Hormone variation in Robinia pseudoacacia L. (Fabaceae) leaves during gall formation by Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae)
摘要
Gall-inducing insects modify plant metabolism to convert host tissue cells into new forms of galls. The black locust gall midge Obolodiplosis robiniae (Haldeman) forms marginal rolling gall on black locust leaves (Robinia pseudoacacia L.). We investigated the hormonal changes in host plants after infection and gall growth to senescence. A wide range of phytohormones was analysed for the first time in gall tissue. Hierarchical cluster analysis demonstrated that young gall (YGall) composition corresponds with non-galled leaflets control (NGLC) and non-galled leaflets of galled leaves (NGLG). A second cluster was formed by mature gall (MGall) and senescent gall (SGall). Through all stages of gall formation the level of hormones increased ABA, GA3, auxins (IAA and PAA), different types of brassinosteroids, 7-oxalactone (BL, EBL, and HBL), 6-oxo type (CS, ECS, TY, and CT), and 6-deoxo type (6dTY) as well as different types of cytokinins, such as free bases (