Phenotypic analysis of exogenous application of citrate, malate and ABA
For phenotype analysis, 6-week-old seedlings with the same growth status were transplanted to a new vermiculite pot and subjected with different treatments for 3 weeks. Citric acid (citrate) (Aladdin, Shanghai, China) and malic acid (malate) (Aladdin, Shanghai, China) were dissolved with ddH2O into 0.5 M stock solution and stored at 4℃. For exogenous citrate and malate treatment, the nutrient solutions are as follows: 15 mM KNO3 + 200 μM ferrozine, 15 mM KNO3 + 200 μM ferrozine + 0.5 mM citrate/malate, 0.5 mM KNO3 + 200 μM ferrozine, 0.5 mM KNO3 + 200 μM ferrozine + 0.5 mM citrate/malate, with KCl was added to maintain the same K+ concentration (15 mM). Abscisic acid (BBI, Toronto, Canada) was dissolved with 100 µL ethanol and diluted with ddH2O into 5 mM stock solution, stored in brown reagent bottle at 4℃. ddH2O containing 100 µL ethanol was used as control. For exogenous ABA treatment, the nutrient solutions are as follows: 15 mM KNO3 + 200 μM ferrozine + control, 15 mM KNO3 + 200 μM ferrozine + 1 µM ABA, 0.5 mM KNO3 + 200 μM ferrozine + control, 0.5 mM KNO3 + 200 μM ferrozine + 1 µM ABA, with KCl was added to maintain the same K+ concentration (15 mM). Each treatment contained at least 3 biological replicates; each replicate contained 10 plant samples.