Figure 5.

A, 2D ¹³C DP-based J-INADEQUATE spectrum of inflorescence #1 (black) overlaid with the spectrum of seedling cell walls (red). The spectra were measured using direct ¹³C polarization and a short recycle delay of 2 s to preferentially detect the signals of mobile polysaccharides. α-l-Ara signals are observed in both inflorescence and seedling cell walls. The inflorescence cell wall shows highly branched 2,5-linked α-l-Ara (type a) and 2,3,5-linked α-l-Ara (type b) signals, which are absent in the seedling cell wall. Assignment superscripts indicate the different linkages and conformations within each sugar. The ω₁ spectral widths are 82.7 and 79.4 ppm for inflorescence #1 and seedling cell walls, respectively. The GA carbonyl and Rha C6 signals are folded in the ω₁ dimension. B, Selected regions of the 2D spectra showing the resolution of multiple types of Ara, GalUA, Gal, and Rha signals. Orange circles indicate missing Rha C5 cross peaks, whose chemical shifts are unambiguous based on the observed Rha C6 chemical shifts. C, Representative structures of 2,5-Ara^a, 2,3,5-Ara^b, 5-Ara^c, and t-Ara^d observed in the inflorescence cell walls. D, Selected regions of the inflorescence #1 INADEQUATE spectrum (black) overlaid with a previously measured B. distachyon spectrum (orange). B. distachyon cell walls exhibit abundant xylan (Xn) signals, which are absent in the Arabidopsis inflorescence cell wall.