Fig. 2

Sensitivity enhancement from DNP. a DNP enhances the NMR sensitivity by 26-fold on the wild-type sample. This value is obtained by quantifying the intensity ratio between the spectra collected with microwave on (MW on) and microwave off (MW off). The DNP-enhanced spectrum of ctl1 ctl2 (orange dashline) is compared with the wild-type (WT) sample. b Lignin region of the room-temperature spectrum (RT; top), DNP-enhanced spectrum (MW on; middle), and non-DNP spectrum (MW off; bottom). The experimental time is labeled for each panel. DNP significantly saves experimental time and enhances NMR sensitivity. c, Spectral deconvolution of the interior cellulose carbon 4 (i4) and surface cellulose carbon 4 (s4) region (dashline square in panel a) reveals the crystallinity change in rice cellulose. The experimentally measured spectra (black) are overlaid with the simulated spectra (blue), with the deconvoluted peaks underlying the spectral envelope. The interior-to-surface (i/s) ratio of cellulose is quantified for both samples, which has shown an increase in cellulose crystallinity in the ctl1 ctl2 mutant. The fit parameters are listed in Additional file 1: Tables S1 and S2