AUTHOR=Zhang Zenglin , Xu Mengmeng , Guo Yongfeng 

TITLE=Ring/U-Box Protein AtUSR1 Functions in Promoting Leaf Senescence Through JA Signaling Pathway in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.608589

DOI=10.3389/fpls.2020.608589

ISSN=1664-462X

ABSTRACT=<p>Leaf senescence is regulated by a large number of internal and environmental factors. Here, we report that AtUSR1 (U-box Senescence Related 1) which encodes a plant Ring/U-box protein, is involved in age-dependent and dark-induced leaf senescence in Arabidopsis. Expression of <italic>AtUSR1</italic> gene in leaves was up-regulated in darkness and during aging. Plants of <italic>usr1</italic>, an <italic>AtUSR1</italic> gene knock-down mutant, showed a significant delay in age-dependent and dark-induced leaf senescence and the delayed senescence phenotype was rescued when the <italic>AtUSR1</italic> gene was transferred back to the mutant plants. Meanwhile, overexpression of <italic>AtUSR1</italic> caused accelerated leaf senescence. Furthermore, the role of AtUSR1 in regulating leaf senescence is related to MYC2-mediuated jasmonic acid (JA) signaling pathway. MeJA treatments promoted the accumulation of <italic>AtUSR1</italic> transcripts and this expression activation was dependent on the function of MYC2, a key transcription factor in JA signaling. Dual-luciferase assay results indicated that MYC2 promoted the expression of <italic>AtUSR1</italic>. Overexpression of <italic>AtUSR1</italic> in <italic>myc2</italic> mutant plants showed precocious senescence, while <italic>myc2</italic> mutation alone caused a delay in leaf senescence, suggesting that AtUSR1 functions downstream to MYC2 in the JA signaling pathway in promoting leaf senescence.</p>