BACTERIOSIS IN A DIVERSE MAIZE GERMPLASM IN SOUTH CÓRDOBA, ARGENTINA

LOPEZ, VIVIANA; PRINCIPE, ANALÍA; RUIZ, MARCOS; ROSSI, EZEQUIEL A.; FERNANDEZ, MARIA; BONAMICO NATALIA C.; FISCHER, SONIA

Mendoza

Congreso; XXXVI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2018

Sociedad de Biología de Cuyo

The maize is one of the most important crops of the Argentinian pampa region. Plant pathogens, such as fungi, bacteria, and virus cancause serious damage to agriculture and significantly reduce the yield and quality of crops. Diseases caused by bacteria, however, arethe few studied. The objective of this work was to identify bacterial pathogens based on symptoms observed in a diverse maizegermplasm. Therefore, a population of 200 maize inbred lines developed and provided by the International Maize and WheatImprovement Center (CIMMYT) were evaluated at Río Cuarto location during the summer cycle of 2017/2018. Light-colorednecrotic streaks or yellow irregular blotches were observed on leaves from symptomatic maize inbred lines. The leaves withsymptoms were rinsed with sterile distilled water and cut into small bits. These pieces were immersed in 0.85% (w/v) NaCl(physiological solution) and macerated. The samples were serially diluted and plated onto Luria-Bertani (LB) medium, containingdicloran (to prevent fungal growth). Plates were incubated at 30 °C. A total of twenty isolates were obtained from symptomaticmaize inbred lines. Gram staining, pigment production in LB medium and catalase reaction were tested in all isolates. In addition, βgalactosidase production was assessed by X-Gal test. Most of the strains were Gram-negative and five isolates were catalase positive.The isolates were distinguished by their different colonial morphologies. Light yellow, orange, red or white convex colonies wereobserved on LB medium. Moreover, three strains produced blue color colonies on X-Gal containing plates, indicating the presence ofβ-galactosidase enzyme in those bacteria. Representative isolates were chosen for further identification through the use ofphylogenetic analysis of 16S rRNA gene sequences. A single product of about 1.5 kb was amplified by PCR with the primers fD1and rD1 from each of strains analyzed. The purified PCR products were sent to Macrogen Inc. (Seoul, South Korea) for thesequencing of the gene encoding 16S rRNA. The identification of bacterial pathogenic strains in maize is relevant. Since the study ofthese emerging diseases in the maize region of Argentina is yet little explored.