The identity of the fragments was checked by sequencing. Light induction of the orange pigmentation (putative carotenoid accumulation) was assessed in two sexually compatible wild-type strains of F. verticillioides

FGSC 7600 and FGSC 7603, as well as three independent ΔFvMAT1-2-1 mutants (M6, M7, and M15) of FGSC 7603, grown on NM agar under different illumination conditions (Fig. 2). On this medium, the two wild-type strains acquired a faint pigmentation in the dark, but this was not apparent in the mutant strains under the same culture conditions (Fig. 2a). When incubation occurred under continuous illumination, the wild-type strains developed an intense orange color, while the three ΔFvMAT1-2-1 mutants showed a paler pigmentation (Fig. 2b). These findings indicate that (1) the orange Protein Tyrosine Kinase inhibitor pigmentation is light inducible and (2) the synthesis is HM781-36B reduced in the

absence of an operational MAT1-2-1 gene in the MAT1-2 background. The color development of these five strains on CA and CM agar was similar to that observed on NM (data not shown), suggesting that the deficiency of orange pigmentation in the ΔFvMAT1-2-1 mutants was not limited to minimal nutrient conditions. To further analyze the effect of light on pigment accumulation, fungi were grown in liquid NM under different illumination conditions for 5 days. As presented in Fig. 2c, all strains showed an albino phenotype when they were

cultured in the dark. Five-day culture under continuous illumination Tolmetin resulted in intense orange coloration in the wild-type strains, but much less pigment accumulation occurred in the three ΔFvMAT1-2-1 mutants (Fig. 2e). When 4-day-old cultures grown in the dark were exposed to 24-h illumination, a moderate pigment accumulation was observed in the wild-type strains, while the ΔFvMAT1-2-1 mutants exhibited albino-like phenotypes (Fig. 2d). Similar pigmentation patterns were observed with shorter light exposures (i.e. 8-h illumination, followed by further incubation for 16 h in the dark) after 4-day culturing in the dark (data not shown). To reveal the biochemical bases of the orange pigmentation, the carotenoid contents of the cultures were measured. Carotenoids were extracted and analyzed by column chromatography to determine the amounts of both polar and nonpolar carotenoids in the wild-type strains of F. verticillioides and the ΔFvMAT1-2-1 mutants of strain FGSC 7603 grown in liquid NM under different illumination conditions (Fig. 3). As expected, only trace amounts (<0.2 μg g−1 dry mass) of carotenoids were found in the albino cultures of any strain grown in the dark.