Linkage drag definition
Linkage drag means that when a gene possessing a superior trait is introduced from another variety, a linked gene possess- ing an inferior t rait is simultaneously introduced. We have also analyzed morpho- logical and physiological traits observed in CSSLs. The analyzed traits were related to the differentiation between indica and japonica in terms of grain shape and heading time. Our results showed that several genes causing morphological and physiological traits were adjacent to genes causing hybrid sterility. To our knowledge, no study has investigated the relationship between the loci of adjacent genes that cause linkage drag in the whole genome.