Identification of strains isolated from symptoms of bacteriosis in maiza

BARRIONUEVO, L; RUIZ, M; ZUBER, N; LOPEZ RAMIREZ, V; ASCONAPE, J; BONAMICO, N; FISCHER, S; GAMBETTA, C; ROSSI, E; LAGARES, A

Mendoza

Congreso; LVII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Identification of strains isolated from symptoms of bacteriosis in maize leavesLópez-Ramírez, V (1); Barrionuevo, L (1); Gambetta, C (1); Asconapé, J (1); Ruiz, M (1); Rossi, E (1); Bonamico, N (1); Zuber, N (2); Lagares, A (2); Fischer, S (1)(1) Instituto de Investigaciones Agrobiotecnológicas (INIAB), Universidad Nacional de Río Cuarto (UNRC)?CONICET . (2) Instituto de Biotecnología y Biología Molecular (IBBM), Universidad Nacional de La Plata (UNLP) - CONICET, CCT-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, UNLP, La Plata, ArgentinaMaize is one of the most important cereals used in human and animal diets as well as industrial alcohol, fuel, and bioethanol. In Argentina, maize is the primary grain grown and the province of Córdoba is the main producer providing about 33% of the national production. Bacteriosis is a significant disease in crop production; little is known about the bacteria that produce this disease in maize. A recent increase in the incidence of bacteriosis in maize is possibly due to the massive adoption of direct seeding and the absence of resistant genotypes. This work aimed to isolate and identify bacterial pathogens from foliar symptoms in maize during the 2019 summer season. A phenotypic evaluation of symptoms was carried out in the field. Yellow and brownish necrotic lesions were observed. Infected leaves were collected, and samples were taken from the lesions, macerated in physiological solution, serially diluted, and grown in Petri dishes containing LB with fungicide. Plates were incubated at 30 °C for 24 h. Colonies with different morphological characteristics of size, shape, texture, and color were selected. The isolates were identified using MALDI-TOF?MS, and sequencing of the 16S rRNA gene. The 16S rDNA sequences of isolates were analyzed and compared with sequences retrieved from the GenBank database using the Basic Local Alignment Search Tool (BLAST). A comparative phylogenetic analysis with phytopathogenic strains was carried out using MEGAX software. Pathogenicity tests were carried out with candidate strains. Four different genera were successfully identified by both MALDI-TOF and 16S rDNA sequencing: Enterobacter, Pseudomonas, Pantoea, and Curtobacterium. In addition, the MALDI-TOF MS analysis demonstrated a higher resolution power at the species level than 16S rDNA sequencing in several cases, allowing the identification of Enterobacter pyrinus with high scores. Members of the genus Pantoea were predominant in the studied samples. Isolates were grouped in the phylogenetic analysis with other plant-associated strains of the same species. The pathogenicity tests showed that most of the evaluated strains brought about bacteriosis symptoms in maize. A bibliographic search showed that the genus Enterobacter pyrinus has been previously reported as a maize pathogen. The isolation and identification of pathogenic bacteria from maize provides a starting point for identifying diseases in crops and future strategies to mitigate them..