Bob Buchanan and his team focus primarily on thioredoxin-linked regulatory mechanisms in plants.
In the past several years, they have found that a thioredoxin system occurring in the cytosol of plant cells--the NADP/thioredoxin system--acts as a signal in seed germination. Thioredoxin, a small protein with a catalytically active disulfide group, is reduced early in germination by the NADPH generated by metabolic reactions of the seed. In the best understood case (wheat), thioredoxin reduces selected proteins of the seed endosperm, thereby leading to the mobilization of storage proteins and starch. Thioredoxin acts by reducing disulfide (S-S) groups of storage proteins, increasing their susceptibility to proteolysis. Thioredoxin also reduces enzyme inhibitor proteins, leading to their inactivation, and enzymes, leading to their activation. They currently are characterizing these and other regulatory events promoted by thioredoxin during germination.