Plant Immunity Strategies Against Microbial Pathogen Infection

Research Summary

In-depth understanding of the molecular mechanisms evolved by plants to tolerate biotic and abiotic stress will be critical to guarantee food security in the future. We focus our research in exploring the activities of oxylipins, a family of lipid derivatives activating immune responses in plants. Our studies have revealed that oxylipins produced by the biosynthetic pathways initiated by fatty acid alpha-dioxygenases (alpha-DOXs) and 9-lipoxigenases (9-LOXs) contribute to the activation of local and systemic defense. Analyses with 9-HOT and 9-KOT (two members of the 9-LOX pathway) and signaling mutants (noxy for non-responding to oxylipins) showed the role of mitochondria in 9-LOX signaling and the action of 9-HOT and 9-KOT by enhancing ROS production at complex III of the respiratory mitochondrial chain; a response that protects plants against subsequent mitochondrial damage and activates plant defense. Our results support the action of oxylipins as inducers of retrograde signaling pathways mediating communication and functional coordination of organelles during the activation of plant immunity.

Research Lines

1. Signaling Activities of Oxylipins in Plant Immunity
2. Functional Coordination of Organelles During Plant Immunity Activation
3. Mitochondrial stress responses

Major contributions from the research team include:

• The identification of the oxylipins produced by the 9-LOX and alpha-DOX oxylipin pathways as part the defense mechanisms activated by Arabidopsis following infection by hemibiotrophic bacteria. In this response, both enzymes participate in the three layers of defense -pre-invasion, apoplastic and systemic defense- triggered by plants to prevent Pst DC3000 infection (Montillet JL et al., 2013; Vicente J et al., 2012).
• The identification of alpha-dioxygenases in lipid droplets (LDs) which are formed after bacterial infection. We showed that LDs participate in the production and transport of defense components affecting the interaction of plants with invading pathogens (Fernández-Santos R et al., 2020).
• The characterization of 9-HOT (9(S)-hydroxy-10,12,15-octadecatrienoic acid) and its ketone derivative 9-KOT, act as activators of cell-wall defense, expression of defense-related genes and regulators of hormone homeostasis (Ethylene, ABA, and Brassinoesteroids) (Lopez MA et al., 2011; Vicente J et al., 2012; Marcos R et al., 2015).
• The characterization of Arabidopsis GCN1 as a translational regulator during the adaptation of plants to mitochondrial dysfunction, high boron concentration and plant immunity. We found that GCN1 act via a non-canonical pathway to regulate translation of specific transcripts playing a role in plant immunity and that oxylipins may participate in the regulation of this response (Izquierdo Y et al., 2018; Sesma A et al., 2017)
• The identification of 9-HOT- and 9-KOT-insensitive mutants (noxy mutants, for non-responding to oxylipins) helping to elucidate 9-LOX signaling and the role of mitochondria in this pathway (Vellosillo T et al., 2013; Izquierdo Y et al., 2021).
• The finding that oxylipins activate mild mitochondrial stress responses protecting plants against further mitochondrial stress and cell wall damage (Vellosillo et al., 2013; Marcos R et al., 2015)
• The finding that mitochondrial stress by exogenous application of Antimycin A in Arabidopsis activates plant resistance against different types of pathogens thus, supporting the contribution of mitochondrial stress to plant defense (Lopez A et al., 2021).
• The characterization of 9-HOT and 9-KOT as activators of mitochondrial retrograde signals mediating communication and functional coordination between organelles. (Izquierdo Y et al., 2021; López et al 2024).

Group Members

Funding