Developmental Expression of Sunflower 11S Storage Protein Genes

Helianthinin is the major globulin storage protein of sunflower seeds. Antiserum prepared against purified helianthinin was used to study storage protein accumulation in developing sunflower embryos. Synthesis of helianthinin begins within 7 days after anthesis (DAA) and it accumulates rapidly until 19 DAA. Storage protein synthesis then slows until seed maturation at 30 DAA. Anti-helianthinin was also used to select specific cDNA recombinants from a bacteriophage λ gt11 cDNA expression library prepared from immature sunflower embryo polyadenylated RNA. One of these recombinants, λ gt11H3, contained a 300 bp cDNA insert which was used as a hybridization probe for RNA gel blot and RNA dot blot analyses. This probe hybridizes with an approximately 1.9 kb sunflower embryo transcript. Helianthinin mRNA is present in embryos 7 DAA and accumulates to maximum prevalence at 12 DAA which corresponds to the period of maximum helianthinin accumulation. Soon after 12 DAA helianthinin RNA begins to decrease. Full length helianthinin mRNA is not detectable in mature seeds or in germinated seedlings. These results indicate that synthesis of the 11S sunflower seed storage protein occurs during a specific stage of embryogenesis and is regulated by the accumulation of helianthinin mRNA.