Fig 1.
Specialist herbivores induced large metabolite variations in kelps.
PLS-DA score plots of metabolite ions detected by LC-MS in L. digitata (A) and L. spicata (B) juveniles under controlled conditions (211 and 818 monoisotopic peaks or ions, respectively). Blue spots represent control algae and green spots represent grazed algae.
Fig 2.
Metabolic profiling in grazed L. spicata highlighted distinctive accumulation dynamics of Amino Acids and Free Fatty Acids.
(A) Heat map of the amino acids, free fatty acids and oxylipins detected in L. spicata under grazing pressure in laboratory-controlled conditions. Values represent the average log fold-change compared to control conditions (n = 3). Time points and compounds were clustered according to Pearson Correlation. The letters (g) and (t) indicate significant effects of grazing and time, respectively (P<0.05, Kruskal-Wallis test). (B-D) Time course of relative abundances of free amino acid (B), free fatty acid (C) and oxylipin contents (D) in control and grazed L. spicata (mean of three replicates ± SE).
Table 1.
General features of 454-generated ESTs libraries.
Fig 3.
EST libraries combined to qPCR analyses of grazed L. digitata and L. spicata revealed differentially expressed transcripts.
(A,B) Scatter-plot representations of relative EST abundance per unigene in Grazed and Control libraries of L. digitata and L. spicata. For calculation of Relative EST abundance, see Methods. Red and green dots respectively represent identified putative up- or down-regulated unigenes in grazed compared to control conditions. (C,D) Heatmaps showing the qPCR validation of grazing markers in laboratory controlled conditions. The expression pattern of selected unigenes are presented according to a hierarchical clustering analysis. Values are represented as log fold-change (LFC) of grazed vs control conditions (n = 3). The letters "g", "t" and "i" indicate significant effects of grazing, time and their interaction, respectively (P<0.05, 2-way ANOVA).
Fig 4.
Validation of grazing marker genes in natural kelp populations of L. digitata and L. spicata.
(A-B) Whisker-plot representations of qPCR expression values from candidate grazing marker sequences in ungrazed (white) or grazed (blue) natural populations of L. digitata and L. spicata (n = 7–8). Expression values were normalized to a maximum of 1 for each marker. Continous horizontal bars along boxes represent the median values. For each marker, the effect of grazing was tested using U-test (*P<0.05, **P<0.01, ***P<0.001).