Effects of tobacco ethylene receptor mutations on receptor kinase activity, plant growth and stress responses.
Ethylene receptor is the first component of ethylene signaling that regulates plant growth, development and stress responses. Previously, we have demonstrated that tobacco subfamily 2 ethylene receptor NTHK1 had Ser/Thr kinase activity, and overexpression of NTHK1 caused large rosette, reduced ethylene sensitivity, and increased salt sensitivity in transgenic Arabidopsis plants. Here we found that N-box mutation in the NTHK1 kinase domain abolished the kinase activity and led to disruption of NTHK1 roles in conferring reduced ethylene sensitivity and salt sensitive response in transgenic Arabidopsis plants. However, N-box mutation had partial effects on NTHK1 regulation of rosette growth and expression of salt- and ethylene-responsive genes AtNAC2, AtERF1 and AtCor6.6. Mutation of conserved residues in the H box did not affect kinase activity, seedling growth, ethylene sensitivity or salt-induced epinasty in transgenic plants but did influence NTHK1 function in control of specific salt- and ethylene-responsive gene expression. Compared with NTHK1, the tobacco subfamily 1 ethylene receptor NtETR1 had His kinase activity and played a weak role in regulation of rosette growth, triple response and salt response. Mutation of the conserved His residue in the NtETR1 H box eliminated phosphorylation and altered the effect of Ntetr1-1 on reporter gene activity. These results imply that the Ser/Thr kinase activity of NTHK1 is differentially required for various responses, and NTHK1 plays a larger role than NtETR1.
Chen
Tao
T
Plant Gene Expression Center, National Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
Liu
Jun
J
Lei
Gang
G
Liu
Yun-Feng
YF
Li
Zhi-Gang
ZG
Tao
Jian-Jun
JJ
Hao
Yu-Jun
YJ
Cao
Yang-Rong
YR
Lin
Qing
Q
Zhang
Wan-Ke
WK
Ma
Biao
B
Chen
Shou-Yi
SY
Zhang
Jin-Song
JS
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics*; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*
D005030:Ethylenes; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083750:ethylene receptors, plant; D012965:Sodium Chloride; C036216:ethylene; D017346:Protein Serine-Threonine Kinases