型细胞质雄性不育恢复因子RF2基因高度同源的育性恢复因子类基因。     

Identification of a single nucleotide deletion causing frameshift mutation in OsDFR2A in a genic male sterile mutant of rice and its possible application to F1 hybrid breeding

Stable genic male sterility (GMS), which is not influenced by environmental factors, has not been used for F₁ hybrid seed production because male-sterile inbred lines cannot be developed and male-sterile plants must be selected from segregating populations every time. However, the stability of male sterility may provide a reliable system for F₁ seed production without contamination of selfed seeds. A genic male-sterile mutant in rice (Oryza sativa L.), C204, which was selected from progeny of the cultivar ‘Koshihikari’ irradiated by gamma rays, has shorter and whiter anthers than those of ‘Koshihikari’ and has no pollen grains. Segregation analysis of C204 suggested the male sterility of this mutant to be controlled by a recessive allele of a single gene. Linkage analysis of a mutated gene responsible for the male sterility revealed the gene to be in a region of ca. 75 kb on the long arm of chromosome 9. The nine genes predicted in the 75-kb region were sequenced, and compared with the published Nipponbare genome sequences. A single-base deletion was found in the first exon of a C204 allele of Os09g0493500, which encodes an NAD-dependent epimerase/dehydratase family protein, resulting in a frameshift causing a premature stop codon. A dot-blot single nucleotide polymorphism marker for detection of the single-base deletion in Os09g0493500 was developed. We herein propose an F₁ hybrid seed production system using stable GMS with a simple selection method of GMS plants.     

大豆细胞核雄性不育基因研究进展

雄性不育是指植物雄蕊不能正常生长和产生有活力花粉粒的现象。利用雄性不育突变体开展杂交育种工作,是快速提高作物单产的有效途径。目前,通过杂种制种已大幅度提高了水稻(Oryza sativa L.)、玉米(Zea mays L.)和小麦(Triticum aestivum L.)等作物的产量。大豆(Glycinemax(L.)Merr.)作为自花授粉作物,通过人工去雄生产杂交种子不仅困难而且经济上不可行。由于适用于杂交种生产的不育系资源短缺,目前大豆还没有实现大规模杂种优势利用。因此,快速实现大豆杂种优势利用迫切需要鉴定稳定的大豆雄性不育系统。本文总结了大豆细胞核雄性不育(genic male sterility, GMS)突变体及不育基因研究进展,同时结合拟南芥(Arabidopsis thaliana)、水稻和玉米中已报道的细胞核雄性不育基因,从反向遗传学的角度,为大豆核雄性不育基因的鉴定提供依据。     

Analysis of Cytoplasmic Effects and Fine-Mapping of a Genic Male Sterile Line in Rice

Cytoplasm has substantial genetic effects on progeny and is important for yield improvement in rice breeding. Studies on the cytoplasmic effects of cytoplasmic male sterility (CMS) show that most types of CMS have negative effects on yield-related traits and that these negative effects vary among CMS. Some types of genic male sterility (GMS), including photo-thermo sensitive male sterility (PTMS), have been widely used in rice breeding, but the cytoplasmic effects of GMS remain unknown. Here, we identified a GMS mutant line, h₂s, which exhibited small, white anthers and failed to produce mature pollen. Unlike CMS, the h₂s had significant positive cytoplasmic effects on the seed set rate, weight per panicle, yield, and general combining ability (GCA) for plant height, seed set rate, weight per panicle, and yield. These effects indicated that h₂s cytoplasm may show promise for the improvement of rice yield. Genetic analysis suggested that the phenotype of h₂s was controlled by a single recessive locus. We mapped h₂s to a 152 kb region on chromosome 6, where 22 candidate genes were predicted. None of the 22 genes had previously been reported to be responsible for the phenotypes of h₂s. Sequencing analysis showed a 12 bp deletion in the sixth exon of Loc_Os06g40550 in h₂s in comparison to wild type, suggesting that Loc_Os06g40550 is the best candidate gene. These results lay a strong foundation for cloning of the H₂S gene to elucidate the molecular mechanism of male reproduction.     

A tapetal ablation transgene induces stable male sterility and slows field growth in Populus

The field performance of genetic containment technologies–considered important for certain uses of transgenic trees in forestry–is poorly known. We tested the efficiency of a barnase gene driven by the TA29 tapetum-dominant promoter for influencing growth rate and inducing male sterility in a field trial of transgenic hybrid poplar (Populus tremula?×?Populus tremuloides). When the growth of 18 transgenic insertion events with the sterility transgene were compared to non-transgenic controls after two growing seasons, they grew 40 % more slowly in stem volume, and all but one transgenic event grew significantly more slowly than the control. In contrast, when we compared the growth of transgenic trees containing four kinds of β-glucuronidase (GUS) reporter gene constructs to non-transgenic trees—all of which had been produced using the same transformation method and poplar clone and grown at the same field site—there were no statistically significant differences in growth after three growing seasons. In 2 years where gross pollen release from catkins was monitored and found to be abundant in the control, no pollen was visible in the transgenic trees; microscopy suggested the cause was tapetal collapse and revealed the presence of a very few normal-sized pollen grains of unknown viability. In two additional years when viable, well-formed pollen was microscopically documented in controls, and no pollen could be observed in any transgenic trees. We conclude that this construct resulted in robust and possibly complete male sterility that was stable over 4 years in the field.     

Allelic relationship of four male sterility genes and nucleo-cytoplasmic interactions in the expression of male sterility in pearl millet,Pennisetum americanum (L.) leeke

Summary Male sterility genes isolated in four inbred lines of pearl millet were found allelic. The differences between male fertile and male sterile phenotypes is mainly due to a single gene. Presence of a dominant gene (Ms) resulted in male fertility and double recessiveness (ms ms) in male sterility. However, genic male sterility (GMS) in Pennisetum is not a simply inherited case of monogenic recessive condition but is influenced by cytoplasmic and several nuclear factors. In a male sterile, the stage at which the male sterility gene is expressed during the development of the male gametophyte resulting in breakdown of the cells is influenced by cytoplasmic and other nuclear factors. Two types of cytoplasm, C-1 and C-2, are recognized. Presence of any two recessive male sterility alleles in C-1 led to breakdown of male development before differentiation of an archesporium in the anther (Arc-type); in C-2 cytoplasm, degeneration started during meiosis with fusion of meiocytes and syncyte formation (Syn-type), or at post-meiotic stages terminating in abortion of microspores before first pollen mitosis (PGM type). The triggering of activity of recessive male sterility genes in C-2 cytoplasm appeared to be regulated by two nuclear factors, R ₁ and R ₂ with duplicate gene action. Recessiveness for both the R factors in C-2 cytoplasm resulted in PGM-type expression. The action of R ₁ and R ₂ is specific to C-2 cytoplasm. Mutation of cytoplasm from C-1 to C-2 and C-2 to C-1 was observed.