Two Alleles for Watermelon Mosaic Virus 1 Resistance in Melon

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Cucurbit Genetics Cooperative Report 6:52-53 (article 27) 1983

M. Pitrat and H. Lecoq
I. N. R. A., B. P. 94, 84140 Montfavet-Avignon, France

Two sources of resistance to Watermelon Mosaic Virus 1 (WMV-1) have been used independently. In the U. S., Webb and Bohn (10) found some resistant (symptomless) plants in PI 180280 from India. Cantaloup lines with this resistance have been released: B66-5 by Webb (8), and WMR 29 by Bohn et al. (2). Resistance is governed by one dominant allele symbolized Wmv-1 by Webb (9). In Guadeloupe (French West Indies) Quiot et al. (5) confirmed the resistance of B66-5, and found that PI 180283 from India was also resistant to local isolates. Kaan (3) reported monogenic dominant control of resistance in PI 180283. Anais and Kaan (1) selected the resistant Charentais-type breeding line 72025 from PI 180283. Sowell and Demski (6) compared the reactions of PI 180280 and PI 180283 to WMV-1 and concluded that mechanisms of resistance in these two lines could be similar according to the color and dimensions of local lesions. PI 124112 has also been reported as reacting with local necrotic lesions (7), but apparently has not been used in breeding programs.

Lecoq et al. (4) described WMV-1 in France where it has only recently become widespread on melon. We compared the behavior of the resistant lines B66-5, WMR 29 and 72025 towards French isolates (E2 and E115). B66-5 and WMR 29 exhibit no symptoms or local necrotic lesions; 72025 reacts with systemic necrotic lesions that are often followed by a top necrosis and death of the plants.

F2 progenies of crosses between B66-5 or 72025 and susceptible Charentais lines, segregated 3/4 symptomless:1/4 with typical vein clearing symptoms (Table 1). These results confirm the analysis of Kaan (3) and Webb (9) that resistance is controlled by a single dominant gene. In F2 progenies between B66-5 or WMR 29 and 72025 we found no susceptible plants (i.e. with vein clearing symptoms); 1/4 exhibited top necrosis (typical of 72025) and 3/4 were symptomless (Table 1). These results suggest multiple alleles for WMV-1 resistance which may be symbolized as follows: WMV-11 from PI 180280, Wmv-12 from PI 180283, and Wmv-1+ (susceptible). The order of dominance is Wmv-11 > Wmv-12 > Wmv-1+.

From a practical point of view, Wmv-11 should be used instead of Wmv-12 which conditions for top necrosis and death of the plants with isolates such as E2 or E115.

Table 1. Segregation in F2 progenies after inoculation of E2 strain of Watermelon Mosaic Virus 1.
Number of plants with the same symptoms as:

 X2 (3:1) Probability (%)
F2 Progeny Test 72025 B66-5 Charentais
(72025 x Charentais) 1  72 28 0.480 30–50
     line FR2 3  75 25 0.000   >99
Sum 147 53 0.240 50–75
(B66-5 x Charentais) 1  76 24 0.53 75–90
     line BRICHE 3  74 26 0.053 75–90
Sum 150 50 0.000   >99
(B66-5 x 72025) 2  28  78 0.113 50–75
3  26  74 0.053 75–90
Sum  54 152 0.162 50–75
(WMR 29 x 72025) 2  25  81 0.113 50–75

Literature Cited

  1. Anais, G. and F. Kaan. 1978. La selection de varieties de Melon (Cucumis melo L.) aux Antilles pour la resistance aux maladies et l’aptitude au transport. Agronomie Tropicale XXXIII:323–331.
  2. Bohn G W., A. N. Kishaba and J. D. McCreight. 1980. WMR 29 Muskmelon breeding line. HortScience 15:539–540.
  3. Kaan, F. 1973. Recherches sur la resistance du melon aux maladies, notamment a la mosaique de la pasteque et au mildiou, appliquees au type varietal “Cantaloup charentais”. C. R. Eucarpia “La selection du Melon” 19–22 juin 1973 (Avignon), 41–49.
  4. Lecoq, H., H. Lot and M. Pitrat. 1982. Mise en evidence du virus de la mosaique de la pasteque type I (WMV-1) dans le Sud Est de la France. (Abst.), Agronomie 2:787.
  5. Quiot, J. B., F. Kaan and M. Beramis. 1971. Identification d’une souche de la mosaique de la pasteque (Watermelon Mosaic Virus 1) aux Antilles francaises. Ann. Phytopathol. 3:125–130.
  6. Sowell, G. and J. W. Demski. 1981. Resistance du melon au virus de la mosaique de la pasteque. Bull. phyto sanitaire FAO 29:71–73.
  7. Webb, R. E. 1963. Local-lesion hosts for some isolates of watermelon mosaic virus. Plant Dis. Rep. 47:1036–1038.
  8. Webb, R. E. 1967. Cantaloup breeding line B66-5: Highly resistant to watermelon virus 1. HortScience 2:58–59.
  9. Webb, R. E. 1979. Inheritance of resistance to watermelon mosaic virus I in Cucumis melo L. HortScience 14:265–266.
  10. Webb, R. E. and G. W. Bohn. 1962. Resistance to cucurbit viruses in Cucumis melo L. (Abst.) Phytopathology 52:1221.