The Plant Growth-Promoting Fungus Aspergillus ustus Promotes Growth and Induces Resistance Against Different Lifestyle Pathogens in Arabidopsis thaliana

• Published in: Journal of microbiology and biotechnology Vol. 21; no. 7; pp. 686 - 696
• Main Authors: Salas Marina Miguel Angel, Miguel Angel Silva Flores, Mayte Guadalupe Cervantes Badillo, Maria Teresa Rosales Saavedra, Maria Auxiliadora Islas Osuna, Sergio Casas Flores
• Format: Journal Article
• Language: Korean
• Published: 한국미생물생명공학회 30.07.2011
• Subjects: Arabidopsis; Aspergillus; jasmonic acid; plant growth-promoting fungus; salicylic acid; systemic resistance; Aspergillus; plant growth-promoting fungus; salicylic acid; systemic resistance; Arabidopsis; jasmonic acid
• ISSN: 1017-7825; 1738-8872

To deal with pathogens, plants have evolved sophisticated mechanisms including constitutive and induced defense mechanisms. Phytohormones play important roles in plant growth and development, as well as in the systemic response induced by beneficial and pathogen microorganisms. In this work, we identified an Aspergillus ustus isolate that promotes growth and induces developmental changes in Solanum tuberosum and Arabidopsis thaliana. A. ustus inoculation on A. thaliana and S. tuberosum roots induced an increase in shoot and root growth, and lateral root and root hair numbers. Assays performed on Arabidopsis lines to measure reporter gene expression of auxin-induced/ repressed or cell cycle controlled genes (DR5 and CycB1, respectively) showed enhanced GUS activity, when compared with mock-inoculated seedlings. To determine the contribution of phytohormone signaling pathways in the effect elicited by A. ustus, we evaluated the response of a collection of hormone mutants of Arabidopsis defective in auxin, ethylene, cytokinin, or abscisic acid signaling to the inoculation with this fungus. All mutant lines inoculated with A. ustus showed increased biomass production, suggesting that these genes are not required to respond to this fungus. Moreover, we demonstrated that A. ustus synthesizes auxins and gibberellins in liquid cultures. In addition, A. ustus induced systemic resistance against the necrotrophic fungus Botrytis cinerea and the hemibiotrophic bacterium Pseudomonas syringae DC3000, probably through the induction of the expression of salicylic acid, jasmonic acid/ethylene, and camalexin defense-related genes in Arabidopsis.