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Cadmium‐induced oxalate secretion from root apex is associated with cadmium exclusion and resistance in Lycopersicon esulentum
Author(s) -
ZHU XIAO FANG,
ZHENG CHENG,
HU YI TING,
JIANG TAO,
LIU YU,
DONG NING YU,
YANG JIAN LI,
ZHENG SHAO JIAN
Publication year - 2011
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/j.1365-3040.2011.02304.x
Subject(s) - oxalate , cadmium , lycopersicon , secretion , chemistry , cultivar , calcium oxalate , biology , biochemistry , botany , inorganic chemistry , organic chemistry
The mechanisms of heavy metal resistance in plants can be classified into internal tolerance and exclusion mechanisms, but exclusion of heavy metals with the help of organic acids secretion has not been well documented. Here we demonstrated the contribution of oxalate secretion to cadmium (Cd) exclusion and resistance in tomato. Different Cd resistance between two tomato cultivars was evaluated by relative root elongation (RRE) and Cd accumulation. Cultivar ‘Micro‐Tom’ showed better growth and lower Cd content in roots than ‘Hezuo903’ at different Cd concentrations not only in short‐term hydroponic experiment but also in long‐term hydroponic and soil experiments, indicating that the genotypic difference in Cd resistance is related to the exclusion of Cd from roots. ‘Micro‐Tom’ had greater ability to secrete oxalate, suggesting that oxalate secretion might contribute to Cd resistance. Cd‐induced secretion of oxalate was localized to root apex at which the majority of Cd accumulated. Phenylglyoxal, an anion‐channel inhibitor, effectively blocked Cd‐induced oxalate secretion and aggravated Cd toxicity while exogenous oxalate supply ameliorated Cd toxicity efficiently. These results indicated that the oxalate secreted from the root apex helps to exclude Cd from entering tomato roots, thus contributes to Cd resistance in the Cd‐resistant tomato cultivar.