Calcium Uptake Pattern and Its Transport Pathway in ‘Shixia’ Longan Fruit

Calcium plays an irreplaceable role as an essential mineral nutrient in plants, particularly in the formation of calcium pectinate, which is critical for cell wall construction. Fruits deficient in calcium are more susceptible to cell wall disintegration, bacterial infections, and the development of various physiological disorders and fungal diseases. Despite its importance, limited research has focused on calcium nutrition in longan, and the pathways and regulatory mechanisms underlying calcium uptake in this fruit remain unclear. In this study, we investigated calcium uptake in longan at different developmental stages, examined its variation patterns, analyzed the correlations between calcium concentrations in the pedicel and the fruit, and explored the distribution of calcium in the pedicel. We also studied the functions of xylem/apoplastic and symplastic pathways using dye tracers. Our findings contribute to a deeper understanding of calcium nutrition in longan and clarify the transportation characteristics of calcium within longan fruit.