Horwitz B A, Trad C H, Lipson E D
Department of Physics, Syracuse University, Syracuse, New York 13244-1130.
Plant Physiol. 1986 Jul;81(3):726-30. doi: 10.1104/pp.81.3.726.
A brief pulse of blue light induces the common soil fungus Trichoderma harzianum to sporulate. Photoresponse mutants with higher light requirements than the wild type are available, including one class, dim Y, with modified absorption spectra. We found blue-light-induced absorbance changes in the blue region of the spectrum, in wild-type and dim Y mutant strains. The light-minus-dark difference spectra of the wild type and of several other strains indicate photoreduction of flavins and cytochromes, as reported for other fungi and plants. The difference spectra in strains with normal photoinduced sporulation have a prominent peak at 440 nm. After actinic irradiation, this 440 nanometer difference peak decays rapidly in the dark. In two dim Y photoresponse mutants, the difference spectra were modified; in one of these, LS44, the 440 nanometer peak was undetectable in difference spectra. Detailed study of the dark-decay kinetics in LS44 and the corresponding control indicated that the 440 nanometer difference peak escaped detection in LS44 because it decays faster than in the control. The action spectrum of the 440 nm difference peak is quite different from that of photoinduced sporulation. The light-induced absorbance changes are thus unlikely to be identical to the primary photochemical reaction triggering sporulation. Nevertheless, these results constitute genetic evidence that physiologically relevant pigments participate in these light-induced absorbance changes in Trichoderma.
短暂的蓝光脉冲可诱导常见的土壤真菌哈茨木霉产生孢子。现已获得对光需求高于野生型的光反应突变体,包括一类吸收光谱发生改变的dim Y突变体。我们发现野生型和dim Y突变体菌株在光谱的蓝光区域均有蓝光诱导的吸光度变化。野生型及其他几种菌株的光暗差光谱表明黄素和细胞色素发生了光还原,这与其他真菌和植物的情况一致。具有正常光诱导产孢能力的菌株的差光谱在440纳米处有一个明显的峰值。光化辐射后,这个440纳米的差峰在黑暗中迅速衰减。在两个dim Y光反应突变体中,差光谱发生了改变;其中一个,即LS44,在差光谱中未检测到440纳米的峰值。对LS44及其相应对照的暗衰减动力学进行的详细研究表明,LS44中未检测到440纳米的差峰是因为它的衰减速度比对照快。440纳米差峰的作用光谱与光诱导产孢的作用光谱有很大不同。因此,光诱导的吸光度变化不太可能与触发产孢的初级光化学反应相同。尽管如此,这些结果构成了遗传学证据,表明生理相关色素参与了木霉中这些光诱导的吸光度变化。