Figure 2.

Guard cell size, nucleus size and genome size are strongly correlated across species. (a) Two guard cells forming a single stoma in the epidermis of Allium cepa. (b) Fluorescing guard cell nuclei from (a) after preparation with a DNA fluorophore. Scale bar in (a) and (b): 10 µm. (c–e) Linear relationship between (c) guard cell nucleus diameter versus guard cell width, (d) genome size, as 1C DNA amount, versus guard cell nucleus volume and (e) log₁₀ 1C DNA versus log₁₀ guard cell width cubed across phylogenetically diverse species. (d,e) Without Asplenium because its 1C DNA amount is unknown. Linear regressions (solid lines): (c) y = 0.67x − 1.24, r² = 0.93, p < 0.001; (d) y = 0.037 − 0.65, r² = 0.96, p < 0.001; (e) y = 1.83x − 5.46, r² = 0.94, p < 0.001.