Figure 5.

DARX1 Is Crucial for Xylan Binding to Cellulose.

(A) DNP enhances NMR sensitivity 21-fold in the wild-type sample.

(B) 2D ¹³C-¹³C correlation spectra measured on the unlabeled matured wild-type and darx1-1 internode slices in the natural isotope abundance (1%). The double-quantum (DQ) shift is the sum of the single-quantum (SQ) shifts of two bonded (J-coupled) ¹³C nuclei. The two- and threefold xylan signals are labeled in purple and blue, respectively. For example, Xn4^3f represents Carbon 4 of threefold xylan. WT, wild type.

(C) A cross section of threefold xylan ¹³C extracted at the 141-ppm double-quantum (DQ) shift from the 2D spectra in (B). WT, wild type.

(D) AFM of metaxylem cell walls, showing cellulose macrofibrils/microfibrils of wild-type and darx1-1 plants. Scale bars = 100 nm. WT, wild type.

(E) Distribution of macrofibril/microfibril orientation. The orientation of macrofibril/microfibril is represented as percentage frequency of the orientation of macrofibril/microfibril segments (snakes) identified using the software SOAX (n = 60,000 snakes from three images of three cells of three individual plants). WT, wild type.