Genetic Relationships of Cultivated Flax and Its Wild Progenitor as Revealed by 454 Pyrosequencing, Sanger Resequencing and Microsatellite Data

Abstract

Flax (Linum usitatissimum L.), as the earliest oil and fiber crop, is a model plant for genetic inferences of plant domestication processes involving multiple domestication events. However, a puzzle has emerged from several genetic studies, as dehiscent cultivated flax is genetically more related to its progenitor pale flax (L. bienne Mill.), and winter cultivated flax is well mixed with oil or fiber cultivated flax, while capsular dehiscence and winter hardiness are the major characteristics of pale flax. For this, a comparative analysis was conducted with 16 Linum samples representing pale flax and four domestication groups of cultivated flax (oil, fiber, winter, and dehiscent) using 454 pyrosequencing, Sanger resequencing and microsatellite data. It was found that the genomic sampling of genetic variants from the three applied methods yielded similar genetic information on pale flax and four groups of cultivated flax. The revealed genetic relationships did not show significant departures from the previous findings, but instead supported an early, independent domestication of a primitive flax lineage for oil use, followed by a subsequent flax domestication process with multiple domestication events for capsular dehiscence, oil, fiber and winter hardiness. Domestication on capsular dehiscence occurred earlier than domestication on winter hardiness. Domestication on winter hardiness was more complicated than domestication on capsular dehiscence.