Diversity and geographical distribution of seed lipoxygenase‐1 thermostability types in barley

To understand the diversity in the thermostability of the seed lipoxygenase‐1 (LOX‐1), 1040 cultivars of worldwide barley (Hordeum vulgare ssp. vulgare) genetic resources were investigated. The relative thermostability of LOX‐1 (LOX‐RTS) in these lines showed a bimodal frequency distribution and these lines were categorized into the high and low thermostability types (H‐type and L‐type, respectively). The H‐type lines predominated in the wild progenitor, ssp. spontaneum. The geographical distribution of these types in the cultivars was surveyed. The frequencies of the H‐ and L‐types were almost equal to one another in southwestern Asia. The occurrence of the H‐type predominated in eastern Asia and Africa, whereas in Europe and Turkey, the L‐type did. The predominance of the L‐type in Europe and Turkey can be understood through the hypothesis that the Fertile Crescent domestication contributed the majority of diversity in Europe. The uneven geographical distribution of the LOX‐1 thermostability types in the cultivars may reflect a polyphyletic origin of barley.