GERMINATION-RELATED GENES ENCODING PROTEOLYTIC-ENZYMES ARE EXPRESSED IN THE NUCELLUS OF DEVELOPING WHEAT GRAINS

During wheat (Triticum aestivum) grain germination the aleurone layer Shows a high expression of genes encoding hydrolytic enzymes. In this study we analyzed the spatio-temporal pattern of expression of two of these genes, a carboxypeptidase III and a thiol protease, in developin g grains. Our results show that transcripts of both genes accumulate a t early stages of grain development (5-15 dpa) in the nucellus, a mate rnal tissue that degenerates during wheat grain development. In additi on, the thiol protease gene is expressed in the nucellar projections a nd the modified aleurone cells, the cellular pathway of photosynthate transfer in the developing wheat grain. These results show that genes related to the germination programme are also expressed in the develop ment programme where they may be implicated in the degenerative proces s that takes place in the nucellar tissue and the cytoplasm of nucella r projections cells.