Flow cytometric analysis of nuclear DNA content in Musa

Nuclear genome size variation was studied in Musa acuminata (A genome), Mus a balbisiana (B genome) and a range of triploid clones differing in genomic constitution (i.e. the relative number of A and B genomes). Nuclear DNA co ntent was estimated by flow cytometry of nuclei stained by propidium iodide . The A and B genomes of Musa differ in size, the B genome being smaller by 12% on average. No variation in genome size was found among the accessions of M. balbisiana (average genome size 537 Mbp). Small, but statistically s ignificant, variation was found among the subspecies and clones of M. acumi nata (ranging from 591 to 615 Mbp). This difference may relate to the geogr aphical origin of the individual accessions. Larger variation in genome siz e (8.8%) was found among the triploid Musa accessions (ranging from 559 to 613 Mbp). This variation may be due to different genomic constitutions as w ell as to differences in the size of their A genomes. It is proposed that a comparative analysis of genome size in diploids and triploids may be helpf ul in identifying putative diploid progenitors of cultivated triploid Musa clones. Statistical analysis of data on genome size resulted in a grouping which agreed fairly well with the generally accepted taxonomic classificati on of Musa.