Abstract:

 Confronted with herbivores, plants have evolved a sophisticated network of defense, which can be classified as constitutive and induced. After perceiving herbivore-derived molecular via receptors, the tea plant (Camellia sinensis) will initiate early signaling events, and then activate multiple signaling pathways of plant pheromones, such as jasmonic acid (JA), salicylic acid (SA), ethylene (ET), gibberellin and other phytohormones, resulting in the accumulation of secondary metabolites, and eventually induce direct and indirect resistances to pests. Based on the recent research progress in tea plant defense responses induced by main insect pests and their regulatory mechanisms, we summarized the components and ecological functions of herbivore-induced plant volatiles (HIPVs) of the tea plant, and their application in green pest control, uncovered the important defense signaling network involved in the regulation of insect-induced resistance in the tea plant, emphasized on the research progress of the JA pathway in the tea plant, and proposed suggestions for future research. The infestation of Ectropis obliqua, Matsumurasca onukii and Myllocerinus aurolineatus induces 17 shared volatiles from tea plants, but induces eight, three and two specific volatiles from tea plants, respectively. Among the above volatiles, five, one and six volatiles were found to have attractiveness to E. obliqua, M. onukii and M. aurolineatus, respectively, while two volatiles and one volatile are involved in the repellence against E. obliqua and M. onukii, respectively. Thus, the attractants to these three insect species and the repellents against M. onukii have been screened out. The JA pathway and SA pathway are the two main pathways involved in the defense responses in tea plants to multiple insect pests, and the JA pathway plays a vital role. Meanwhile, several plant hormones, including auxin, abscisic acid, gibberellin, etc., also take part in tea plant induced defense processes. So far, many genes associated with JA biosynthesis and regulation have been cloned and characterized. Based on the understanding of their functions in tea plant resistance against insects, the fact that JA pathway positively regulates direct or indirect tea plant resistance to insects was revealed. We suggest that the further study should focus on further clarifying the molecular mechanisms of insect-induced resistance in the tea plant, and the utilization of induced defense against insect pests in tea plants. This article will provide guidance for in-depth research on the molecular mechanisms in induced resistance in the tea plant and further development of green pest prevention and control technologies.

Key words: Camellia sinensis, tea pests, herbivore-induced plant volatiles, phytohormones, green pest prevention and control technologies