Simple Sequence Repeat Allelic Diversity in Zoysiagrass Released from 1910 to 2016

Abstract

[EN] Z. japonica know as Zoysiagrass has been cultivated in China, Japan and Korea for centuries. 11 different species have been found to be part of Zoysiagrass but when it comes to commercial varieties Zoysia japonica Steud and Zoysia matrella (L.) Merr are mostly used in the United States for turfgrass purposes. Zoysiagrass has a relatively high heat and drought tolerance and has disease resistance. However, it could use more cold tolerance for colder weather places in the United States. Over the years, zoysiagrass cultivars have been improved using conventional breeding methods such as hybridization, clonal selection and mutagenesis. Subsequently, a better understanding of genetic diversity in Zoysiagrass would help improve breeding efforts. The purpose of this study is to analyze levels of genetic diversity at gene and population levels in 39 Zoysia cultivars (Zoysia spp. Willd.). 23 primer SSR markers were used to determine whether allelic diversity among these cultivars has change over a century of modern plant breeding. In this study, Zoysiagrass varieties analyzed were released between 1910 and 2016 and most of the samples were from North Carolina State University. The DNA was extracted from Zoysia cultivars and amplified with SSR markers using PCR. Then, the DNA was separated by size in polyacrylamide gel electrophoresis. Finally, all the results were analyzed. We evaluated genetic diversity at population level and conclude that allelic diversity declined during the 1990s but recovered during the 2000s. Our study demonstrates that the influence of science based plant breeding in Zoysiagrass has not been very successful because allelic diversity has decreased after reaching the peak in 2000s. In the future, the levels of genetic diversity should increase through future germplasm collections and the inclusion of less Zoysia species to create new hybrids. Additionally, SSR has proved to be useful to detect molecular variation in Zoysiagrass cultivars.