ISHS Acta Horticulturae 510: VII Eucarpia Meeting on Cucurbit Genetics and Breeding
HISTOLOGICAL OBSERVATIONS OF POWDERY MILDEW RESISTANCE IN DIPLOID AND HAPLOID MELONS |
| Authors: | M. Kuzuya, K. Hosoya, Y. Hayato Masuya, K. Tomita, H. Ezura |
| Keywords: | Cucumis melo, disease resistance, ploidy, Sphaerotheca fuliginea |
| Abstract:
Sphaerotheca fuliginea is a major causal fungus of powdery mildew in melon, Cucumis melo. Melon cultivars PMR 45 and WMR 29 are resistant to different races of S. fuliginea. As a preliminary experiment for elucidating the mechanism of resistance, the conidial infection process of S. fuliginea on the leaves of diploid and haploid plants of ‘PMR 45’, ‘WMR 29’, and the susceptible ‘Fuyu 3’ was observed histologically. Conidia on the diploid leaves of the susceptible cultivar germinated and formed appressoria and haustoria within 24 hours, and hyphae began to grow out from the appressoria and branched within 48 hours, whilst on the resistant cultivars hyphal growth was inhibited after the development of the haustoria. The inhibition of hyphal growth was also observed on the haploid plants of the resistant cultivars. The features of inhibition were similar on diploid and haploid plants. These observations suggest that some substance(s) related to an initial infection step accounts for the resistance of ‘PMR 45’ and ‘WMR 29’ to S. fuliginea. | |
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