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Cucurbit Genetics Cooperative Report 18:40-42 (article 19) 1995

New Sources for Powdery Mildew Resistance in Melon From Spanish Local Cultivars

E. Floris, J.M. Alvarez

Universidad de Zaragoza, Departmento de Agricultura, Crta. Zaragoza, Km 67, 22071, Huesca, Spain; Servico de Investigacion Agraria, D.G.A., Apartado 727, 50080 Zaragoza, Spain

Resistance to powdery mildew (Sphaerotheca fuliginea [Schlech. ex Fr.] Poll.), was firstly found in a seed lot from India (5). That material has been extensively used in many breeding programs until today and most of the work done concerned with powdery mildew resistance in melon is mainly based in the first material, although other sources of resistance have been reported (3).

Spain is a secondary diversification center for Cucumis melo L. (2) and varietal characteristics of Spanish accessions are quite different to those of the Hindu material. For this reason a program to screen this Spanish material was thought to be of interest. The research we present in this paper was the continuation of a preliminary study carried out in 1986 (1).

For that purpose 10 plants for each genotype of a collection of 44 Spanish accessions of Cucumis melo L. kindly supplied by the Vegetable Germplasm Bank of Zaragoza, were grown in pots containing a mixture of peat: sand: loamy soil (1:1:1 by volume) and placed in a growth chamber at 24C constant temperature, 15 hours of light and 9 of darkness. Light intensity was about 1,300 microeinsteins m2 x sg1 provided by "Sylvania day light" tubes.

Artificial inoculation was done by spraying over the second true leaf of the plants a suspension of conidia of S. fuliginea race 1 (40,000 sp/ml) as described before (4).

To assess resistance, thirteen days post-inoculation the number of conidia/cm2 x ml was estimated according to the method described before (4), and visual symptoms were recorded:

With both methods, we could classify the cultivars in three different classes:

  • Resistance: Less than 10% of affected tissue, or less than 1 conidia/cm2 x ml.
  • Intermediate: Among 10% to 30% of affected tissue, or 1 to 4 conidia/cm2 x ml.
  • Susceptible: More than 30% of affected tissue, or more than 4 conidia/cm x ml.

After the results shown in Table 1 new sources of resistance can be reported.

Six local cultivars were found to be resistant to S. fuliginea race 1:

  • 'Amarillo', C. melo, var. sacharinus (Naud.), yellow skinned
  • 'BG069', C. melo var. inodorus (Naud.), green skinned
  • 'Comun', C. melo var. indorus (Naud.), green skinned
  • 'Mochuelos', C. melo var. sacharinus (Naud.), green skinned
  • 'Moscatel Grande', C. melo var. sacharinus (Naud.), green skinned
  • 'Negro', C. melo var. inodorus (Naud.), dark green skinned
  • 'Tendral l', C. melo var. inodorus (Naud.), green skinned

Also fourteen moderately resistant cultivars were found. These cultivars were:

  • 'Agostizo', C. melo var. sacharinus (Naud.), green skinned
  • 'BG064', C. melo var. sacharinus (Naud.), green skinned
  • 'Invernizo', C. melo var. inodorus (Naud.), green skinned
  • 'Loperano', C. melo var. sacharinus (Naud.), yellow skinned
  • 'Melon de Olor', C. melo var. cantalupensis (Naud.), yellow skinned
  • 'Mochuelo 1', C. melo var. sacharinus (Naud.)., green skinned
  • 'Negros', C. melo var. inodorus (Naud.), green skinned
  • 'Rajado', C. melo var. sacharinus (Naud.), yellow skinned
  • 'Relancia', C. melo var. sacharinus (Naud.), yellow skinned
  • 'Roteno', C. melo var. sacharinus (Naud.), green skinned
  • 'Tendral 2', C. melo var. inodorus (Naud.), green skinned
  • 'Tendral 3', C. melo var. inodorus (Naud.), green skinned
  • 'Tendral Temprano', C. melo var. inodorus (Naud.), green skinned

All of them, moderately resistant and resistant cultivars, were white or yellow-white fleshed.

These 21 local cultivars could be useful for future breeding program, especially for Spanish melon types, and in general, as a source of new genes for resistance to melon powdery mildew.

Table 1.. Means and variances of the percentage of affected tissue and number of conidia/cm2x ml at 13 dayspost-inoculation with a suspension of S. fuliginea race 1 of 44 Spanish accessionsof C. melo.

 
% affected tissue
n ˚ of conidia/cm/ml*
Acccessions
mean
variance
mean
variance
Moscatel Grande
1.0
0.0
0.15
0.05
Amarillo
2.6
0.1
0.10
0.18
Tendral 1
4.2
.2
0.45
0.29
Negro
5.0
0.0
0.60
0.23
BG. 069
7.0
20.0
1.15
0.83
Invernizo
10.0
0.0
1.85
0.62
Tendral 2
10.0
0.0
2.85
0.70
Mochuelos
10.0
0.0
0.59
0.15
Comun
11.0
5.0
0.80
0.10
BG 064
15.0
0.0
1.40
0.30
Tendral Temprano
16.0
36.0
1.70
1.80
Rajado
22.0
45.0
3.20
1.41
Mochuelo 1
23.0
20.0
3.05
0.98
Melon de olor
25.0
0.0
3.22
3.12
Negros
25.0
50.0
3.15
3.36
Relancia
26.0
30.0
3.05
0.98
Agostizo
29.0
5.0
2.72
0.63
Loperano
30.0
0.0
2.88
4.55
RotenoTendral 3
30.0
0.0
3.55
1.32
Marina
40.0
150.0
4.00
0.87
Amarillo oro
42.0
20.0
8.50
6.46
Baza
44.0
30.0
4.50
0.20
Tempranillo
44.0
30.0
7.40
7.33
Melao
46.0
80.0
9.05
25.04
Moscatel
50.0
150.0
9.65
1.89
Cuenca
50.0
50.0
6.85
4.20
Banda
50.0
0.0
10.96
1.35
Cana dulce
54.0
70.0
12.09
0.74
Esento
54.0
80.0
9.40
3.51
Piel de Sapo
56.0
80.0
6.15
11.92
Amarillo cascara pinta
56.0
330.0
8.45
3.79
Pipa blanca
56.0
130.0
11.67
1.60
Moschuelo 2
60.0
30.0
11.92
.43
BG .45
60.0
0.0
10.44
5.46
Tortuga
64.0
0.0
10.55
0.23
Amarillo manchado
66.0
80.0
9.55
2.60
Pedroso
76.0
1300
15.95
32.45
Escrito
84.0
280.0
17.75
32.45
BG .4078
88.0
320.0
20.85
4.43
PS. Pinonet
92.0
120.0
16.25
21.06
Rocket
100.0
0.0
13.60
1.33

Acknowledgement: This work was supported by a grant, AGF92-1064-03-02, from the Comision Interministerial de Ciencia y Tecnologia (CICYT).

Literature Cited:

  1. Alvarez, J.M. 1987. Comportamiento frente a oidio de autoctonos de melon. 6a Joradas de seleccion y mejora de plantas horticolas, 137-142.
  2. Espinat, C., M. Pitrat, and F. Bertrand. 1992. Inheritance of resistance of melon to powdery mildews. Eucarpia meeting Cucurbitaceae 92 Skierniewice (Poland), July, 1992: 185-190.
  3. Esquinas-Alcazar, J.T. 1983. Genetic resources of Cucurbitaceae, a global report. IPGR Secretariat, Rome. 101 pp.
  4. Floris, E. and J.M. Alvarez. 1991. A rapid and sensitive method for evaluation of melon resistance to Sphaerotheca fuliginea. Cucurbit Genet. Coop. Rpt. 14:
  5. Whitaker, T.W. and G.N. Davis. 1962. Cucurbits, Botany, cultivation and utilization. Leonard Hill (Books) Ltd. London/Interscience (Eds.) Publishers Inc. New York. 250 pp.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 15 December, 2009