3.1 Application of exogenous MT improved the low-nitrate tolerance of apple plants
To characterize the roles of MT in response to low-N stress, the effects of different concentrations of MT (0, 0.05, 0.5 and 2.5 μM) on plant height and biomass were examined in apple plants under low-N (0.1 mM) conditions. Among all MT concentrations, plants treated with 0.5 µM MT showed the highest plant height, shoot and root fresh weight (Figure 1a-c). Thus, MT treatment improved the low-nitrate tolerance, with 0.5 µM MT was determined as the optimal concentration.