Transgenic basmati rice transformed with the Xa21 gene shows resistance against bacterial leaf blight

Rice (Oryza sativa L.) cultivar Super Basmati was transformed with a cloned gene, Xa21, through particle bombardment method. Twenty-two plants were recovered from the selected calli. Initial screening through PCR confirmed the presence of the transgene in 21 plants. Southern analysis further confirmed the integration of the Xa21 gene into the genome of these transgenic plants. Analysis of the T1 generation revealed that both the hpt and Xa21 genes were successfully transmitted from the primary transformants to the progeny. Bioassays with two local isolates of bacterial leaf blight pathogen, Xanthomonas oryzae pv. oryzae (Xoo), showed that 14 transgenic lines were resistant to both Xoo isolates. No significant differences were observed in yield and grain characteristics between transgenic lines and the control; however, the transgenic lines took 8-12 days longer to flower and showed reduced plant height compared to the control plants. In conclusion, we have developed bacterial blight-resistant transgenic lines that can be further exploited by breeders for rice improvement.