Transcriptome response of resistance and susceptible winter wheat to wheat curl mite herbivory

Wheat is one of the most crucial crops worldwide, contributing significantly to human food security. Wheat curl mite (WCM) (Aceria tosichella Keifer) is a major pest of winter wheat (Triticum aestivum L.) in North America, being the only known vector of three damaging plant viruses, Wheat streak mosaic virus, Triticum mosaic virus, and High Plains wheat mosaic virus. Host plant resistance to WCM has been used as an important management strategy for this wheat-mite-virus complex. Reproduction rate of WCM on resistant wheat has been shown frequently to be reduced compared to susceptible varieties, thus contributing to reduction of virus spread. However, WCM is a cryptic species complex, resulting in great variability in WCM responses to resistance genes in winter wheat. The stability of WCM resistance has been questioned because adaptation to one mite resistance gene has been demonstrated previously. Furthermore, little is known regarding the interactions between WCMs and winter wheat on a molecular-level, adding more challenges in breeding for resistant varieties. The underlying defense mechanisms to WCMs were explored by quantifying transcriptomic differences between mite-resistant and susceptible winter wheat varieties by using RNA-seq technology. More than 11,000 differentially expressed genes were identified among treatments. Numerous genes and pathways involved in plant defenses were found up-regulating in the resistant line while down-regulating in the susceptible line when exposed WCM herbivory.