Examinando por Autor "Montealegre, Jaime"
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Ítem Enhanced secretion of biocontrol enzymes by Trichoderma harzianum mutant strains in the presence of Rhizoctonia solani cell walls(Pontificia Universidad Católica de Chile. Facultad de Agronomía e Ingeniería Forestal, 2015-08) Polanco, Rubén; Pino, Constanza; Besoain, Ximena; Montealegre, Jaime; Pérez, Luz M.The secretion of enzymes involved in biocontrol from the wild T. harzianum strains Th11 and Th12 and the mutants Th11A80.1, Th11C40.1 and Th12A10.1 was studied after their cultivation in the presence of R. solani cell walls as the sole carbon source. The results showed that endoprotease activity in the supernatants from Th11A80.1 and Th11C40.1 increased 2.77 and 4.79-fold, respectively, and the P-1,3-glucanase and P-1,4-chitinase activity from Th12A10.1 increased 1.86 and 1.54-fold, respectively, compared with the corresponding parental strains. The role of the three enzymes in the biocontrol of R. solani is discussed.Ítem Selection of bioantagonistic bacteria to be used in biological control of Rhizoctonia solani in tomato(Pontifiicia Universidad Católica de Valparaíso, 2003) Montealegre, Jaime; Reyes, Rodrigo; Pérez, Luz María; Herrera, Rodrigo; Silva, Polyana; Besoaín, XimenaBacteria from the rhizoplane and surrounding soil of healthy and Rhizoctonia solani diseased tomato plants, cropped in greenhouse of the V Region of Chile, were collected. The best bacterial strains, based on their ability to control development of three R. solani isolates (identified as belonging to the anastomosis groups AG-2-1, AG-4), were identified as B. subtilis (one isolate) and B. lentimorbus (two different isolates). All bacterial isolates resulted effective for the in vitro control of growth of all R. solani isolates, where the control mechanisms used by the bacteria do not involve the secretion of fungal cell wall hydrolytic enzymes. R. solani AG-2-1 was more sensitive than R. solani AG-4. On the other hand, all bacteria grew well in conditions similar to those that can be found at the field level (considering pH, salinity, Fe3+ and temperature) and showed a good capacity of tomato root colonization. These results suggest that the B. subtilis and B. lentimorbus isolates studied have an excellent potential to be used as biocontrol agents of R. solani in tomato greenhouses at the field level.