Figure 3.

SEP1 Is a Spatial Regulator of Cytokinesis in M. oryzae.

(A) M. oryzae SEP1 is a functional homolog of the A. nidulans sepH septation gene. The M. oryzae SEP1 gene was expressed in an A. nidulans sepH1 thermosensitive mutant under the native SepH promoter and restored its ability to form septa at 42°C, as shown by calcofluor white staining (right panels; light micrographs are on the left).

(B) Schematic representation of the sep1^G849R allele, which was introduced into M. oryzae Guy-11 by homologous recombination.

(C) Thermosensitivity of the sep1^G849R mutant of M. oryzae. Plugs of mycelium (5-mm diameter) from putative sep1^G849R transformants, and Guy-11, were incubated at 24 or 32°C for 4 d. Restoration of hyphal growth was assessed by incubation for a further 3 d at 24°C.

(D) Quantitative analysis of infection-associated septation in sep1^G849R mutants. The grg(p):H1:eRFP vector was introduced into the M. oryzae sep1^G849R strain. Conidial suspensions were then prepared from the M. oryzae H1:RFP and sep1^G849R strains and allowed to form appressoria at 24 or 29°C. After 10 h, the number of septa was recorded following calcofluor white staining.

(E) Quantitative analysis of nuclear number in sep1^G849R. Conidial suspensions were allowed to form appressoria at 24 or 29°C, and nuclear number was recorded after 10 h.

(F) Representative images of nuclear distribution during appressorium morphogenesis of sep1^G849R. Bars = 10 μm; error bars are 1 se.