Transcriptional Coactivators: Driving Force of Plant Immunity

Abstract

Salicylic acid (SA) is a plant defense signal that mediates local and systemic immune responses against pathogen invasion. However, the underlying mechanism of SA-mediated defense is very complex due to the involvement of various positive and negative regulators to fine-tune its signaling in diverse pathosystems. Upon pathogen infections, elevated level of SA promotes massive transcriptional reprogramming in which Non-expresser of PR genes 1 (NPR1) acts as a central hub and transcriptional coactivator in defense responses. Recent findings show that Enhanced Disease Susceptibility 1 (EDS1) also functions as a transcriptional coactivator and stimulates the expression of PR1 in the presence of NPR1 and SA. Furthermore, EDS1 stabilizes NPR1 protein level, while NPR1 sustains EDS1 expression during pathogenic infection. The interaction of NPR1 and EDS1 coactivators initiates transcriptional reprogramming by recruiting cyclin-dependent kinase 8 in the Mediator complex to control immune responses. In this review, we highlight the recent breakthroughs that considerably advance our understanding on how transcriptional coactivators interact with their functional partners to trigger distinct pathways to facilitate immune responses, and how SA accumulation induces dynamic changes in NPR1 structure for transcriptional reprogramming. In addition, the functions of different Mediator subunits in SA-mediated plant immunity are also discussed in light of recent discoveries. Taken together, the available evidence suggests that transcriptional coactivators are essential and potent regulators of plant defense pathways and play crucial roles in coordinating plant immune responses during plant–pathogen interactions.

Genetic and morphological variants of Acidovorax avenae subsp. avenae cause red stripe of sugarcane in China

“…SA and the SA-mediated signal transduction pathway are major players in plant immunity by mediating local and systemic immune responses against pathogen invasion ( Seyfferth and Tsuda, 2014 ; Khan et al., 2022 ). SA levels are usually elevated in plants upon pathogen infections, thus promoting massive transcriptional reprogramming including increased expression of gene PR-1 ( Chu et al., 2020 ; Chu et al., 2022 ; Khan et al., 2022 ). SA and Jasmonic (JA) treatments induced tolerance to Aaa infection in creeping bentgrass ( Liu et al., 2018 ).…”

Decoding the molecular mechanism underlying salicylic acid (SA)‐mediated plant immunity: an integrated overview from its biosynthesis to the mode of action

“…This interaction may also involve other co‐regulators and chromatin remodelling complexes, further fine‐tuning the expression of defence genes. Enhanced Disease Susceptibility 1 (EDS1) acts as a transcriptional coactivator that functions in collaboration with other proteins, including Phytoalexin Deficient 4 (PAD4), to create a complex that aids in signal transduction in response to pathogen‐derived signals (Khan et al 2022). The EDS1‐PAD4 complex modulates NPR1 activity to promote the expression of defence‐responsive genes and the synthesis of antimicrobial compounds.…”

Phytomelatonin: A key regulator of redox and phytohormones signaling against biotic/abiotic stresses

“…Different stress responses trigger different Ca 2+ signaling pathways to counter the stress in plants. Cold stress primarily affects plant cell membranes, detecting stress signals and activating various cellular responses [ 48 , 49 ]. During low-temperature stress, the Ca 2+ channels are activated, resulting in rapid Ca 2+ signal induction that confers cold tolerance by activating downstream phosphorylation pathways, including C-repeat binding factors (CBFs) [ 23 ].…”