Li Qi, Deng Zhuyun, Gong Chunyan, Wang Tai
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of SciencesBeijing, China; University of Chinese Academy of SciencesBeijing, China.
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences Beijing, China.
Front Plant Sci. 2016 Apr 26;7:532. doi: 10.3389/fpls.2016.00532. eCollection 2016.
Microgametogenesis is the post-meiotic pollen developmental phase when unicellular microspores develop into mature tricellular pollen. In rice, microgametogenesis can influence grain yields to a great degree because pollen abortion occurs more easily during microgametogenesis than during other stages of pollen development. However, our knowledge of the genes involved in microgametogenesis in rice remains limited. Due to the dependence of pollen development on the regulatory mechanisms of protein expression, we identified the encoding gene of the eukaryotic translation initiation factor 3, subunit f in Oryza sativa (OseIF3f). Immunoprecipitation combined with mass spectrometry confirmed that OseIF3f was a subunit of rice eIF3, which consisted of at least 12 subunits including eIF3a, eIF3b, eIF3c, eIF3d, eIF3e, eIF3f, eIF3g, eIF3h, eIF3i, eIF3k, eIF3l, and eIF3m. OseIF3f showed high mRNA levels in immature florets and is highly abundant in developing anthers. Subcellular localization analysis showed that OseIF3f was localized to the cytosol and the endoplasmic reticulum in rice root cells. We further analyzed the biological function of OseIF3f using the double-stranded RNA-mediated interference (RNAi) approach. The OseIF3f-RNAi lines grew normally at the vegetative stage but displayed a large reduction in seed production and pollen viability, which is associated with the down-regulation of OseIF3f. Further cytological observations of pollen development revealed that the OseIF3f-RNAi lines showed no obvious abnormalities at the male meiotic stage and the unicellular microspore stage. However, compared to the wild-type, OseIF3f-RNAi lines contained a higher percentage of arrested unicellular pollen at the bicellular stage and a higher percentage of arrested unicellular and bicellular pollen, and aborted pollen at the tricellular stage. These results indicate that OseIF3f plays a role in microgametogenesis.
小孢子发生是减数分裂后的花粉发育阶段，在此阶段单细胞小孢子发育成成熟的三细胞花粉。在水稻中，小孢子发生对籽粒产量有很大影响，因为与花粉发育的其他阶段相比，小孢子发生过程中更容易发生花粉败育。然而，我们对水稻小孢子发生相关基因的了解仍然有限。由于花粉发育依赖于蛋白质表达的调控机制，我们鉴定了水稻（Oryza sativa）中真核翻译起始因子3亚基f的编码基因（OseIF3f）。免疫沉淀结合质谱分析证实，OseIF3f是水稻eIF3的一个亚基，水稻eIF3至少由12个亚基组成，包括eIF3a、eIF3b、eIF3c、eIF3d、eIF3e、eIF3f、eIF3g、eIF3h、eIF3i、eIF3k、eIF3l和eIF3m。OseIF3f在未成熟小花中显示出高mRNA水平，并且在发育中的花药中高度丰富。亚细胞定位分析表明，OseIF3f定位于水稻根细胞的细胞质和内质网中。我们使用双链RNA介导的干扰（RNAi）方法进一步分析了OseIF3f的生物学功能。OseIF3f-RNAi株系在营养生长阶段生长正常，但种子产量和花粉活力大幅降低，这与OseIF3f的下调有关。对花粉发育的进一步细胞学观察表明，OseIF3f-RNAi株系在雄配子减数分裂阶段和单细胞小孢子阶段没有明显异常。然而，与野生型相比，OseIF3f-RNAi株系在二细胞阶段含有更高比例的停滞单细胞花粉，在三细胞阶段含有更高比例的停滞单细胞和二细胞花粉以及败育花粉。这些结果表明，OseIF3f在小孢子发生中起作用。
