Te results in Table 1 show the presence of a large number of cultivars that have previously been misclassified. Many of the cultivars historically thought of as Z. japonicas or Z. matrellas are actually hybrids carrying genetic material from both species. For example, cultivars previously considered Z. japonicas that are actually hybrids include Crowne, DeAnza, El Toro, Empire, Empress, GNZ, Jamur, Marion, Palisades, Serene, Southern Gem, Victoria, and Y2. All of these cultivars were more genetically similar to Z. japonica than Z. matrella except for GNZ and Y2. Cultivars previously considered matrellas that are actually hybrids include Cavalier, Matrella, Royal, Zeon, and Zorro and all of them had more markers in common with Z. matrella than Z. japonica, except for Matrella which, despite its name has more in common with Z. japonica.


Looking at the data for the inflorescence traits that were collected, not only were the Z. japonica, Hybrid I, Hybrid II and Z. matrella groups different from each other for these traits, but Hybrid I measurements were closer to those of Z. japonica and Hybrid II measurements were closer to Z. matrella (Figure 3). Tese observations further support the DNA results indicating the presence of hybrids among various zoysiagrass species.


Figure 3


Researchers examine Zoysiagrass plots at North Carolina State University.


A working knowledge of this new information on relationships between zoysiagrass species is helpful in many ways. One, it can help plant breeders to exploit the variation present in germplasm collections for improving important performance and appearance traits. Two, it may help sod farmers, golf course superintendents, and landscape industry personnel develop management plans more tailored to the specific zoysiagrass species they are managing. Te significant presence of hybridity in Zoysia highlights both the historical and future importance of hybrid-based breeding strategies in the genus. Moreover,


So, what does this all mean? Tis study not only verified the presence of interspecific hybrids between Z. japonica and Z. matrella, but more importantly it was able to tell us that these hybrids are the reason for the continuous range of variation commonly observed between the two species. When these hybrids were divided into their own groups, a clear separation between the two species could be observed for the majority of the traits analyzed. In other words, it’s not that Z. japonica and Z. matrella species are so variable that they overlap, but instead it’s the presence of interspecific hybrids between the two species that makes it appear that way. Te reality is that once these hybrids are accounted for, there is a clear distinction between Z. japonica and Z. matrella species with the presence of hybrids in the middle.


it provides further support to the hypothesis from a group of researchers in 1955 who suggested that what we now call Zoysia species are not really separate species but rather subpopulations or ecotypes of the same species.


Tus, the question, “Is Z. japonica really a different species than Z. matrella or Z. pacifica?” will continue to merit research by plant breeders and geneticists.


Tis research was performed by the North Carolina State University Turfgrass Breeding Program (https://nctbg.wordpress.ncsu.edu/) and was published in the academic journal Crop Science 53:285-295.


Susana Milla-Lewis, PhD, is associate professor of Crop Science at North Carolina State University. Jennifer A. Kimball, PhD, is assistant professor in the Department of Agronomy and Plant Genetics at the University of Minnesota. Casey Reynolds, PhD, is executive director of Turfgrass Producers International.


All graphics, tables and photos courtesy of the North Carolina State Turfgrass Breeding Program.


TPI Turf News May/June 2018 51


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