Symbiosis-stimulated chitinase isoenzymes of soybean (Glycine max (L.) Merr.)

Isoforms of endochitinase in soybean were studied in relation to root symbi osis, Five selected cultivars differing in their nodulation potential were inoculated with two strains of Bradyrhizobium japonicum, the broad host-ran ge Rhizobium sp, NGR234, and with the mycorrhizal fungus Glomus mosseae, to tal chitinase activity in nodules was up to 7-fold higher than in uninocula ted roots and in mycorrhizal roots, the chitinase activity in nodules varie d depending on the strain-cultivar combination. On semi-native polyacrylami de gels, four acidic isoforms were identified. two isoforms (CH 2 and On 4) were constitutively present in all analysed tissues, the other two isoform s (CH 1 and CH 3) were strongly induced in nodules and were stimulated in m ycorrhizal roots as compared to uninoculated roots, The induction of CH 1 v aried in nodules depending on the soybean cultivar, this isoform was also s timulated in uninfected roots when they were treated with tri-iodobenzoic a cid, rhizobial lipochitooligosaccharides (Nod factors) and chitotetraose. O n 3 was not affected by these stimuli indicating that this isoform could re present a marker for enzymes induced in later stages of the symbiotic inter actions.