Exogenous auxin alleviates cadmium toxicity in Arabidopsis thaliana by stimulating synthesis of hemicellulose 1 and increasing the cadmium fixation capacity of root cell walls.
Auxin is involved in not only plant physiological and developmental processes but also plant responses to abiotic stresses. In this study, cadmium (Cd(2+)) stress decreased the endogenous auxin level, whereas exogenous auxin (α-naphthaleneacetic acid, NAA, a permeable auxin analog) reduced shoot Cd(2+) concentration and rescued Cd(2+)-induced chlorosis in Arabidopsis thaliana. Under Cd(2+) stress conditions, NAA increased Cd(2+) retention in the roots and most Cd(2+) in the roots was fixed in hemicellulose 1 of the cell wall. NAA treatment did not affect pectin content and its binding capacity for Cd(2+), whereas it significantly increased the content of hemicellulose 1 and the amount of Cd(2+) retained in it. There were highly significant correlations between Cd(2+) concentrations in the root, cell wall and hemicellulose 1 when the plants were subjected to Cd(2+) or NAA+Cd(2+) treatment for 1 to 7d, suggesting that the increase in hemicellulose 1 contributes greatly to the fixation of Cd(2+) in the cell wall. Taken together, these results demonstrate that auxin-induced alleviation of Cd(2+) toxicity in Arabidopsis is mediated through increasing hemicellulose 1 content and Cd(2+) fixation in the root, thus reducing the translocation of Cd(2+) from roots to shoots.
Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou 310058, China; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
Xiao Fang
XF
Zhu
Zhi Wei
ZW
Wang
Fang
F
Dong
Gui Jie
GJ
Lei
Yuan Zhi
YZ
Shi
Gui Xin
GX
Li
Shao Jian
SJ
Zheng
D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism; D002104:Cadmium / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity; D002473:Cell Wall / Q000187:drug effects; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000737:chemistry*; D018517:Plant Roots / Q000187:drug effects* / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects* / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry*; D013312:Stress, Physiological; D014574:Uronic Acids / Q000737:chemistry
D007210:Indoleacetic Acids; D011134:Polysaccharides; D014574:Uronic Acids; D002104:Cadmium; C007916:hemicellulose
Arabidopsis; Auxin; Cd(2+) stress; Cell wall; Hemicellulose 1; Root