Identification of putative voltage-dependent Ca2+-permeable channels involved in cryptogein-induced Ca2+ transients and defense responses in tobacco BY-2 cells.
Ca(2+) is the pivotal second messenger for induction of defense responses induced by treatment of pathogen-derived elicitor or microbial infection in plants. However, molecular bases for elicitor-induced generation of Ca(2+) signals (Ca(2+) transients) are largely unknown. We here identified cDNAs for putative voltage-dependent Ca(2+)-permeable channels, NtTPC1A and NtTPC1B, that are homologous to TPC1 (two pore channel) from suspension-cultured tobacco BY-2 cells. NtTPC1s complemented the growth of a Saccharomyces cerevisiae mutant defective in CCH1, a putative Ca(2+) channel, in a low Ca(2+) medium, suggesting that both products permeate Ca(2+) through the plasma membrane. Cosuppression of NtTPC1s in apoaequorin-expressing BY-2 cells resulted in inhibition of rise in cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)) in response to sucrose and a fungal elicitor cryptogein, while it did not affect hypoosmotic shock-induced [Ca(2+)](cyt) increase. Cosuppression of NtTPC1s also caused suppression of cryptogein-induced programmed cell death and defense-related gene expression. These results suggest that NtTPC1s are involved in Ca(2+) mobilization induced by the cryptogein and sucrose, and have crucial roles in cryptogein-induced signal transduction pathway.
Kadota
Yasuhiro
Y
Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
Furuichi
Takuya
T
Ogasawara
Yoko
Y
Goh
Tatsuaki
T
Higashi
Katsumi
K
Muto
Shoshi
S
Kuchitsu
Kazuyuki
K
D020418:Algal Proteins / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D005656:Fungal Proteins; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000254:growth & development; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000166:cytology / Q000502:physiology*
D020418:Algal Proteins; D015220:Calcium Channels; D017931:DNA Primers; D005656:Fungal Proteins; C061032:cryptogein protein, Phytophthora cryptogea; D002118:Calcium