Exploring the role of nitrogen and potassium in photosynthesis implications for sugar: Accumulation and translocation in horticultural crops

The soil contributes to the main pool of crucial mineral nutrients for plant growth. These essential nutrients play an important role in the formation of plant biomolecules, perform fundamental functions in cellular processes, and participate in a wide range of enzymatic reactions. The roots serve as the primary gateway through which mineral nutrients enter the plant, facilitating its growth and seed production. In this context, a diverse set of plant nutrient transport systems, sensors, and signaling proteins operate to acquire mineral nutrients via the roots in plants. Chemical fertilizers, primarily consisting of nitrogen (N) and potassium (K), are globally applied in agricultural areas to boost crop yields. K and N are macronutrients that are required in large quantities by plants. Both K and N are dynamic elements and significantly play a prominent role in photosynthesis and the subsequent long-distance transport of the end products during photosynthesis. Imbalances in their levels in photosynthetic organelles can lead to excessive or insufficient assimilation, resulting in an interesting response at biochemical, physiological, and anatomical levels which ultimately impact the sugar metabolism and photosynthetic carbon assimilation. In this review article, we reviewed the functioning of K and N uptake in roots, and directly or indirectly associated with photosynthesis. We focused on the impact of K and N on sugar metabolism, and the translocation of photosynthetic end products from source (leaves) to sink (fruit). Furthermore, we summarized the current understanding of K and N transport of sugar and discussed the influence of both K and N nutrients mainly on photosynthetic and sugar metabolic systems in horticultural crops. We also discussed the mechanisms with coordination to the transport of N and K uptake mechanisms and regulatory key genes in plants and sugar metabolism. Overall, this review provides comprehensive insights into the interplay between sugar metabolism, nutrient uptake, and photosynthesis, with a specific emphasis on the roles of N and K transport in plants. This review enhances our understanding of the mechanisms underlying K and N nutrient transport and their regulation and provides valuable knowledge for improving nutritional quality and crop productivity.