Photosynthetic plasticity aggravates the susceptibility of magnesium‐deficient leaf to high light in rapeseed plants: the importance of Rubisco and mesophyll conductance

作者：Xiaolei Ye, Ziyi Gao, Ke Xu, Binglin Li, Tao Ren, Xiaokun Li, Rihuan Cong, Zhifeng Lu, İsmail Çakmak, Jianwei Lü · 发表于：The Plant Journal · 年份：2023 · DOI：10.1111/tpj.16504 · 被引用次数：23 · 研究领域：Plant Stress Responses and Tolerance、Plant Micronutrient Interactions and Effects、Magnesium in Health and Disease

SUMMARY Plants grown under low magnesium (Mg) soils are highly susceptible to encountering light intensities that exceed the capacity of photosynthesis ( A ), leading to a depression of photosynthetic efficiency and eventually to photooxidation (i.e., leaf chlorosis). Yet, it remains unclear which processes play a key role in limiting the photosynthetic energy utilization of Mg‐deficient leaves, and whether the plasticity of A in acclimation to irradiance could have cross‐talk with Mg, hence accelerating or mitigating the photodamage. We investigated the light acclimation responses of rapeseed ( Brassica napus ) grown under low‐ and adequate‐Mg conditions. Magnesium deficiency considerably decreased rapeseed growth and leaf A , to a greater extent under high than under low light, which is associated with higher level of superoxide anion radical and more severe leaf chlorosis. This difference was mainly attributable to a greater depression in dark reaction under high light, with a higher Rubisco fallover and a more limited mesophyll conductance to CO 2 ( g m ). Plants grown under high irradiance enhanced the content and activity of Rubisco and g m to optimally utilize more light energy absorbed. However, Mg deficiency could not fulfill the need to activate the higher level of Rubisco and Rubisco activase in leaves of high‐light‐grown plants, leading to lower Rubisco activation and carboxylation rate. Additionally, Mg‐deficient leaves under high light invested more carbon per l...