Abstract: In order to obtain marker-free transgenic rice with improved disease resistance, the AP1 gene of Capsicum annuum and hygromycin-resistance gene (HPT) were cloned into the two separate T-DNA regions of the binary vector pSB130, respectively, and introduced into the calli derived from immature seeds of two elite Japonica rice varieties, Guanglingxiangjing and Wuxiangjing 9, mediated by Agrobacterium-mediated transformation. Many co-transgenic rice lines, containing both the AP1 gene and the marker gene, were regenerated, and the integration of both transgenes in the transgenic rice plants was confirmed by either PCR or Southern blotting technique. Several selectable-marker free transgenic rice plants were subsequently obtained from the progeny of the co-transformants, and confirmed by both PCR and Southern blotting analysis. These transgenic rice lines were tested in the field and their resistance to disease was carefully investigated, the results showed that after inoculation the resistance to either bacterial blight or sheath blight of the selected transgenic lines was improved when compared with those of wild type.

Key words: Rice (Oryza sativa L.), Disease resistance, AP1 gene, Selectable marker-free, Bacterial leaf blight, Sheath blight