Pollen tube germination and elongation are important processes for double fertilization in flowering plants. However, little is known about the regulatory mechanism of pollen germination and tube growth in rice. Here, we reported that OsAPT1, a pollen-high expression gene and encoding a putative APT1 protein in Oryza sativa, regulating pollen tube germination and elongation in rice. Real-time quantitative PCR (qRT-PCR) and in situ hybridization analysis showed high expression level of OsAPT1 at late stage of microsporogenesis including late uninucleate stage, binucleate pollen stage, and mature pollen grains. OsAPT1 RNA interference (OsAPT1-RNAi) lines showed that the pollen tube germination and elongation rate were decreased. Compared with wild type (WT), the integrity and assembly of actin microfilaments were abnormal in hydrated pollen grains of OsAPT1-RNAi plants, and the fluorescence signals of actin microfilaments were altered in the pollen tube of OsAPT1-RNAi plants. GO analysis of the co-expressing genes of OsAPT1 showed that the GO terms such as pollination, cell growth, cellular cytoskeleton organization, and motor activity were enriched. In addition, the qRT-PCR results showed variations in the expression of some genes related to pollen tube growth. Overall, our results indicated that OsAPT1 is required for pollen tube germination and elongation in rice.

中文翻译：

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OsAPT1 是一种花粉优先表达的基因，是水稻花粉管萌发和伸长所必需的

花粉管萌发和伸长是开花植物双受精的重要过程。然而，人们对水稻花粉萌发和管状生长的调控机制知之甚少。在这里，我们报道了 OsAPT1，一种花粉高表达基因，在水稻中编码假定的 APT1 蛋白，调节水稻花粉管的萌发和伸长。实时定量 PCR (qRT-PCR) 和原位杂交分析表明 OsAPT1 在小孢子发育后期高水平表达，包括单核晚期、双核花粉期和成熟花粉粒。OsAPT1 RNA干扰（OsAPT1-RNAi）系显示花粉管萌发率和伸长率下降。与野生型（WT）相比，OsAPT1-RNAi植物水合花粉粒中肌动蛋白微丝的完整性和组装异常，OsAPT1-RNAi植物花粉管中肌动蛋白微丝的荧光信号发生改变。OsAPT1共表达基因的GO分析表明，授粉、细胞生长、细胞骨架组织和运动活动等GO术语得到了丰富。此外，qRT-PCR 结果显示一些与花粉管生长相关的基因表达存在差异。总的来说，我们的结果表明 OsAPT1 是水稻花粉管萌发和伸长所必需的。细胞骨架组织和运动活动得到丰富。此外，qRT-PCR 结果显示一些与花粉管生长相关的基因表达存在差异。总的来说，我们的结果表明 OsAPT1 是水稻花粉管萌发和伸长所必需的。细胞骨架组织和运动活动得到丰富。此外，qRT-PCR 结果显示一些与花粉管生长相关的基因表达存在差异。总的来说，我们的结果表明 OsAPT1 是水稻花粉管萌发和伸长所必需的。