Abstract:In order to provide the foundation for flax conventional and molecular breeding, we explored the genetic diversity level of 161 flax germplasm resources from five different regions of the world, using SRAP molecular marker technology. The results showed that: (1) twenty pairs of SRAP primers produced 307 bands, of which 192 polymorphism, with the polymorphic rate of 62.54%, and 9.60 polymorphic loci for each pair of primers. The polymorphism information content (PIC) of each pair of primers ranged from 0.51~0.76, with an average of 0.61. (2) At the species level, effective number of alleles (Ne), Shannons information index (I), Neis genetic similarity coefficient (H) were 1.582 0, 1.521 1, and 0.346 5, respectively; but at the population level, Ne = 1.491 1, I = 0.431 1, H = 0.286 3, with the genetic diversity of northwestern Chinese population being the highest. (3) The order of the populations according to their diversity indices: population from the northwestern China > population from the northern China > American population > Asian population > European population. (4) The clustering analysis results showed that when the genetic similarity coefficient was 0.335 5 and 0.455 0, the 161 flax resources could be divided into two major categories and five subgroups, respectively, coinciding with the five different origins in the world. It can be seen from the study that flax cultivars from northwestern China showed the richest genetic diversity, suggesting that growing region was the main factor that had affected the genetic diversity of flax germplasms. There were relatively large distance of genetic relationship between the Chinese varieties and those from abroad.