title: Root release and metabolism of organic acids in tea plants in response to phosphorus supply.
abstract: Self-rooted, 10-month-old, uniform tea [Camellia sinensis (L.) O. Kuntze cv. Huangguanyin] plants were supplied for 17 weeks with 0, 40, 80, 160, 400, or 1000μM phosphorus (P) to investigate the effects of P supply on root citrate and malate release, the concentrations of malate and citrate and the activities of acid-metabolizing enzymes in leaves and roots. Root malate release and accumulation was induced by both 0 and 40μM P, while root citrate release and accumulation was induced only by 0μM P. Phosphorus-deficiency-induced malate and citrate release coincided with higher concentrations of root malate and citrate. The higher concentrations of malate and citrate were accompanied by increased activities of phosphoenolpyruvate carboxylase (PEPC), phosphoenolpyruvate phosphatase (PEPP), citrate synthase (CS) and NAD-malic enzyme (NAD-ME) and decreased activities of pyruvate kinase (PK), NADP-ME and NADP-isocitrate dehydrogenase (NADP-IDH) in roots. In contrast to roots, malate accumulated in the leaves only in response to 0μM P, and no change was observed in citrate levels. The P-deficiency-induced leaf malate accumulation coincided with increased activities of NADP-ME, NAD-ME and PK. Overall, the P-deficiency-induced changes in organic acid (OA) metabolism differed between roots and leaves. The high tolerance of tea plants to P-deficiency might be involved in two major processes: (a) increasing the availability of P by inducing root release of OA anions; and (b) improving the ability to use P efficiently by inducing bypass enzymes involved in tissue P economy.
authors.affiliation: College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, PR China.
authors.forename: Zheng-He
authors.initials: ZH
authors.lastname: Lin
authors.forename: Li-Song
authors.initials: LS
authors.lastname: Chen
authors.forename: Rong-Bing
authors.initials: RB
authors.lastname: Chen
authors.forename: Fang-Zhou
authors.initials: FZ
authors.lastname: Zhang
authors.forename: Huan-Xin
authors.initials: HX
authors.lastname: Jiang
authors.forename: Ning
authors.initials: N
authors.lastname: Tang
authors.forename: Brandon R
authors.initials: BR
authors.lastname: Smith
mesh_terms: D028241:Camellia sinensis / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D002950:Citrate (si)-Synthase / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism*; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008293:Malates / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D010758:Phosphorus / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*
chemical_list: D008293:Malates; D010758:Phosphorus; D019343:Citric Acid; C030298:malic acid; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D002950:Citrate (si)-Synthase; D010730:Phosphoenolpyruvate Carboxylase