Supplementary Materials Supplemental Data supp_169_4_2342__index. strain stiffening (Kierzkowski et al., 2012), wall hardening (Huang et al., 2012), or by having a thicker cell wall (Schopfer, 2006). In future studies, it will be interesting to use the results of our study to validate numerical models (Dupuy et al., 2010; PRKD2 Koumoutsakos et al., 2011; Huang et al., 2012; Kierzkowski et al., 2012; Fozard et al., 2013) within a Bayesian uncertainty Pipamperone quantification and propagation platform (Angelikopoulos et al., 2012). Such a platform would be able to quantify which model is definitely most probable given the data. The impressive similarity in the shape of the sepal cell lineage growth curves and the finding that all cell lineages reach the same maximum RGR have, to our knowledge, not been observed previously. These getting suggest a common underlying growth curve. How can this underlying similarity be explained? The similarity could imply that there is global coordination between cells within the growing tissue, or intrinsic constraints due to gene regulation or mechanical properties of the walls. Although we do see differences between neighboring cells, overall, our analysis shows that the growth of cells in the sepal is usually less heterogeneous than it initially appears. The initial appearance Pipamperone of growth heterogeneity observed in our results (Fig. 3) as well as others results can be explained by shifting the S curves of each cell lineage in time. At a single time point, one cell lineage may be in the initial part of the S curve where its RGR is usually low, whereas its neighbor may be at the point of the sigmoid curve where its RGR is at the maximum. At a single time point, cell lineages will have different RGRs, whereas if we observed each cell lineage when the RGR is at the maximum, they would have the same RGR. Thus, neighboring cells are simply at different stages of growth and consequently have different RGRs at a single time point. Most of the variability in the growth of cell lineages is in the time accession were conducted as described previously (Roeder et al., 2010; Cunha et al., 2012; see Supplemental Text S1 for details). Individual plants from different plants imaged in the first session were given identifiers A and D, whereas plants imaged in a second session were given identifiers B and C. Flower A Pipamperone was imaged for 72 h, flower B for 90 h, Pipamperone flower C for 102 h, and flower D for 66 h. The division pattern of the cells for plants A and D have been previously analyzed (Roeder et al., 2010). Results for plants C Pipamperone and D are presented in Supplemental Figures S1, S3 to S7, S9 to S12, S16, and S17. To define comparable initial time points for the plants (Fig. 2), we manually aligned the fluorescent stacks of plants A and B such that they looked similar in size and shape (Supplemental Fig. S18). We observed that, 72 h after the chosen initial time point, the sepals were similar in length, but flower B was wider. Most likely, this was because we looked at a lateral sepal for flower A, which was partly being masked by other overlying sepals. We compared the size of the sepals with the staging of Smyth et al. (1990) by considering the sepal height. We observed that flower A was in stages 8 and 9, flower B was in stages 7 to 9, flower C was in stages 8 and 9, and flower D was in earlier stages 4 to 8. We note that at those stages, guard cells have not fully designed, but giant cells are forming. We also considered the sepal width and compared with the data analyzed by Mndermann et al. (2005). We estimated that their analysis started right after our data sets end for plants A, B, and C. Image Processing.