Action Spectrum for Photosporogenesis in Botrytis cinerea Pers. ex Fr

Abstract

An action spectrum for photoinduced conidium (8). This latter group of fungi has been studied by Leach (9) and others (10, 11,15). Several action spectra have been reported for light-induced sporulation (1, 3, 5, 7, 9-11, 13, 15) Half-band widths of monochromatic radiations were measured with an UV wavelength distribution analyzer (UV-55, Japan Spectroscopic Co., Ltd. modified to cover 200-750 nm), and are given in Table I. They were all less than 9 nm. Intensity of monochromatic radiation was measured with a radiometer (RMA-8, Japan Spectroscopic Co., Ltd.). The radiometer was a calibrated vacuum thermopile having a quartz window and was coupled with a nanovoltmeter and AC amplifier. Measurements were made before and after the experiments and these were averaged.Irradiation. The Petri dish lids of 4-day-old colonies were replaced with thick black paper covers having windows (30 x 60 mm) of uncoated cellophane (Fig. 1). The hyphal fronts were marked on the bottom of the Petri dish to locate the region to be irradiated. Colonies were then placed on the optical bench designed to hold a Petri dish in a precise position for exposure to monochromatic radiation. The horizontal beam of radiation from the monochromator was directed through the uncoated cellophane onto the colony using a front surface aluminum mirror.Light intensities ranged from 15.2 to 4,448 erg/cm2 sec as shown in Table I. Exposure times ranged from 15 min to 2 hr. The spectroirradiator was located in a dark room controlled at 22 C.Temperature of the specimen chamber was kept at 22.5 + 0.5 C during irradiation. Unirradiated control cultures were handled similarly to the irradiated cultures but kept in darkness. None of the controls developed conidia. After irradiation, colonies were incubated in darkness for an additional 48 hr at 22.5 C to allow spores to develop.Spore Counts and Dose Response Curves. After the final incubation, samples were removed from the irradiated portion of a colony. These samples were 30 mm long at the irradiated perimeter of the colony and 10 mm wide. The sample was comminuted in 10 ml of distilled H20 with 0.1% Tween 20 by blending 60

Photocontrol of Fungal Development

“…6). Helminthosporium oryzae has a peak at 298 nm (Y AMA- MURA et al 1977) and Botrytis cinerea has its closest major peak at 283 nm (HONDA and YUNOKI 1978) (Fig. 6).…”

“…UV induction of fungal sporulation. Action spectra or wavelength dependencies were redrawn and superimposed for Helminthosporium oryzae conidiation (Y AMAMURA et al 1977), Alternaria dauci sporulation , Leptosphaerulina trifolii sexual perithecia (LEACH 1972) Pleospora herbarum and Botrytis cinerea sporogenesis (HONDA and YUNOKI 1978). Similarly a pulse of UV radiation will also induce conidia from preconidia in Stemphylium solani (SPROSTON and SETLOW 1968) The characteristic cryptochrome action spectrum has a sharp peak in the NUV at 350-380 nm and a broad peak in the blue with a maximum at 440-450 and a sharp shoulder at 480 and a sometimes discernable minor shoulder at 420 nm.…”

Photobiological Control of Crop Production and Plant Diseases

“…This is common for many other fungi with light-affected sporulation (Tan, 1978). Honda and Yunoki (1978) have defined a precise action spectrum for photosporogenesis in B. cinerea with a lower limit of effective wavelength at 355 nm and three major peaks of effectiveness at about 231, 268 and 283 nm and a minor peak at about 303 nm. Any attempt to correlate the role of light with vegetable diseases should not ignore other environmental factors (Leach, 1962(Leach, , 1971Vakalounakis et al, 1983).…”

Molecular cloning, sequence analysis and expression of a novel gene induced by near-UV light in Bipolaris oryzae

“…We found that conidiation in 99% of isolates of B. oryzae is induced by near-UV light (Kihara et al 1997). Furthermore, conidiation in certain fungi imperfecti, such as Ascochyta pisi (Leach and Trione 1965), Alternaria dauchi (Leach and Trione 1966), A. solani (Honda and Yunoki 1981), A. tomato (Kumagai 1983), A. cichorii (Vakalounakis 1986), Stemphylium solani (Sproston 1971), and Botrytis cinerea (Honda and Yunoki 1978) is also induced by exposure to near-UV light.…”