Figure 4.

Estimated dimensions of nonlesion epidermal cells, and cell numbers along lateral and longitudinal axes of leaf blades from csld1 mutant and nonmutant plants. Epidermal impressions from abaxial surfaces of fully expanded leaf blades from mature, greenhouse-grown plants were used to estimate cell dimensions and cell numbers along leaf axes. Nonmutant plants included both wild-type and heterozygous individuals from segregating progeny after three back-crosses into the W22 inbred. Cell numbers were quantified (each designated by a tick mark on impressions such as those shown to the right) along longitudinal and lateral axes of defined length. Mean cellular dimensions were determined by dividing the number of cells along a given axis by the length of that axis (mutant, n = 14; nonmutant, n = 10; longitudinal axis, 1.88 mm; lateral axis, 1.40 mm). Axes used for analyses of epidermal cell size from mutant leaves were analyzed using transects that did not cross cells in the ballooning protrusions. Approximate cell numbers across and along leaf blades were estimated by comparing cell size estimates with average leaf length and width measurements (Fig. 3). These analyses did not include the midrib (0.5 cm was subtracted from total leaf width). The mean width of epidermal cells was 17% greater in csld1 mutants, whereas mean cell numbers were 48% less across the lateral axis and 16% less along the longitudinal axis. Values are marked with asterisks where they differ significantly from those of nonmutant plants (P < 0.05).