Secretome Analysis of <i>Arabidopsis</i>–<i>Trichoderma atroviride</i> Interaction Unveils New Roles for the Plant Glutamate:Glyoxylate Aminotransferase GGAT1 in Plant Growth Induced by the Fungus and Resistance against <i>Botrytis cinerea</i>

• Main Authors: María del Carmen González-López, Saúl Jijón-Moreno, Mitzuko Dautt-Castro, Cesaré Ovando-Vázquez, Tamar Ziv, Benjamin A. Horwitz, Sergio Casas-Flores
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Arabidopsis</i>; <i>Trichoderma</i>; secretome; enzymes; glycosidases; GGAT1
• Online Access: https://www.mdpi.com/1422-0067/22/13/6804

The establishment of plant–fungus mutualistic interaction requires bidirectional molecular crosstalk. Therefore, the analysis of the interacting organisms secretomes would help to understand how such relationships are established. Here, a gel-free shotgun proteomics approach was used to identify the secreted proteins of the plant <i>Arabidopsis thaliana</i> and the mutualistic fungus <i>Trichoderma atroviride</i> during their interaction. A total of 126 proteins of <i>Arabidopsis</i> and 1027 of <i>T. atroviride</i> were identified. Among them, 118 and 780 were differentially modulated, respectively. Bioinformatic analysis unveiled that both organisms’ secretomes were enriched with enzymes. In <i>T. atroviride</i>, glycosidases, aspartic endopeptidases, and dehydrogenases increased in response to <i>Arabidopsis</i>. Additionally, amidases, protein-serine/threonine kinases, and hydro-lyases showed decreased levels. Furthermore, peroxidases, cysteine endopeptidases, and enzymes related to the catabolism of secondary metabolites increased in the plant secretome. In contrast, pathogenesis-related proteins and protease inhibitors decreased in response to the fungus. Notably, the glutamate:glyoxylate aminotransferase GGAT1 was secreted by <i>Arabidopsis</i> during its interaction with <i>T. atroviride</i>. Our study showed that GGAT1 is partially required for plant growth stimulation and on the induction of the plant systemic resistance by <i>T. atroviride</i>. Additionally, GGAT1 seems to participate in the negative regulation of the plant systemic resistance against <i>B. cinerea</i> through a mechanism involving H₂O₂ production.