ARS | Publication request: Genome size variation in three Saccharum species

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 12, 2012
Publication Date: March 25, 2012
Repository URL: http://handle.nal.usda.gov/10113/55242
Citation: Zhang, J., Nagai, C., Yu, Q., Pan, Y., Ayala Silva, T., Schnell Ii, R.J., Comstock, J.C., Arumuganathan, A.K., Ming, R. 2012. Genome size variation in three Saccharum species. Euphytica. 185:511-519. DOI: 10.1007/S10681-012-0664-6.

Interpretive Summary: Flow cytometry was used to estimate the genome size of Saccharum species, one of the most complex crop plants. The size of S. officinarum ranged from 7.50 to 8.55 Gb and was the least variable compared to S. robustum that ranged from 7.65 to 11.78 Gb and to S. spontaneum that ranged from 3.36 to 12.64 Gb. The genome size of S. robustum and S. spontaneum was variable due to ploidy level. The genome size was correlated to chromosome number. This technique is valuable in aiding the selection of which clones with the smaller genome to sequence.

Technical Abstract: Saccharum species are autopolyploid with ploidy level ranging from 5x to 16x, and is considered one of the most complex genomes among crop plants. In this study, the genome sizes of 28 S. spontaneum accessions, 15 S. officinarum accessions, 28 S. robustum accessions, and 12 Saccharum Hybrids were analyzed using flow cytometry. The estimated genome sizes of S. officinarum accessions ranged from 7.50 to 8.55 Gb with an average size of 7.88 Gb. In S. robustum, the estimated genome sizes ranged from 7.65 to 11.78, reflecting the variation of ploidy level. In S. spontaneum, the estimated genome sizes vary widely, with a range from 3.36 to 12.64 Gb, also due to variation of ploidy level. The average monoploid genome size of S. officinarum is 985 Mb, and that of S. spontaneum is 843 Mb. Our results also showed that genome sizes are correlated with chromosome numbers, on the basis of which, the unknown chromosome numbers of the accessions could be predicted. The estimates of genome sizes of Saccharum germplasm clarified some mislabeled clones and yielded information critical for sugarcane breeding and genome sequencing programs.