Fig. 4. Early paternal MSI1 expression does not rescue the msi1 mutant phenotype. (A) Early paternal expression of the PHE1::MSI1 transgene was tested by RT-PCR in Arabidopsis seeds derived from msi1 mutants pollinated with PHE1::MSI1 pollen. The primers specifically detect only the transgene-derived MSI1 transcript. Paternal MSI1 expression in seeds derived from MSI1^* plants pollinated with wild-type pollen is shown as a control. `Standard' refers to a dilution series of the PHE1::MSI1 plasmid, with 1-4 containing 0.48, 2.4, 12 and 60 ng DNA, respectively. (B) msi1 mutants pollinated with PHE1::MSI1 pollen have 50% aborted seeds. (C) Cleared seeds derived from the same silique of an msi1 mutant pollinated with PHE1::MSI1 pollen. Wild-type (wt) seed (left), msi1 mutant seed (right). (D) Quantification of seed abortion observed after crosses of msi/MSI1 xmsi1/MSI1 (n=583) and msi1/MSI1 xPHE1::MSI1; msi1/MSI1 #1 (n=278), msi1/MSI1 xPHE1::MSI1; msi1/MSI1 #2 (n=498), msi1/MSI1 xPHE1::MSI1; msi1/MSI1 #3 (n=166). Scale bars: 200 µm in B; 50 µm in C.