P-527 - Phytohormonal responses in wheat infected by wheat curl mite-vectored viruses

Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) significantly constrain wheat production in the US Great Plains and are transmitted by wheat curl mites (WCM, Aceria tosichella, Keifer). WCM survival and reproductive rate were positively and negatively impacted when feeding on WSMV- and TriMV-infected wheat plants, respectively. However, the mechanisms underlying these differential WCM survival and reproduction rates remain unclear. We hypothesize that TriMV-induced phytohormone alterations influence WCM survival and reproduction. In this study, we compared phytohormone levels in wheat (cv. Settler CL) infected with either WSMV, TriMV, or coinfected with both viruses. Fourteen-day-old wheat seedlings were inoculated mechanically using infected sap or through viruliferous mites. Each treatment included 3 individual plant replicates, and the experiment was repeated three times. Composite leaf samples (0.1 g) were collected from each treatment at 0- and 21-days post-inoculation, immediately flash-frozen with liquid nitrogen, and later analyzed using liquid chromatography-mass spectrometry (LC-MS). Prior to LC-MS analysis, virus presence was confirmed with ELISA and RT-PCR. Initial results indicated that salicylic acid (SA) levels were strongly induced in mechanically inoculated TriMV-infected plants compared to WSMV-infected and mock-inoculated control plants. Whereas the WSMV-TriMV coinfection increased abscisic acid and OPDA levels but decreased SA levels. Ongoing experiments are comparing phytohormone levels in wheat inoculated with viruliferous WCM.