Media preferences, micro-morphometric analysis, and cardinal growth temperature determination for Phytophthora infestans sensu lato isolated from different hosts in Colombia

During the last years Phytophthora infestans sensu lato (Mont. De Bary) has caused epidemics in Colombia in Andean fruit crops such as Solanum quitoense and Solanum betaceum. Establishment of new or modified experimental procedures to study this pathogen is a mandatory subject for scientists. Twelve isolates of Phytophthora spp. obtained from six different Solanum hosts in Colombia were used to evaluate the effect of five different solid media for growth and ability to produce sporangia and liberate zoospores. Determination of the best media culture and optimal growth temperature were necessary to perform measurements and correlate the provenance of isolates with phenotypic traits. Modifications were made to use ingredients available in local markets on the following media: lime bean agar (LEA), Tree tomato or tree tomato agar (TA), carrot agar (AZ), Rye A modified agar and 32% non-clarified V8 agar. Cardinal temperature determination was performed at 10, 15, 20, and 25 degrees C. Morphometric traits were measured once the optimal media culture and temperature were defined. Correlation analysis showed that there is a relationship between the host and isolate's preferences for media culture and optimal growth temperature. In addition, the production of characteristic sporangia, sporangiophore and mycelia was related with the media type used and host from which the isolate was collected. In this work useful information was provided to make studies about the biology and development of isolates gathered from cultivated and wild non-traditional hosts.