Resistance of transgenic zoysiagrass overexpressing the zoysiagrass class II chitinase gene Zjchi2 against Rhizoctonia solani AG2-2 (IV)

Zoysiagrass ( Zoysia japonica Steud.) is an important turfgrass species used in golf courses and athletic fields. However, zoysiagrass is susceptible to large patch disease caused by Rhizoctonia solani AG2-2 (IV). Chitinases are pathogen-related (PR) proteins induced by viruses, bacteria, and fungi that hydrolyze chitin. Recently, we isolated a class II chitinase gene ( Zjchi2 ) from zoysiagrass. The purified recombinant Zjchi2 showed broad-spectrum activity against various fungi, including R . solani AG2-2 (IV). In the current study, we generated transgenic zoysiagrass overexpressing Zjchi2 and then verified the resistance of transgenic plants to R . solani AG2-2 (IV). Polymerase chain reaction and Southern blot hybridization showed the integration of transgenes in zoysiagrass genomes and constitutive expression of Zjchi2 , respectively. Antifungal activity was enhanced significantly in the transgenic zoysiagrass compared with wild-type plants. To our knowledge, this report is the first on the antifungal activity of a class II chitinase in transgenic zoysiagrass.