Adaptation and genetic differentiation in common wheat revealed by the analysis of SCAR markers

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In east Asia, spring wheat is mainly cultivated under dry condition in north/west China, while winter wheat adapted to wet condition is predominant in south/east China. Therefore, they should exhibit different adaptability to abiotic stresses such as low temperature and drought.In the present study, RAPD polymorphism as adaptatively neutral marker and PCR-RFLP polymorphism for ABA responsive genes (Em and EmH2A) were analyzed, to understand the genetic and ecological differentiation in east Asian wheat.Genetic differentiation between north/west China and south/east China was clearly indicated by RAPD analysis for 56 wheat landraces of China, Korea and Japan. Clear differentiation was observed specially among spring type wheat. PCR-RFLP and sequence analysis for Em gene revealed the existance of four site changes in 5' untranslated region, and wheat landraces were classified into three types (A, B and C types). A single site change (+, -) was also detected in 3' untranslated region of EmH2A gene. Geographical variation of these PCR-RFLP showed clear difference again among spring type wheat, type B of Em and "+" type of EmH2A being frequent in eastern areas. The frequency of three types of Em was different between cultivar clusters classified by RAPD polymorphism. Specially in spring type wheat, type B of Em was only seen in three clusters (I, III and IV). In type B, ABA response of Em gene could be changed, since base substitution was frequently found in ABA responsive element. It was indicated from these results that type B of Em was selected for the adaptation to autumn sowing and/or wet condition in south/east China, being resulted in the establishment of a unique cultivar group which was genetically differentiated from those of north/west China.