Resistance in melon toMonosporascus cannonballusandM. eutypoides: Fungal pathogens associated with Monosporascus root rot and vine decline

Abstract

The fungal species Monosporascus cannonballus and M. eutypoides have been described as the causal agents of Monosporascus root rot and vine decline disease (MRRVD), which mainly affects melon and watermelon crops. Resistance to M. cannonballus has been reported in some melon cultivars (ssp. melo). Moreover, melon ssp. agrestis accessions have proven to be better resistance sources. This is the case of the Korean accession 'Pat 81', highly resistant under field and artificial inoculation. The objective of the work here presented was the evaluation of the resistance to MRRVD of different accessions representing the variability of Cucumis melo ssp. agrestis, against both, M. cannonballus and M. eutypoides, in a multiyear assay under different infection conditions. In general, M. eutypoides was less aggressive than M. cannonballus in the different environmental conditions. There was a strong influence of temperature on MRRVD, with more severe symptoms with higher temperatures and with variable effect of infection on plant development depending on the fungal species considered. Resistance to MRRVD has been confirmed in 'Pat 81' and in its derived F1 with a susceptible Piel de Sapo melon.Among the new germplasm explored, African accessions (both wild agrestis and exotic cultivated acidulus) showed good performance in artificial inoculation assays and in field conditions. These sources do not present compatibility problems with commercial melons, so they can be introduced in backcrossing programs. The accession assayed of the wild relative Cucumis metuliferus, also resistant to Fusarium wilt and to root-knot nematode, was highly resistant to MRRVD. The interest of this accession mainly relies in its advantages as a rootstock for melon.

Tomato and Melon Meloidogyne Resistant Rootstocks Improve Crop Yield but Melon Fruit Quality Is Influenced by the Cropping Season

“…Nonetheless, rootstocks also bear other sources of resistance against soil-borne plant pathogens increasing its interest to be included in integrated disease management strategies. For example, C. metuliferus is also resistant to Monosporascus root rot and Fusarium wilt as well as to vine decline ( Castro et al, 2020 ). Some other putative hybrid Cucumis rootstocks, such as C. ficifolius x C. anguria and C. ficifolius x C. myriocarpus , which are tolerant to Monosporascus cannonballus , and resistant to Fusarium oxysporum f.sp melonis and to RKN and did not affect the quality of melon fruit compared to non-grafted or self-grafted ( Cáceres et al, 2017 ), will increase the number of possible rootstocks that could be available for growers in the near future.…”

Melon Genetic Resources Characterization for Rind Volatile Profile

“…The presence in this wild accession of high levels of monoterpenoids in contrast to the remaining accessions may be an interesting starting point for future studies about possible resistant/repellent responses against pests. This accession has been reported as resistant to soil pathogens [55,56], although to date no studies have focused on its behavior in relation to insects. Surprisingly, this wild PI 185111, with no good scent, also presented one of the highest levels for some acetates (6-nonenyl acetate) and ethyl esters (ethyl propanoate) in the collection (LSD test, p < 0.05, Supplementary Table S3), showing that non-cultivated types present more variability than expected and can have also high levels of some esters.…”

Characterization of Five New Monosporascus Species: Adaptation to Environmental Factors, Pathogenicity to Cucurbits and Sensitivity to Fungicides

“…These authors concluded that low inoculum densities (0.1, 0.5, and 1.0 colony-forming unit (CFU)/g soil) produced high levels of disease, and this severity level did not increase when densities were increased. More recently, Castro et al [ 46 ], evaluated the response of different melon genotypes to inoculation with M . cannonballus and M .…”

“…These variables were previously shown as being useful to evaluate the severity of the disease caused by M . cannonballus in cucurbits [ 37 , 46 ]. Differences in the root system, shoot length and dry weights were also observed in pumpkin, with emphasis on infection by M .…”