Submitted to: Journal of Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 1997
Publication Date: N/A
Interpretive Summary: Sugarcane has a very complicated genetic structure compared to many other grasses. Cultivated varieties (elite plants), have many (>100) small chromosomes, making chromosome study very tedious. In most grasses, each parent in a cross transmits one-half its chromosome complement to the progeny. This is true for many, but certainly not all, sugarcane crosses. Some plants transmit twice their normal chromosome complement to progeny, and this type of transmission could improve sugarcane breeding. Objectives of this study were to determine the number of chromosomes transmitted when elite plants were crossed with wild sugarcane relatives (exotic plants). In studies of 47 progeny from 19 crosses, I found that the elite plants transmitted half their chromosome complement to progeny. Results suggested that new research approaches may be needed to survey larger populations in the search for parents that transmit twice their chromosome complement.
Technical Abstract: Elite (commercial or near-commercial) sugarcane (Saccharum) is a tri-species hybrid derived from the exotic species S. officinarum, S. robustum, and S. spontaneum. Elite clones continue to be bred with these and other exotic species for germplasm enhancement and cultivar development, but the mode of chromosome transmission has not been thoroughly studied. Chromosome transmission was studied in 47 F1, F2, and BC1 progeny derived in most cases from elite x exotic crosses. Counts ranged from 2n = 73 to 137. Hybrids of sugarcane x Miscanthidium violaceum (2n = 28) or Miscanthus sinensis (2n = 38) were n+2n. Hybrids of sugarcane x Erianthus spp., M. japonicus (2n = 38), North American Saccharum spp. (2n = 60 and 90), S. robustum, and S. spontaneum were n+n. These were the first known counts for progeny of sugarcane x North American Saccharum. All F2 and BC1 progeny were n+n. Counts suggested that seven progeny of sugarcane x Erianthus spp. (2n = 20) were 2n+n, but subsequent DNA analyses failed to confirm this. The exotic crosses S. officinarum x S. robustum, S. officinarum x S. spontaneum, S. sinense x E. elephantinus (2n = 20), and S. spontaneum x S. officinarum were n+n. Chromosome pairing was most regular in progeny of S. officinarum x S. robustum. All other clones had univalents, and most had trivalents or quadrivalents. Meiosis was disturbed in sugarcane x North American S. giganteum (2n = 90) indicating cytogenetic divergence.