ESCRT components ISTL1 andLIP5 are required for tapetal function and pollen viability
ESCRT components ISTL1 andLIP5 are required for tapetal function and pollen viability
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DOI：
10.1093/plcell/koab132
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发表时间：
2021-05-10
期刊：
影响因子：
11.6
通讯作者：
Otegui, Marisa S.
中科院分区：
文献类型：
--
作者：
Goodman, Kaija;Paez-Valencia, Julio;Otegui, Marisa S.
花粉壁组装对花粉发育和植物育性至关重要。持久的生物聚合物孢粉素和tryphine外壳的成分通过周围绒毡层细胞高度协调的分泌活性传递给发育中的花粉粒。然而，膜运输在这一过程中的作用在很大程度上是未知的。在这项研究中，我们使用拟南芥来表征两种晚作用的内体转运所需分选复合物（ESCRT）成分ISTL1和LIP5在绒毡体功能中的作用。缺乏ISTL1和LIP5的植物形成的花粉具有异常的外叶模式，导致花粉部分致死。我们发现ISTL1和LIP5是游离小孢子期绒毡层细胞质膜胞吐和分泌蛋白所必需的，有助于花粉壁发育和tryphine沉积。尽管ESCRT机制因其在内体运输中的作用而闻名，但ISTL1和LIP5在胞吐中的功能并不是典型的ESCRT功能。ist1 lip5双突变体还显示绒毡层细胞和发育中的花粉粒中多泡内体的腔内囊泡连接减少，以及早期内体/反式高尔基网络的形态缺陷，这表明ESCRT晚期成分在早期内体途径和胞外作用中起作用。
Pollen wall assembly is crucial for pollen development and plant fertility. The durable biopolymer sporopollenin and the constituents of the tryphine coat are delivered to developing pollen grains by the highly coordinated secretory activity of the surrounding tapetal cells. The role of membrane trafficking in this process, however, is largely unknown. In this study, we used Arabidopsis thaliana to characterize the role of two late-acting endosomal sorting complex required for transport (ESCRT) components, ISTL1 and LIP5, in tapetal function. Plants lacking ISTL1 and LIP5 form pollen with aberrant exine patterns, leading to partial pollen lethality. We found that ISTL1 and LIP5 are required for exocytosis of plasma membrane and secreted proteins in the tapetal cells at the free microspore stage, contributing to pollen wall development and tryphine deposition. Whereas the ESCRT machinery is well known for its role in endosomal trafficking, the function of ISTL1 and LIP5 in exocytosis is not a typical ESCRT function. The istl1 lip5 double mutants also show reduced intralumenal vesicle concatenation in multivesicular endosomes in both tapetal cells and developing pollen grains as well as morphological defects in early endosomes/trans-Golgi networks, suggesting that late ESCRT components function in the early endosomal pathway and exocytosis.