The Plasma Membrane H+-ATPase AHA1 Plays a Major Role in Stomatal Opening in Response to Blue Light.
Stomata open in response to a beam of weak blue light under strong red light illumination. A blue light signal is perceived by phototropins and transmitted to the plasma membrane H(+)-ATPase that drives stomatal opening. To identify the components in this pathway, we screened for mutants impaired in blue light-dependent stomatal opening. We analyzed one such mutant, provisionally named blus2 (blue light signaling2), and found that stomatal opening in leaves was impaired by 65%, although the magnitude of red light-induced opening was not affected. Blue light-dependent stomatal opening in the epidermis and H(+) pumping in guard cell protoplasts were inhibited by 70% in blus2 Whole-genome resequencing identified a mutation in the AHA1 gene of the mutant at Gly-602. T-DNA insertion mutants of AHA1 exhibited a similar phenotype to blus2; this phenotype was complemented by the AHA1 gene. We renamed blus2 as aha1-10 T-DNA insertion mutants of AHA2 and AHA5 did not show any impairment in stomatal response, although the transcript levels of AHA2 and AHA5 were higher than those of AHA1 in wild-type guard cells. Stomata in ost2, a constitutively active AHA1 mutant, did not respond to blue light. A decreased amount of H(+)-ATPase in aha1-10 accounted for the reduced stomatal blue light responses and the decrease was likely caused by proteolysis of misfolded AHA1. From these results, we conclude that AHA1 plays a major role in blue light-dependent stomatal opening in Arabidopsis and that the mutation made the AHA1 protein unstable in guard cells.
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.).
Shota
S
Yamauchi
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.).
Atsushi
A
Takemiya
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.).
Tomoaki
T
Sakamoto
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.).
Tetsuya
T
Kurata
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.).
Toshifumi
T
Tsutsumi
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.).
Toshinori
0000-0001-7621-1259
T
Kinoshita
Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan (S.Y., A.T., T.T., K.S.); Plant Global Education Project, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan (T.S., Te.K.); and Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan (To.K.) kenrcb@kyushu-u.org.
Ken-Ichiro
0000-0001-6450-8506
K
Shimazaki
D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant; D006027:Glycosides / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008027:Light; D009154:Mutation / Q000235:genetics; D054046:Plant Stomata / Q000166:cytology / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D059748:Proteolysis / Q000187:drug effects / Q000528:radiation effects; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D006027:Glycosides; D007527:Isoenzymes; D061988:Proteasome Inhibitors; D012333:RNA, Messenger; C007808:fusicoccin; D046988:Proteasome Endopeptidase Complex; D006180:Proton-Translocating ATPases; C544444:AHA1 protein, Arabidopsis