|Kimball, Jennifer -|
|Zuleta, M. Carolina -|
|Kenworthy, Kevin -|
|Lehman, Virginia -|
|Milla-Lewis, Susana -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 5, 2012
Publication Date: November 26, 2012
Citation: Kimball, J.A., Zuleta, M., Harris-Shultz, K.R., Kenworthy, K.E., Lehman, V.G., Milla-Lewis, S. 2012. Genetic relationships in Zoysia species and the identification of putative interspecific hybrids using simple sequence repeat markers and inflorescence traits. Crop Science. 53(1):285-295. Interpretive Summary: Two Zoysia species, Z. japonica Steud. and Z. matrella Merrthat, are used as warm-season turfgrasses in the southern United States, but can persist north of the transition zone. Zoysiagrasses are typically used for home lawns, golf courses, and recreational areas. Zoysia species designations have been called into question as these species are able to form hybrids and the two species look similar. In this study, markers were used that could determine the relatedness of each Zoysia specie and hybrids were identified. The authors suggest a reclassification of Zoysia such that a single Zoysia species exist with at least two major varieties: japonica and matrella.
Technical Abstract: Zoysia spp. are warm-season turfgrasses used throughout the southern U.S. and upwards into the transition zone for their superior heat and drought tolerances and their relatively low input requirements. Understanding the population structure present within Zoysia germplasm can assist plant breeders in exploiting available variation. The objectives of this study were to assess SSR allelic diversity within and among Zoysia spp., evaluate the genetic constitution of putative interspecific hybrids, and determine if Zoysia spp. and hybrids can be differentiated by inflorescence traits. Sixty-two Zoysia accessions selected as a subset of genotypically and phenotypically diverse genotypes were evaluated with fifty SSR markers. Both a UPGMA phylogram and PCO analyses revealed a continuous flow of genetic variation present within and among the species. The model-based program STRUCTURE, revealed two distinct subpopulations within Z. japonica as well as a distinct Z. matrella subpopulation. Based on SSR analysis, twenty-three Zoysia accessions evaluated had evidence of admixture. Six inflorescence phenotypes also revealed a continuous range of variation. Based on these findings, this study was able to verify the presence of hybrids between Z. japonica and Z. matrella and further validate the hypothesis that Zoysia spp. are actually subpopulations or ecotypes within one species and not separate species.