Pollen-Specific Aquaporins NIP4;1 and NIP4;2 Are Required for Pollen Development and Pollination in Arabidopsis thaliana
Pollen-Specific Aquaporins NIP4;1 and NIP4;2 Are Required for Pollen Development and Pollination in Arabidopsis thaliana
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DOI：
10.1105/tpc.15.00776
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发表时间：
2016-05-01
期刊：
影响因子：
11.6
通讯作者：
Prometeo Muschietti, Jorge
中科院分区：
文献类型：
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作者：
Perez Di Giorgio, Juliana Andrea;Patrick Bienert, Gerd;Prometeo Muschietti, Jorge
在柱头干燥的花中，花粉发育、授粉和花粉管生长都需要水分和养分运输的时空调节。为了更好地理解参与生殖过程的分子机制，我们对NIP4进行了表征；1和NIP4；2、拟南芥的两个花粉特异性水通道蛋白。NIP4;1和NIP4；2种是只在被子植物谱系中发现的类似物。虽然它们有84%的氨基酸同源性，但它们表现出不同的表达模式。NIP4;1在成熟花粉中表达量低，NIP4；2个表达高峰在花粉管生长期间。此外,NIP4;1(pro): GUS花在成熟花粉和花粉管中显示GUS活性，而NIP4；2（赞成）：GUS花只在花粉管中。单个T-DNA突变体和两次人工敲低microRNA的突变体每硅片的种子数量减少，花粉萌发率和花粉管长度减少。卵母细胞转运试验显示NIP4；1和NIP4；2作为水和非离子通道。我们还发现NIP4；1和NIP4；2c末端被花粉特异性CPK磷酸化，从而改变其水渗透性。酵母存活试验表明，NIP4；1也运输氨、尿素、硼酸和H2O2。因此，我们提出水通道蛋白NIP4；1和NIP4；2是被子植物生殖器官的唯一组成部分，在花粉发育和授粉中起部分冗余作用。
In flowers with dry stigmas, pollen development, pollination, and pollen tube growth require spatial and temporal regulation of water and nutrient transport. To better understand the molecular mechanisms involved in reproductive processes, we characterized NIP4;1 and NIP4;2, two pollen-specific aquaporins of Arabidopsis thaliana. NIP4;1 and NIP4;2 are paralogs found exclusively in the angiosperm lineage. Although they have 84% amino acid identity, they displayed different expression patterns. NIP4;1 has low expression levels in mature pollen, while NIP4;2 expression peaks during pollen tube growth. Additionally, NIP4;1(pro): GUS flowers showed GUS activity in mature pollen and pollen tubes, whereas NIP4;2(pro): GUS flowers only in pollen tubes. Single T-DNA mutants and double artificial microRNA knockdowns had fewer seeds per silique and reduced pollen germination and pollen tube length. Transport assays in oocytes showed NIP4;1 and NIP4;2 function as water and nonionic channels. We also found that NIP4;1 and NIP4;2 C termini are phosphorylated by a pollen-specific CPK that modifies their water permeability. Survival assays in yeast indicated that NIP4;1 also transports ammonia, urea, boric acid, and H2O2. Thus, we propose that aquaporins NIP4;1 and NIP4;2 are exclusive components of the reproductive apparatus of angiosperms with partially redundant roles in pollen development and pollination.