Effect of transgenic expression in rice of a calmodulin on salt stress response

Abstract

Calcium signaling has been implicated in transducing signals from environmental changes into adaptive responses in plants. Calmodulin (CaM), members of the EF-hand family of Ca2+-binding proteins, represent important relays in plant calcium signals. Here, transgenic rice plants containing OsCam1-1 gene under the control of 35SCaMV promoter (35SCaMV-OsCam1-1) were constructed by Agrobacterium-mediated transformation via pCAMBIA1301 plasmid. Three putative transgenic rice lines harboring the 35SCaMV-OsCam1-1 and two putative transgenic lines harboring the T-DNA from pCAMBIA1301 alone as negative controls have been produced. PCR analyses confirm that all transgenic plants harboring the 35SCaMV-OsCam1-1 with positive histochemical assay of the GUS reporter gene contain the OsCam1-1 transgene in their genomes. Northern blot analysis indicates that expression of the OsCam1-1 gene was highly increased in these transgenic lines. As a result, transgenic plants over-expressing this gene exhibited higher growth rate and better resistance to salt stress than the control plants. In addition, OsCam1-1-over-expressing plants were shown to contain higher levels of ABA than the control plants when grown in normal conditions or under salt stress. These results suggest that the OsCam1-1 gene product functions as a sensor for salt stress-induced calcium signals that lead to ABA biosynthesis, which in turn helps the plant to cope with salt stress.