Genetic diversity and relationships among 177 public sunflower inbred lines assessed by trap markers
This study investigated the genetic diversity and relationships among the 177 public sunflower (Helianthus annuus L.) inbred lines developed and released by USDA-ARS from the 1970s to 2005 using the target region amplification polymorphism (TRAP) marker technique. Twelve primer combinations generated a total of 230 polymorphic markers that could discriminate each of these lines, suggesting that TRAP is a powerful marker technique for fingerprinting sunflower inbred lines. The pairwise genetic similarity coefficients (simple matching) based on the TRAP markers ranged from 0.30 to 0.97 with a mean of 0.58, indicating that there is substantial genetic variability in this public collection. The average similarity coefficient of 41 confection inbred lines was significantly higher than that of 136 oilseed inbred lines. Cluster analysis grouped the 177 lines into two classes, oilseed (O) class and confection (C) class with only two exceptions. The O and C classes were further categorized into two groups: fertility maintainer (OB and CB) and fertility restorer groups (OR and CR). Moreover, inbred lines in the OB, OR, CR, and CB groups were placed into four, three, two, and two clusters, respectively. These results are useful to sunflower breeders and would promote the utilization of these public inbred lines.