Sufficient potassium improves inorganic phosphate‐limited photosynthesis in<i>Brassica napus</i>by enhancing metabolic phosphorus fractions and Rubisco activity
Jinyao Yan, Xiaolei Ye, Yi Song, Tao Ren, Chongmin Wang, Xiaokun Li, Rihuan Cong, Zhifeng Lu, Jianwei Lü
Abstract
SUMMARY Crop photosynthesis ( A ) and productivity are often limited by a combination of nutrient stresses, such that changes in the availability of one nutrient may affect the availability of another nutrient, in turn influencing A . In this study, we examined the synergistic effects of phosphorus (P) and potassium (K) on leaf A in a nutrient amendment experiment, in which P and K were added individually or in combination to Brassica napus grown under P and K co‐limitation. The data revealed that the addition of P gradually removed the dominant limiting factor (i.e. the limited availability of P) and improved leaf A . Strikingly, the addition of K synergistically improved the overall uptake of P, mainly by boosting plant growth, and compensated for the physiological demand for P by prioritizing investment in metabolic pools of P (P‐containing metabolites and inorganic phosphate, Pi). The enlarged pool of metabolically active P was partially associated with the upregulation of Pi regeneration through release from triose phosphates rather than replacement of P‐containing lipids. This process mitigated P restrictions on A by maintaining the ATP/NADPH and NADPH/NADP + ratios and increasing the content and activity of Rubisco. Our findings demonstrate that sufficient K increased Pi‐limited A by enhancing metabolic P fractions and Rubisco activity. Thus, ionic synergism may be exploited to mitigate nutrient‐limiting factors to improve crop productivity.