How Tea Plant Defends Blister Blight Disease: Facts Revealed and Unexplored Horizons.

Tea ( Camellia sinensis (L.) O. Kuntze) is cultivated as a beverage crop. Despite being a hardy perennial, the tea plant is susceptible to various biotic stresses. Among them, foliar disease, blister blight (BB) is considered the most serious threat to the tea industry, particularly in Asia. Blister blight caused by Exobasidium vexans (Basidiomycetes) was first reported from Northern India in 1868 and gradually established in other tea-growing countries. The fungus E. vexans attacks young harvestable shoots and causes 20-50% crop loss. Over the past 150 years, scientific research has delved into various aspects of BB disease, including pathogen biology, disease cycle, epidemiology, disease forecasting, crop loss assessment, and disease management strategies. In a recent shift in research focus, scientists have begun to investigate the resistance mechanisms of tea plants against BB and apply this knowledge to commercial tea cultivation. While progress has been significant in understanding the fundamental aspects of BB resistance, the detailed molecular mechanisms driving this resistance remain under investigation. This paper focuses on the current understanding of defense mechanisms employed by tea plants against E. vexans , and conversely, how E. vexans overcomes these defenses. Furthermore, we discuss the application of plant resistance strategies in commercial tea cultivation. Lastly, we identify existing research gaps and propose future research directions in the field.