Figure 7
From: Insights into the complex role of GRAS transcription factors in the arbuscular mycorrhiza symbiosis
Molecular and phenotypical effects of an MtGras1 knockdown in mycorrhizal roots. (A) Expression of MtGras1 and selected AM marker genes in transgenic, mycorrhized RNAi:MtGras1 and RNAi:gusAint control roots. Roots were harvested at 35 days post inoculation with R. irregularis. Medicago Transcriptome Assay hybridizations were performed, using three biological replicates per experimental group. The standard error of the mean is shown. Percental values shown are based on the calculated linear signal intensities. Genes shown are defined in the Fig. 2 legend. (B) Transcriptional response of M. truncatula ram1-1 and MtGras1 RNAi roots to colonization with R. irregularis. Comparison of gene expression in M. truncatula ram1-1 mutant as well as MtGras1 RNAi roots in relation to control roots. Numbers indicate genes downregulated at least 2-fold (p < 0.05) in the ram1-1 mutant line or the MtGras1 RNAi knock-down roots. (C) Comparative visualization of fold changes in ram1-1 (blue) and MtGras1 RNAi (yellow) roots in comparison to the corresponding control roots. A selection of 31 well-characterized AM-induced marker genes, downregulated at least 2-fold (p < 0.05) in relation to control roots were compared in both mutants. The expression data and identifiers corresponding to the genes studied are listed in Supplementary Table S4. (D) Quantification of fungal structures in MtGras1 RNAi (black) and control roots (white). Roots were harvested at 35 days after inoculation with R. irregularis. Standard errors are indicated as error bars. MYC, colonized root fragments; ARB, arbuscules; VES, vesicles. (E) Alexa WGA Fluor 488 stained mycorrhizal MtGras1 RNAi (I) and control roots (II). (F) Distribution of arbuscule sizes in MtGras1 RNAi (black) and control roots (grey). Sizes were measured for nine biological replicates of independent MtGras1 RNAi, and control root systems, respectively (appr. 3000 arbuscules in total for each group). Roots were harvested at 35 days post inoculation with R. irregularis. Bars represent standard errors. *p < 0.05; **p < 0.01 (Student’s t-test).
