Rice ETHYLENE RESPONSE FACTOR 101 Promotes Leaf Senescence Through Jasmonic Acid-Mediated Regulation of OsNAP and OsMYC2

Abstract

Leaf senescence is the final stage of leaf development and an important step that relocates nutrients for grain filling in cereal crops. Senescence occurs in an agedependent manner and under unfavorable environmental conditions such as deep shade, water deficit, and high salinity stresses. Although many transcription factors that modulate leaf senescence have been identified, the mechanisms that regulate leaf senescence in response to environmental conditions remain elusive. Here, we show that rice (Oryza sativa) ETHYLENE RESPONSE FACTOR 101 (OsERF101) promotes the onset and progression of leaf senescence. OsERF101 encodes a predicted transcription factor and OsERF101 transcript levels rapidly increased in rice leaves during dark-induced senescence (DIS), indicating that OsERF101 is a senescence-associated transcription factor. Compared with wild type, the oserf101 T-DNA knockout mutant showed delayed leaf yellowing and higher chlorophyll contents during DIS and natural senescence. Consistent with its delayed-yellowing phenotype, the oserf101 mutant exhibited downregulation of genes involved in chlorophyll degradation, including rice NAM, ATAF1/2, and CUC2 (OsNAP), STAY-GREEN (SGR), NON-YELLOW COLORING 1 (NYC1), and NYC3 during DIS. After methyl jasmonate treatment to induce rapid leaf de-greening, the oserf101 leaves retained more chlorophyll compared with wild type, indicating that OsERF101 is involved in promoting jasmonic acid (JA)-induced leaf senescence. Consistent with the involvement of JA, the expression of the JA signaling genes OsMYC2/JA INSENSITIVE 1 (OsJAI1) and CORONATINE INSENSITIVE 1a (OsCOI1a), was downregulated in the oserf101 leaves during DIS. Transient transactivation and chromatin immunoprecipitation assays revealed that OsERF101 directly binds to the promoter regions of OsNAP and OsMYC2, which activate genes involved in chlorophyll degradation and JA signaling-mediated leaf senescence. These

Low Light/Darkness as Stressors of Multifactor-Induced Senescence in Rice Plants

“…Rice jasmonate ZIM-domain protein (OsJAZ8)—a repressor of JA signaling, degradation, and ubiquitination—enables the release and regulation of downstream TFs (e.g., MYC2 and its homologs MYC3/4), which are positively regulated by ANAC019, ANAC055, and ANAC072 TFs in JA-mediated leaf senescence under DIS conditions [ 51 ]. After 3 days of dark treatment, the expressions of JA signaling-related genes ( OsMYC2 and OsCOI1a ) and JA biosynthesis-related genes ( OsLOX2 and OsAOS1 ) were down-regulated in the ethylene-responsive factor ( oserf101 ) mutant as compared to WT [ 52 ]. Meanwhile, low endogenous JA levels and low expressions of JA-biosynthesis-related genes ( OsLOX2 , OsLOX8 , OsHI-LOX , OsAOS1, and OsAOS2 ) were reported in the osdof24-D (gain-of-function lines), suggesting a delayed senescing phenotype during DIS [ 53 ].…”

“…OsEIL1, the homolog of EIN3, up-regulated the downstream target gene β subunit of polygalacturonase subfamily ( OsBURP16 ) expression by a 270-fold response to dark treatment, causing decreased pectin content and thus affected the cell integrity [ 77 , 78 ]. Regarding another ethylene response factor ERF101, its loss-of-function mutants ( oserf101 ) retained their leaves’ green color, which exhibited down-regulation of chlorophyll degrading enzymes (NYC1 and NYC3) and SGR, in addition to NAM and CUC TF candidates, as compared to the WT leaves [ 52 ].…”

Genome-Wide Identification, Expression and Potential Function Analysis of the ERF and DREB Subfamily Members in Tomato

“…For example, AtERF115 can repress adventitious rooting in Arabidopsis through the JA and CTK signaling pathways [64], but PUCHI (At5g18560) can positively regulate oral meristems, organ initiation, and lateral root development in Arabidopsis [12,13]. Rice OsERF101 regulates leaf senescence and responses to drought stress in reproductive tissues [65,66]. These ndings suggest that some ERF proteins often regulate several plant life processes.…”

Jasmonates and Plant Salt Stress: Molecular Players, Physiological Effects, and Improving Tolerance by Using Genome-Associated Tools

“…JA–ET crosstalk can be complex and depends on the specific situation. A synergistic effect has been observed in promoting leaf senescence [ 127 , 128 ], but antagonistic interaction was found in controlling apical hook curvature [ 129 ]. JA–ET interactions in response to pathogen infections, herbivore attacks, and environmental stress are context-specific.…”