Graduate School of Green-Bio Science & Crop Biotech Institute, Kyung Hee University, Yongin, 17104, Republic of Korea.
Department of Plant Bioscience, Pusan National University, Miryang, 50463, Republic of Korea.
Plant Physiol. 2022 Aug 29;190(1):562-575. doi: 10.1093/plphys/kiac299.
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.
花粉管（PT）的伸长对于被子植物的双受精很重要，并且会影响结实率和作物的生产力。与拟南芥（Arabidopsis thaliana L.）相比，由于难以获得纯合突变体，因此有关水稻（Oryza sativa L.）PT 伸长的信息有限。在 T-DNA 插入突变体的筛选中，我们通过基因型分析鉴定了一个在花粉管伸长中的肌球蛋白运输固定蛋白（Tethering protein of actomyosin transport in pollen tube elongation，TAPE）基因中的突变体，该突变体具有不寻常的分离比。TAPE 的 CRISPR/Cas9 敲除突变体产生的短花粉管不育，并且 TAPE 特异性在花粉粒中表达。TAPE 是拟南芥肌球蛋白 XI 衔接蛋白的同源物，具有三个四肽重复和 Phox 和 Bem1 蛋白结构域。TAPE 显示出 latrunculin B 敏感的、肌动蛋白依赖性的内质网定位。酵母双杂交筛选和转录组分析表明，TAPE 与花粉特异性 LIM 蛋白 2b 和延伸因子 1-α相互作用。TAPE 的缺失会影响 1259 个基因的转录，特别是与细胞组织相关的基因，这些基因被下调。总之，TAPE 编码了一个肌球蛋白 XI 衔接蛋白，对水稻花粉管伸长是必需的。
