Systemin‐mediated long‐distance systemic defense responses

Abstract

Systemin, a peptide plant hormone of 18 amino acids, coordinates local and systemic immune responses. The activation of the canonical systemin-mediated systemic signaling pathway involves systemin release from its precursor prosystemin, systemin binding to its membrane receptor SYSTEMIN RECEPTOR1 (SYR1), and the transport of long-distance signaling molecules, including jasmonic acid, the prosystemin mRNA, volatile organic compounds and possibly systemin itself. Here, we review emerging evidence that the disordered structure and unconventional processing and secretion of systemin contribute to the regulation of systeminmediated signaling during plant defense. We highlight recent advances in systemin research, which elucidated how cells integrate multiple long-distance signals into the systemic defense response. In addition, we discuss the perception of systemin by SYR1 and its mediation of downstream defense responses.

Jasmonic Acid Signaling and Molecular Crosstalk with Other Phytohormones

“…Since cell-cell transportation of JA involves both influx and efflux across plasma membranes, it is likely that other JATs, such as the JA exporters AtJAT1 [47] and another potential JA exporter, AtJAT5 [48], are involved. These findings support the idea that JA may act as one component of the mobile molecular signatures in stress-or wound-induced systemic responses [53].…”

“…JA has also been reported to be involved in a wide range of abiotic stress responses, including salt, drought, heavy metal, high and low temperature, light stress and ozone stress [23,127]. Furthermore, mounting evidence suggests that JA and its precursors, such as OPDA, participate in systemic signaling in plants, through which local stress can be perceived throughout the entire plant to induce systemic defense response or systemic acquired acclimation (SAA) [47,49,53,[170][171][172][173].…”

Genome-wide dynamic network analysis reveals the potential genes for MeJA-induced growth-to-defense transition

“…JAs-mediated growth-to-defense tradeoffs regulate plant defense against necrotrophic pathogens and insect herbivores [ 16 , 17 ]. In previous studies, many genes of the JA signaling pathway were identified as participants of plant defense [ 18 – 20 ]. By the crosstalk with other phytohormones, JAs take part in the defense against abiotic stresses and biotic stresses [ 21 – 23 ].…”

Phytocytokines function as immunological modulators of plant immunity

“…Systemin was found in most species of the Solanaceae family (Ryan and Pearce 2003). Treatment of tomatoes with systemin triggers an array of resistance responses, including the production of proteinase inhibitors, the induction of extracellular alkalization and ethylene emission, and defense against insect herbivory (Zhang et al 2020a). PEP1, a 23-aa peptide, is the first phytocytokine identified in Arabidopsis.…”