Pollen tube (PT) elongation is important for double fertilization in angiosperms and affects the seed-setting rate and, therefore, crop productivity. Compared to Arabidopsis (Arabidopsis thaliana L.), information on PT elongation in rice (Oryza sativa L.) is limited by the difficulty in obtaining homozygous mutants. In a screen of T-DNA insertional mutants, we identified a mutant in the Tethering protein of actomyosin transport in pollen tube elongation (TAPE) gene with an unusual segregation ratio by genotyping analysis. A CRISPR/Cas9 knockout mutant of TAPE that produced a short PT was sterile, and TAPE was expressed specifically in pollen grains. TAPE is a homolog of a myosin XI adaptor in Arabidopsis with three tetratricopeptide repeat and Phox and Bem1 protein domains. TAPE showed latrunculin B-sensitive, actin-dependent localization to the endoplasmic reticulum. Yeast two-hybrid screening and transcriptome analysis revealed that TAPE interacted with pollen-specific LIM protein 2b and elongation factor 1-alpha. Loss of TAPE affected transcription of 1,259 genes, especially genes related to cell organization, which were downregulated. In summary, TAPE encodes a myosin XI adaptor essential for rice PT elongation.

中文翻译：

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肌球蛋白 XI 适配器 TAPE 对水稻花粉管的伸长至关重要。

花粉管 (PT) 伸长对于被子植物的双重受精很重要，并影响结实率，从而影响作物生产力。与拟南芥 (Arabidopsis thaliana L.) 相比，水稻 (Oryza sativa L.) 中 PT 延伸的信息受到难以获得纯合突变体的限制。在 T-DNA 插入突变体的筛选中，我们通过基因分型分析鉴定了花粉管伸长 (TAPE) 基因中肌动球蛋白转运的束缚蛋白中的突变体，该突变体具有不寻常的分离率。产生短 PT 的 TAPE 的 CRISPR/Cas9 敲除突变体是不育的，并且 TAPE 在花粉粒中特异性表达。TAPE 是拟南芥中肌球蛋白 XI 适配器的同源物，具有三个四肽重复序列以及 Phox 和 Bem1 蛋白结构域。TAPE 显示 latrunculin B 敏感，肌动蛋白依赖性定位到内质网。酵母双杂交筛选和转录组分析显示，TAPE 与花粉特异性 LIM 蛋白 2b 和延伸因子 1-α 相互作用。TAPE 的缺失影响了 1,259 个基因的转录，尤其是与细胞组织相关的基因，这些基因被下调。总之，TAPE 编码了一个对水稻 PT 延伸至关重要的肌球蛋白 XI 适配器。