Feedstock Development projects
Selection of High-Yielding Energy Cane Clones from Transgressive Segregating Populations
Energy cane and sugarcane cultivars are generally derived from interspecific hybridization between high sugar content Saccharum offlclnarum and wild Saccharum species, primarily S. spontaneum. Commercial sugarcane cuItlvars are subsequently developed through additional rounds of back crossing to S. officlnarum or hybrids to recover the high biomass yield and high sugar content while retaining biotic and abiotic stress resistance provided by S. spontaneum. For breeding, this project utilizes the transgressive segregation in true F2 populations from interspecific crosses, because sugar content is not a limiting factor for selecting high biomass energy cane cultivars. Yield trials of the high-biomass-yield segregants will be conducted in Hawaii and Florida. This project could accelerate energy cane breeding, shorten the typical breeding cycle of 13 years in energy cane and sugarcane breeding programs, and maximize the biomass yield from new germplasm generated from interspecific recombination (started in 2012)
The objective of this project is to select high-biomass-yield energy cane clones for second-generation biofuel production. We started 2 replicated field trials in August to test the biomass yield of F2 clones from 2 interspecific F2 populations. In 2013 flowering season, 2 additional F2 populations were generated from interspecific crosses. Including the original interspecific F2 population, now we have generated 4 interspecific F2 populations with all possible combinations of the 3 primary Saccharum species. Reciprocal crossing and selfing of top 5 high-yielding F2 clones yielded 2 F3 families from 2 F2 clone in 2013 flowering season, and the other 3 top F2 clones are likely with reduced fertility, often the consequence of interspecific hybridization. One F3 family with 123 individuals from 2012 flowering season were grown in the field in 2014 and the top 10 clones were selected for replicated yield trials. The 2 additional F3 families with 232 and 211 individuals were planted in the field in August, 2014. High-yielding clones will be selected from these 2 F3 populations next year. Fifteen S. officinarum accessions were selected and planted in March for making intraspecific crosses in 2014 flowering season.
Energy cane and sugarcane cultivars are derived from interspecific hybridization between high sugar content Saccharum officinarum and wild Saccharum species, primarily S. spontaneum, and followed by backcrossing to S. officinarum or hybrids to recover the high biomass yield and high sugar content while retaining stress tolerance from S. spontaneum. This scheme has been practiced for over a century due to the need to recover high sugar content. We tested a new paradigm for energy cane breeding by utilizing transgressive segregation in true F2 populations from interspecific crosses, because sugar content is not a limiting factor for high biomass energy cane cultivars. Our initial field trial of 261 F2 individuals on Maui yielded clones with 338% increase of biomass yield compared to its high yielding parent. We have selected 120 extreme segregants for yield trials on Oahu for two years, including a ratoon crop (growth from harvested stalk remains). Seven of the top 10 high biomass yield clones remained in the top 10 after yield tests in three years at two locations. This new strategy would accelerate energy cane breeding, shorten the typical breeding cycle of 13 years, and maximize the biomass yield from new germplasm generated through interspecific recombination.