ISOLATION AND CHARACTERIZATION OF fad 2-1 cDNA SEQUENCE FROM GLYCINE

Microsomal ω-6 desaturase encoded by fad2-1 gene catalyzes the production of polyunsaturated fatty acids in seed storage lipids. A cDNA library was constructed in λTriplEx2 vector using poly (A) RNA isolated from developing seeds (19-26 DAF) of Glycine max L. The putative clones from library screening were converted into plasmid clones following in vivo excision and analyzed for insert size by restriction digestion. A positive clone PR2 with largest insert size spanning a total of 1139 bp revealed a 3’ UTR region of 184 bp specific to fad2-1. Conceptual translation indicated an open reading frame of 955bp encoding a 317 amino acid protein with a predicted molecular weight of 37kD. A high degree of sequence identity was found with Glycine max cDNA for ω-6-desaturase and with fad2-1 of Arachis hypogea. PR2 was also used as a labelled probe to analyse the expression of fad2-1 transcripts by northern blotting. High levels of fad2-1 mRNA transcripts were detected at the mid maturation stages of seed development (19-26 DAF).

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