Kikuyugrass germplasm collections in the United States and Australia show low levels of genetic diversity as revealed by DArTseq genotyping

Abstract

AbstractKikuyugrass [Cenchrus clandestinus (Hochst. ex Chiov.) Morrone (= Pennisetum clandestinum Hochst. ex Chiov.)] is a warm‐season grass native to Africa. It was introduced into the United States as forage in Hawaii and for erosion control in California. Kikuyugrass is considered invasive and currently is on the USDA's noxious weed list. Since complete eradication is difficult, it has become the primary species on several golf courses, athletic fields, and lawns. Kikuyugrass possesses exceptional quality with considerable cultural inputs, and little or no winter dormancy compared with other warm‐season turfgrasses. With breeding efforts directed specifically at reducing aggressiveness and improving texture, thus reducing inputs, it could become a valuable turf‐type species in coastal and inland California. The genetic diversity of kikuyugrass was investigated using single nucleotide polymorphism (SNP) and silicoDArT (presence or absence) markers revealed by the Diversity Arrays Technology sequencing (DArTseq) platform. Accessions were sampled throughout California, Hawaii, and Australia, both from natural stands and various collections. Among the 254 accessions tested, two distinct groups were discovered, and there was no geographic pattern to this differentiation. The overall level of SNP polymorphism was low (polymorphic information content [PIC] average = .33, PIC median = .38). Most (76%) of the observed genetic variation was within populations, whereas 24% was among populations. Average genetic distances within populations ranged from 0.09 to 0.16, whereas distances among populations ranged from 0.13 to 0.36. Accessions from Hawaii and Australia were the most diverse; however, a detectable level of genetic diversity of kikuyugrass also exists in California, mostly because of the past introductions from Australia.