Evolution of genome sizes in Chinese Bambusoideae (Poaceae) in relation to karyotype

DNA contents of Chinese 134 bamboo species were first time announced, and FISH of 45S rDNA shows that paleotropical woody bamboo species may be originated from a multi-source system. Woody bamboo mainly includes two types of species: the temperate woody bamboo and the tropical woody bamboo. Both vary widely in genome sizes, chromosome number, and ploidy. In this study, the DNA contents of 135 bamboo species (22 genera) mainly distributed in China were analyzed by the flow cytometry. The DNA contents of the 134 bamboo species were first time announced. In contrast to the paleotropical woody bamboos, the temperate woody species is larger in genome size. Both the average arm ratio and the average symmetric coefficient of karyotype of the temperate woody species are less than those of the paleotropical woody bamboos, suggesting that the karyotypes of temperate woody bamboo species are more symmetrical than that of paleotropical bamboos. Also, FISH (fluorescence in situ hybridization) was applied to evaluate the distribution of 45S rDNA in the chromosomes of the representative bamboo species. Only one pair of sites was detected for 45S rDNA in temperate woody bamboo species, while three pairs of sites in paleotropical woody bamboo species, implying that the paleotropical woody bamboo species may be originated from a multi-source system. This study exposed a corner of the complex genomic relationships in the woody bamboos and provided an initial framework for future phylogenic studies.