Germplasm Collection and Karyological Evaluation of wild sugarcane (Saccharum spontaneum L.) in Iran

Commercial sugarcane plants are the result of a limited series of crosses and backcrosses derived from the domesticated species Saccharum officinarum and the wild species S. spontaneum. In order to broadening genetic resources of sugarcane, wild species S. spontaneum from some regions of Iran were collected for the first time and evaluated karyologically. Microscopic examination of squashed root tips showed that these samples are in the two groups of diploid and tetraploid (2n = 2x = 20 and 2n = 4x = 40) in terms of number of chromosomes. Multivariate and cluster analysis showed that 20 chromosome samples had a significant difference in chromosomal and karyotypic variables and the diversity of samples in the southern region was higher than that of the northern region. The 20 chromosome samples had the longest chromosomes and the most symmetric karyotype, and the southern tetraploid samples were placed in a separate cluster. The karyotype indices of tetraploid samples were similar and no significant difference was observed between them. S. spontaneum diploid with 2n=2x=20 is a new case and has the smallest number of chromosomes that are ever identified and reported in this species.