Figure 1.

Phenotypes of mature Arabidopsis plants and IFs in WT, OE-FLA11, and mutant variants. A) Schematic representation of FLA11 and YFP-FLA11 protein structure with posttranslational modifications and introduced FLA11 domain mutations. Changes are indicated in the text. AG1 and AG2, arabinogalactan motif 1 and 2; N-gly, N-glycosylation motif; GPI, glycosylphosphatidylinositol; Surf A and B, predicted protein surface regions in FAS1 domain. B) Representative images of plants at growth stage 6.5 (Boyes et al. 2001) of WT, OE-FLA11, and OE-FLA11 mutant variants with a 1TC in the T2 generation. proFLA11 promoter was used for all OE-FLA11 and OE-FLA11 mutant variants transgene lines. C) TEM imaging of transverse sections at 1 cm above the stem base of plants at stage 6.9 (Boyes et al. 2001). IF common to the SCWs shows 3 layers (S1, S2, and S3) in WT. Increased IF SCW thickness and occurrence of multiple internal layers (ILs) are observed in 1TC OE-FLA11 and similar wall phenotypes occur in lines with mutations in AG1, AG2, AG1 + 2, SurfA, SurfB, and N-glyB. IF SCWs of lines with mutations in GPI and N-glyA show similar organization to WT. D) Stage 6.9 plant stems were hand sectioned at 1 cm from the base and stained with Mäule reagent which stains S-lignin-rich IF cell walls a pink/red color in WT and lines with mutations in GPI and N-glyA plant stems, and red-brown staining indicating lower S/G-lignin ratio in lines that show similar stem phenotypes to OE-FLA11. PW, primary wall; ML, middle lamella. Scale bar = 10 cm in B), 1 µm in C), and 20 µm in D).