Assessment of Genetic Diversity in Zoysiagrass Germplasm Using AFLP Markers.

Zoysiagrass (Zoysia sp.) is a warm-season turfgrass species widely used in the Southern United States for its superior heat tolerance and low input requirements. A better understanding of the levels of genetic diversity present in Zoysiagrass germplasm would be a prerequisite for the use of these materials in future breeding efforts. The objectives of this study are to (i) characterize AFLP molecular variation and structure of the North Carolina State University Zoysia germplasm collection and (ii) compare levels of molecular diversity within and among Zoysia cultivars, plant introductions, collections, and public vs. private germplasm stocks. Two-hundred and forty-three Zoysiagrass accessions from public and private contributors were genotyped with twelve AFLP primer combinations. Five hundred and sixty-five polymorphic AFLP loci were scored. AFLP based genetic similarities among genotypes ranged from 0.63 to 0.89 with an average 0.72. Genetic diversity was highest between plant introductions and a private collection from Florida, while cultivars and samples from a private collection in Oregon were the most genetically similar. AMOVA results indicated that 31.67% and 68.33% of the total AFLP variation could be explained by differences among and within populations, respectively. UPGMA cluster analysis and PCA identified high levels of admixture among all genotypes. Genotypes were grouped into clusters mainly according to their population types and their geographical distribution. Understanding the distribution of genetic diversity within and among the Zoysiagrasses will enable researchers to exploit the pools of variation for future cultivar development.