A physical, enzymatic, and genetic characterization of perturbations in the seeds of the brownseed tomato mutants.

The brownseed mutants (bs(1), bs(2), and bs(4)) of tomato all possess dark testae and deleteriously affect seed germination speed and/or final percentage. Poor germination performance of the bs(1) but not the bs(4) mutant, was due to greater impediment to radicle egress. Testa toughening (bs(1)) was prevented by drying in N(2). However, poor germination speed was hardly affected by drying. GA(4+7) did not ameliorate germination percentage or speed (bs(1), bs(2)), whereas bs(4) seeds commenced radicle protrusion sooner and had a greater germination percentage. bs(1) mutant seeds have two times more catalase activity while those of bs(4) contained six times more peroxidase and almost two times more catalase activity than WTs. bs(4) release only half of the reactive oxygen species into the media than WT during imbibition. EPR detected the presence of free radicals in bs(1) and its WT. bs mutants were epistatic to 12 anthocyaninless mutations, at least some of which produce seeds of lighter than usual testa colour. Macro-arrays of subtractive, suppressive PCR products identified differentially regulated transcripts between seeds of bs(4) and WT. EST identity suggests bs(4) does not exit the developmental programme upon attaining maturity.