Anatomical and Metabolome Features of Haloxylon aphyllum and Haloxylon persicum Elucidate the Resilience against Gall-Forming Insects.

Globally, gall-forming insects significantly contribute to the degradation of desert ecosystems. Recent studies have demonstrated that Haloxylon persicum suffers less damage from gall-formers compared to Haloxylon aphyllum . However, the mechanisms driving the long-term metabolic responses of these species to gall-forming biotic stress in their natural environment remain unclear. The current study comparatively analyzes the anatomical features and metabolomic changes in H. aphyllum and H. persicum damaged by gall-forming insects. This research aimed to uncover potential metabolic tolerance mechanisms through GC-MS analysis. The study findings indicate that gall-forming insects cause a reduction in nearly all the anatomical structures of Haloxylon shoots, with the effects being less severe in H. persicum than in H. aphyllum . Thus, the metabolic pathways responsible for the biosynthesis of biologically active substances that enhance resistance to gall inducers were different, specifically in H. aphyllum -the biosynthesis of fatty acids (+their derivatives) and γ-tocopherol (vitamin E) and H. persicum -the biosynthesis of fatty acids (+their derivatives), dialkyl ethers, carbohydrates (+their derivatives), aromatic acid derivatives, phytosterols, γ-tocopherol (vitamin E), phenols, and terpenoids. The results suggest that the modulation of metabolic pathways under biotic stress plays a crucial role in the enhanced survival and growth of H. persicum .