Assessment of Molecular Variability within St. Augustinegrass Cultivar 'Raleigh' Using AFLP and SRAP Markers.

St. Augustinegrass (Stenotaphrum secundatum) is a popular turfgrass in the southeastern United States due its superior shade tolerance and relatively low input requirements. However, it is the least freezing-tolerant of the warm-season grasses and severe freezing injury may occur during some winters in USDA hardiness zones 8 and 9. ‘Raleigh’ is a cultivar known for its superior cold tolerance, and is therefore very popular in those regions. The cultivar was collected from a home lawn in Raleigh, North Carolina, and developed by Dr. W.B. Gilbert at North Carolina State University in the early 1980’s. Due to a couple of unusually cold winters in North Carolina, first in 1984 and then in 2005, all original foundation fields of Raleigh were lost, and as a result, only registered fields are currently available.  Given that more than 25 years after its release Raleigh is still the industry’s standard in terms of cold tolerance, it is important to investigate whether or not  St. Augustinegrass currently produced across the Southeastern United States and sold as Raleigh is true to the original ‘Raleigh’ selected in the late 1980s. The objective of this study was to use AFLP and SRAP markers to assess levels of genetic variability present among five samples of original Raleigh and 48 samples of Raleigh obtained from sod farms in eight different states. Additionally, foundation class and commercial samples of ‘Palmetto’ were included as reference standards to gauge genetic diversity. Twenty AFLP and eight SRAP primer combinations were used to differentiate between Raleigh samples. Phenetic analyses based on both unweighted pair-group cluster analysis and principal coordinate analysis revealed separation between putative Raleigh and some of the commercial samples. The pattern of genetic variation among samples collected from different states was analyzed by means of the analysis of molecular variance (AMOVA). Results will be discussed in terms of their relevance to St. Augustinegrass breeding.