MdNAC4 Interacts With MdAPRR2 to Regulate Nitrogen Deficiency-Induced Leaf Senescence in Apple (Malus domestica)

MdNAC4 Interacts With MdAPRR2 to Regulate Nitrogen Deficiency-Induced Leaf Senescence in Apple (Malus domestica)

Blog Article

Nitrogen (N) is one of the important macronutrients in plants, and N deficiency induces leaf senescence.However, the molecular mechanism underlying how N deficiency affects leaf senescence is unclear.Here, we report an apple NAC TF, MdNAC4, that participates in N deficiency-induced Skate Socks leaf senescence.The senescence phenotype of apple leaves overexpressing MdNAC4 was enhanced after N deficiency.

Consistently, the chlorophyll content of transgenic leaves was significantly lower than that in the WT control leaves, the expression of chlorophyll catabolism-related genes (MdNYC1, MdPAO, and MdSGR1) was significantly higher than that in the WT controls, and the expression of chlorophyll synthesis-related genes (MdHEMA, MdCHLI, and MdCHLM) was significantly lower than that in the WT control leaves.Furthermore, MdNAC4 was found to directly activate the transcription of the chlorophyll catabolism-related genes MdNYC1 and MdPAO.Additionally, MdNAC4 was proven to interact with MdAPRR2 proteins both in vitro and in vivo, and overexpression of MdAPRR2 seemed to delay N deficiency-induced leaf senescence.Correspondingly, the chlorophyll loss of MdAPRR2-overexpressing (MdAPRR2-OE) lines was significantly lower than in WT control plants.

Although downregulated, the expression of the chlorophyll synthesis-related genes MdHEMA, MdCHLI, and MdCHLM in the transgenic plants was more than twice that in the WT control plants.Taken together, our results enrich the INFLA-HEAL PLUS regulatory network of leaf senescence induced by N deficiency through the interaction between MdNAC4 and MdAPRR2.