TY  - JOUR
A1  - Schopper, S.
A1  - Muhlenbock, P.
A1  - Sorensson, C.
A1  - Hellborg, L.
A1  - Lenman, M.
A1  - Widell, S.
A1  - Fettke, Jörg
A1  - Andreasson, Erik
T1  - Arabidopsis cytosolic alpha-glycan phosphorylase, PHS2, is important during carbohydrate imbalanced conditions
JF  - Plant biology
N2  - Arabidopsis thaliana has two isoforms of alpha-glycan phosphorylase (EC 2.4.1.1), one residing in the plastid and the other in the cytosol. The cytosolic phosphorylase, PHS2, acts on soluble heteroglycans that constitute a part of the carbohydrate pool in a plant. This study aimed to define a physiological role for PHS2. Under standard growth conditions phs2 knock-out mutants do not show any clear growth phenotype, and we hypothesised that during low-light conditions where carbohydrate imbalance is perturbed, this enzyme is important. Soil-grown phs2 mutant plants developed leaf lesions when placed in very low light. Analysis of soluble heteroglycan (SHG) levels showed that the amount of glucose residues in SHG was higher in the phs2 mutant compared to wild-type plants. Furthermore, a standard senescence assay from soil-grown phs2 mutant plants showed that leaves senesced significantly faster in darkness than the wild-type leaves. We also found decreased hypocotyl extension in in vitro-grown phs2 mutant seedlings when grown for long time in darkness at 6 degrees C. We conclude that PHS2 activity is important in the adult stage during low-light conditions and senescence, as well as during prolonged seedling development when carbohydrate levels are unbalanced.
KW  - Lesion formation
KW  - low light stress conditions
KW  - phosphorylase
KW  - PHS2
KW  - senescence
KW  - soluble heteroglycans
Y1  - 2015
U6  - https://doi.org/10.1111/plb.12190
SN  - 1435-8603
SN  - 1438-8677
VL  - 17
IS  - 1
SP  - 74
EP  - 80
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -