Characterisation of the Barley Oxalate Oxidase Gene and Generation of Rice Transformant

In the last two decades efforts have been made to identify, isolate and characterise disease resistance or defense related genes. One such gene is the oxalate oxidase (OXO; EC 1.2.3.4) gene which is an enzyme that enhances plants disease resistance by catalyzing the conversion of oxalic acid to hydrogen peroxide. Here, we isolated and transformed a putative OXO gene from a barley BAC clone 450N4 through PCR using specifically designed primers based on the barley OXO cDNA sequence from NCBI. The amplified sequence was identical to the barley OXO gene (Y14203) and barley OXO germin protein. The amplified gene has a coding region of 675 bp and has been shown to be involved in abiotic and biotic stress regulation. The OXO sequence was then introduced into a binary vector that was built using the pGA1611 and pCambia1301. This gene was then transformed into Oryza sativa indica cultivar MR81. The resulting construct, pCam-Ubi-MyOXO has a maize ubiquitin promoter and a NOS terminator. This construct was transformed into induced calli from rice immature embryo of a local elite cultivar, MR81, as explant. PCR analysis detected the presence of MyOXO gene with transformation efficiency of 1.7% (5/280). As a defense related gene and the role it plays in biotic stress regulation makes OXO a food candidate for resistance against diseases rice.