Thioredoxins are ubiquitous disulfide reductases involved in a wide range of cellular processes including DNA synthesis, oxidative stress response and apoptosis. In cereal seeds thioredoxins are proposed to facilitate the germination process by reducing disulfide bonds in storage proteins and other targets in the starchy endosperm. Here we have applied a thiol-specific labeling approach to identify specific disulfide targets of barley thioredoxin in proteins released from barley aleurone layers incubated in buffer containing gibberellic acid.