Genetic diversity trends in sugarcane germplasm: Analysis in the germplasm bank of the RB varieties

Brazil is the largest sugarcane producer in the world and, the main varieties grown in Brazil, known as RB cultivars, were developed by the Interinstitutional Network for the Development of the Sugar and Alcohol Sector (RIDESA) and are used in 58.9% of the planted area in Brazil. These varieties were obtained through intercrosses between genotypes from the Serra do Ouro germplasm bank and successive crosses with related genotypes may have increased the level of genetic similarity. The aim of the present study was to analyze the genetic base of the Serra do Ouro germplasm bank over the past decades using microsatellite molecular markers. The genetic similarity among varieties using all the markers ranged from 0.166 to 0.823, and regression analysis showed an increase in genetic similarity in the 1970s; however, a narrowing of the genetic base over the last five decades was not observed.