Abstract
Seed storage proteins from naturally occurring lysine-rich cultivars namely IS 21702, CVS 365, G 1058, G 205 and CVS 549 were analyzed biochemically, immunologically and compared with a low-lysine cultivar (White Martin) and a chemically induced high-lysine mutant (P7210). Protein fractionation studies indicated that the high lysine cultivars contained 25% less kafirin and an increased alcohol insoluble reduced glutelin without affecting the total protein content. SDS-PAGE analysis of total kafirin showed the absence of 25.3 kD and 25.9 kD alpha -kafirin proteins in lysine-rich cultivars IS 21702, CVS 365 and G 1058, while in G 205 only the 25.9 kD protein was absent compared to low-lysine cultivar White Martin. A genomic clone lambda GK5 encoding an alpha -kafirin has been isolated from cv White Martin genomic library using pSKR3 as hybridizing probe and sequenced. Transient expression studies by particle bombardment of immature seeds of sorghum allowed to detect beta -glucuronidase (GUS) activity only in endosperm cells confirming that the alpha -kafirin gene promoter is functional and tissue specific.