NtNCED3 regulates responses to phosphate deficiency and drought stress in Nicotiana tabacum

Plants are sessile and encounter to abiotic environmental stressors, such as nutrient deficiency and drought stress. Identifying stress tolerance genes and their mechanisms is vital to ensuring plant survival. In this study, we characterized NCED3 in the tobacco plant Nicotiana tabacum, a key enzyme in the biosynthesis of abscisic acid that is widely involved in abiotic stress responses, using overexpression and RNA interference knockdown. Overexpression of NtNCED3 promoted primary root development, leading to increased dry weight, root-to-shoot ratio, photosynthetic capacity, and acid phosphatase activity, coinciding with highly increased phosphate uptake capability under low phosphate conditions. Under both drought and extreme phosphate deficiency conditions, the phosphate starvation response preceded the drought stress response. However, under high phosphate conditions, the drought stress phenotype emerged before the symptoms of phosphate deficiency. Plants overexpressing NtNCED3 grew better than the wild-type and NtNCED3 knockdown plants, with more developed root systems and higher biomass, phosphorus content, and hormone content. This study provides evidence that NtNCED3 enzyme participates in plant responses to phosphate deficiency and drought stress in N. tabacum, and NtNCED3 may serve as a potentially valuable gene for genetic modification of plant tolerance to both drought stress and phosphate starvation.