Banca de DEFESA: GUSTAVO RODRIGUES SALDANHA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GUSTAVO RODRIGUES SALDANHA
DATE: 29/08/2025
TIME: 13:00
LOCAL: Sala Marcelo Nunes Camargo, n°24, Departamento de Solos
TITLE:

Soil Microbial Diversity under Tomato (Solanum lycopersicum) Cultivation with Wilt and Bioprospecting of Plant Growth-Promoting Microorganisms

KEY WORDS:

Fusarium oxysporum f. sp. lycopersici; Bacterial wilt; Ralstonia solanacearum.

PAGES: 74
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Microbiologia e Bioquímica do Solo
SUMMARY:

Tomato wilt, which can be caused by the bacterium Ralstonia solanacearum or the fungus Fusarium oxysporum f. sp. lycopersici, represents one of the main challenges in crop management due to the persistence of these pathogens in the soil and the limited efficiency of available chemical methods. In the first chapter, the composition of the bacterial community in the rhizosphere of tomato plants with and without symptoms of bacterial wilt was investigated in two protected production units in Vassouras, RJ. Analyses of alpha and beta diversity, differential abundance, and co-occurrence networks indicated differences between the rhizospheres of symptomatic and asymptomatic plants. Families such as Bacillaceae, Fictibacillaceae, Nocardiaceae, Chitinophagaceae, and Streptomycetaceae predominated in the rhizosphere of asymptomatic plants, possibly associated with natural pathogen suppression, whereas Pseudomonadaceae, Microbacteriaceae, and Rhizobiaceae were more abundant in the rhizosphere of wilted plants. Microbial networks indicated higher connectivity and a predominance of negative interactions in the presence of disease, with Beijerinckiaceae central in symptomatic plants and Mycobacteriales and Burkholderiaceae central in asymptomatic plants. The second chapter focused on the characterization of 22 Pseudomonas isolates previously identified by MALDI-TOF and confirmed by rrs gene sequencing, as well as the evaluation of their biocontrol potential against F. oxysporum f. sp. lycopersici and their plant growth-promoting traits. A predominance of P. aeruginosa, P. putida, and P. plecoglossicida was observed. In direct antagonism tests, P. aeruginosa isolates showed greater ability to inhibit the pathogen, whereas isolates of the putida group stood out for their phosphate solubilization and indole-3-acetic acid production, indicating potential for plant growth promotion. Taken together, the results demonstrate that the microbial composition of the rhizosphere was altered in wilted plants and that Pseudomonas strains stand out as promising candidates for the formulation of bioinputs aimed at disease management in tomato crops and plant growth promotion. These findings reinforce the importance of developing strategies based on soil microbiota manipulation and the use of microbial consortia, fostering the advancement of more efficient and environmentally sustainable agricultural practices.

COMMITTEE MEMBERS:
Presidente - 1815763 - IRENE DA SILVA COELHO
Externo à Instituição - JOSÉ IVO BALDANI - EMBRAPA
Externa à Instituição - MARCIA SOARES VIDAL - EMBRAPA