[Inhibition of IAA-induced growth of wheat coleoptile fragments by chitin-chitosan oligomers].

We studied the comparative effects of the phytohormone indolylacetic acid (IAA) and chitooligosaccharides (5-10 kDa, degree of deacetylation 35%) on the growth of coleoptile fragments of 3-day wheat germlings. IAA (10 mg/l) stimulated elongation of coleoptile fragments by 80%, as compared to the control (water). Chitooligosaccharides at 0.01-1500 mg/l or higher did not exert auxin-like effects, but at 100 mg/l or higher, suppressed elongation of the coleoptile fragments, as compared to the control (water). Incubation of coleoptile fragments in solutions containing both IAA and chitooligosaccharides (100 mg/l or higher) suppressed their IAA-induced elongation, which correlated with the inhibition of growth of 3-day wheat germlings after wetting seeds in solutions of chitooligosaccharides. It has been proposed that the phytohormone-like properties of chitooligosaccharides can be related to changes in the endogenous balance of phytohormones in plants.