Resumo

RETANA, Kenneth; RAMIREZ-COCHE, José Adolfo; CASTRO, Oscar  e  BLANCO-MENESES, Mónica. Morphological and molecular characterization of Fusarium oxysporum f. sp. apii associated to yellow wilt on celery in Costa Rica. Agron. Costarricense [online]. 2018, vol.42, n.1, pp.115-126. ISSN 0377-9424.  http://dx.doi.org/10.15517/rac.v42i1.32199.

Celery is cultivated in provinces of Costa Rica, such as Cartago, Heredia, Alajuela and San José. Total production is approximately 25 metric tons annually. This crop is affected by different pathogens but in the last few years Fusarium oxysporum has caused substantial damage at the plantation level. In celery, 4 pathogenic Fusarium races are known, they are defined using the tolerance of the celery cultivars to the pathogen. Race 1 affects only yellow celery; race 2 affects both yellow and green celery; race 3, the least pathogenic, is virulent only for green celery; and race 4, is the most aggressive causing losses in green as yellow celery. In Costa Rica only the presence of Fusarium oxysporum has been reported. To better identify and describe the pathogen, isolates were obtained from diseased plants that showed a variety of symptoms including: delayed plant growth, dwarfism, yellow and wilting foliage, as well as blackening and damaged root systems.Koch postulates and a morphological description of the pathogen was done based on different characteristics of spore quantity and the presence of macro and microconidia on carnation leaf agar (CLA), as well as colony appearance (color and pigmentations), which were observed on potato dextrose agar (PDA). Molecular characterization was performed by sequencing the elongation factor 1-alpha region (EF-1a). Results matched some isolates found at the National Center for Biotechnolgy Information (NCBI) related to F. oxysporum f. sp. apii and our results further suggested that we are dealing with the presence of race 3 and/or 4 in Costa Rica.

Palavras-chave : Apium graveolen; Fusariumoxysporum f. sp. apii; FOA; Koch postulate; molecular markers..

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