Genotyping and assessment of genetic relationships in elite polycross breeding cultivars of sweet potato in Taiwan based on SAMPL polymorphisms

Selective amplification of microsatellite polymorphic loci (SAMPL) markers was used to analyze the genetic relationships between 22 elite cultivars of sweet potato [Ipomoea batatas (L.) Lam.] used in polycross breeding in Taiwan. These elite cultivars included varieties introduced from China and Japan and landraces from Taiwan as well as cultivars derived either from hybrid or polycross breeding programs. Among 12 SAMPL primer pairs tested, 7 amplified 19 loci while the other 5 SAMPL primer pairs gave ambiguous banding profiles. Fifty-five alleles were amplified in total. The unweighted pair group method with arithmetic mean (UPGMA) and principal coordinate analysis (PCA) of SAMPL data suggest that Taiwan landraces are distantly related to Chinese and Japanese cultivars after many years of independent selection and may have originated from Java and Brahman. Polycross derived cultivars are closely related to different landraces. Employment of SAMPL markers is efficient compared to other molecular marker methods, such as random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR), in assessing the genetic relationships of sweet potato cultivars used in the polycross breeding program in Taiwan.