Physico-chemical properties of Arabidopsis Ca²⁺/H⁺ antiporter transgenic rice grain

In this study, calcium contents, physico-chemical compositions, and grain related cytological & agronomic traits of CAX1 (CAtione Xange) transgenic rice plants were examined. The average content of calcium in brown seeds of transgenic plants was 183.3ppm, which was elevated to 71% more than that of the parental cultivar 'llpum'. CLMS analysis revealed that the starch granule compound was more compact and dense in the endosperm of the CAX1 transgenic grain. Green fluorescence was observed having strong signals in the cell and the vacuolar membranes, respectively. The grain size of CAX1 transgenic rice was similar to the parental cultivar; however, one thousand grain weight was reduced to 21.8g from that of 25.9g in the parental cultivar 'llpum'. Physico-chemical properties of the endosperm such as amylose, protein and lipid content were similar to the parental cultivar 'llpum'. The results indicate that Arabidopsis CAX1 is successfully expressed in rice and found to increase calcium contents in the endosperm. Among the transgenic plants, elite plants can be selected with elevated calcium content of about 2.4 times more than parental cultivar, 'llpum'. These lines can be used as a good genetic resource for releasing calcium fortified rice in the future.