Location: Crop Genetics and Breeding ResearchTitle: Detection of genetic and ploidy variation within vegetatively propagated zoysiagrass cultivars Author
|Waltz, F. Clint|
Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2014
Publication Date: 9/19/2014
Citation: Harris-Shultz, K.R., Milla-Lewis, S., Patton, A.J., Kenworthy, K., Chandra, A., Waltz, F., Hodnett, G.L., Stelly, D. 2014. Detection of genetic and ploidy variation within vegetatively propagated zoysiagrass cultivars. Journal of the American Society for Horticultural Science. 139(5):547-552. Interpretive Summary: During 2001 to 2005 homeowners and landscapers in Alabama and Georgia noticed inconsistent spring greenup patterns in the vegetatively propagated zoysiagrass cultivar Emerald. A study was conducted and the problem was found to be due to the presence of multiple genotypes arising from contamination or mislabeling. Since that time, another study identified differences in the sources of the vegetatively propagated cultivar Diamond. To determine the extent of genetic variability of vegetatively propagated zoysiagrass cultivars which are fully fertile tetraploids, samples were collected from six commercially available zoysiagrass cultivars; Diamond, Emerald, Empire, JaMur, Meyer, and Zeon from five states; Arkansas, Florida, Georgia, North Carolina, and Texas. Seventy-five samples were collected from sod farms and universities and genetic differences, using DNA markers, were identified from four samples. Three of these samples were from Texas and one of these samples was from Florida. Furthermore one of these differing samples was found to be an octoploid which had never been previously seen without genetic modification (the use of colchicine). This study directly benefits sod producers and university researchers that provide plant material for consumers as technology exists that can determine if visual differences in zoysiagrass are due to genetic differences. Furthermore, the identification of an octoploid zoysiagrass will enable turfgrass breeders to produce zoysiagrass cultivars with an odd number of chromosomes which would be effectively sterile and thus genetically uniform.
Technical Abstract: Zoysiagrass (Zoysia spp. Willd.) is used as a warm-season turfgrass for lawns, parks, and golf courses in the warm-humid and transitional climatic regions of the United States. Zoysiagrass is an allotetraploid species (2n= 4x= 40) and some cultivars are known to easily self and cross-pollinate. Previous studies showed that genetic variability in the clonal cultivars Emerald and Diamond was likely due to contamination (seed production or mechanical transfer) or mislabeling. To determine the extent of genetic variability of vegetatively propagated zoysiagrass cultivars, samples were collected from six commercially available zoysiagrass cultivars; Diamond, Emerald, Empire, JaMur, Meyer, and Zeon from five states; Arkansas, Florida, Georgia, North Carolina, and Texas. Two of the newest cultivar releases ‘Geo’ and ‘Atlantic’ were to serve as outgroups. Where available, one sample from university research plots and two samples from sod farms were collected for each cultivar per state. Forty zoysiagrass SSR markers and flow cytometry were used to assess genetic and ploidy variation of each collected sample to a reference sample. Seventy-five samples were genotyped and unweighted pair group method with arithmetic mean (UPGMA) clustering revealed four groups. Group I (Z. japonica) included samples of Meyer and Empire11 (Empire, sample location #11), Group II (Z. japonica x Z. pacifica) included samples of Emerald and Geo, Group III (Z. matrella) included samples of Diamond and Zeon, and Group IV (Z. japonica) consisted of samples from Empire, JaMur, Atlantic and Meyer3 (Meyer, sample location #3). Samples of Empire, Atlantic, and JaMur were indistinguishable with the markers used. Four samples were found to have alleles different than the respective reference cultivar. These different samples included two samples of Meyer, one sample of Empire, and one sample of Emerald. Three of these samples were from Texas and one of these samples was from Florida. Three out of the four samples that were different than the reference cultivar were university samples. Furthermore one sample, Empire 11, was found to be an octoploid (2n= 8x= 80). Our study showed that most of the samples we obtained matched the fingerprint of the reference cultivar. For those samples that were different, contamination, selfing, and hybridization with other zoysiagrasses may have occurred.