Cucurbit Genetics Cooperative Report 12:42-43 (article 18) 1989
C. Soria and M.L. Gomez-Guillamon
Universidad Politecnica de Valencia, Spain
The unpromising results obtained from earlier experiments seeking sources of resistance to muskmelon yellowing disease in a large collection of different muskmelon (Cucumis melo L.) cultivars under conditions of natural infection led to this present search for wild species with resistance to this disease.
In addition to three wild species — Cucumis zeyheri, C. anguria var. longipes, and C. myriocarpus (A) and (B) — shown the year before to have satisfactory resistance to yellowing disease (2), this present work studied six new wild species of the genus Cucumis. The two sensitive cultivars Piel de Sapo and Bola de Oro were used as controls.
Previous work in this laboratory (3) demonstrated that the greenhouse whitefly Trialeurodes vaporariorum is the vector of transmission of the causal agent of yellowing disease; consequently, in this work, the populations of whitefly on each species were estimated. The 12 species (Table 1) were cultivated in the same polyethylene greenhouse in sandy soil with drip irrigation.
Table 1. Incidence of yellowing disease and presence of whitefly Trialeurodes vaporariorum.
Species |
Yellowing symptoms |
Whitefly population |
| Cucumis myriocarpus (A) | 1/10 | + |
| Cucumis myriocarpus (B) | 10/10 | +++ |
| Cucumis zeyheri | 10/10 | +++ |
| Cucumis anguria var. longipes | 1/10 | ++ |
| Cucumis anguria var. anguria | 0/10 | + |
| Cucumis africanus | 0/10 | +++ |
| Cucumis meeusii | 0/4 | ++ |
| Cucumis dipsaceus | 0/10 | +++ |
| Cucumis figarei | 0/10 | + |
| Cucumis melo var. agrestis | 3/10 | ++ |
| Piel de Sapo (*) | 10/10 | +++ |
| Bola de Oro (*) | 10/10 | +++ |
(A) Resistant line. (B) Sensitive line. (*) Controls (C. melo cultivars). n/n = Plants with symptoms / Plants observed.
Cucumis zeyheri exhibited resistance the year before (2), but was found to be sensitive in this present work. The appearance of symptoms of yellowing in some generally resistant accessions suggests the need for controlled artificial inoculations using T. vaporariorum as the vector.
Cucumis melo var. agrestis showed good resistance. Because this accession belongs to C. melo, it is the most interesting one to introduce the yellowing resistance into cultivated muskmelons.
In the experiments with Cucumis africanus and C. dipsaceus no symptoms were observed although the populations of whitefly were similar to those of the controls. It can be supposed that these accessions are resistant to the disease transmission by T. vaporariorum, but it is necessary to prove this behavior using controlled infections before making such an assertion.
A study has been initiated of the genetics of the resistance to yellowing found in C. myriocarpus. Likewise, there is on-going a program seeking to transfer the genes for disease resistance discovered in some wild species to commercial cultivars. This bridge was designed to exploit the known interspecies compatibilities of the Cucumis genus described in (1).
Literature Cited
- Esquinis-Alcazar, J.T., and P.J. Gulik. 1983. Genetic resources of Cucurbitaceae. AGPGR: IBPGR/83/48:20.
- Esteva, J., F. Nuez, and J. Cuartero. 1988. Resistance to yellowing disease in wild relatives of muskmelon. Cucurbit Genetics Cooperative 11:52-53.
- Soria, C., and M.L. Gomez-Guillamon. 1988. Transmission of a muskmelon yellowing disease by Trialeurodes vaporariorum Westwood. Eucarpia. Cucurbitaceae 88. Avignon-Montfavet. (France).