Unveiling the intrinsic mechanism of photoprotection in bamboo under high light

The study aims to unveil the intrinsic photoprotection mechanism of bamboo under high light. Bamboo, a fast-growing and regenerative plant, exhibits a wide distribution in temperate, subtropical, and tropical regions. Bamboo frequently exposed to various environmental stresses, including excessive light, which can cause photoinhibition and even photooxidative damage to the photosynthetic apparatus. However, the characteristics and intrinsic mechanism of bamboo photoprotection are still unclear. The photosynthetic performance and photoprotective capacity of 20 bamboo species by the chlorophyll fluorescence parameters are investigated in this study. Based on the results of similar photosynthetic and photoprotective characteristics in diverse bamboo species, moso bamboo (Phyllostachys edulis) is selected as the representative bamboo species for further investigation. The light energy allocation in leaves of moso bamboo under different light intensities is analyzed to reveal its adaptability to light fluctuations in nature. Meanwhile, the expression levels of non-photochemical quenching (NPQ)-related genes in leaves of moso bamboo under high light is analyzed. The results demonstrate that the expression of NPQ-related genes is induced by high light, especially that of PsbSs and VDE is significant, indicating they play important roles in photoprotection. Furthermore, in-planta gene editing of PsbSs and VDE is conducted respectively. The sequencing results reveal that the mutation rates of edited PsbS1, PsbS2, and VDE were 12.48 %, 13.42 %, and 14.43 % respectively. As a result, the NPQ values with edited PsbSs, VDE, and both are all lower than those of control under high light, indicating that the photoprotective capacity of bamboo leaves is weakened after gene editing. These findings contribute to a deeper understanding of the photoprotection mechanism in bamboo and establish a foundation for breeding new germplasm with enhanced carbon fixation capacity and higher bamboo timber yield.