Plant galls induced by insects: Coordinated developmental reprogramming and defence manipulation.

Galls, especially those induced by insects, represent one of the most dramatic examples of plant developmental reprogramming, combining complex de novo organogenesis with compromised defence. Insect-induced galls are not just a fascinating natural phenomenon but a unique system for future discoveries in developmental biology, plant defence, and evolutionary ecology. Gall development is under the control of their insect manipulators and in sync with insect growth to provide tailored nutritive and protective environments. But this alone does not explain the huge diversity in their morphology which evolved within complex ecological niches. In this review, we summarise recent findings in this underexplored field and examine the defining features of insect-induced galls compared to non-gall herbivores, microbial gall inducers, and symbionts. By exploring commonalities and differences in developmental reprogramming, defence and nutrition, we highlight the uniqueness of insect-induced galls and their potential for discoveries in plant biology.