Nuclear DNA Content Diversity in Chinese Soybean Introductions

Abstract

Abstract Intraspecific nuclear DNA content has been documented in various angiosperm species. The purpose of this study was to determine the nuclear DNA content variation in soybean (Glycine max(L.) Merr.). Several studies have suggested that DNA content variation exists in soybean. Ninety soybean lines representing diverse geographic locations in China were analysed by flow cytometry. Nuclei were isolated and stained with either the fluorochrome DAPI or PI. After analysis, it was determined that PI stained nuclei more accurately assessed the total DNA content in soybean. A 12% variation in nuclear DNA content was observed among the 90 lines. The amount of nuclear DNA in the lines was within the DNA range of United States cultivars previously examined. Nuclear DNA content 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 addition, unlike maize, the amounts of DNA variation did not decrease as a result of more intensive breeding in United States cultivars. Intraspecific nuclear DNA content variability is very different between these two major agronomic species.