Molecular analysis of flax 2S storage protein conlinin and seed specific activity of its promoter

The biochemical properties of conlinin, a 2S storage protein of flax (Linum usitatissimum L.), are known but the gene encoding the protein has not been defined. Here, we report the identification of cDNA and genomic clones of two conlinin genes, conlinin1 (cnl1) and conlinin2 (cnl2). The cDNAs contain a single exon encoding a polypeptide containing a putative signal peptide and some features (conserved cysteine residues, glutamine-rich stretches, amino acid composition) characteristic of 2S storage proteins. The promoter regions of the two conlinin genes contain G-box and RY-like cis-acting elements. Northern analysis indicated that the genes are preferentially expressed in developing seeds with the maximal level at 20–35 d after flowering. Analysis of transgenic flax and Arabidopsis thaliana containing the GUS reporter gene under the control of the cnl1 promoter confirmed the seed specific pattern of expression.