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Ethylene is involved in root phosphorus remobilization in rice (Oryza sativa) by regulating cell-wall pectin and enhancing phosphate translocation to shoots

Zhu, Xiao Fang, Zhu, Chun Quan, Zhao, Xu Sheng, Zheng, Shao Jian, Shen, Ren Fang
Annals of botany 2016 v.118 no.4 pp. 645-653
1-aminocyclopropane-1-carboxylic acid, Oryza sativa, cell walls, cultivars, ethylene, ethylene production, genes, nutrient solutions, pectins, phosphates, phosphorus, rice, roots, shoots, solubilization
Background and aims Plants are able to grow under phosphorus (P)-deficient conditions by coordinating Pi acquisition, translocation from roots to shoots and remobilization within the plant. Previous reports have demonstrated that cell-wall pectin contributes greatly to rice cell-wall Pi re-utilization under P-deficient conditions, but whether other factors such as ethylene also affect the pectin-remobilizing capacity remains unclear. Methods Two rice cultivars, ‘Nipponbare’ (Nip) and ‘Kasalath’ (Kas) were cultured in the +P (complete nutrient solution), −P (withdrawing P from the complete nutrient solution), +P+ACC (1-amino-cyclopropane-1-carboxylic acid, an ethylene precursor, adding 1 μm ACC to the complete nutrient solution) and −P+ACC (adding 1 μm ACC to −P nutrient solution) nutrient solutions for 7 d. Key Results After 7 d −P treatment, there was clearly more soluble P in Nip root and shoot, accompanied by additional production of ethylene in Nip root compared with Kas. Under P-deficient conditions, addition of ACC significantly increased the cell-wall pectin content and decreased cell-wall retained P, and thus more soluble P was released to the root and translocated to the shoot, which was mediated by the expression of the P deficiency-responsive gene OsPT2, which also strongly induced by ACC treatment under both P-sufficient and P-deficient conditions. Conclusions Ethylene positively regulates pectin content and expression of OsPT2, which ultimately makes more P available by facilitating the solubilization of P fixed in the cell wall and its translocation to the shoot.