Transformation of barley with antifungal protein genes

The serpins constitute a superfamily of proteins (~40 kDa) found in eukaryotes and some viruses. Most serpins are serine proteinase inhibitors, a few are cysteine proteinase inhibitors, and some are non-inhibitory. They are known to be involved in a large range of physiological processes in mammals - from blood coagulation and complement activation to hormone transport and chromatin folding - but the physiological functions of plant serpins are unknown (1). Serpins are abundant (2-3 mg/g grain) in barley endosperm and are the major antigens in beer (2,3). Active (uncleaved) barley serpins inhibit mammalian serine proteinases of the chymotrypsin family in vitro by forming 1:1 irreversible complexes (1). Inactive (cleaved) serpins are stable proteins resistant to boiling, extreme pH, and protease treatment. Barley serpins form heterodimers with b-amylase, and are assumed to influence beer foam stability and haze formation, and are thus of interest for the malting and brewing industry (3). As a part of a research project continuing to focus on the properties and functions of plant serpins, we have initiated immunomicroscopy studies to localize serpins in barley.