Plant Pathology Journal (2007) 6, 104-111

Rie Nakamura, Shunji Suzuki, Shin-Ichi Fuji, Hiromitsu Furuya and Hideki Naito (2007)
Suppressive effect of darkness on the development of powdery mildews
Plant Pathology Journal 6 (2), 104-111
Abstract: The effect of darkness on powdery mildew development was evaluated in the present study. Blumeria graminis f. sp. tritici, Erysiphe pisi and Sphaerotheca cucurbitae were incubated under various light conditions. The formation of haustoria and appressoria on hyphae and the elongation of hyphae were suppressed drastically by incubation in the continuous dark condition. Development of the powdery mildews was delayed by incubation in the continuous light condition. These suppressive effects of light conditions were consistent among the three powdery mildews investigated. B. graminis incubated in the continuous dark condition formed only primary haustoria that were larger in size than those formed in regular light conditions (12 h light/12 h dark), while E. pisi and S. cucurbitae formed secondary haustoria in the continuous dark condition. Re-irradiation of the powdery mildews incubated in the continuous dark condition led to recovery of development of the powdery mildews. Treatment of host plants with glucose and sucrose reversed the suppressive effect of darkness and promoted development of the powdery mildews. These results suggest that the reduced growth of powdery mildews under continuous dark or light condition might be due to loss of nutrients, such as carbohydrates, from host cells under these conditions. On red, green, yellow and blue light re-irradiation following incubation in the continuous dark condition, the formation of secondary haustoria by B. graminis was observed, although the number of haustoria per colony was significantly smaller than that by white light re-irradiation. Black blue light (310 to 410 nm) did not induce the formation of secondary haustoria. Taken together, this study demonstrated that light conditions affect powdery mildew development, suggesting that light conditions are indispensable for the infection of host plants by powdery mildew.
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Database assignments for author(s): Shin-ichi Fuji, Hiromitsu Furuya

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Blumeria graminis		Japan
	Erysiphe pisi
	Podosphaera xanthii		Japan