Salt tolerance of Arabidopsis thaliana requires maturation of N-glycosylated proteins in the Golgi apparatus.
Protein N-glycosylation in the endoplasmic reticulum (ER) and in the Golgi apparatus is an essential process in eukaryotic cells. Although the N-glycosylation pathway in the ER has been shown to regulate protein quality control, salt tolerance, and cellulose biosynthesis in plants, no biological roles have been linked functionally to N-glycan modifications that occur in the Golgi apparatus. Herein, we provide evidence that mutants defective in N-glycan maturation, such as complex glycan 1 (cgl1), are more salt-sensitive than wild type. Salt stress caused growth inhibition, aberrant root-tip morphology, and callose accumulation in cgl1, which were also observed in an ER oligosaccharyltransferase mutant, staurosporin and temperature sensitive 3a (stt3a). Unlike stt3a, cgl1 did not cause constitutive activation of the unfolded protein response. Instead, aberrant modification of the plasma membrane glycoprotein KORRIGAN 1/RADIALLY SWOLLEN 2 (KOR1/RSW2) that is necessary for cellulose biosynthesis occurred in cgl1 and stt3a. Genetic analyses identified specific interactions among rsw2, stt3a, and cgl1 mutations, indicating that the function of KOR1/RSW2 protein depends on complex N-glycans. Furthermore, cellulose deficient rsw1-1 and rsw2-1 plants were also salt-sensitive. These results establish that plant protein N-glycosylation functions beyond protein folding in the ER and is necessary for sufficient cell-wall formation under salt stress.
Kang
Jae Sook
JS
Brain Korea-21, Division of Applied Life Science and Environmental Biotechnology National Core Research Center, Graduate School of Gyeongsang National University, Jinju 660-701, Korea.
Frank
Julia
J
Kang
Chang Ho
CH
Kajiura
Hiroyuki
H
Vikram
Meenu
M
Ueda
Akihiro
A
Kim
Sewon
S
Bahk
Jeong Dong
JD
Triplett
Barbara
B
Fujiyama
Kazuhito
K
Lee
Sang Yeol
SY
von Schaewen
Antje
A
Koiwa
Hisashi
H
D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000737:chemistry / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000096:biosynthesis*; D006023:Glycoproteins / Q000096:biosynthesis*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism*; D012492:Salts
D029681:Arabidopsis Proteins; D006023:Glycoproteins; D012492:Salts