Resistance to Papaya Ringspot virus-W, Zucchini Yellow Mosaic Virus, and Watermelon Mosaic Virus-2 in C. maxima

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Cucurbit Genetics Cooperative Report 14:123-124 (article 42) 1991

Mark E. Herrington, Svenning Pryt, and Peter Brown, D.M. Persley, and R. Greber
Department of Primary Industries, Horticulture Branch, Redlands Research Station, Q. 4163, Australia, Department of Primary Industries, Plant Pathology Branch, Agricultural Research Laboratories, Indooroopilly, Q. 4068, Australia.

Papaya ringspot virus type W (PRV-W), zucchini yellow mosaic virus (ZYMV) and to a lesser degree watermelon mosaic virus 2 (WMV-2) cause losses in cucurbits in Australia. There are a number of isolates of ZYMV and PRV-W in Australia (Greber et al. 1988, Herrington et al. 1989). Cucurbita ecuadorensis is resistant to PRV-W, ZYMV, WMV-2 and CMV (Provvidenti et al. 1978, 1984).

We have transferred through backcrossing, the resistances to PRV-W, ZYMV and WMV-2 from C. ecuadorensis (Cutler and Whitaker) into C. maxima (Duch) to produce cv. Redlands Trailblaer. The cultivar has fruit of flattened globe shape and a grey slightly-ribbed skin. The skin has cracked severely in some environments. The high resistance to PRV-W, ZYMV and WMV-2 following mechanical inoculation of the cotyledons cv. of Redlands Trailblazer (Table 1) should be useful in breeding programmes. However the degree of resistance appears less than that in C. ecuadorensis. Some systemic movement of virus is apparent. The reaction to PRV-W and ZYMV usually involves necrotic lesions on the cotyledons. These lesions are most obvious following inoculation with our ‘K-isolate’ of ZYMV. In other segregating populations of C. maxima derived from C. ecuadorensis differences in the size of the lesion appear related to the degree of resistance.

Table 1. Response of C. maxima cultivars to inoculation with virus.

Disease severityz

Cultivar
PRV-W
ZYMV-K
ZYMV-G4
WMV-2
Redlands Trailblazer 0.3 2.0 2.3 0.2
Queensland Blue 58.7 83.7 62.8 80.7
Jarrahdale 53.5 72.5 59.3 48.5
LSD (P = 0.05) 8.0 5.9 19.5 13.9
Av. S.E.M. 2.46 1.81 5.97 4.27

z As a percentage of leaf area chlorotic; estimated on the youngest expanded leaf at the 5 leaf stage. 17-21 days after inoculation of cotyledons with infective sap (1:20) in 0.1M phosphate buffer pH 7.0.

Literature Cited

  1. Greber, R.S., D.M. Persley, and M.E. Herrington. 1988. Some characteristics of Australian isolates of zucchini yellow mosaic virus. Australian Journal of Agricultural Research 39:1085-94.
  2. Herrington. M.E., D.E. Bytyh, D.S. Teakle, and P.J. Brown. 1989. Inheritance of resistance to papaya ringspot virus type W in hybrids between Cucurbita ecuadorensis and C. maxima. Australian Journal of Experimental Agriculture 29:253-9.
  3. Herrington, M.E., R.S. Greber, P.J. Brown, and D.M. Persley. 1988. Inheritance of resistance to zucchini yellow mosaic virus in Cucurbita maxima cv. Queensland Blue x C. ecuadorensis. Queensland Journal of Agricultural and Animal Sciences. 45:145-9.
  4. Provvidenti, R., D. Gonsalves, and H.S. Humaydan. 1984. Occurrence of zucchini yellow mosaic virus in cucurbits from Connecticut, New York, Florida and California. Plant Disease 68:443-6.
  5. Provvidenti, R. , R.W. Robinson, and H.M. Munger. 1978. Resistance in feral species to six viruses infecting Cucurbita. Plant Disease Reporter 62:326-9.