Factors affecting the prolongation of NMR relaxation times of water protons in leaves of woody plants affected by formation of insect galls

Changes in NMR relaxation times (T₁) of water protons and water contents of leaves of woody plants affected by formation of insect galls were studied in Machilus, Zelkova and Cinnamomum parasitized with a gall-midge, an aphid and two different Triozine psyllids, respectively. The presence of galls in Machilus leaves increased both T₁ and water contents in the galled leaf tissues, while such tissues in Zelkova showed only increases in T₁. Similar trends for both parameters were also observed in gall-bearing leaf tissues of Machilus and Cinnamomum, with galls caused by two different psyllids. It seems that it is the particular characteristics of leaf tissues of the host plant that determine whether the systemic effect of the presence of galls is reflected both in T₁ and in water content, or only in T₁. Histologic features, including the presence of tannins in and leakage of electrolytes from these materials, were compared with those of normal (ungalled) leaves to determine possible causative factors involved in the prolongation of T₁ relaxation times that were associated with the presence of insect galls. The eco-physiological implication of tannins with respect to the host-parasite relationship is also discussed.