Figure 1.
Two-week-old colonies of the five isolates on PDA.
Two-week-old colonies of the five isolates on PDA. A, Gaeumannomyces cylindrosporus (B145); B, Paraphoma chrysanthemicola (B100); C, Phialophora mustea (BC42); D, Exophiala salmonis (BC5); E, Cladosporium cladosporioides (B142).
Figure 2.
Neighbor-joining phylogenetic trees showing the placement of B145 and BC42 (A), B100(B), BC5(C), and B142(D) based on ITS1-5.8S-ITS2 sequences.
The Kimura two-parameter model was used for pairwise distance measurement. Numbers on branches were values generated from 1000 bootstrap replicates. Bootstrap values of 50% were shown above branch nodes. • denoted the isolates.
Figure 3.
Typical structures of DSE fungi colonized in the roots of A. adsurgens seedlings.
A, Structure of microsclerotia formed by P. chrysanthemicola; B, Intercellular melanized septate hyphae formed by G. cylindrosporus.
Figure 4.
The biomass of the five DSE fungi treated with different concentrations of Pb(II).
The biomass of the five DSE fungi grown on solid MMN medium amended with different concentrations of Pb(II), Zn (II), and Cu(II) for two weeks. Data are means ± SE (n = 4).
Table 1.
The MIC and EC50 values of Pb(II), Zn(II), and Cu(II) for the DSE fungi.
Figure 5.
Colony morphology of G. cylindrosporus exposed to different concentrations of Pb(II).
Colonies of G. cylindrosporus on MMN medium with different concentrations of Pb(II) for 2 weeks. A, Colony of G. cylindrosporus with no Pb(II) stress; B, Colony of G. cylindrosporus on MMN medium supplemented with 0.2 mg/ml of Pb(II); C, Colony of G. cylindrosporus on MMN medium supplemented with 0.6 mg/ml of Pb(II); D, Colony morphology of G. cylindrosporus on MMN medium supplemented with 1.0 mg/ml of Pb(II).
Figure 6.
Hyphal morphology of G. cylindrosporus cultured on solid medium.
Scanning electron micrographs of the hyphae from the colony edge of G. cylindrosporus. Twisting and looping of individual hyphae and formation of intertwined hyphal strands occurred when Pb(II) was added in the medium. However, there was no obvious relationship between the number of hyphal coils or the extent of hyphal twisting and the concentrations of Pb(II). A, Hyphae from the untreated control; B, Hyphae from a colony treated with 0.2 mg/ml Pb(II); C–F, Mycelial special morphology of G. cylindrosporus under Pb(II) stress.
Figure 7.
Hyphal morphology of G. cylindrosporus cultured in liquid medium.
Scanning electron micrographs of the hyphae of G. cylindrosporus cultivated for a week in liquid medium supplemented with different concentrations of Pb(II). A–D, Mycelial morphology of G. cylindrosporus treated with 0, 0.1, 0.3, and 0.5 mg/ml Pb(II), respectively.
Figure 8.
Melanin content in G. cylindrosporus under different Pb(II) concentrations stress.
The influence of Pb(II) on melanin content in G. cylindrosporus under liquid culture condition. DW represented dry weight. Different letters above bars indicate significant differences (P<0.05) assessed by Duncan's test. Data are means ± SE (n = 4).
Figure 9.
The responses of antioxidant substances to the toxicity of Pb(II).
The contents of total soluble protein (A) and GSH (B) and the activities of SOD (C) and CAT (D) in the hyphae of G. cylindrosporus cultivated for a week in liquid MMN medium supplemented with a series of increasing Pb(II). FW represented fresh weight. Different letters above bars indicate significant differences (P<0.05) assessed by Duncan's test. Data are means ± SE (n = 4).