A carrot gene, Gea8 (Globular embryo abundant), has been identified that en
codes a novel seed protein that is abundantly expressed in embryos from the
globular: to the cotyledon stages and in endosperm of maturation-stage see
ds, Analysis of the Gea8 gene revealed that it encodes a protein with appro
ximately 47% sequence similarity (25% sequence identity) to both dicot and
monocot globulins, a class of seed storage proteins. However, the Gea8 prom
oter region lacks some of the key regulatory elements characteristic of oth
er known globulins, especially the 'G box' sequence. Analysis of Gea8 mRNA
accumulation during both somatic and zygotic embryogenesis showed that mRNA
for this gene accumulates by the; globular stage of embryogenesis and reac
hes a high abundance by the heart stage that is sustained throughout embryo
development. Expression is also high in the developing endosperm of seeds
of both carrot and Arabidopsis. In addition, analysis of the! developmental
and spatial expression of the? Gea8 gene, using several Gea8 promoter/GUS
fusion constructs, suggests that the promoter contains at least two separab
le regions directing the spatial accumulation of Gea8 mRNA in the heart and
torpedo stages of embryogenesis. These studies suggest that Gea8 is a new
form of seed protein that is expressed early in embryo development, initial
ly in an embryo-specific pattern, and subsequently in both the embryo and t
he endosperm through regulation by a complex promoter.