GENETIC-VARIABILITY IN FOXTAIL MILLET, SETARIA-ITALICA (L.) P. BEAUV.- RFLP USING A HETEROLOGOUS RDNA PROBE

Ribosomal DNA was surveyed in a world collection (43 lines) of Setaria italica for variation in repeat unit length and restriction enzyme si te variability using a non-radioactive wheat rDNA probe. Only two leng ths of repeat units of about 7.9 or 7.6 kb were observed. The fact tha t these two repeat unit lengths were not randomly dispersed throughout the world collection suggests the existence of three genetic groups. The central European lines and most western European accessions have o nly the 7.6 kb repeat unit and most Asiatic lines have a 7.9 kb repeat unit. Lines originating from the north or the south of Asia showed di fferent numbers of BamHI fragments. The fact that the difference betwe en the Asiatic and European pool is not continuous (7.9 or 7.6 kb) exc ludes the hypothesis of domestication being based on the spread of an initial population over Eurasia.