Melatonin Promotes Iron Uptake and Accumulation in Peach

Iron deficiency leads to stunted growth in fruit trees and reduces the yield and quality of fruits. To increase the uptake of iron in fruit trees and provide a reference to control iron deficiency, the effects of different concentrations of melatonin (MT) on iron uptake in peach (Prunus persica) were studied by a pot experiment. Concentrations of 0, 50, 100, 150, and 200 mu M MT were used in this experiment. MT increased the biomass of peach. Concentrations of 100, 150, and 200 mu M MT increased the contents of total and active iron in peach. Concentration of 150 mu M MT got the maxmiums of total iron contents in stems and leaves, which increased by 28.79% and 36.11%, respectively, compared with the control. Correspondingly, concentrations of 100 and 150 mu M MT upregulated the genes related to iron absorption, including the ferric reduction oxidase 7 (FRO7), vacuolar iron transporter 1 (VIT1), and ferric reduction oxidase 4 (FRO4), while downregulating the vacuole genes vacuolar iron transporter homolog 4 (VITH4) and natural resistance-associated macrophage protein 3 (NRAMP3) that are related to vacuolar iron transport. The concentrations of absorbable iron forms, including the water soluble iron, adsorbed iron, carbonate and strongly adsorbed iron, and manganese oxide bound iron, in the soil increased, and the soil pH value decreased following the addition of 100, 150, and 200 mu M MT. A correlation analysis showed that the contents of total and active iron in peach correlated with the biomass, soil pH value, absorbable soil iron forms, and level of expression of the iron absorption related genes. These observations indicate that treated with 100-200 mu M MT could promote the iron uptake and accumulation in peach by regulating the physiological metabolism related to iron.