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P tr BAM 1 , a β ‐amylase‐coding gene of P oncirus trifoliata , is a CBF regulon member with function in cold tolerance by modulating soluble sugar levels
Author(s) -
PENG TING,
ZHU XIAOFANG,
DUAN NIAN,
LIU JIHONG
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12384
Subject(s) - maltose , regulon , biochemistry , chemistry , yeast , starch , sugar , maltose binding protein , gene , gene expression , enzyme , fusion protein , recombinant dna
β ‐Amylase ( BAM ) catalyses starch breakdown to generate maltose, which can be incorporated into sugar metabolism. However, the role of BAM genes in cold tolerance is less characterized. In this study, we report the isolation and functional characterization of a chloroplast‐localizing BAM ‐encoding gene P tr BAM 1 from P oncirus trifoliata . P tr BAM 1 was induced by cold, dehydration and salt, but repressed by maltose. Overexpression of P tr BAM 1 in tobacco ( N icotiana nudicaulis ) increased BAM activity, promoted starch degradation and enhanced the contents of maltose and soluble sugars, whereas opposite changes were observed when P tr BAM 1 homolog in lemon ( C itrus lemon ) was knocked down. The tobacco overexpressing lines exhibited enhanced tolerance to cold at chilling or freezing temperatures. Under cold stress, higher BAM activity and greater accumulation of maltose and soluble sugars were observed in the overexpressing lines when compared with the wild‐type or empty vector transformants. Bioinformatics analysis demonstrated that P tr BAM 1 promoter contained a CBF ‐recognizing element. Yeast one‐hybrid assay demonstrated that PtrCBF could interact with the promoter fragment containing the element. Taken together, these results demonstrate that P tr BAM 1 is a member of CBF regulon and plays an important role in cold tolerance by modulating the levels of soluble sugars acting as osmolytes or antioxidants.