Abstract
Leaf senescence is a highly complex genetic process that is finely tuned by multiple layers of regulation. Among them, transcriptional regulation plays a critical role in controlling the initiation and progression of leaf senescence. Here, we found that the NAC transcription factor NAC075 functions as a novel negative regulator of leaf senescence. Loss of function of NAC075 promotes leaf senescence in an age-dependent manner, whereas constitutive overexpression of NAC075 delays senescence in Arabidopsis. Transcriptome analysis revealed that transcript levels of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) are significantly suppressed in nac075 mutants compared with wild-type plants. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) analyses revealed that NAC075 directly binds the promoter of catalase 2 (CAT2). Moreover, genetic analysis showed that overexpression of CAT2 suppresses the overproduction of reactive oxygen species (ROS) and the early senescence phenotypes of nac075 mutants, suggesting that CAT2 acts downstream of NAC075 to delay leaf senescence by repressing ROS accumulation. Collectively, our findings provide a new regulatory module involving NAC075-CAT2-ROS in controlling leaf senescence in Arabidopsis.
Highlights
Leaf senescence is a universal biological phenomenon in nature that contributes to the recycling of nutrients (Guo and Gan, 2005; Hughes and Reynolds, 2005)
Time-course analysis of mRNA level monitored by quantitative RT-PCR (qRT-PCR) revealed that the transcript level of NAC075 gradually increased during leaf development and senescence (Figure 1A)
We found that treatment with the ethylene precursor ACC (1aminocyclopropane-1-carboxylate), methyl jasmonate (MeJA), salicylic acid (SA), abscisic acid (ABA), H2O2, and salt increased the expression levels of NAC075 compared to the mock-treated plants (Figure 1C)
Summary
Leaf senescence is a universal biological phenomenon in nature that contributes to the recycling of nutrients (Guo and Gan, 2005; Hughes and Reynolds, 2005). NAC075 Negatively Regulates Leaf Senescence of macromolecular substances such as proteins, lipids, and nucleic acids are transferred to active growing organs such as new buds and developing fruits and seeds, or stored for use in the growing season (Guo and Gan, 2005; Lim et al, 2007; Woo et al, 2019). Significant advances in understanding the regulatory mechanisms of leaf senescence will provide valuable clues for the manipulation of traits of agronomical important plants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
