Vicia globulins

Abstract

Vicia faba L. (faba bean) is one of the historically oldest crop plants used by man. In Egypt it can be traced back to the 18th century B.C. Until the advent from the New World of crops like garden bean and potato, the faba bean played an important role as a grain legume for human nutrition in the Old World. Although its economic importance progressively decreased from the second half of the 17th century A.D. it still is the grain legume with the highest grain yield potential in the moderate and Mediterranean climate zones (Müntz et al., 1972). Mature field beans (Vicia faba L. var. minor) contain at maximum 30 % total protein in the dry matter (Hanelt et al., 1978). Globulins are the major storage proteins in faba bean seeds and amount to approximately 85 % of the total protein. Vicilin, the 7S protein, and legumin, the US protein, are the major globulin fractions found in seeds of all Vicia species. In Vicia narbonensis L., the narbon bean, in addition to the 7S and US globulins a 2S globulin has been found (Schlesier and Scholz, 1974) which is completely different from other 2S proteins that have been reported from the seeds of other grain legumes and crops (see this book chapter 24). Minor amounts of vicilin and legumin are deposited in protein bodies of the embryonic axis, including the radicle and embryonic shoot (Schlereth et al., unpublished from the author’s group). The majority is accumulated in the storage cotyledons of maturing Vicia seeds, where vicilin and legumin together were found in the same protein bodies (Zur Nieden et al. 1982). Transient formation of both globulins was detected immuno-histochemically in the inner cell layers of the seed coat and in the suspensor, endosperm and globular embryo at very early stages of faba bean seed development (Borisjuk et al., 1995; Panitz et al. 1995).