title: Expression of an Arabidopsis CAX2 variant in potato tubers increases calcium levels with no accumulation of manganese.
abstract: Previously, we made a chimeric Arabidopsis thaliana vacuolar transporter CAX2B [a variant of N-terminus truncated form of CAX2 (sCAX2) containing the "B" domain from CAX1] that has enhanced calcium (Ca(2+)) substrate specificity and lost the manganese (Mn(2+)) transport capability of sCAX2. Here, we demonstrate that potato (Solanum tuberosum L.) tubers expressing the CAX2B contain 50-65% more calcium (Ca(2+)) than wild-type tubers. Moreover, expression of CAX2B in potatoes did not show any significant increase of the four metals tested, particularly manganese (Mn(2+)). The CAX2B-expressing potatoes have normally undergone the tuber/plant/tuber cycle for three generations; the trait appeared stable through the successive generations and showed no deleterious alternations on plant growth and development. These results demonstrate the enhanced substrate specificity of CAX2B in potato. Therefore, CAX2B can be a valuable tool for Ca(2+) nutrient enrichment of potatoes with reduced accumulation of undesirable metals.
authors.affiliation: Department of Horticulture, Sangju National University, Sangju, 742-711, Korea. ckkim@sangju.ac.kr
authors.forename: Chang Kil
authors.initials: CK
authors.lastname: Kim
authors.forename: Jeung-Sul
authors.initials: JS
authors.lastname: Han
authors.forename: Hyun-Suk
authors.initials: HS
authors.lastname: Lee
authors.forename: Joung-Youl
authors.initials: JY
authors.lastname: Oh
authors.forename: Thoshiro
authors.initials: T
authors.lastname: Shigaki
authors.forename: Sung Hun
authors.initials: SH
authors.lastname: Park
authors.forename: Kendal
authors.initials: K
authors.lastname: Hirschi
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics; D017920:Antiporters / Q000096:biosynthesis* / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D002413:Cations, Divalent; D003300:Copper / Q000378:metabolism; D017343:Genes, Plant / Q000502:physiology; D007501:Iron / Q000378:metabolism; D008345:Manganese / Q000378:metabolism*; D035281:Plant Tubers / Q000235:genetics / Q000502:physiology*; D011198:Solanum tuberosum / Q000235:genetics / Q000502:physiology*; D013379:Substrate Specificity
chemical_list: D017920:Antiporters; D027682:Cation Transport Proteins; D002413:Cations, Divalent; C027614:calcium-hydrogen antiporters; D008345:Manganese; D003300:Copper; D007501:Iron; D002118:Calcium