Chromosome location of genes controlling the content of dietary fibre and arabinoxylans in rye

Abstract

To identify the chromosomes responsible for synthesis of dietary fibre (DF)and arabinoxylans (AX) in rye, four sets of disomic and several ditelosomicrye addition lines of wheat, several centric wheat-rye translocation lines ofwheat and two sets of single D(R) substitution lines of hexaploid triticalewere tested and compared to the parental lines. The DF and AX levels wereanalysed as soluble and insoluble fractions. All octoploid triticales and alladdition lines had higher contents of the insoluble DF and AX fractionsthan wheats and these were strongly correlated with test weight. Becausedifferent additions of rye chromosomes to wheat have different effects onkernel characteristics, only the results of the soluble fractions appearsignificant. Among rye additions to Chinese Spring (CS), a wheat with lowcontent of both soluble fractions, rye chromosomes 2R, 5R and 6R wereassociated with significantly increased amounts of soluble DF and AX.Among rye additions to BH1146 wheat that had substantially highercontent of soluble fibre and arabinoxylans than CS, addition 5R resultedin significantly higher amounts while additions 1R, 3R, 4R and 7R insignificantly lower levels of soluble DF and AX. These results were partiallyconfirmed in substituted triticales, as removal of chromosomes 5R and 6Rresulted in reductions of soluble DF and AX relative to the originalcultivars. Analyses of ditelosomic rye additions to wheat and of centricwheat-rye translocation lines of wheat indicated that the factors responsiblefor increased soluble DF and AX contents in 2R were located on botharms, and in 6R either on S or in the proximal part of L. However,chromosome arms 3RL and 7RL also were associated with higher solubleDF and AX even though complete chromosomes did not show any effect.This suggests that factors with contrasting effects could be located on theopposite arms of the same chromosome. Clearly, the DF and AX contentsin rye are controlled by many factors scattered throughout the genome andtherefore, may not be easily manipulated in breeding.