期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：11
页码：3096-3101
DOI：10.1073/pnas.1524629113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：In flowering plants, pollen tubes are guided into ovules by multiple attractants from female gametophytes to release paired sperm cells for double fertilization. It has been well-established that Ca2+ gradients in the pollen tube tips are essential for pollen tube guidance and that plasma membrane Ca2+ channels in pollen tube tips are core components that regulate Ca2+ gradients by mediating and regulating external Ca2+ influx. Therefore, Ca2+ channels are the core components for pollen tube guidance. However, there is still no genetic evidence for the identification of the putative Ca2+ channels essential for pollen tube guidance. Here, we report that the point mutations R491Q or R578K in cyclic nucleotide-gated channel 18 (CNGC18) resulted in abnormal Ca2+ gradients and strong pollen tube guidance defects by impairing the activation of CNGC18 in Arabidopsis. The pollen tube guidance defects of cngc18-17 (R491Q) and of the transfer DNA (T-DNA) insertion mutant cngc18-1 (+/−) were completely rescued by CNGC18. Furthermore, domain-swapping experiments showed that CNGC18’s transmembrane domains are indispensable for pollen tube guidance. Additionally, we found that, among eight Ca2+ channels (including six CNGCs and two glutamate receptor-like channels), CNGC18 was the only one essential for pollen tube guidance. Thus, CNGC18 is the long-sought essential Ca2+ channel for pollen tube guidance in Arabidopsis.
