水稻花器官发育基因DPS2的鉴定和精细定位

【目的】鉴定和克隆花器官发育相关基因,为进一步研究水稻花发育的分子机制奠定基础。【方法】在大田常规种植条件下比较了突变体dps2 (Defective pistil and stamens 2)和野生型春江06的主要农艺性状及花器官形态特征差异;扫描电镜及石蜡切片观察花药结构并用染色法观察花粉和胚囊的育性;利用图位克隆方法进行基因精细定位;qRT-PCR分析了花发育相关基因在野生型和突变体中的表达水平。【结果】dps2突变体抽穗期变长,不能正常扬花,雄蕊和雌蕊皱缩且花药和柱头数目增多;进一步研究发现,dps2突变体花药腔室塌陷,内无可见小孢子,即使部分花药形成腔室,花粉粒也无淀粉积累呈干瘪状。此外,突变体胚囊育性也受到影响;遗传分析表明该突变性状受一对隐性核基因控制,该基因位于第4染色体短臂上91.2 kb的区间内,区间内未见花器官发育相关基因的报道。qRT-PCR检测发现,水稻ABCDE模型中的B类、C类和E类基因的表达在突变体中显著升高。【结论】dps2突变体的雄蕊及雌蕊均发育异常,最终导致完全不育,推测DPS2可能在水稻第3轮雄蕊发育和第4轮雌蕊发育调控中发挥重要作用。

Identification and Fine Mapping of Defective Pistil and Stamens 2 in Rice

【Objective】 Identification and cloning of organ development-related genes can lay a foundation for further study on the molecular mechanism of rice flower development.【Method】The main agronomic traits and morphological characteristics of floral organs of wild type Chunjing 06 and dps2 (Defective pistil and stamens 2) mutant were compared under conventional planting conditions in field. The structure of anther was observed under a scanning electronic microscope by paraffin sectioning, and the fertility of pollen and embryo sac was observed by staining. Map-based cloning was used for the gene localization. Quantitative RT-PCR was performed to analyze the relative expression of genes associated with flower development in the wild type and the mutant. 【Result】 Longer heading date, abnormal flowering, shriveled pistils and stamens, increased anthers and stigmas were presented in the dps2 mutant. Further study revealed that the anther chamber of the dps2 mutant collapsed, and no microspores were found. Though some anthers had their chambers, there was no starch accumulation in the shriveled pollen grains, and the embryo sac fertility of dps2 was also affected. Genetic analysis indicated that the mutant’s phenotype of dps2 was controlled by a single recessive nuclear gene. The DPS2 gene was mapped to a 91.2 kb region on the short arm of chromosome 4. The expression levels of some genes associated with class B, C and E genes in ABCDE model were up-regulated in the mutant. 【Conclusion】 The abnormal development of stamens and pistils attributed to the complete infertility of the dps2 mutant, which indicated that DPS2 play an important role in third round of stamen development and the fourth round of pistil development.