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Here, we analyzed the effects on Capsicum annuum plants of Trichoderma atroviride P. Karst strains altered in the expression of SWOLLENIN (SWO1), a protein with amorphogenic activity on plant cell wall components. Strains of T. atroviride that overexpressed the Taswo1 gene were constructed as well as deletion mutants. A novel, cheap and accurate method for assessing root colonization was developed. Colonization assays showed that the Taswo1 overexpressing strains invaded the host root better than the WT, resulting in a stronger plant growth-promoting effect. The expression of plant defense marker genes for both the systemic acquired resistance and induced systemic resistance pathways was enhanced in plants inoculated with Taswo1 overexpressing strains, while inoculation with deletion mutant strains resulted in a similar level of expression to that observed upon inoculation with the wild-type strain. Response to pathogen infection was also enhanced in the plants inoculated with the Taswo1 overexpressing strains, and surprisingly, an intermediate level of protection was achieved with the mutant strains. Tolerance to abiotic stresses was also higher in plants inoculated with the Taswo1 overexpressing strains but was similar in plants inoculated with the wild-type or the mutant strains. Compatible osmolyte production in drought conditions was studied. This study may contribute to improving Trichoderma biocontrol and biofertilization abilities.

In the present study, 62 endophytic bacterial strains of cedar seeds (Cedrela odorataL.), collected in the municipalities of Huehuetán, Motozintla, and Pijijiapan in the state of Chiapas, Mexico were isolated. The goal was to identify characteristics of biotechnological interest such as biocontrol, promotion of plant growth, and growth in aromatic compounds. The strains were identified by the partial sequence of the 16S ribosomal gene as belonging to the Bacillusgenus. The biocontrol capacity of phytopathogenic fungi, production of indoleacetic acid (IAA), solubilization of phosphate, and growth in xenobiotic compounds (phenanthrene, benzene, anthracene, or phenol) were detected in 26 strains of the 62 isolates. 21 % of the strains inhibited the mycelial growth of Alternaria solaniand Fusariumsp., and 13 % of the Phytophthora capsicioomycete. IAA production was detected in 24 isolates, phosphate solubilizing activity was identified in 18 isolates, while the ability to grow in the presence of phenanthrene and benzene was found in 26 isolates; 24 isolates grew in the presence of anthracene and only two isolates grew in phenol as the only carbon sources. This is the first report of the isolation and identification of endophytic bacteria from cedar seeds, where biotechnological characteristics were detected for biological control, promotion of plant growth, and growth in the presence of xenobiotic compounds.