Canonical Rab5 GTPases are essential for pollen tube growth through style in Arabidopsis.
Canonical Rab5 GTPases are essential for pollen tube growth through style in Arabidopsis.
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DOI：
10.1111/nph.19059
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
Guangyu Hao;Lu Li;Xin-Ying Zhao;Jun Ying;Miao Zhang;Xue-Chun Cui;Tiantian Sun;En Li;
中科院分区：
文献类型：
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作者：
Guangyu Hao;Lu Li;Xin-Ying Zhao;Jun Ying;Miao Zhang;Xue-Chun Cui;Tiantian Sun;En Li;
花粉管具动态管状液泡。AP-3（一种液泡运输途径的调节因子）的功能丧失会减少花粉管的生长。然而，典型的Rab 5 GTP酶的作用是负责其他两个液泡运输途径在拟南芥花粉管是模糊的。通过使用基因组编辑，共聚焦显微镜，花粉管生长测定和透射电子显微镜，我们证明了在拟南芥，RHA 1和ARA 7的典型Rab 5s的功能丧失，导致花粉管通过花柱生长失败，从而损害雄性传递。典型Rab 5s的功能丧失损害液泡膜蛋白的液泡运输、液泡生物发生和膨压调节。然而，rha 1; ara 7的花粉管生长通过微流控测定狭窄通道的野生型。我们证明，典型Rab 5s的功能丧失会影响质膜（PM）的内吞和分泌贩运，而PM相关ATP酶的靶向作用基本上不受影响。尽管如此，rha 1; ara 7花粉管含有降低的胞质pH和破坏的肌动蛋白微丝，与空泡ATP酶（VHA）的错误靶向相关。这些结果表明，液泡在维持细胞质质子稳态和花粉管穿透花柱生长中起着关键作用。
Pollen tubes have dynamic tubular vacuoles. Functional loss of AP-3, a regulator of one vacuolar trafficking route, reduces pollen tube growth. However, the role of canonical Rab5 GTPases that are responsible for two other vacuolar trafficking routes in Arabidopsis pollen tubes is obscure. By using genomic editing, confocal microscopy, pollen tube growth assays, and transmission electron microscopy, we demonstrate that functional loss of canonical Rab5s in Arabidopsis, RHA1 and ARA7, causes the failure of pollen tubes to grow through style and thus impairs male transmission. Functional loss of canonical Rab5s compromises vacuolar trafficking of tonoplast proteins, vacuolar biogenesis, and turgor regulation. However, rha1;ara7 pollen tubes are comparable to those of wild-type in growing through narrow passages by microfluidic assays. We demonstrate that functional loss of canonical Rab5s compromises endocytic and secretory trafficking at the plasma membrane (PM), whereas the targeting of PM-associated ATPases is largely unaffected. Despite that, rha1;ara7 pollen tubes contain a reduced cytosolic pH and disrupted actin microfilaments, correlating with the mis-targeting of vacuolar ATPases (VHA). These results imply a key role of vacuoles in maintaining cytoplasmic proton homeostasis and in pollen tube penetrative growth through style.