Stepwise selection of natural variations at <i>CTB2</i> and <i>CTB4a</i> improves cold adaptation during domestication of <i>japonica</i> rice

The improvement of cold adaptation has contributed to the increased growing area rice. Standing variation and de novo mutation are distinct natural sources beneficial alleles in plant adaptation. However, genetic mechanisms evolutionary patterns underlying these a single population during crop domestication remain elusive. Here we cloned CTB2 gene, encoding UDP-glucose sterol glucosyltransferase, for tolerance rice at booting stage. A standing (I408V) conserved UDPGT domain originated from Chinese Oryza rufipogon sativa ssp. japonica. is located 56.8 kb region, including previously reported gene CTB4a which arose c. 3200 yr BP Yunnan province, China, conferring tolerance. underwent stepwise selection facilitate expand cultivation high-altitude high-latitude regions. These results provide an example on two kinds describe new molecular mechanism japonica