(a-j) Representative confocal images of cotyledon abaxial epidermis from 10-day-old light-grown transgenic seedlings of the following genotypes, wild type (a); STOMAGEN-ami (b); epf2 (c); epf2 STOMAGEN-ami (d); Dominant-negative ER (ERΔK) in er (e); ERΔK er STOMAGEN-ami (f); epf1 (g); epf1 STOMAGEN-ami (h); Dominant-negative ERL1 (ERLΔK) in erl1 (i); ERLΔK erl1 STOMAGEN-ami (j). STOMAGEN-ami dramatically reduces stomatal differentiation in wild type (a, b). Blocking ER or lacking EPF2 produces small stomatal-lineage cells due to excessive entry divisions (c and e; yellow brackets). STOMAGEN-ami rather exaggerates the small stomatal-lineage cells of epf2 (d; yellow brackets). STOMAGEN-ami ERΔK er shows excessive asymmetric entry as well as amplifying divisions (f; yellow and pink brackets, respectively). Blocking ERL1 or lacking EPF1 causes a stomatal pairing due to a violation of one-cell-spacing rule (g and i; dots). STOMAGEN-ami suppresses these mild stomatal pairing phenotypes and reduces stomatal differentiation (h, j). Images were taken under the same magnification. Scale bars = 30 μm. n=13 (a); n=26 (b); n=15 (c); n=23 (d); n=11 (e); n=17 (f); n=12 (g); n=22 (h); n=18 (i); n=13 (j).(k-n) Stomatal Density (k) Stomatal Index (l), Stomatal Cluster Distribution (in %: m), and non-stomatal epidermal cell density (n) from 10-day-old abaxial cotyledons of each genotype with or without carrying STOMAGEN-ami construct. Error bars, S.E.M. ***, p< 0.001; *, p≤0.05, NS, not significant; Welch 2-sample T test. n=9-16. Total numbers of stomata counted: wt, 719; STOMAGEN-ami, 204; epf1, 1004, epf1 STOMAGEN-ami, 383; ERL1ΔK erl1, 1558; ERL1ΔK erl1 STOMAGEN-ami, 504; epf2, 1505; epf2 STOMAGEN-ami, 1165; ERΔK er, 1361; ERΔK er STOMAGEN-ami, 782; tmm, 2495; tmm STOMAGEN-ami, 2688; er erl1 erl2, 1853; er erl1 erl2 STOMAGEN-ami, 2028. Total numbers of non-stomatal epidermal cells counted: wt, 1494; STOMAGEN-ami, 1299; epf1, 1584, epf1 STOMAGEN-ami, 2711; ERL1ΔK erl1, 871; ERL1ΔK erl1 STOMAGEN-ami, 1348; epf2, 3980; epf2 STOMAGEN-ami, 8808; ERΔK er, 5739; ERΔK er STOMAGEN-ami, 6939; tmm, 790; tmm STOMAGEN-ami, 962; er erl1 erl2, 479; er erl1 erl2 STOMAGEN-ami, 391. wt, n=8; STOMAGEN-ami, n=8; epf1, n=9, epf1 STOMAGEN-ami, n=17; ERL1ΔK erl1, n=13; ERL1ΔK erl1 STOMAGEN-ami, n=9; epf2, n=11; epf2 STOMAGEN-ami, n=15; ERΔK er, n=9; ERΔK er STOMAGEN-ami, n=11; tmm, n=8; tmm STOMAGEN-ami, n=8; er erl1 erl2, n=8; er erl1 erl2 STOMAGEN-ami, n=8.