The Gene Pool of Saccharum Species and Their Improvement

Current taxonomy divides sugarcane into six species, two of which are wild and always recognized (Saccharum spontaneum L. and Saccharum robustum Brandes and Jewiet ex Grassl). The other species are cultivated and classified variously. Of the four domesticated species of Saccharum, S. officinarum L. was the first named and is the primary species for production of sugar. Recent genomic data for evaluating genetic diversity within Saccharum suggests relationships among accessions that may ultimately produce a definitive classification of the species. Sugarcane breeders have long realized that germplasm diversity is essential for sustained crop improvement, with accessions from at least 31 separate expeditions deposited in the two world collections as genetic reservoirs. Cultivated sugarcanes of today are complex interspecific hybrids primarily between Saccharum officinarum, known as the noble cane, and Saccharum spontaneum, with contributions from S. robustum, S. sinense, S. barberi, and related grass genera such as Miscanthus, Narenga, and Erianthus. Sugarcane has long been recognized as one of the world’s most efficient crops in converting solar energy into chemical energy harvestable as biomass, and is of growing interest as a biofactory for production of fossil fuel alternatives and other high-value bioproducts.