EXPRESSED SEQUENCE TAGS FROM DEVELOPING CASTOR SEEDS

To expand the availability of genes encoding enzymes and structural pr oteins associated with storage lipid synthesis and deposition, partial nucleotide sequences, or expressed sequence tags (ESTs), were obtaine d for 743 cDNA clones derived from developing seeds of castor (Ricinus communis L.). Enrichment for seed-specific cDNA clones was obtained b y selecting clones that did not detectably hybridize to first-strand c DNA from leaf mRNA. Similarly, clones that hybridized to storage prote ins or other highly abundant mRNA species from developing seeds were s elected against. To enrich for endomembrane-associated proteins, some clones were selected for sequencing by immunological screening with an tibodies prepared against partially purified endoplasmic reticulum mem branes. Comparison of the deduced amino acid sequences of the ESTs wit h the public data bases resulted in the assignment of putative identit ies of 49% of the clones selected by differential hybridization and 71 % of the clones selected by immunological screening. Open reading fram es in 100 of the ESTs exhibited higher homology to 78 different nonpla nt gene products than to any previously known plant gene product.