We investigated the variation and geographical distribution of the Pseudo-regulator response 37 (Setaria italica PRR37= SiPRR37) gene involved in heading time (photoperiodism) in foxtail millet. An allele of the SiPRR37 gene, in which an approximately 4.9-kb transposable element (designated as TE1 in this article) is inserted (a loss-of-function or reduction-of-function type), is distributed sporadically in East Asia and broadly in Southeast Asia and South Asia, which implies that this gene is important in latitudinal adaptation. In addition, we found a new allele of SiPRR37 with an insertion of a 360-bp TE (designated as TE2) at this locus and investigated the geographical distribution of this new type. This SiPRR37 allele with TE2 is distributed in Japan, Korea, Nepal, Iran, and Turkey. Both TE1 and TE2 are useful markers for tracing foxtail millet dispersal pathways in Asia.
Keywords: Adaptation; PRR37 gene; foxtail millet; heading time; transposable elements.