title: A de novo synthesis citrate transporter, Vigna umbellata multidrug and toxic compound extrusion, implicates in Al-activated citrate efflux in rice bean (Vigna umbellata) root apex.
abstract: Al-activated organic acid anion efflux from roots is an important Al resistance mechanism in plants. We have conducted homologous cloning and isolated Vigna umbellata multidrug and toxic compound extrusion (VuMATE), a gene encoding a de novo citrate transporter from rice bean. Al treatment up-regulated VuMATE expression in the root apex, but neither in the mature root region nor in the leaf. The degree of up-regulation of VuMATE was both partially Al concentration and time dependent, consistent with the delay in the onset of the Al-induced citrate efflux in rice bean roots. While La(3+)  moderately induced VuMATE expression, Cd(2+)  and Cu(2+)  did not induce the expression. Electrophysiological analysis of Xenopus oocytes expressing VuMATE indicated this transporter can mediate significant anion efflux across the plasma membrane. [(14) C]citrate efflux experiments in oocytes demonstrated that VuMATE is a H(+) -dependent citrate transporter. In addition, expression of VuMATE in transgenic tomato resulted in increased Al resistance, which correlated with an enhanced citrate efflux. Taken together, these findings suggest that VuMATE is a functional homolog of the known citrate transporters in sorghum, barley, maize and Arabidopsis. The similarities and differences of all the known citrate transporters associated with Al stress in the MATE family are also discussed.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xiao Ying
authors.initials: XY
authors.lastname: Yang
authors.forename: Jian Li
authors.initials: JL
authors.lastname: Yang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Piñeros
authors.forename: Leon V
authors.initials: LV
authors.lastname: Kochian
authors.forename: Gui Xin
authors.initials: GX
authors.lastname: Li
authors.forename: Shao Jian
authors.initials: SJ
authors.lastname: Zheng
mesh_terms: D000535:Aluminum / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D019343:Citric Acid / Q000378:metabolism; D003001:Cloning, Molecular; D007887:Fabaceae / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D015854:Up-Regulation; D014981:Xenopus
chemical_list: D002352:Carrier Proteins; D010940:Plant Proteins; D018749:RNA, Plant; C020723:citrate-binding transport protein; D019343:Citric Acid; D000535:Aluminum