Interspecific Cross Between Cucurbita pepo and C. martinezii

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Cucurbit Genetics Cooperative Report 2:35 (article 20) 1979

R. D. de Vaulx and M. Pitrat
Station d’Amélioration des Plantes Maraîchères, I.N.R.A., Domaine Saint Maurice, 84140 Montfavet-Avignon, France

Powdery mildew, cucumber mosaic virus (CMV), and watermelon mosaic virus (WMV) are important and common diseases of Cucurbita pepo in France. High levels of resistance have not been described in this species.

Resistances exist in some wild and cultivated Cucurbita species. Particularly, C. martinezii is resistant to powdery mildew and CMV (1, 2). In our field conditions, C. martinezii is completely resistant to powdery mildew and CMV and exhibits only mild symptoms of WMV.

Reciprocal interspecific crosses between C. pepo and C. martinezii were attempted in field and greenhouse conditions. One F1 hybrid seedling was obtained using C. pepo as female parent and seven seedlings with C. martinezii as female parent. The F1 plants were quite different in vigor and in leaf and fruit shape (the C. pepo parent is a commercial F1 hybrid). One plant did not produce male flowers. The fertility was sufficient to obtain F2 and BC1 progenies.

The resistance to CMV is dominant (the F1 plants are apparently free from virus like C. martinezii) but the resistance to powdery mildew is intermediate. We are now studying the heredity of the resistances in the F2 and BCI progenies.

Literature Cited

  1. Munger, H. M. 1976. Cucurbita martinezii as a source of disease resistance Veg. Impt. Newsl. 18:4.
  2. Provvidenti, R., R. W. Robinson and H. M. Munger. 1978. Resistance in feral species to six viruses infecting Cucurbita. Plant Dis. Rep. 62:326-329.