The Mg-chelatase H subunit is an abscisic acid receptor.
Abscisic acid (ABA) is a vital phytohormone that regulates mainly stomatal aperture and seed development, but ABA receptors involved in these processes have yet to be determined. We previously identified from broad bean an ABA-binding protein (ABAR) potentially involved in stomatal signalling, the gene for which encodes the H subunit of Mg-chelatase (CHLH), which is a key component in both chlorophyll biosynthesis and plastid-to-nucleus signalling. Here we show that Arabidopsis ABAR/CHLH specifically binds ABA, and mediates ABA signalling as a positive regulator in seed germination, post-germination growth and stomatal movement, showing that ABAR/CHLH is an ABA receptor. We show also that ABAR/CHLH is a ubiquitous protein expressed in both green and non-green tissues, indicating that it might be able to perceive the ABA signal at the whole-plant level.
Shen
Yuan-Yue
YY
China State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, 100094 Beijing, China.
Wang
Xiao-Fang
XF
Wu
Fu-Qing
FQ
Du
Shu-Yuan
SY
Cao
Zheng
Z
Shang
Yi
Y
Wang
Xiu-Ling
XL
Peng
Chang-Cao
CC
Yu
Xiang-Chun
XC
Zhu
Sai-Yong
SY
Fan
Ren-Chun
RC
Xu
Yan-Hong
YH
Zhang
Da-Peng
DP
D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008190:Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D021122:Protein Subunits; D000040:Abscisic Acid; D008190:Lyases; C086788:magnesium chelatase