Figure 5.

Ectopic vessel development in stems of 7-week-old Arabidopsis plants over-expressing different phosphovariants of MYB75. Stems were harvested from 7-week-old plants and the bottom 5 cm of each stem was hand sectioned and stained in phloroglucinol-HCl or toluidine blue. Neither (a), Col-0 WT nor 35Spr:MYB75^WT plants showed any signs of ectopic vessels in stem sections at this stage, while 35Spr:MYB75^T131A plants displayed a mild phenotype, with isolated cells or small clusters of cells resembling vessel elements in the interfascicular arc. Conversely 35Spr:MYB75^T131E display prominent cell files of vessels in the interfascicular region. (b) The presence of vessel elements in the interfascicular region of 35Spr:MYB75^T131E plants was confirmed using toluidine blue stain; prominent clusters of vessel elements appear as large olive green staining cells in the interfascicular arc of 35Spr:MYB75^T131E plants, but not observed in 35Spr:MYB75^WT lines. (c) Western blot and gene expression analysis confirms that recombinant MYB75 is expressed in the stems at this stage