Effect of short chain fatty acids on physiology of barley grains cv. Triumph with a different level of dormancy

Abstract

We studied the role of fatty acids in dormancy of barley cv. Triumph using isogenic grains grown in phytotrons with either a relatively high or a low degree of dormancy and non-dormant grains grown in the field. The level of endogenous short chain saturated fatty acids (SCSFAs) and unsaturated fatty acids (USFAs) were analysed in these grains. We did not detect SCSFAs and could not find a significant difference in the levels of USFAs between the different types of grain. Exogenous SCSFAs had inhibitory effects on both grain germination and germination of isolated embryos and GA 3-induced α-amylase secretion of isolated aleurone layers. In the concentration range between 6.7 mM and 10 mM the germination of non-dormant grains grown in the field was sharply inhibited by heptanoic acid (C7), octanoic acid (C8) and nonanoic acid (C9). A 10-mM concentration of decanoic acid (C10) did not affect the grain germination significantly; however, C10 reduced the germination of isolated embryos and the GA 3-induced α-amylase secretion of isolated aleurone layers. Embryos from dormant grains were more sensitive to C9 and C10 than embryos from non-dormant grains, whereas aleurone layers from both types of grain did not show a clear difference in responses towards these fatty acids. C9, however, had a stronger inhibitory effect on isolated embryos and on isolated aleurone layers from both types of grain than C10 had. As compared with grains, a 20-fold and a 40-fold lower concentration SCSFAs were effective on isolated embryos and aleurone layers, respectively. The findings as presented underline the obviously different role of the aleurone and embryo in grain dormancy.