StHY5 regulates potato plant morphology to accommodate UV-B radiation

Potato serves as both a principal crop and dietary staple across numerous low-latitude, high-altitude agricultural regions worldwide. The intense ultraviolet radiation characteristic of these environments and its detrimental effects on potato cultivation have garnered considerable scientific interest. In this study, we demonstrate that UV-B radiation suppresses plant height and canopy area in potato, resulting in diminished biomass accumulation and tuber yield. RNA sequencing combined with quantitative analysis of bioactive gibberellic acid (GA) levels revealed that UV-B-induced activation of GA catabolism represents a critical mechanism underlying these morphological adaptations. Our investigation revealed that UV-B radiation enhanced StHY5 expression levels. To elucidate the functional role of this gene, we generated StHY5 overexpression (OE_StHY5) and RNA interference (StHY5_RNAi) lines in cultivated potato varieties. These functional analyses demonstrated that StHY5 serves as a critical regulatory gene governing potato plant architecture. Specifically, OE_StHY5 lines exhibited significant reductions in both plant height and canopy area compared to StHY5_RNAi lines and Wild Type (WT) plants. Despite enhanced net photosynthetic rates, OE_StHY5 lines exhibited reduced plant biomass accumulation and yield performance relative to WT and StHY5_RNAi lines. Our findings indicate that StHY5 functions as a pivotal regulatory node linking UV-B signaling pathways with GA metabolic processes. These findings elucidate the molecular mechanisms underlying potato morphological adaptation to UV-B stress, providing valuable insights for optimizing potato cultivation strategies in low-latitude, high-altitude agricultural systems.