State Key Laboratories of Agrobiotechnology, Joint International Research Laboratory of Crop Molecular Breeding, Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Sciences, China Agricultural University, 100193, Beijing, China.
Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain.
Nat Commun. 2023 Jan 17;14(1):258. doi: 10.1038/s41467-023-35936-z.
Pollen tube guidance within female tissues of flowering plants can be divided into preovular guidance, ovular guidance and a connecting stage called pollen tube emergence. As yet, no female factor has been identified to positively regulate this transition process. In this study, we show that an ovary-expressed bHLH transcription factor Cucumis sativus ALCATRAZ (CsALC) functions in pollen tube emergence in cucumber. CsALC knockout mutants showed diminished pollen tube emergence, extremely reduced entry into ovules, and a 95% reduction in female fertility. Further examination showed two rapid alkalinization factors CsRALF4 and CsRALF19 were less expressed in Csalc ovaries compared to WT. Besides the loss of male fertility derived from precocious pollen tube rupture as in Arabidopsis, Csralf4 Csralf19 double mutants exhibited a 60% decrease in female fertility due to reduced pollen tube distribution and decreased ovule targeting efficiency. In brief, CsALC regulates female fertility and promotes CsRALF4/19 expression in the ovary during pollen tube guidance in cucumber.
在开花植物的雌性组织中，花粉管的引导可以分为受精前引导、胚珠引导和一个称为花粉管萌发的连接阶段。到目前为止，还没有发现任何雌性因子能够正向调控这个转变过程。在这项研究中，我们表明，一种在黄瓜中表达的 bHLH 转录因子 Cucumis sativus ALCATRAZ（CsALC）在花粉管萌发中起作用。CsALC 敲除突变体表现出花粉管萌发减少、进入胚珠的数量极显著减少以及雌性育性降低 95%。进一步的检查表明，与 WT 相比，CsALC 突变体的两个快速碱化因子 CsRALF4 和 CsRALF19 在子房中的表达减少。除了拟南芥中由于花粉管过早破裂导致雄性育性丧失之外，Csralf4 Csralf19 双突变体由于花粉管分布减少和胚珠靶向效率降低，雌性育性降低了 60%。总之，CsALC 调节雌性育性，并在花粉管引导过程中促进黄瓜子房中 CsRALF4/19 的表达。
