Control of pigmentation of Ustilago hordei: the effect of pH, thiamine, and involvement of the cAMP cascade.
Lichter, A.; Mills, D.;
Fungal Genetics and Biology Year: 1998 Vol: 25 Issue: 1 Pages: 63-74 Ref: 40 ref.
1998
บทคัดย่อ
Pigment formation was studied in U. hordei [U. segetum] strains 8.2a, 10.1a, 1-2, 2-1, 3-1, 4-1, 6-1, 7-1, 9-1, 11-1, 12-1 and Uh100. Strain 8.2a developed a black pigmentation on complex media after 4-5 days, whereas strain 10.1a did not. Cell pigmentation and morphology were both affected by medium composition. Strain 8.2a had black pigmentation at acidic pH and elevating the pH to neutral or basic conditions resulted in a red pigmentation. Cell morphology was also affected by medium pH, with sporidia produced in the range of pH 4.5-5.0 and more hyphae produced at neutral pH. Pigment formation was also found to be controlled by thiamin in some strains of U. segetum, with pigment formation inhibited at thiamin concentrations above 0.02 mu M. Pigment formation was repressed by cAMP transiently, whereas isobutryl-3-methyl xanthine (a cAMP phosphodiesterase inhibitor) completely repressed pigment formation. Transient inhibition of pigment formation was also observed in cultures expressing the G al
pha subunit gene FIL1. When the mutant allele FIL1Q206R was expressed, which renders the gene active, pigment formation was not observed. Wild-type strains were transformed with random cosmid clones of a genomic library which resulted in approximately 30 cosmid members per genome equivalent, causing pigment repression and 6 cosmid members inducing pigment formation. It is suggested that a number of genes were involved in pigment formation.