Cloning and characterization of new repetitive sequences in field bean (Vicia faba L.)

Five new repetitive sequences have been isolated from the Vicia faba genome , by cloning bands visible on agarose gel electrophoresis after digestion o f genomic DNA with various restriction enzymes. The sequences were 109 to 5 84 bp long, their abundance ranging from 5x10(4) to 5x10(5) copies per hapl oid genome. Southern blot and in situ hybridization revealed that four of f ive newly isolated repeats were dispersed in the V. faba genome. One of the repeats (TIII15) showed tandem organization with several major hybridizati on spots on mitotic chromosomes in situ. These sites were distributed in eu chromatic as well as in heterochromatic chromosomal regions, and in several loci they were simultaneously localized with previously described FokI rep eated elements. The sequence of TIII15 comprises four 26-27 bp subrepeats, but shares no homology to FokI elements which have similar sequence organiz ation. All newly described sequences were highly specific for V. faba, with little or no hybridization to DNA of other Vicia species, and no hybridiza tion to DNA of other legumes tested. (C) 1999 Annals of Botany Company.