Fig. 7.

Deletion of rga4 allows polarized growth in cells with constitutive Morphogenesis Orb6 (MOR) activity. (A) Cells expressing nak1-mor2 (thiamine) show cell lysis (arrows) at the division site during cytokinesis in rga4⁺ cells, while in rga4Δ mutants nak1-mor2 expression leads to a PrESS-like phenotype (arrowhead). (B) Growth curve of rga4⁺ or rga4Δ cells either expressing nak1-mor2 or repressing nak1-mor2. Optical density was measured every 15 min at 595 nm for 2 days (ordinary one-way ANOVA with Tukey's multiple comparisons; P<0.0001; five experiments averaged for each genotype). (C) rga4⁺ cells expressing nak1-mor2 (n-m) showed significantly more lysis than rga4Δ cells either repressing (P=0.0042) or expressing (P=0.0030) nak1-mor2. (D) Percentage of cells displaying a PrESS-like phenotype. rga4Δ cells containing nak1-mor2 (n-m) display a higher PrESS-like frequency than rga4⁺ cells containing nak1-mor2 (P<0.0001). (E) rga4⁺ and rga4Δ cells expressing nak1-mor2 and containing CRIB-3xGFP. Whereas only a few septated rga4⁺ cells show CRIB-3xGFP at their ends, a large fraction of septated rga4Δ cells do. (F) Quantification of CRIB-3xGFP at cell ends in rga4⁺ and rga4Δ cells expressing nak1-mor2 (n-m). Ordinary one-way ANOVA with Tukey's multiple comparisons was used for statistical analysis. Experiments repeated in triplicate. n.s., not significant; *P<0.05; **P<0.01; ****P<0.0001. Scale bars: 5 µm.