Tolerance evaluation of celery commercial cultivars and genetic variability of Fusarium oxysporum f. sp. apii

Abstract

Celery is affected by several plant diseases such as Fusarium oxysporum f. sp. apii (Foa). Four races have been found in the US. Our goal was to find which races are present in Costa Rica using a multigene phylogenetic analysis and to quantify the tolerance of the imported commercial cul-tivars of celery. Isolates from 125 celery symptomatic plants from three different geographical locations were analyzed and 65 isolates were selected to perform the phylogenetic analysis. All isolates present the five nucleotides which differentiate Foa race 3 from the other races in the IGS rDNA region. Three different haplotypes close to race 3 were found, all of them were highly virulent, produced high losses, and affected all cultivars of imported commercial celery, which are genetically improved for resistance to races 2 and 4. Additionally, five different cultivars of commercial celery were evaluated against seven pathogen isolates identified as race 3 in green-house conditions. Two of the cultivars showed significantly less chlorosis, wilting, mortality, and higher fresh weight. Most of the Foa isolates significantly increased chlorosis, wilting and mor-tality compared to non-inoculated control. Celery producers in Costa Rica lack a seed that could offer total resistance to the Foa race 3 present in the country.