The Arabidopsis senescence associated gene 13 regulates dark-induced senescence and plays contrasting roles in the defense against bacterial and fungal pathogens

Authors: DHAR, NIKHILESH - University Of California; CARUANA, JULIE - Syracuse University; ERDEM, IRMAK - Syracuse University; SUBBARAO, KRISHNA - University Of California; Klosterman, Steven; RAINA, RAMESH - Syracuse University

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2020
Publication Date: 2/16/2020
Citation: Dhar, N., Caruana, J., Erdem, I., Subbarao, K., Klosterman, S.J., Raina, R. 2020. The Arabidopsis senescence associated gene 13 regulates dark-induced senescence and plays contrasting roles in the defense against bacterial and fungal pathogens. Molecular Plant-Microbe Interactions. 33(5):754-766. https://doi.org/10.1094/MPMI-11-19-0329-R.
DOI: https://doi.org/10.1094/MPMI-11-19-0329-R

Interpretive Summary: Plant senescence and programmed cell death in plants are developmentally controlled processes, and the latter process may also occur in response to plant pathogens. A common genetic marker of senescence is a gene known as Senescence-Associated Gene 13 (SAG13), but the role of SAG13 in plant cell death processes has been unknown. This work reveals that SAG13 protects the plant against oxidative stress and other stresses, and is also required for normal seed germination, seedling growth, purple-red pigment accumulation, and for resistance against the fungus Botrytis cinerea. Since the SAG13 gene is widely present in plants, the gene can be useful as a marker in crop plant development, fungal resistance, for normal seed germination and oxidative stress responses.

Technical Abstract: Senescence associated gene 13 (SAG13) of Arabidopsis is a widely conserved gene of unknown function that has been extensively used as a marker of plant senescence. SAG13 induction occurs during plant cell death processes, including senescence and hypersensitive response (HR), a type of programmed cell death that occurs in response to pathogens. This implies that SAG13 expression is regulated through at least two different signaling pathways affecting these two different processes. Our work highlights a contrasting role for SAG13 in regulating resistance against disease causing biotrophic bacterial and necrotrophic fungal pathogens with contrasting infection strategies. We provide further evidence that SAG13 is not only induced during oxidative stress but also plays a role in protecting the plant against other stresses. SAG13 is also required for normal seed germination, seedling growth, and anthocyanin accumulation. The work presented here provides evidence for the role of SAG13 in regulating multiple plant processes including senescence, defense, seed germination, and abiotic stress responses. Since SAG13 is a valuable molecular marker for these processes, and is conserved in multiple plant species, and this knowledge has important implications for crop improvement.