CAROTENE AND CYTOCHROME c DEPENDENT MITOTIC RECOMBINATION AND KILLING IN RESPONSE TO VISIBLE LIGHT AND UV‐C IN THE SMUT FUNGUS Ustilago Violacea

Abstract

Abstract— The carotene (carotenoid hydrocarbons) and cytochrome c compositions for the phlph+ pink diploid strain of Ustilago violacea and three newly developed color variants, white (w), orange (o), and yellow (y) were quantitatively determined using high‐performance liquid chromatography of lipid extracts and difference spectroscopy of alkali extracts. In addition, the effect of high‐intensity incandescent and far UV (UV‐C) radiation on survival and mitotic recombination in all four phlph+ strains were studied. The phlph+w and phlph+y strains contained relatively small amounts of cytochrome c; however, the phlph+y strain accumulated β‐carotene while in the phlph+w strain only the colorless carotene phytoene was found. The phlph+w was very sensitive to incandescent radiation, with complete killing by 90 min of exposure. The induction of mitotic recombination in the phlph+w strain was inversely proportional to the level of survival, with 96% induction by 90 min of exposure. The β‐carotene‐accumulating phlph+y strain was considerably more resistant to photokilling, and exhibited induction of mitotic recombination at a lower level. Similar results were observed with these strains in response to UV‐C. The phlph+y strain was significantly more resistant to UV‐C killing than the phlph+w strain and it also exhibited lower induced levels of mitotic recombination.The phlph+o and phlph+ pink strains accumulated over 10 times the cytochrome c as the phlph+w or phlph+y strains. The phlph+o strain accumulated β‐carotene at the level of the phlph* y strain, but the phlph+ pink strain contained only about one‐tenth as much β‐carotene. The phlph+ o and phi ph+ pink strains exhibited sensitivity to visible radiation that was intermediate to the phlph+y and phlph+w strains. Mitotic recombination induction by visible radiation in the orange and pink strains was slightly less than that in the phlph+w strain. In response to UV‐C, the phlph+o and phlph+ pink strains had survival and mitotic recombination induction characteristics that were similar to the phlph+w strain.