Resistance of Cucurbita spp. germplasm tothe fungus Macrophomina phaseolina

Resistência de germoplasma de Cucurbita spp. para o fungo Macrophomina phaseolina

ABSTRACT

The objective of this study was to evaluate genotypes of Cucurbita moschata and Cucurbita maxima for resistance to the fungus Macrophomina phaseolina (Taissi) Goid. The experiment evaluated 17 accessions of Cucurbita moschata Duchesne and 20 accessions of Cucurbita maxima Duchesne preserved in the Cucurbit Germplasm Collection of the Federal Rural University of the Semi-Arid Region (UFERSA). Four commercial controls were also used, two for each species. In both studies, three isolates of M. phaseolina were inoculated, which are kept at the Fungal Culture Collection of UFERSA: MM1531 (GenBank identificatio: MM1531 (GenBank identification: MN136199), ME249 and ME250. Plants received inoculum of the pathogen in pieces of colonized toothpick and were evaluated for the incidence and severity of the disease. Both species showed resistant plants, but with varied frequencies for the accessions. Considering the species, the frequencies observed for C. moschata were higher than those observed for C. maxima. The accessions of C. moschata ABPUN 206 F1, P114-1, P160-2, P11-2, P114-6, P14-02 and P97-1 show different levels of resistance to the Macrophomina phaseolina isolates MM1531, ME-249 and ME-250.Thus, for an efficient selection in a breeding program for the characteristic, the selection strategies adopted must consider each source of resistance in isolationand not each species.

Keywords:
Cucurbita moschata ; Cucurbita maxima ; Soil-borne pathogen; Variability; Plant Genetic Resources