Figure 1.
Effect of carbon source and light on vel1 transcript levels in T. reesei.
Transcript levels of vel1 during growth on glucose, glycerol and lactose in T. reesei QM 9414 in the presence of ambient light (white bars) and darkness (full bars). Transcript levels are given in arbitrary units, which were calculated by normalizing the vel1/tef1 ratio to that on glucose (12 h, ambient light). Data are means of at least 3 biological replicas. The asterisk indicates the time point where the cultures started to sporulate (this time point was the same in light and darkness).
Figure 2.
The impact of VEL1 on morphology of T. reesei in submerged culture.
Morphology of growing hyphae of T. reesei QM9414 (A–E) and the Δvel1 (F–L) strains during submerged growth on Mandels-Andreotti medium with glycerol (1%, w/v) as a carbon source at 12 (A–B and F–G), 48 (C and H–I) and 72 (D–E and J–K) hours following inoculation.
Figure 3.
VEL1 is required for T. reesei development.
(A) Effect of vel1 on asexual development of T. reesei. Formation of conidia in the presence of ambient light (empty bars) and darkness (full bars) by T. reesei QM 9414 (1), in two vel1OE (2,3) and three Δvel1 strains (4–6). Data are means of at least three independent biological experiments, and only results with p<0.05 are shown. (B) Phenotype of the parent strain and two Δvel1 strains (RKA14 and RKA17; see Table 1) after 5 days of growth on PDA. (C) absence of fruiting body formation between Δvel1 (top) and the compatible mating partner strain CBS 999.79 (bottom) in the presence of ambient light,L, and darkness, D. (D) control plate between QM 9414 (left) and CBS 999.79 (right) in the presence of ambient light. Note that fruiting in the wild-type does not occur in darkness [35], and thus no such plate is shown. (E) Fruiting body formation between vel1OE (bottom) and CBS 999.79 (top) under ambient light (L) or darkness (D). One of at least three replicate experiments is shown. The insert represents a magnification of the boxed part, highlighting the primordia.
Figure 4.
The impact of VEL1 on the utilization of different carbon sources by T. reesei.
Effect of vel1 on the growth of T. reesei on various carbon sources either in light or in darkness Photos were taken 5 days (120 h) after inoculation of the plates. Additional 2 days of cultivation did not alter the phenotypes shown.
Figure 5.
Impact of vel1 deletion or overexpression on growth and cellulase formation by T. reesei on lactose.
Cellulase formation by T. reesei QM 9414, a Δvel1 mutant and a vel1OE strain during growth on lactose. Only one strain is shown, but other strains with the same genotype gave consistent data. Data shown are means of at least two independent experiments and three measurements. Blue line and empty blue circles: lactose concentration; dark red dotted line and empty triangles: cellulase activity; bright red dashed line and full red triangles, extracellular protein concentration; black dashed line and black squares, fungal biomass concentration.
Figure 6.
Impact of vel1 deletion or overexpression on transcript levels of two cellulase, one hemicellulase and a cellulase regulator gene in T. reesei during growth on lactose.
mRNA levels of two cellulase genes (cel7a, cel6a), one xylanase gene (xyn2) and the cellulase regulator xyr1 in T. reesei QM 9414 (full circles and solid line), a Δvel1 strain (empty circles and dotted line) and a vel1OE strain (full traingles and dashed line) under the fermentation conditions on lactose as shown in Figure 5. mRNA levels are given in arbitrary units, which were calculated by normalizing the ratio of the respective gene transcript to that of the housekeeping gene tef1, and relating all ratios to that obtained for the given gene at 17.5 hrs in T. reesei QM9414. Only one mutant strain is shown, but other strains with the same genotype gave consistent data. Data shown are means of at least two independent experiments and three measurements.
Figure 7.
Impact of vel1 deletion or overexpression on transcript levels of two cellulase, one hemicellulase and a cellulase regulator gene in T. reesei upon induction by sophorose.
Transcript levels of two cellulase genes (cel7a, cel6a), one xylanase gene (xyn2) and the cellulase regulator xyr1 in T. reesei QM 9414 (full symbols), a vel1 strain (empty symbols) and a vel1OE strain (grey symbols) upon induction of mycelia, pregrown on glycerol for 20 hrs, by sophorose for 4 hrs. Transcript levels are given in arbitrary units, as specified in legend to figure 6. The asterisks indicate cases were the relative mRNA level was below the limit of detection. Only one mutant strain is shown, but other strains with the same genotype gave consistent data. Data shown are means of at least two independent experiments and three measurements.
Table 1.
Strains used in the present work.