NUCLEAR-DNA CONTENT DIVERSITY IN CHINESE SOYBEAN INTRODUCTIONS

Intraspecific nuclear DNA content has been documented in various angio sperm species. The purpose of this study was to determine the nuclear DNA content variation in soybean (Glycine max (L.) Merr.). Several stu dies have suggested that DNA content variation exists in soybean. Nine ty soybean lines representing diverse geographic locations in China we re analysed by flow cytometry. Nuclei were isolated and stained with e ither the fluorochrome DAPI or PI. After analysis, it was determined t hat PI stained nuclei more accurately assessed the total DNA content i n soybean. A 12% variation in nuclear DNA content was observed among t he 90 lines. The amount of nuclear DNA in the lines was within the DNA range of United States cultivars previously examined. Nuclear DNA con tent Variation in soybean is much less than the variation reported in maize. These results could be due to the lack of polymorphism in large chromosomal elements containing large blocks of repetitive DNA. In ad dition, unlike maize, the amounts of DNA variation did not decrease as a result of more intensive breeding in United States cultivars. Intra specific nuclear DNA content variability is very different between the se two major agronomic species. (C) 1997 Annals of Botany Company.