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

To identify the chromosomes responsible for synthesis of dietary fibre (DF) and arabinoxylans (AX) in rye, four sets of disomic and several ditelosomic rye addition lines of wheat, several centric wheat-rye translocation lines of wheat and two sets of single D( R) substitution lines of hexaploid triticale were tested and compared to the parental lines. The DF and AX levels were analysed as soluble and insoluble fractions. All octoploid triticales and all addition lines had higher contents of the insoluble DF and AX fractions than wheats and these were strongly correlated with test weight. Because different additions of rye chromosomes to wheat have different effects on kernel characteristics, only the results of the soluble fractions appear significant. Among rye additions to Chinese Spring (CS), a wheat with low content of both soluble fractions, rye chromosomes 2R, 5R and 6R were associated with significantly increased amounts of soluble DF and AX. Among rye additions to BH1146 wheat that had substantially higher content of soluble fibre and arabinoxylans than CS, addition 5R resulted in significantly higher amounts while additions 1R, 3R, 4R and 7R in significantly lower levels of soluble DF and AX. These results were partially confirmed in substituted triticales, as removal of chromosomes 5R and 6R resulted in reductions of soluble DF and AX relative to the original cultivars. Analyses of ditelosomic rye additions to wheat and of centric wheat-rye translocation lines of wheat indicated that the factors responsible for increased soluble DF and AX contents in 2R were located on both arms, and in 6R either on S or in the proximal part of L. However, chromosome arms 3RL and 7RL also were associated with higher soluble DF and AX even though complete chromosomes did not show any effect. This suggests that factors with contrasting effects could be located on the opposite arms of the same chromosome. Clearly, the DF and AX contents in rye are controlled by many factors scattered throughout the genome and therefore, may not be easily manipulated in breeding.