Figure 1.

Plant growth promotion by Trichoderma hamatum GD12. (A) Amendment of peat compost with T. hamatum GD12 promotes growth of Arabidopsis thaliana accession Landsberg—erects. Photographed at 3 weeks. (B) Soluble, autoclaved bran extracts from GD12 or the N-acetyl-β-D-glucosaminidase knockout mutant (ΔThnag1::hph) promote growth of lettuce (Lactuca sativa cultivar Webb's Wonderful) in sterile peat. Lettuce were supplemented with the indicated amount of sterilized bran exudate on alternate days. Control plants were watered with a corresponding aliquot of dH₂O. After 21 days growth plants were harvested to determine root and shoot weights. Each microcosm diameter is 15 mm. The photograph, taken 21 days after sowing is representative of a microcosm replicate. Histogram showing dry weights of lettuce root (C) or shoot (D) biomass 21 days after growth in peat microcosms supplemented by application of sterilized bran extracts. Each plant was treated with the indicated amount of metabolite extract from either T. hamatum strain GD12 (black bars) or ΔThnag::hph (Δnag; gray bars) on alternate days. Control plants (white bars) were watered with dH₂O. Each bar represents the mean of 25 samples, each with 3 experimental replicates ± SE. Same letter denote no significant difference and ^*denote significant difference at 95% confidence level (t-test).