A MODERATELY REPETITIVE DNA-SEQUENCE IN ALFALFA IS TRANSCRIBED IN A FLORAL-SPECIFIC MANNER

Based on DNA sequence analysis of 5 clones of repetitive DNA from alfa lfa (Medicago sativa), we propose the existence of a dispersed middle repetitive element about 3400 bp long with a copy number in the range of 2-3 X 10(3) per haploid genome. The average A+T content of the sequ ences was 54.6%, compared with 61.4% for the alfalfa genome. Sequence homologies between overlapping regions of the clones ranged from 85 to 89.5% with an average of 86.6%; sequence divergence was due largely t o single base pair changes, with deletions or insertions occurring ran domly across sequences. An open reading frame (ORF) in one clone, RPE1 5, contained homologies to cereal prolamin genes and a legumin box was located upstream of the coding region. A Northern blot of RNA from va rious alfalfa tissues, probed with the above clone containing this ORF , showed an extensive heterodispersed pattern of hybridization in the late stages of flower bud development but in no other tissues.