Phosphatidylinositol 4,5-bisphosphate is important for stomatal opening.
Previously, we demonstrated that a protein that binds phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] inhibits both light-induced stomatal opening and ABA-induced stomatal closing. The latter effect is due to a reduction in free PtdIns(4,5)P(2), decreasing production of inositol 1,4,5-trisphosphate and phosphatidic acid by phospholipases C and D. However, it is less clear how PtdIns(4,5)P(2) modulates stomatal opening. We found that in response to white light irradiation, the PtdIns(4,5)P(2)-binding domain GFP:PLCdelta1PH translocated from the cytosol into the plasma membrane. This suggests that the level of PtdIns(4,5)P(2) increases at the plasma membrane upon illumination. Exogenously administered PtdIns(4,5)P(2) substituted for light stimuli, inducing stomatal opening and swelling of guard cell protoplasts. To identify PtdIns(4,5)P(2) targets we performed patch-clamp experiments, and found that anion channel activity was inhibited by PtdIns(4,5)P(2). Genetic analyses using an Arabidopsis PIP5K4 mutant further supported the role of PtdIns(4,5)P(2) in stomatal opening. The reduced stomatal opening movements exhibited by a mutant of Arabidopsis PIP5K4 (At3g56960) was countered by exogenous application of PtdIns(4,5)P(2). The phenotype of reduced stomatal opening in the pip5k4 mutant was recovered in lines complemented with the full-length PIP5K4. Together, these data suggest that PIP5K4 produces PtdIns(4,5)P(2) in irradiated guard cells, inhibiting anion channels to allow full stomatal opening.
Lee
Yuree
Y
POSTECH-VZH Global Research Lab., Division of Molecular Life Sciences, POSTECH, Pohang, 790-784, Korea. ylee@postech.ac.kr
Kim
Yong-Woo
YW
Jeon
Byeon Wook
BW
Park
Ki-Youb
KY
Suh
Su Jeoung
SJ
Seo
Jiyoung
J
Kwak
June M
JM
Martinoia
Enrico
E
Hwang
Inhwan
I
Lee
Youngsook
Y
D017360:Arabidopsis / Q000201:enzymology* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001665:Binding Sites; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000032:analysis; D017136:Ion Transport; D008027:Light; D018408:Patch-Clamp Techniques; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018515:Plant Leaves / Q000201:enzymology / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology* / Q000528:radiation effects / Q000648:ultrastructure
D029681:Arabidopsis Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D049452:Green Fluorescent Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C526696:PIP5K4 protein, Arabidopsis