Expression of maize gamma-zein and beta-zein genes in transgenic Nicotianatabacum and Lotus corniculatus

Accumulation of zeins, the endosperm storage proteins of maize, in a hetero logous plant expression system was attempted. Plants of Nicotiana tabacum a nd Lotus corniculatus were transformed by Agrobacterium with binary vectors harbouring genes that code for gamma -zein and beta -zein, two zeins rich in sulphur amino acids. Adding the ER retention signal KDEL to the C-termin al domain modified the zein polypeptides. Significant levels of gamma -zein :KDEL and beta -zein:KDEL were detected in primary transformants of tobacco . Moreover, the two zeins colocalized in leaf protein bodies of gamma-/beta -zein:KDEL plants derived from a cross between two primary transformants. Coexpression of gamma -zein:KDEL and beta -zein:KDEL could be a useful stra tegy to obtain genotypes of forage legumes which are able to accumulate sul phur amino acids to high levels. As a first step, L. corniculatus plants ex pressing gamma -zein:KDEL in the leaves were obtained.