Gr. Heck et al., BARLEY EMBRYO GLOBULIN-1 GENE, BEG1 - CHARACTERIZATION OF CDNA, CHROMOSOME MAPPING AND REGULATION OF EXPRESSION, MGG. Molecular & general genetics, 239(1-2), 1993, pp. 209-218
We report identification of a 2189 bp cDNA clone from barley correspon
ding to a single-copy gene, Beg1 (Barley embryo globulin), on chromoso
me 4, which encodes a storage globulin. In barley, the major protein r
eserve in the aleurone layer belongs to the 7S globulin class of prote
ins found in many seeds. Electrophoretically and antigenically similar
proteins are present in the barley embryo. Accumulation of Beg1 mRNA
was noted beginning 15-20 days post-anthesis in both the aleurone laye
r and embryo of the developing barley grain but. not in the starchy en
dosperm. A high level of Beg1 mRNA is also present in the mature imbib
ed aleurones, which can be repressed by treatment with gibberellic aci
d. This repressive effect of gibberellin on the levels of Beg1 mRNA is
confirmed in the gibberellin response-constitutive mutant, slender, w
hose aleurone layers do not accumulate Beg1 mRNA even in the absence o
f applied gibberellic acid. The deduced primary translation product of
the Beg1 mRNA is a 637 amino acid (72 kDa) protein with homology to m
aize embryo globulin 1 (GLB1) and a partial sequence of a wheat 7S glo
bulin. The internal amino acid sequence of BEG1 closely matches the N-
terminal sequence of isolated barley aleurone globulin. Seven imperfec
t tandem repeats of 16 amino acids each are present near the N-terminu
s of BEG1, which conform to the consensus HGEGEREEEXGRGRGR, and contri
bute to the observed unusual amino acid composition of this protein. A
second, distinct barley globulin gene, Beg2, which is homologous to m
aize Glb2, was detected by Northern and Southern analysis. Beg2 and Be
g1 are regulated differently which may indicate variation in storage o
r utilization properties among the barley globulins.