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Cucurbit Genetics Cooperative Report 17:81-82 (article 23) 1994

Response Reaction of Melon Genotypes Heterozygous for the Prv1 Gene to Mechanical Inoculation of PRSV-W

Vitti, A.J., P.T. Della Vecchia, and R. Wierzbicki

Agroflora S/A, Caixa Postal 427, 12900-000, Braganca Paulista, SP, BRAZIL

In a previous study on the inheritance of Papaya Ring Spot Virus-Watermelon (PRSV-W) on melon (1) we have observed the appearing of necrotic local lesion on cotyledons of mechanically inoculated plants, which were heterozygous for the Prv1 gene, that eventually became systemic, killing the entire plant. It was of interest to know whether this kind of response reaction to PRSV-W would be present in F1 hybrids of melon heterozygous for the PRV1 gene, with different genetic backgrounds.

Materials and Methods. The pedigree and the PRSV-W status of the inbreed lines used in the present study to produce the F1 hybrids are presented in Table 1. Inoculum was prepared by grinding leaves of C. pepo cv. Caserta, showing strong symptoms of the virose, in 0.02 M phosphate buffer (pH 7.0) containing 0.01 M sodium sulfite (1:10 - w/v) and rubbing extracts on fully expanded cotyledons of 4- to 6-day old plants, previously dusted with 600 mesh Carborundum.

Results and Discussion. The response reaction of the melon genotypes to the mechanical inoculation of PRSV-W are presented in Table 2. regardless of the genetic background, necrotic local lesion on the cotyledons and systemic necrotic response reaction were observed for all F1 hybrids, except for the AF605LxA647L F1 hybrid, which is homozygous for the PRv1 gene. On this F1 hybrid and on the resistant inbreed lines the necrotic local lesions observed on the cotyledons were usually smaller in number and in size when compared to those observed on the heterozygous Prv1 F1 hybrids. These results suggest that it may not be commercially feasible to use the Prv1 gene ion the heterozygous condition for resistance to PRSV-W.

Table 1. Pedigree and PRSV-W status of the melon inbreed lines used to produce the F1 hybrids to evaluate the response reaction to mechanical inoculation of PRSV-W.
Inbreed Line
Melon type
Origin
PRSV-W Status1
AF605L S9
Casaba
Brazil
R
AF647L S7
Casaba
Brazil
R
AF111L S3
Santa Claus
France
S
AF137L S3
Cantaloupe
USA
S
AF581L S4
Cantaloupe
Brazil
S
AF584L S5
Casaba
USA
S
AF652L S6
Casaba
USA
S
AF659L S6
Casaba
Israel
S

 1R = resistant; S = susceptible.

 
Number of Plants
18 D.A.I.1
26 D.A.I.
 
Genotype
NC2
NC+SN3
H4
M5
NC
NC+SN
H
M
TOTAL
AF605L
1
0
11
0
1
0
11
0
12
AF647L
2
0
12
0
2
0
12
0
14
AF605L x AF647L
2
0
10
0
2
0
10
0
12
AF647L x AF111L
0
14
1
0
0
14
1
0
15
AF605L x AF137L
1
4
9
0
0
5
9
0
14
AF647L x AF137L
2
10
3
0
3
11
1
0
15
AF605L x AF426L
0
10
2
0
0
10
2
0
12
AF647L x AF426L
5
5
2
0
4
7
1
0
12
AF647L x AF581L
3
5
6
0
3
6
5
0
15
AF605L x AF584L
5
4
1
0
3
6
1
0
10
AF647L x AF584L
6
3
3
0
3
8
1
0
12
AF605L x AF652L
0
4
4
0
1
4
3
0
8
AF647L x AF652L
1
7
4
0
1
7
4
0
12
AF605L x AF659L
2
9
0
0
1
10
0
0
11
AF647L x AF659L
3
7
1
0
1
10
0
0
11
AF426L
0
0
0
12
0
0
0
0
12

1D.A.I. = days after inoculation.
2 NC = necrotic local lesion on the cotyledons.
3 SN = systemic necrotic lesions on the plants.
4 H = healthy plants.
5 M = systemic mosaic

Literature Cited

  1. Della Vecchia, P.T. and A.C. Aviila. 1985. Heranca da resistencia ao Virus do Mosaico da Melancia-i em melao. Fitapatologia Brasileira 10:467-474.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
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