INDOLE‐3‐ACETIC ACID INDUCIBLE 17 positively modulates natural leaf senescence through melatonin‐mediated pathway in Arabidopsis

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) functions as a ubiquitous modulator in multiple plant developmental processes and various stress responses. However, the involvement of melatonin in natural leaf senescence and the underlying molecular mechanism in Arabidopsis remain unclear. In this study, we found that the endogenous melatonin level was significantly induced in a developmental stage-dependent manner, and exogenous melatonin treatment delayed natural leaf senescence in Arabidopsis. The expression level of AUXIN RESISTANT 3 (AXR3)/INDOLE-3-ACETIC ACID INDUCIBLE 17 (IAA17) was significantly downregulated by exogenous melatonin treatment and decreased with developmental age in Arabidopsis. Further investigation indicated that AtIAA17-overexpressing plants showed early leaf senescence with lower chlorophyll content in rosette leaves compared with wild-type plants, while AtIAA17 knockout mutants displayed delayed leaf senescence with higher chlorophyll content. Notably, exogenous melatonin-delayed leaf senescence was largely alleviated in AtIAA17-overexpressing plants, and AtIAA17-activated senescence-related SENESCENCE 4 (SEN4) and SENESCENCE-ASSOCIATED GENE 12 (SAG12) transcripts might have contributed to the process of natural leaf senescence. Taken together, the results indicate that AtIAA17 is a positive modulator of natural leaf senescence and provides direct link between melatonin and AtIAA17 in the process of natural leaf senescence in Arabidopsis.

Melatonin Application to Pisum sativum L. Seeds Positively Influences the Function of the Photosynthetic Apparatus in Growing Seedlings during Paraquat-Induced Oxidative Stress

“…Additionally, melatonin enhanced the activity of antioxidant enzymes (including SOD, POD, CAT, and APX) and concentrations of antioxidants (ascorbic acid and glutathione), reducing in this way the oxidative damage and increasing salinity tolerance of plants. Natural senescence of Arabidopsis thaliana leaves was also delayed by exogenous melatonin treatment and one positive regulator of natural leaf senescence -AtIAA17 [gene of auxin-resistant 3 (AXR3)/indole-3-acetic acid–inducible 17] was significantly repressed (Shi et al, 2015). Transcriptome analysis of A. thaliana suggests that melatonin may play critical role(s) in plant defense systems (Weeda et al, 2014).…”

A new balancing act: The many roles of melatonin and serotonin in plant growth and development

“…The ability of MEL to delay senescence has also been widely examined with much more insight now being available into the potential mechanisms of action 58,[106][107][108][109] . An interesting aspect of MEL is its ability to promote formation of new tissues while maintaining ageing tissues.…”

“…From a metabolic perspective, the antioxidant capacity of MEL is able to maintain the photosynthetic process, preventing chlorophyll degradation and increasing efficiency of photosystem II as well as regulating sugar and nitrogen metabolism and preventing protein degradation [106][107][108]110 . At the genetic level in particular, three senescence-related genes may be involved: indole-3-acetic acid inducible 17 (AXR3), senescence associated gene 12 (SAG 12) and senescence 4 (SEN4) suggesting a potential interaction with auxin signaling 109 . In apple, autophagy-related genes involved in age-related protein degradation have been found to be suppressed by MEL possibly also contributing metabolically to this mechanism 106 .…”

The ERF transcription factor EPI1 is a negative regulator of dark-induced and jasmonate-stimulated senescence in <i>Arabidopsis</i>

“…Because the present results suggest that EPI1 and EPI1-SRDX negatively affect MeJA-stimulated senescence, we examined whether the expression levels of the wellknown senescence-induced genes SENESCENCE-ASSOCIATED GENE (SAG) 12, SAG13, and SAG29 (Otegui et al 2005;Park et al 1998;Shi et al 2015;Weaver et al 1998) are also affected by MeJA treatment in WT and EPI1-SRDX plants under the constant dark condition. Because EPI1-ox and EPI1-SRDX plants displayed similar responses in all experiments, further data shown here were obtained by using EPI1-SRDX plants.…”