JASMONIC ACID EFFECTS MYCORRHIZATION OF SPRUCE SEEDLINGS WITH LACCARIA-LACCATA

Jasmonic acid (JA) was shown to be an important regulating molecule af ter wounding and pathogen attack, but it also conveys mycorrhizal sign alling. It was therefore applied to the ectomycorrhizal system. Root g rowth patterns of 2-month-old spruce seedlings mycorrhized with Laccar ia laccata after treatment with 0.5 mu M JA, 5.0 mu M JA, or none for the control, were studied using a paper-sandwich technique. Changes in plant weight, root length, the degree of branching, presence of root hairs, and infection parameters were monitored for 26 days. Data were analysed by means of Student's t-test and ANOVA factorial. Shoot and r oot dry weights were significantly increased by mycorrhizal infection, especially when JA was applied. Lateral root formation and the presen ce of roots with hairs were dramatically decreased in the presence of the fungus. A synergistic effect of JA and mycorrhization on decrease of lateral root length was shown. The first mycorrhizal contact of fun gal hyphae with roots was significantly accelerated after treatment wi th JA.