ISHS Acta Horticulturae 588: II International Symposium on Cucurbits
EXPRESSION OF POWDERY MILDEW RESISTANCE IN F1 PROGENIES AND HOST-PATHOGEN INTERACTION IN CUCUMBER |
| Authors: | M. Morishita, K. Sugiyama, T. Saito, Y. Sakata |
| Keywords: | Cucumis sativus, Sphaerotheca fuliginea, Disease resistance, Hypersensitive reaction Inheritance |
| Abstract:
The expression of powdery mildew resistance (PMR) genes in F1 and the nature of the host-pathogen interaction were studied under two different temperature conditions using three different types of cucumber cultivars. When ‘PI197088-5’ (Type 1) showing PMR irrespective of temperature condition was crossed with susceptible cultivar Sharp 1 (Type 3) or cultivars Natsufushinari and F9-5-2 (Type 2) showing PMR at high temperature condition, a partial dominance was observed in the F1. On the other hand, the F1s of ‘Natsufushinari’ or ‘F9-5-2’ crossed with ‘Sharp 1’ showed complete dominance for susceptibility. Then it was considered that ‘PI197088-5’ is more useful for breeding material in resistance level and heredity than ‘Natsufushinari’ or ‘F9-5-2’. The development of powdery mildew on leaf surface of the resistant host PI197088-1 which is sib-line of ‘PI197088-5’ was observed at different times after inoculation. Conidia on leaf surface of ‘PI197088-1’ germinated within 12 hr after inoculation and first hyphae began to grow within 24 hr. The retardation of hyphal growth and development was observed since two days after inoculation. Conidia were hardly formed on epidermal of ‘PI197088-1’. The number of haustorium in epidermal of ‘PI197088-1’ was less than susceptible cultivar Sharp 1. Also fluorescing of epidermal cell was observed along the hyhae in ‘PI197088-1’ at about 6 days after inoculation. This was considered to be a hypersensitive reaction. These results would suggest that the PMR of ‘PI197088-1’ results from the inhibition of haustorium formation or of nutrition absorption through haustorium or hypersensitive reaction of epidermal cells. | |
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