TY - JOUR
T1 - Arabidopsis AHP2, AHP3, and AHP5 histidine phosphotransfer proteins function as redundant negative regulators of drought stress response
AU - Nishiyama, Rie
AU - Watanabe, Yasuko
AU - Leyva-Gonzalez, Marco A.
AU - Van Ha, Chien
AU - Fujita, Yasunari
AU - Tanaka, Maho
AU - Seki, Motoaki
AU - Yamaguchi-Shinozaki, Kazuko
AU - Shinozaki, Kazuo
AU - Herrera-Estrella, Luis
AU - Tran, Lam Son Phan
PY - 2013/3/19
Y1 - 2013/3/19
N2 - Cytokinin is an essential phytohormone controlling various biological processes, including environmental stress responses. In Arabidopsis, although the cytokinin (CK)-related phosphorelay-consisting of three histidine kinases, five histidine phosphotransfer proteins (AHPs), and a number of response regulators-has been known to be important for stress responses, the AHPs required for CK signaling during drought stress remain elusive. Here, we report that three Arabidopsis AHPs, namely AHP2, AHP3, and AHP5, control responses to drought stress in negative and redundant manner. Loss of function of these three AHP genes resulted in a strong drought-tolerant phenotype that was associated with the stimulation of protective mechanisms. Specifically, cell membrane integrity was improved as well as an increased sensitivity to abscisic acid (ABA) was observed rather than an alteration in ABA-mediated stomatal closure and density. Consistent with their negative regulatory functions, all three AHP genes' expression was down-regulated by dehydration, which most likely resulted from a stress-induced reduction of endogenous CK levels. Furthermore, global transcriptional analysis of ahp2,3,5 leaves revealed down-regulation of many well-known stress- and/or ABA-responsive genes, suggesting that these three AHPs may control drought response in both ABA-dependent and ABA-independent manners. The discovery of mechanisms of activation and the targets of the downstream components of CK signaling involved in stress responses is an important and challenging goal for the study of plant stress regulatory network responses and plant growth. The knowledge gained from this study also has broad potential for biotechnological applications to increase abiotic stress tolerance in plants.
AB - Cytokinin is an essential phytohormone controlling various biological processes, including environmental stress responses. In Arabidopsis, although the cytokinin (CK)-related phosphorelay-consisting of three histidine kinases, five histidine phosphotransfer proteins (AHPs), and a number of response regulators-has been known to be important for stress responses, the AHPs required for CK signaling during drought stress remain elusive. Here, we report that three Arabidopsis AHPs, namely AHP2, AHP3, and AHP5, control responses to drought stress in negative and redundant manner. Loss of function of these three AHP genes resulted in a strong drought-tolerant phenotype that was associated with the stimulation of protective mechanisms. Specifically, cell membrane integrity was improved as well as an increased sensitivity to abscisic acid (ABA) was observed rather than an alteration in ABA-mediated stomatal closure and density. Consistent with their negative regulatory functions, all three AHP genes' expression was down-regulated by dehydration, which most likely resulted from a stress-induced reduction of endogenous CK levels. Furthermore, global transcriptional analysis of ahp2,3,5 leaves revealed down-regulation of many well-known stress- and/or ABA-responsive genes, suggesting that these three AHPs may control drought response in both ABA-dependent and ABA-independent manners. The discovery of mechanisms of activation and the targets of the downstream components of CK signaling involved in stress responses is an important and challenging goal for the study of plant stress regulatory network responses and plant growth. The knowledge gained from this study also has broad potential for biotechnological applications to increase abiotic stress tolerance in plants.
KW - Microarray analysis
KW - Plant adaptation
KW - Stress mitigation
KW - Two-component system
UR - http://www.scopus.com/inward/record.url?scp=84875274467&partnerID=8YFLogxK
U2 - 10.1073/pnas.1302265110
DO - 10.1073/pnas.1302265110
M3 - Article
C2 - 23487796
AN - SCOPUS:84875274467
SN - 0027-8424
VL - 110
SP - 4840
EP - 4845
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 12
ER -