Pollen tube emergence is mediated by ovary-expressed ALCATRAZ in cucumber

• Published in: Nature communications 2023-01, Vol.14 (1), p.258-258, Article 258
• Main Authors: Cheng, Zhihua, Liu, Xiaofeng, Yan, Shuangshuang, Liu, Bin, Zhong, Yanting, Song, Weiyuan, Chen, Jiacai, Wang, Zhongyi, Che, Gen, Liu, Liu, Ying, Ao, Lv, Hanli, Han, Lijie, Li, Min, Zhao, Jianyu, Xu, Junqiang, Yang, Zhengan, Zhou, Zhaoyang, Zhang, Xiaolan
• Format: Article
• Language: English
• Subjects: 13/106; 13/44; 14; 14/63; 38; 38/22; 38/23; 38/32; 38/77; 38/88; 38/91; 631/449/1659; 631/449/2679/1489; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Cucumbers; Cucumis sativus - genetics; Females; Fertility; Flowering; Flowering plants; Helix-loop-helix proteins (basic); Humanities and Social Sciences; multidisciplinary; Mutants; Ovaries; Ovary - metabolism; Ovule - metabolism; Ovules; Plants (botany); Pollen; Pollen Tube - genetics; Pollen Tube - metabolism; Pollen tubes; Science; Science (multidisciplinary); Vegetables
• ISSN: 2041-1723; 2041-1723
• 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. Pollen tube growth is guided towards ovules. Here the authors show that a bHLH transcriptional factor CsALC functions in pollen tube emergence towards ovules to regulate female fertility in cucumber and promotes the expression of two rapid alkalinization factors CsRALF4/19 in the ovary.