Expression of an Arabidopsis CAX2 variant in potato tubers increases calcium levels with no accumulation of manganese.
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.
Kim
Chang Kil
CK
Department of Horticulture, Sangju National University, Sangju, 742-711, Korea. ckkim@sangju.ac.kr
Han
Jeung-Sul
JS
Lee
Hyun-Suk
HS
Oh
Joung-Youl
JY
Shigaki
Thoshiro
T
Park
Sung Hun
SH
Hirschi
Kendal
K
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
D017920:Antiporters; D027682:Cation Transport Proteins; D002413:Cations, Divalent; C027614:calcium-hydrogen antiporters; D008345:Manganese; D003300:Copper; D007501:Iron; D002118:Calcium