Cyclic nucleotide-gated channel 18 is an essential Ca2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis.
|Title||Cyclic nucleotide-gated channel 18 is an essential Ca2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis.|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Gao Q-F, Gu L-L, Wang H-Q, Fei C-F, Fang X, Hussain J, Sun S-J, Dong J-Y, Liu H, Wang Y-F|
|Journal||Proc Natl Acad Sci U S A|
|Date Published||2016 Mar 15|
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 Ca(2+) gradients in the pollen tube tips are essential for pollen tube guidance and that plasma membrane Ca(2+) channels in pollen tube tips are core components that regulate Ca(2+) gradients by mediating and regulating external Ca(2+) influx. Therefore, Ca(2+) channels are the core components for pollen tube guidance. However, there is still no genetic evidence for the identification of the putative Ca(2+) 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 Ca(2+) 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 Ca(2+) 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 Ca(2+) channel for pollen tube guidance in Arabidopsis.
|Alternate Journal||Proc. Natl. Acad. Sci. U.S.A.|
|PubMed Central ID||PMC4801260|