Characterization of synergy between Cucumber mosaic virus and Alternaria alternata in Nicotiana tabacum

• Published in: Physiological and molecular plant pathology 2019-12, Vol.108, p.101404, Article 101404
• Main Authors: Tang, Zhong-Qin, Shang, Jing, Zhang, Lei, Du, Jun-Bo, Yang, Hui, Zeng, Shu-Hua, Li, Pei-Li, Bawa, George, Yu, Liang, Hou, Xin-Xin, Yang, Wen-Yu
• Format: Article
• Language: English
• Subjects: Alternaria alternata; Cucumber mosaic virus; Defense genes expressions; Physiological change; Synergy
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1016/j.pmpp.2019.03.001

Co-infections in plants regularly occur in natural ecosystems. In the present study, we simulated co-infection in Nicotiana tabacum (N. tabacum) with Cucumber mosaic virus (CMV) and Alternaria alternata (A. alternata) under laboratory conditions. In the co-infection system of CMV and A. alternata, severe oxidative stress was produced. High concentrations of reactive oxygen species accumulated in Nicotiana tabacum. Antioxidant enzymes were highly activated to resist damage to the body. Photosynthetic parameters and chlorophyll fluorescence parameters showed that the decline of photosynthetic rate (Pn) in co-infection was lower than in single infection. At the same time, the heat dissipation increased. The accumulation of A. alternata and CMV were significantly higher in co-infected plants than single infected plants. Pathogens accumulation was also affected by the inoculation sequence. The expression of salicylic acid (SA)-mediated genes was significantly up-regulated. These results indicated that SA played a key role in the synergistic infection of N. tabacum against CMV and A. alternata. •This paper is the first time investigating the Nicotiana tabacum responds to the co-infection by viruses and fungi.•The synergy between CMV and A. alternata resulted in a significant up-regulation of the expression of SA-mediated genes.•SA-mediated disease-resistance was important for Nicotiana tabacum resistance to CMV and A. alternata.