Closing plant stomata requires a homolog of an aluminum-activated malate transporter.
Plant stomata limit both carbon dioxide uptake and water loss; hence, stomatal aperture is carefully set as the environment fluctuates. Aperture area is known to be regulated in part by ion transport, but few of the transporters have been characterized. Here we report that AtALMT12 (At4g17970), a homolog of the aluminum-activated malate transporter (ALMT) of wheat, is expressed in guard cells of Arabidopsis thaliana. Loss-of-function mutations in AtALMT12 impair stomatal closure induced by ABA, calcium and darkness, but do not abolish either the rapidly activated or the slowly activated anion currents previously identified as being important for stomatal closure. Expressed in Xenopus oocytes, AtALMT12 facilitates chloride and nitrate currents, but not those of organic solutes. Therefore, we conclude that AtALMT12 is a novel class of anion transporter involved in stomatal closure.
Research Institute for Bioresources, Okayama University, Chuo 2-20-1, Kurashiki, Okayama, 710-0046 Japan.
Takayuki
T
Sasaki
Izumi C
IC
Mori
Takuya
T
Furuichi
Shintaro
S
Munemasa
Kiminori
K
Toyooka
Ken
K
Matsuoka
Yoshiyuki
Y
Murata
Yoko
Y
Yamamoto
D000040:Abscisic Acid / Q000378:metabolism; D000535:Aluminum / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D005816:Genetic Complementation Test; D016254:Mutagenesis, Insertional; D009154:Mutation; D009865:Oocytes; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D054046:Plant Stomata / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D014981:Xenopus
D029681:Arabidopsis Proteins; D027361:Organic Anion Transporters; D018749:RNA, Plant; D000040:Abscisic Acid; D000535:Aluminum; D002118:Calcium