Compositions and methods for the alteration of the disulfide status of
plant proteins are provided. Novel nucleotide molecules, comprising
nucleotide sequences for thioredoxin h and NADPH-thioredoxin reductase,
and the proteins encoded thereby are provided. The nucleotide sequences
can be used to transform plants alone or in combination with other
sequences, such as sequences encoding NADPH generating enzymes, to
manipulate the thioredoxin h system and alter the protein disulfide
status in plants. Transformed plants, plant cells, plant tissues, seed
and grain are provided.