Fig. 7. Genetic interactions of ER-family genes with PFS2. (A-D) SEMs of mature Arabidopsis ovules. (A) pfs2-1 ovules have aberrant integument development. (B) er-105 erl1-2 erl2-1/+ ovules. (C,D) er-105 erl1-2 erl2-1/+ pfs2-1 mutant ovules have variability in integument development with reduced growth of the outer integument and some bifurcation of developing integuments. (E-G) DIC images of mature ovules. (E) pfs2-1 ovules have some partially developed embryo sacs. (F) er-105 erl1-2 erl2-1/+ has a penetrant phenotype of a small mass of cells in place of the embryo sac. (G) er-105 erl1-2 erl2-1/+ pfs2-1 mutant ovules display variability in embryo sac development similar to the pfs2-1 single mutant. Embryo sac nuclei are indicated by white arrowheads. (H-K) In situ hybridization in the pfs2-1 mutant using ERL1 (H,I) and ER (J,K) antisense probes. (L,M) In situ hybridization in wild type using a PFS2 antisense probe. (N,O) In situ hybridization in er-105 erl1-2 erl2-1/+ using a PFS2 antisense probe. (P,Q) Extended exposure of PFS2 antisense probe in wild type and er-105 erl1-2 erl2-1/+. Intense signal was observed in the inner integuments (arrowheads). No signal was detected with sense probes for ERL1, ER or PFS2. Scale bars: 20 µm. (R) Real-time RT-PCR analysis of PFS2 expression in stage 3-II ovules, given as fold-difference relative to wild type. ^*, Raw data collected as PFS2 transcript abundance relative to ACTIN 2 (wild type versus er-105 erl1-2 erl2-1/+. Experiment 1: 0.205±0.04 versus 0.351±0.02; Student's t-test P=0.03; 1.72 fold increase in er-105 erl1-2 erl2-1/+. Experiment 2: 0.141±0.003 versus 0.603±0.04; Student's t-test P=0.001; 4.2 fold increase in er-105 erl1-2 erl2-1/+).