Population structure and genetic relatedness in Brazilian Bermudagrass from sugarcane plantations
Cynodon dactylon (Bermudagrass) ise used for forage in Brazilian pastures, as well as in lawns, parks, and sports fields. However, in sugarcane fields, it is a difficult to control weed due to its rapid adaptation and growth mechanisms. It competes with sugarcane plants negatively affecting crop yield. Bermudagrass has polyploidy and easy hybridization, which promote high polymorphism, generating varying responses to the environment. Consequently, understanding the structure and variability of Bermudagrass becomes important for the development of strategies for its management as a weed. We examined the levels of genetic variability and structure of five populations (SP1 to SP5) of Bermudagrass, collected from sugarcane fields in the state of São Paulo (Brazil). Thirteen microsatellites were used. PCoA demonstrated STRUCTURE results (K=4) showing a mixture of SP1 and SP3 populations, with SP2, SP4 and SP5 being the most distant. DAPC also confirmed low genetic differentiation for SP1 and SP3. Genetic variability was found to be greater among than within populations, due to the predominance of vegetative growth of the species, which promotes low diversity, and due to geographic distances, which reduce gene flow or even make it unfeasible. The SSRs showed high resolution in characterizing the genetic diversity and structure of the five populations of Bermudagrass. The findings of this study may help to establish biological control methods against Bermudagrass in sugarcane fields.