The ethylene receptor ETR2 delays floral transition and affects starch accumulation in rice.
Ethylene regulates multiple aspects of plant growth and development in dicotyledonous plants; however, its roles in monocotyledonous plants are poorly known. Here, we characterized a subfamily II ethylene receptor, ETHYLENE RESPONSE2 (ETR2), in rice (Oryza sativa). The ETR2 receptor with a diverged His kinase domain is a Ser/Thr kinase, but not a His kinase, and can phosphorylate its receiver domain. Mutation of the N box of the kinase domain abolished the kinase activity of ETR2. Overexpression of ETR2 in transgenic rice plants reduced ethylene sensitivity and delayed floral transition. Conversely, RNA interference (RNAi) plants exhibited early flowering and the ETR2 T-DNA insertion mutant etr2 showed enhanced ethylene sensitivity and early flowering. The effective panicles and seed-setting rate were reduced in the ETR2-overexpressing plants, while thousand-seed weight was substantially enhanced in both the ETR2-RNAi plants and the etr2 mutant compared with controls. Starch granules accumulated in the internodes of the ETR2-overexpressing plants, but not in the etr2 mutant. The GIGANTEA and TERMINAL FLOWER1/CENTRORADIALIS homolog (RCN1) that cause delayed flowering were upregulated in ETR2-overexpressing plants but downregulated in the etr2 mutant. Conversely, the alpha-amylase gene RAmy3D was suppressed in ETR2-overexpressing plants but enhanced in the etr2 mutant. Thus, ETR2 may delay flowering and cause starch accumulation in stems by regulating downstream genes.
Wuriyanghan
Hada
H
Plant Gene Research Center, National Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Zhang
Bo
B
Cao
Wan-Hong
WH
Ma
Biao
B
Lei
Gang
G
Liu
Yun-Feng
YF
Wei
Wei
W
Wu
Hua-Jun
HJ
Chen
Li-Juan
LJ
Chen
Hao-Wei
HW
Cao
Yang-Rong
YR
He
Si-Jie
SJ
Zhang
Wan-Ke
WK
Wang
Xiu-Jie
XJ
Chen
Shou-Yi
SY
Zhang
Jin-Song
JS
D000595:Amino Acid Sequence; D001665:Binding Sites; D005030:Ethylenes / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012275:Oryza / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010766:Phosphorylation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000254:growth & development / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment; D013213:Starch / Q000378:metabolism*; D000516:alpha-Amylases / Q000235:genetics / Q000378:metabolism
D005030:Ethylenes; D010940:Plant Proteins; D011956:Receptors, Cell Surface; D013213:Starch; C036216:ethylene; D000516:alpha-Amylases