Changes in Cytokinin Concentration in Gall Tissues Induced by Dryocosmus kuriphilus and the Spatiotemporal Distribution Characteristics of Cytokinin in the Body of Dryocosmus kuriphilus

This study aimed to characterize the sources and spatio-temporal distribution patterns of cytokinins in Dryocosmus kuriphilus and its induced galls, providing observational data on possible gall-inducing mechanisms. Specifically, the contents of six cytokinins (TZR, DZR, cis-Zeatin, trans-Zeatin, IP, and IPR) in the epidermal layer (IPR: 3.92 ± 0.15 ng/g), outer protective layer, inner protective layer, and nutritive layer of galls, as well as in D. kuriphilus at different developmental stages, were quantified by UPLC-MS/MS. The results showed that IPR (63.12 ± 2.55 ng/g) was relatively high in larvae. This observational finding is consistent with the hypothesis that cytokinins in D. kuriphilus may originate from the insect itself or from plant sources. Elevated cytokinin levels were found in plant galls compared to normal tissues.