Light micrographs showing structural differences between two wild types and two def mutant pea lines. (A-D). The wild type (JI 116). (A) AZ development in young pea seed at stage 8.1 and (B) In mature pea seed at 2.1. (C) Higher magnification of the AZ development in the young pea seed in (A). (D) Higher magnification of the AZ in the mature pea seed in (B). There is no sign of cell separation in young stage at 8.1 but distinct cell separation occurs in the mature stage at 2.1. (E-H) The def mutant type (JI 1184). (E) Non-abscission in young mutant pea seed at stage 8.1 showing the absence of the hilum palisade layer. (F) Non-abscission in mature mutant seed at stage 2.1. (G-H) Higher magnifications of the abscissionless zones (ALZ) in young and mature seeds of the def mutant in E and F, respectively. (I-L) The wild type (JI 2822). (I) AZ development in the wild type pea at stage 3.1. (J) AZ development in the mature pea at stage 1.1. (K-L) Higher magnification of the AZ in (I) and (J), respectively. (M-P) The def mutant type (JI 3020). (M) Non-abscission in young mutant pea seed at stage 3.1. (N) Mutant pea seed at stage 1.1. (O-P) Higher magnification of the ALZ in (M) and (N), respectively. Seeds in the first (most mature) pod and close to pea stock are designated as 1.1. The youngest pod and close to the pea stock is designated as 8.1 for JI 116, 8.1 for JI 1184, 3.1 for JI 2822 and 3.1 for JI 3020. AZ, Abscission zone; FN, Funicle; PL, Palisade layer; CPL, Counter palisade layer; TR, Tracheid bar. Scale bars = A, B, E, F, I, J, M and N = 12.5 μm; C, D, G, H, K, L, O and P = 25 μm.