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Oral: Oomycete Biology

35-O

Effect of red light on morphology of Peronospora belbahrii sporangia
J. PATEL (1), S. Zhang (1) (1) Tropical Research and Education Center, University of Florida, U.S.A.

Downy mildew of basil, caused by Peronospora belbahrii, has spread to more than 42 US states since it was first detected in Homestead, FL in 2007. Recently, our experiments showed that red light can suppress downy mildew in basil. The aim of this study was to investigate the effect of red light on biology of P. belbahrii sporangia. The red LED lights were hung 4 feet above the greenhouse bench and 5 feet between two adjacent LED lights. The LED in the spectrum of 625 nm wavelength illuminated at an average light intensity of 12 ┬Ámol.m-2.s-1. The LEDs were automatically turned on from 8 pm to 8 am each day. One set of inoculated basil plants was maintained under dark conditions and another set of inoculated basil plants were placed under the exposure of red light. Fresh sporangia were harvested from the basil plants under dark conditions and under red light. A total of fifty sporangia were examined under a microscope with 40x magnification lens. The sporangia produced under dark conditions were brown in color and had oval shaped sporangia, whereas sporangia produced under red illumination were white in color and had round shaped sporangia. The change in morphology of the sporangia is an indication of a possible direct effect of red lights on P. belbahrii sporangia production. These results warrant further investigations to determine the mechanisms underlying changes in biology of P. belbahrii sporangia affected by red light.