The Origin of Bermudagrass (Cynodon) Off‐Types Inferred by DNA Amplification Fingerprinting

Abstract

DNA amplification fingerprinting (DAF) with arbitrary oligonucleotide primers can specify genetic relationships between closely related plant accessions. In this study, DAF was used to characterize bermudagrass (Cynodon) species and cultivars of interspecific crosses, evaluate genetic diversity and origin of bermudagrass off‐types, and certify authenticity of cultivar stocks. Arbitrary octamer primers produced complex and reproducible amplification profiles with high levels of polymorphic DNA. An initial analysis of 13 bermudagrass cultivars was used as a reference to establish genetic relationships between cultivar Tifway and off‐types that produce patches exhibiting contrasting morphology and performance. Phenetic analysis using cluster (UPGMA) and ordination (PCO) techniques showed that Tifway was genetically stable and that off‐types were genetically distant to Tifway and represent a heterogeneous group of bermudagrass probably of interspecific hybrid origin. While Tifway standards from different sources could not be differentiated from each other, the off‐types were diverse at the genetic level, their origin being clearly from sod contamination and not from somatic mutation. DAF was used to fingerprint samples in “phyto‐forensic” applications, identifying bermudagrass plant material based on unique reference profiles generated with selected primers. Exclusions were observed in 63% of 93 bermudagrass samples believed related to cultivars Tifway, Tifgreen, and Tifdwarf. Conversely, calculation of fingerprint matching coefficients facilitated inferences on the probability of a match in inclusion cases as applied to cultivar verification, seed certification, and cultivar protection. This study presented the foundation for the identification of mistakes in plantings, mislabeled plant materials, and contamination or substitutions of sod fields.