Fig. 5.

Phenotypic analysis of insertional mutants and transcript abundance of UM033_0004 under different bacterial regimes. Phenotypes of representative individuals of untransformed “slender” (a), insertional line UM033_0004 (b) and UM005_0337 (c) 12 days after gamete release and grown in tissue culture flask in the presence of their bacterial symbionts. Phenotypes of untransformed “slender” under axenic conditions (d) or in the presence of Roseovarius sp. MS2 only (e), Maribacter sp. MS6 only (f), or in the presence of both Roseovarius sp. MS2 and Maribacter sp. MS6 (g) after 18 days of growth in a 96-well plate. Phenotypes of insertional mutant UM033_0004 under axenic conditions (h) or in the presence of Roseovarius sp. only (i), Maribacter sp. only (j), or in the presence of both Roseovarius sp. and Maribacter sp. (k) after 18 days of growth in a 96-well plate. l Relative transcript abundance of UM033_0004 in Ulva “slender” under different symbiont regimes. Statistical significance was inferred using a one-way ANOVA. Treatments not sharing the same letter are significantly different (Tukey HSD test, P < 0.01). Error bars show the standard error of the mean (n = 3). Arrows highlight bubble-like protrusions that occur in the absence of Maribacter sp., triangles indicate degenerate cells. Size bar is 200 µm