Genomic cloning and sequencing of betaine aldehyde dehydrogenase gene in spinach

A genomic library derived from leaves of spinach was constructed with the lambda Gem11-BamHI Arms as the vector. The library was screened using the BADH cDNA, of mountain spinach as a probe and six positive clones were obtained through three rounds of screening. One of the positive clones named D, which was hybridized with the 5'600 bp fragment of mountain spinach BADH cDNA, was selected and further analyzed. The size of the insert in clone D was about 12 kb. 8 856 nucleotides of the insert were sequenced which contained 2 459 nucleotides of 5' noncoding region, 6 111 nucleotides of the complete sequence of the BADH gene, and 286 nucleotides of a 3' noncoding region. The result of sequence analysis indicated that the BADH gene contained 14 introns and the junction sequences at splicing sites followed the GT-AG rule basically.