A cyclic nucleotide-gated channel (CNGC16) in pollen is critical for stress tolerance in pollen reproductive development.
Cyclic nucleotide-gated channels (CNGCs) have been implicated in diverse aspects of plant growth and development, including responses to biotic and abiotic stress, as well as pollen tube growth and fertility. Here, genetic evidence identifies CNGC16 in Arabidopsis (Arabidopsis thaliana) as critical for pollen fertility under conditions of heat stress and drought. Two independent transfer DNA disruptions of cngc16 resulted in a greater than 10-fold stress-dependent reduction in pollen fitness and seed set. This phenotype was fully rescued through pollen expression of a CNGC16 transgene, indicating that cngc16-1 and 16-2 were both loss-of-function null alleles. The most stress-sensitive period for cngc16 pollen was during germination and the initiation of pollen tube tip growth. Pollen viability assays indicate that mutant pollen are also hypersensitive to external calcium chloride, a phenomenon analogous to calcium chloride hypersensitivities observed in other cngc mutants. A heat stress was found to increase concentrations of 3',5'-cyclic guanyl monophosphate in both pollen and leaves, as detected using an antibody-binding assay. A quantitative PCR analysis indicates that cngc16 mutant pollen have attenuated expression of several heat-stress response genes, including two heat shock transcription factor genes, HsfA2 and HsfB1. Together, these results provide evidence for a heat stress response pathway in pollen that connects a cyclic nucleotide signal, a Ca(2+)-permeable ion channel, and a signaling network that activates a downstream transcriptional heat shock response.
Department of Biochemistry, University of Nevada, Reno, Nevada 89557, USA.
Meral
M
Tunc-Ozdemir
Chong
C
Tang
Maryam Rahmati
MR
Ishka
Elizabeth
E
Brown
Norman R
NR
Groves
Candace T
CT
Myers
Claudia
C
Rato
Lisbeth R
LR
Poulsen
Stephen
S
McDowell
Gad
G
Miller
Ron
R
Mittler
Jeffrey F
JF
Harper
D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002122:Calcium Chloride / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D055864:Droughts; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D053205:Pollen Tube / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; C582324:CNGC16 protein, Arabidopsis; D054815:Cyclic Nucleotide-Gated Cation Channels; D004268:DNA-Binding Proteins; C000620134:HSFA2 protein, Arabidopsis; C000620135:HSFB1 protein, Arabidopsis; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D006152:Cyclic GMP; D002122:Calcium Chloride