Zhu Rui-Min, Li Min, Li Shan-Wei, Liang Xin, Li Sha, Zhang Yan
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin, China.
Plant J. 2021 Oct;108(1):268-280. doi: 10.1111/tpj.15440. Epub 2021 Aug 20.
Propagation of angiosperms mostly relies on sexual reproduction, in which gametophytic development is a pre-requisite. Male gametophytic development requires both gametophytic and sporophytic factors, most importantly early secretion and late programmed cell death of the tapetum. In addition to transcriptional factors, proteins at endomembrane compartments, such as receptor-like kinases and vacuolar proteases, control tapetal function. The cellular machinery that regulates their distribution is beginning to be revealed. We report here that ADP-RIBOSYLATION FACTOR-A1s (ArfA1s) are critical for tapetum-controlled pollen development. All six ArfA1s in the Arabidopsis genome are expressed during anther development, among which ArfA1b is specific to the tapetum and developing microspores. Although the ArfA1b loss-of-function mutant showed no pollen defects, probably due to redundancy, interference with ArfA1s by a dominant negative approach in the tapetum resulted in tapetal dysfunction and pollen abortion. We further showed that all six ArfA1s are associated with the Golgi and the trans-Golgi network/early endosome, suggesting that they have roles in regulating post-Golgi trafficking to the plasma membrane or to vacuoles. Indeed, we demonstrated that the expression of ArfA1b interfered with the targeting of proteins critical for tapetal development. The results presented here demonstrate a key role of ArfA1s in tapetum-controlled pollen development by mediating protein targeting through post-Golgi trafficking routes.
被子植物的繁殖主要依赖有性生殖，其中配子体发育是一个先决条件。雄配子体发育需要配子体和孢子体因子，最重要的是绒毡层的早期分泌和后期程序性细胞死亡。除了转录因子外，内膜区室中的蛋白质，如类受体激酶和液泡蛋白酶，也控制着绒毡层的功能。调节它们分布的细胞机制正开始被揭示。我们在此报告，ADP核糖基化因子A1（ArfA1）对绒毡层控制的花粉发育至关重要。拟南芥基因组中的所有六个ArfA1在花药发育过程中均有表达，其中ArfA1b特异性表达于绒毡层和发育中的小孢子。虽然ArfA1b功能缺失突变体未表现出花粉缺陷，可能是由于冗余性，但通过显性负性方法在绒毡层中干扰ArfA1会导致绒毡层功能障碍和花粉败育。我们进一步表明，所有六个ArfA1都与高尔基体和反式高尔基体网络/早期内体相关，这表明它们在调节高尔基体后向质膜或液泡的运输中发挥作用。事实上，我们证明了ArfA1b的表达干扰了对绒毡层发育至关重要的蛋白质的靶向。本文给出的结果表明，ArfA1通过介导高尔基体后运输途径中的蛋白质靶向，在绒毡层控制的花粉发育中起关键作用。
