title: Cyclic nucleotide gated channels 7 and 8 are essential for male reproductive fertility.
abstract: The Arabidopsis thaliana genome contains 20 CNGCs, which are proposed to encode cyclic nucleotide gated, non-selective, Ca²⁺-permeable ion channels. CNGC7 and CNGC8 are the two most similar with 74% protein sequence identity, and both genes are preferentially expressed in pollen. Two independent loss-of-function T-DNA insertions were identified for both genes and used to generate plant lines in which only one of the two alleles was segregating (e.g., cngc7-1+/-/cngc8-2-/- and cngc7-3-/-/cngc8-1+/-). While normal pollen transmission was observed for single gene mutations, pollen harboring mutations in both cngc7 and 8 were found to be male sterile (transmission efficiency reduced by more than 3000-fold). Pollen grains harboring T-DNA disruptions of both cngc7 and 8 displayed a high frequency of bursting when germinated in vitro. The male sterile defect could be rescued through pollen expression of a CNGC7 or 8 transgene including a CNGC7 with an N-terminal GFP-tag. However, rescue efficiencies were reduced ∼10-fold when the CNGC7 or 8 included an F to W substitution (F589W and F624W, respectively) at the junction between the putative cyclic nucleotide binding-site and the calmodulin binding-site, identifying this junction as important for proper functioning of a plant CNGC. Using confocal microscopy, GFP-CNGC7 was found to preferentially localize to the plasma membrane at the flanks of the growing tip. Together these results indicate that CNGC7 and 8 are at least partially redundant and provide an essential function at the initiation of pollen tube tip growth.
authors: Department of Biochemistry, University of Nevada, Reno, Nevada, United States of America.
authors: Meral
authors: M
authors: Tunc-Ozdemir
authors: Claudia
authors: C
authors: Rato
authors: Elizabeth
authors: E
authors: Brown
authors: Stephanie
authors: S
authors: Rogers
authors: Amanda
authors: A
authors: Mooneyham
authors: Sabine
authors: S
authors: Frietsch
authors: Candace T
authors: CT
authors: Myers
authors: Lisbeth Rosager
authors: LR
authors: Poulsen
authors: Rui
authors: R
authors: Malhó
authors: Jeffrey F
authors: JF
authors: Harper
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D018525:Germination; D009154:Mutation; D011058:Pollen / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D021381:Protein Transport; D012098:Reproduction
chemical_list: D029681:Arabidopsis Proteins; C582719:CNGC7 protein, Arabidopsis; D054815:Cyclic Nucleotide-Gated Cation Channels