Abstract

ARRATIA-CASTRO, Alda A. et al. Alternaria alternata, Fusarium oxysporum and Fusarium verticillioides identified as causal agents of broccoli head rot in Mexico. Rev. Chapingo Ser.Hortic [online]. 2022, vol.28, n.3, pp.175-188.  Epub Dec 13, 2022. ISSN 2007-4034.  https://doi.org/10.5154/r.rchsh.2022.03.003.

Broccoli is one of the most economically important vegetables in Mexico, and one of the diseases that reduces its yield and quality is head rot, which has been associated with different phytopathogens. The objective of this study was to morphologically and molecularly identify the causal agents of head rot in broccoli cultivation in Mexico. Florets with rot symptoms were collected in different municipalities of the state of Guanajuato (León, San Francisco del Rincón, Valle de Santiago, Abasolo, Juventino Rosas and Dolores Hidalgo). The isolates obtained were identified based on their cultural, morphological and molecular characteristics (by PCR-ITS) as Alternaria alternata (AA), Fusarium oxysporum (FO) and Fusarium verticillioides (FV). The pathogenicity of these fungal species was corroborated by Koch's postulates. The fungal isolation frequency was 55, 26 and 19 % for AA, FV and FO, respectively, of the total samples analyzed. The sequence obtained from a representative isolate of each fungus was compared with those reported in the NCBI gene bank, where the highest similarity percentages were 99.6, 98.9 and 98.2 % for FO, FV and AA, respectively, thus confirming the morphological identification results. This is the second report of the presence of AA and FO associated with broccoli head rot in Mexico, and the first report of FV as part of the complex of causal agents of this disease.

Keywords : Brassica oleracea var. italica; morphological identification; necrosis; PCR; ITS.

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