Alteration of Photosynthetic and Antioxidant Gene Expression in Sugarcane Infected by Multiple Mosaic Viruses

Sugarcane mosaic virus (SCMV), sugarcane streak mosaic virus (SCSMV), and sorghum mosaic virus (SrMV) are the causative pathogens of mosaic disease. This study aimed to identify mosaic virus infection and its impact on photosynthetic and antioxidant gene expression in eight commercial sugarcane cultivars grown on sugarcane plantations in East Java, Indonesia. The disease incidence and severity were observed in symptomatic leave samples, and then the virus was identified. A high incidence and severity of mosaic symptoms were observed in the PS881 and NX04 cultivars compared with the other cultivars. RT-PCR analysis detected SCSMV infection in all cultivars; double infections with SCSMV and SCMV in the PS881, PS882, and Cening cultivars; and triple infections with SCSMV, SCMV, and SrMV in the PS881 cultivar. Ascorbate peroxidase (Apx) expression was upregulated in all virus-infected cultivars and significantly increased in the triple-infected PS881 cultivar. However, catalase (Cat) expression was only slightly increased in the PS881 cultivar. The chlorophyll content was reduced, and the PsaA gene was downregulated in all cultivars. The expression of PsaA, RbcS, and Sps was significantly suppressed in the triple-infected PS881 cultivar. Moreover, the downregulation of both the RbcS and Pepc genes was concomitant with that of their protein levels.