FIG 1.

The number of nuclei per compartment is dependent on the hyphal type. (a) Range of number of nuclei per compartment. Calculations were based on 65 hyphae from 5 biological replicates. Both odd and even numbers were found. (b) Different stages of colony development in F. oxysporum. The upper panel shows a schematic representation of stage I, in which each compartment harbors 1 nucleus. This stage was found in germlings and in newly branched hyphae. The lower panel shows colony phenotype after 2 days. Stage II, in which fast-growing hyphae with multinucleate apical compartments are frequently encountered, can be found in the growth front. Stage III with multinucleate intercalary compartments can usually be found in mature hyphae behind the growth front, where aerial hyphae start to emerge. Scale bar, 1 cm. (c) The three developmental stages were found in all three strains tested: F. oxysporum f. sp. lycopersici strain 4287 (Fol4287), F. oxysporum f. sp. melonis strain 001 (Fom001), and nonpathogenic F. oxysporum strain 47 (Fo-47). All strains expressed HH01::GFP and were stained with 1 μM calcofluor white. Scale bars, 10 μm.