• Journal of Plant Biotechnology
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• v.37 no.4
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• pp.549-555
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• 2010

Here we focused on tip-burn and blossom-end rot (BER) symptoms in the tomato plants expressing the constitutively active form of $Ca^{2+}/H^+$ antiporter (sCAX1) and/or a Ca-binding protein (calreticulin, CRT) genes during their whole growth period. Conclusively we demonstrated that CRT is able to suppress the tip-burn and BER symptoms that were induced by sCAX1. Under poor nutrition condition, tomato plants overexpressing sCAX1 showed severe necrotic collapses in both roots and shoot polar tissues, which are in accordance with $Ca^{2+}$ deficient symptoms frequently observed in an agricultural cultivation of tomato. Reciprocal grafting trials using sCAX1 and wild type plants revealed that the tip-burn symptom by sCAX1 overexpression is not caused by hindrance of $Ca^{2+}$ uptake from soil. We constructed CRT overexpressing transgenic tomatoes, and crossed them with sCAX1 transgenic plants to investigate the effects of CRT on the symptoms of sCAX1 transgenic plants. Co-expression of sCAX1 and CRT significantly suppressed the $Ca^{2+}$ deficient symptoms of sCAX1 transgenic plants. Those results suggest the model that $Ca^{2+}$ homeostasis disturbed by the overexpression of sCAX1 may be suppressed by the co-expression of CRT.