Analysis of the secondary cell wall (SCW) cellulose synthase PtrCesA protein concentrations in the Cas9/gRNA‐induced Populus trichocarpa ptrcesa knockout mutants. (a) Immunoblot analysis of PtrCesA4, PtrCesA7A/B and PtrCesA8A/B protein concentrations in secondary xylem of wild‐type (WT), ptrcesa4, ptrcesa7ab and ptrcesa8ab young trees. (b) Immunoblot analysis of PtrCesA4, PtrCesA7A/B and PtrCesA8A/B protein concentrations in secondary xylem of WT, ptrcesa7a, ptrcesa7b, ptrcesa8a and ptrcesa8b young trees. The ACTIN as control was detected using an anti‐Actin antibody (ab197345, Abcam), indicating equal loading proteins. A replicate Coomassie Brilliant Blue (CBB)‐stained gel is shown to confirm equal loading.