Exploring the Role of Autophagy in Defense Priming and Systemic Resistance in Arabidopsis

LACASE, LUZ; CAMBIAGNO, DAMIÁN ALEJANDRO; CECCHINI, NICOLÁS MIGUEL; LESCANO LÓPEZ, IGNACIO; LASCANO, HERNÁN RAMIRO; ROBERT, GERMÁN

Rosario

Congreso; Argentinian meeting of Plant Physiology (RAFV 2023); 2023

SAFV

Cellular memory in plants is regulated by epigenetic and non-epigenetic mechanisms, including the turnover of proteins. After pathogen attack, plants establish broad-spectrum immunity relying on programs that control systemic resistance and immunological memory or priming. Autophagy, a degradation process controlling protein and organelle quality, plays a role in plant immune responses; however, its involvement in defense priming and systemic resistance remains underexplored. In this study, using publicly databases, we assessed the expression of autophagy-related genes (Atg) in Arabidopsis 24 h after applying priming inducers, namely pipecolic acid (Pip) and hydroxy-Pip. The expression level of several Atg genes was significantly modulated. We further explored autophagy regulation during defense priming by treating autophagy-reporter transgenic plants with 1 mM Pip or water (as a control) for 1 h, evaluating autophagic flux 24 h later. No significant differences in autophagic activity were observed between the treatments. We also examined the systemic resistance against Pseudomonas syringae pv. maculicola (Psm) induced by Pip in autophagy-defective mutants. Pip treatment induced systemic resistance to Psm and inhibited primary root growth, though less pronounced than in wildtype plants. As autophagy-defective mutants display a defense-related phenotype that depends on leaf age, likely due to the developmentally controlled increase of SA and reactive oxygen species levels, we are currently analyzing systemic resistance responses and defense priming at various developmental leaf stages. In this regard, preliminary results indicated that Pip treatment, which did not affect the cellular redox state, conferred increased redox capacity to a subsequent oxidative stress, depending on the leaf developmental stage in Arabidopsis.