Figure 1.

Comparison of mature wild-type, bri^TRIPLE and bri^T-RESCUE root tissues.

(A) Transverse and horizontal (optical) sections of representative 8-day-old primary roots, ~1 cm above the root meristem, illustrating reduced anisotropy of mature cells in bri^TRIPLE roots. Average root diameters (n = 33 each) and their SDs are indicated.

(B–D) Comparative quantitative analyses for different cell morphology parameters obtained by processing of 3D stacks with the PlantSeg-MorphoGraphX-3DCellAtlas pipeline, 10 roots per genotype. Overall cell length (B) is reduced in the bri^TRIPLE roots, whereas cell width (C) is increased. Average cell volume (D) is similar between the three genotypes, indicating that it is not cell expansion but rather cellular anisotropy that is reduced in bri^TRIPLE mutants. Whiskers indicate mean and SD.

(E) Statistical comparison between cell types of different genotypes (ANOVA, averages per root). Note that the lignin- and suberin-rich secondary walls of mature endodermal cells caused uneven calcofluor cell wall staining, which oversaturated some images and interfered with cell boundary prediction by the segmentation software. Obviously fused endodermis cells were discarded from the analysis. The attributes of the remaining endodermis cells might still be thwarted by these difficulties, which could explain why differences in (A) and (B) were not statistically significant although the measurements display the same tendencies as in the other tissues.