Figure 1.
Uredinia and urediniospores of Pst are parasitized by Cladosporium cladosporioides.
A: A uredinium infected by C. cladosporioides (×800), B: A non-infected uredinium filled with urediniospores (×700), C: Hyphae of C. cladosporioides growing from or between urediniospores at an early stage of infection (×2,000), note the shriveled urediniospores, D: Numerous hyphae of C. cladosporioides growing on a uredinium at a late stage of infection (×400), note presence of very few normal urediniospores, E: Urediniospores invaded by C. cladosporioides hyphae (×1,800), F: High magnification of a C. cladosporioides hypha invading a urediniospore (×11,000).
Figure 2.
Morphological features of Cladosporium cladosporioides cultured on MEA medium.
A: Fungal colonies on MEA medium, B: Branched ramoconidia and chains of conidia, C: Ramoconidia and dense conidia on the tip of a conidiophore, D: Oval to spherical conidia and separated ramoconidia with a dark scar at one end or both ends.
Figure 3.
Morphological features of Cladosporium cladosporioides under a scanning electron microscope.
A: Conidial chains (×7,000), B: Scars on a conidiophore (×20,000), C: Top view of a conidiophore with scars (×7,000), D: scars on a secondary ramoconidium (×4,000), E: Conidia on conidiophores (×5,000), F: Hyphae (×2,000).
Figure 4.
The pathogenicity test to confirm that C. cladosporioides could hyperparasite Pst.
A, B: CK1, wheat leaves (Cultivar: MingXian169) inoculated with C. cladosporioides, 14 dpi, without symptoms; C, D: CK2, Symptoms on wheat leaves (MingXian169) inoculated with CYR32, 20 dpi; E, F, G: Pustules on wheat leaves (same cultivar and race as above) inoculated at 14 dpi with C. cladosporioides suspension. Symptoms at 5d, 7d and 9d later.
Figure 5.
SEM observations of Pst inoculated with C. cladosporioides.
A: 12 h after inoculation, the spore of C. cladosporioides contacted the urediniospore surface (×7,000), B: 24 h after inoculation, spores of C. cladosporioides germinated (×700), C: 36 h after inoculation, direct penetration by germ tube of C. cladosporioides into a urediniospore (×10,000), D: 48 h after inoculation, amount of urediniospores were surrounded with germinated spores of C. cladosporioides (×2,000), E: 72 h after inoculation, germ tubes of C. cladosporioides have penetrated urediniospores (×3,000), F: 120 h after inoculation, C. cladosporioides has colonized the urediniospores (×1,300).
Figure 6.
A neighbor-joining tree constructed using the sequences of ITS,EF and ACT to determine the phylogenetic relationship of the hyperparasitic fungal strain CGMCC 7.175 (bold and marked with *) isolated from uredinia of Pst with other accessions of Cladosporium spp. in GenBank.
The values at braches are percentages from 1,000 bootstrap replications.
Table 1.
Accession numbers of Cladosporium species used in the molecular characterization.