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Title: Dihaploid stocks for switchgrass isolated by a screening approach

Author
item Young, Hugh
item Hernlem, Bradley - Brad
item Cartwright, Amy
item Lanzatella-Craig, Christina
item Tobias, Christian

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2010
Publication Date: 10/14/2010
Citation: Young, H.A., Hernlem, B.J., Anderton, A.L., Lanzatella-Craig, C., Tobias, C.M. 2010. Dihaploid stocks for switchgrass isolated by a screening approach. BioEnergy Research. 3:305-313.

Interpretive Summary: This research describes the isolation of two individual switchgrass plants with half the normal genome size. These plants may be used to produce genetically true breeding lines by subsequent chromosome doubling. They also shed light on the nature of polyploidy in switchgrass as meiosis was abnormal in these individuals. The plants were smaller than normal switchgrass with reduced cell size, complete sterility, and fewer chloroplasts per guard cell.

Technical Abstract: Additional genetic resources are necessary to facilitate improvement of switchgrass (Panicum virgatum L.) as a bioenergy crop. We have identified two dihaploid individuals isolated from among the progeny of a controlled cross between two mapping parents of the cultivars Alamo and Kanlow. The dihaploid lines were initially distinguished from the parental lines by their reduced heterozygosity and were confirmed by flow cytometry and chromosome counts of metaphase root-tip squash preparations. These plants are functionally sterile, with flowers that do not open and produce no pollen; they can be easily distinguished from tetraploid individuals by their reduced stature, smaller epidermal cell size, and lower number of chloroplasts per guard cell. The reduced genome size of these dihaploids will facilitate basic genome studies and genetic analyses that are impossible or problematic in polyploid accessions. This is not the first report of 2n=18 switchgrass. However, these are the only lines currently available to researchers.