Cucurbit Genetics Cooperative Report 1:26-27 (article 25) 1978
R. Provvidenti, R. W. Robinson and H. M. Munger
New York Agricultural Experiment Station, Geneva NY 14456
Adequate levels of resistance to several viral diseases have not been found in cultivated Cucurbita species. Therefore, we tested wild species of the genus to determine if genes for virus resistance could be transferred to squash and pumpkin.
Cucurbita martinezii has previously (1) been reported to be resistant to cucumber mosaic virus (CMV), frequently a destructive disease of squash in the Northeast. CMV resistance appears to be the rule, rather than the exception, among wild species of Cucurbita (Table 1). All wild species tested, except andreana, sororia, and texana, developed only local necrotic reaction on inoculated leaves without any systemic symptoms of infection.
Resistance was also common for tobacco ringspot virus (TRSV). The three cultivated species and all wild species except digitata, lundelliana, and sororia were resistant, developing only localized nonsystemic symptoms. Resistance to bean yellow mosaic virus (BYMV) was also found in many wild species. Six wild species appeared immune and three were resistant, developing only local symptoms. Six of the 14 wild species were resistant to tomato ringspot virus (TmRSV). Resistance to the important watermelon mosaic viruses (WMV-1 and WMV-2) was less common, but C. ecuadorensis and C. foetidissima were highly resistant to each strain of the watermelon viruses.
The only important virus of Cucurbita for which a high level of resistance was not found was squash mosaic virus. All species became infected, and only C. ecuadorensis, C. okeechobeensis, and C. martineziirecovered from initial systemic symptoms.
Cucurbita ecuadorensis, because of its good resistance to several viruses and compatibility with C. maxima, is an excellent source of resistance for that species. Cucurbita foetidissima is equally good in virus resistance, but is more satisfactory for breeding purposes because of interspecific sterility. Cucurbita martinezii is not resistant to as many viruses, but can be used to transfer resistance to CMV and powdery mildew (1) to C. moschata, and that F1 can be used as a bridge to transfer these resistance genes to C. pepo.
Table 1. Reaction of Cucurbita species to six viruses.
Virus |
||||||
Species |
CMV |
TRSV |
BYMV |
TmRSV |
WMV-1 |
WMV-2 |
| C. andreana | S* | R | 0 | S | S | S |
| C. cordata | R | R | 0 | S | S | S |
| C. cylindrata | R | R | S | R | S | S |
| C. digitata | R | S | S | R | S | S |
| C. ecuadorensis | R | R | S | S | 0 | 0 |
| C. foetidissima | R | R | 0 | S | 0 | 0 |
| C. gracilior | R | R | 0 | R | S | S |
| C. lundelliana | R | S | S | S | S | S |
| C. martinezii | R | R | 0 | S | S | S |
| C. okeechobeensis | R | R | 0 | S | S | S |
| C. palmata | R | R | R | R | S | S |
| C. palmeri | R | R | R | R | S | S |
| C. sororia | S | S | R | R | S | S |
| C. texana | S | R | S | S | S | S |
| C. maxima | S | R | R | S | S | S |
| C. moschata | S | R | 0 | S | S | S |
| C. pepo | S | R | S | S | S | S |
*0 = no infection.
S = systemic symptoms.
R = resistant, developing local reaction but not systemic symptoms.
Literature Cited
- Munger, H. M. 1976. Cucurbita martinezii as a source of disease resistance. Veg. Imp. Newsletter 18:4.