Differences in the responses of melon accessions to fusarium root and stem rot and their colonization by Fusarium oxysporum f. sp. radicis‐cucumerinum

Abstract

Fusarium root and stem rot caused by the fungus Fusarium oxysporum f. sp. radiciscucumerinum is a major disease in greenhouse cucumbers. Over the past decade, the disease has been documented in melon greenhouses in Greece, and recently it has been sporadically recorded in greenhouse melons in Israel. Variations in disease response were found among 41 melon accessions artificially inoculated with the pathogen: 10 accessions were highly susceptible (90-100% mortality), 23 exhibited an intermediate response (20-86%) and eight were resistant (0-4%). Two melon accessions -HEM (highly resistant) and TAD (partially Accepted ArticleThis article is protected by copyright. All rights reserved. resistant) -were crossed with the susceptible accession DUL. The responses of the three accessions and F 1 crosses between the resistant and susceptible parents were evaluated. HEM contributed higher resistance to the F 1 hybrid than TAD. Roots of susceptible and resistant accessions were 100 and 79% colonized, respectively, following artificial inoculation.However, only susceptible plants showed colonization of the upper plant tissues. Microscopic evaluation of cross sections taken from the crown region of the susceptible DUL revealed profuse fungal growth in the intercellular spaces of the parenchyma and in xylem vessels. In the resistant cultivar HEM, very little fungal growth was detected in the intercellular spaces of the parenchyma, and none in the xylem or any other vascular tissue. Finding resistant accessions may create an opportunity to study the genetics of resistance inheritance and to develop molecular markers that will facilitate breeding resistant melon cultivars.

Related mobile pathogenicity chromosomes in Fusarium oxysporum determine host range on cucurbits

“…In contrast to Forc016_HCT#1, Fom-derived HCT strains did not cause disease on cucumber Fo was delayed compared to colonization of susceptible plants, and only the lower hypocotyl was colonized (Zvirin et al, 2010) or only root xylem vessels were colonized (Li et al, 2014). In other studies, colonization of xylem vessels of resistant plant roots by Fo was not observed (Cohen et al, 2015;Upasani et al, 2016). In the present study, colonization of the hypocotyl of cucumber and watermelon plants by Fom005_GFP was also not observed, suggesting strong defence responses of nonhosts cucumber and watermelon at the root-stem transition.…”

“…conglutinans (Li et al, 2014), f. sp. radicis-cucumerinum (Cohen et al, 2015), f. sp. phaseoli (Niño-Sánchez et al, 2015;Garces-Fiallos et al, 2017), f. sp.…”

Development of a Fusarium oxysporum f. sp. melonis functional GFP fluorescence tool to assist melon resistance breeding programmes

“…Similar results have recently been reported for the interaction Fusarium oxysporum f. sp. radicis ‐ cucumerinum– melon (Cohen et al ., ).…”

Antagonistas microbianos a Fusarium spp., como agente causal de pudrición de raíces y tallo en melón

“…El hongo FOM es un habitante del suelo que infecta a las plantas penetrando de forma directa o por heridas de las raíces de donde se extiende hasta el xilema; provocando marchitamiento y muerte, además de persistir en el suelo debido a la producción de clamidosporas (Agrios 2005). El control genético de esta enfermedad es el método más estudiado, se han determinado los mecanismos de respuesta de defensa constitutiva o inducida de genotipos de melón a través de observaciones microscópicas, donde se observa el comportamiento de Fusarium en el xilema (Cohen et al 2015). Para evaluar materiales genéticos por métodos moleculares van Dam et al 2017diseñaron 18 pares de cebadores de PCR, con base a genes efectores candidatos, que discriminan entre siete formas especiales que afectan a cucurbitáceas, lo que permite reconocer los genotipos hospederos de cada una de ellas.…”