Arabidopsis ubiquitin conjugase UBC32 is an ERAD component that functions in brassinosteroid-mediated salt stress tolerance.
Plants modify their growth and development to protect themselves from detrimental conditions by triggering a variety of signaling pathways, including the activation of the ubiquitin-mediated protein degradation pathway. Endoplasmic reticulum (ER)-associated protein degradation (ERAD) is an important aspect of the ubiquitin-proteasome system, but only a few of the active ERAD components have been reported in plants. Here, we report that the Arabidopsis thaliana ubiquitin-conjugating enzyme, UBC32, a stress-induced functional ubiquitin conjugation enzyme (E2) localized to the ER membrane, connects the ERAD process and brassinosteroid (BR)-mediated growth promotion and salt stress tolerance. In vivo data showed that UBC32 was a functional ERAD component that affected the stability of a known ERAD substrate, the barley (Hordeum vulgare) powdery mildew O (MLO) mutant MLO-12. UBC32 mutation caused the accumulation of bri1-5 and bri1-9, the mutant forms of the BR receptor, BRI1, and these mutant forms subsequently activated BR signal transduction. Further genetic and physiological data supported the contention that UBC32 plays a role in the BR-mediated salt stress response and that BR signaling is necessary for the plant to tolerate salt. Our data indicates a possible mechanism by which an ERAD component regulates the growth and stress response of plants.
State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Feng
F
Cui
Lijing
L
Liu
Qingzhen
Q
Zhao
Zhonghui
Z
Zhang
Qingliang
Q
Li
Baoying
B
Lin
Yaorong
Y
Wu
Sanyuan
S
Tang
Qi
Q
Xie
D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids / Q000378:metabolism*; D015151:Immunoblotting; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D012965:Sodium Chloride; C576451:UBC32 protein, Arabidopsis; D044763:Ubiquitin-Conjugating Enzymes; D011494:Protein Kinases; C108270:BRI1 protein, Arabidopsis