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Selection of powdery mildew resistance among haploid plants generated from hybrids of resistant and susceptible melon genotypes

Kuzuya, M., Hosoya, K., Tomita, K., Ezura, H.
Acta horticulturae 2002 no.588 pp. 331-334
Podosphaera xanthii, cultivars, hybrids, haploidy, conidia, diploidy, races, Cucumis melo, breeding, hyphae, powdery mildew, rapid methods, labor, doubled haploids, pathotypes, fungi
The fungus Sphaerotheca fuliginea is the major cause of powdery mildew in melon (Cucumis melo). Several physiological races have been identified in different melon genotypes. For melon breeding programs, it is important to monitor the dominant races in the field and introduce resistance into new cultivars. Haploid breeding is a useful technique for the rapid production of a pure line. However, producing doubled haploids is labor intensive. If resistant plants can be selected at the haploid level and then doubled, haploid breeding of powdery mildew-resistant melon will be more efficient. We previously demonstrated that haploid and diploid plants respond to powdery mildew in the same manner. This study reports the responses to powdery mildew of haploid plants produced from the F1 generations of the susceptible line Fuyu 3 and the resistant lines PMR45 and WMR29. The response to powdery mildew races 1, N1 and N2 was observed in 13 haploids from F1 plants of Fuyu 3 and PMR 45, and in 12 haploids from F1 plants of Fuyu 3 and WMR 29. Seven of 13 haploids from F1 plants of Fuyu 3 x PMR 45 and 10 of 12 haploids from F1 plants of Fuyu 3 x WMR 29 responded to each race in the same manner as their resistant, diploid parent, i.e., S. fuliginea conidia did not elongate secondary hyphae on resistant plants. These results suggest that resistant plants can be selected among haploids generated from F1 plants.