Abstract

JIMENEZ-PEREZ, Omar et al. Characterization and pathogenicity of a Pythium aphanidermatum isolate causing ‘damping off’ in pepper seedlings. Rev. mex. fitopatol [online]. 2022, vol.40, n.1, pp.116-130.  Epub Oct 03, 2022. ISSN 2007-8080.  https://doi.org/10.18781/r.mex.fit.2109-3.

The production of the pepper seedling (Capsicum annuum) is affected by the fungal complex that causes the ‘damping-off’, in which some species of the oomycete Pythium spp., stand out. The objective of the present study was to identify the causal agent of the death of pepper plants and evaluate its pathogenicity in pepper seeds and seedlings. A fast and aggressive growing oomycete was isolate from pepper plants, morphologically identified as P. aphanidermatum based on its sexual and asexual reproduction structures and, by molecular techniques. This isolate had a high degree of in vitro pathogenicity in pre-emergence and post-emergence in chile, showing 100% mortality. In addition, it presented a high rate of mycelial growth in different culture media (V8-Agar, Corn Agar, Corn Potato Agar, Potato Dextrose Agar, Czapek & Oat Agar), being in V8-Agar medium the only medium where it developed reproduction structures sexual and asexual. The isolation presented a mycelial growth rate of 58.3 ± 0.3mm / day at 26 ± 2 °C in PDA medium. Due to its rapid growth and its high degree of pathogenicity in vitro, it is an unusual and aggressive isolate for pepper seedlings.

Keywords : growth; culture media; oomycete; virulence; reproduction.