Figure 2.

GH-grown NaCAD-silenced plants have altered stem morphology, which makes plants structurally unstable. A, The rubbery phenotype of ir-CAD plants is most apparent at the flowering stage, when stems lignify. B, ir-CAD plant supported by a stick to display the altered plant architecture responsible for its bushy appearance. C to E, CAD-silenced plants develop red coloration in roots (C) and stems (D; left is intact and right is peeled) compared with wild-type (WT) plants. This red coloration is largely restricted to xylem tissue of the ir-CAD stem, as shown in the peeled stem segment (D) and transverse sections cut through the root, the root-shoot junction, and the stem of ir-CAD plants (E). Red color provides a visual signature of “frustrated” lignin deposition. F, Light microscopy of an unstained cross-section of a wild-type stem, with the white arrow showing highly lignified xylem. G, The black arrow depicts the zone of red pigment accumulation in xylem of an ir-CAD stem. H to K, N. attenuata wild-type stems have a thick xylem layer that develops blue color (H and J) on staining with toluidine-blue O, whereas ir-CAD stems have thin xylem tissues that stain bluish-green (I and K). J, A magnified toluidine blue O-stained wild-type xylem transverse section reveals that xylem is composed of thick-walled fibers and vessels. K, Collapsed fibers and vessels with thin, wavy, and poorly resolved walls of the ir-CAD stem’s xylem are indicated by black arrows.