Abstract

Cross-tolerance is the phenomenon by which a plant resistance to stress results in resistance to another form of stress. Such intriguing links has made the author to suggest that foliar camel urine (CU) application depending on its amazing constituents may mimic elicitor actions and prime tissues to pathogens in normally susceptible host plants. This study was conducted to assess anatomical and biochemical pathogenesis alterations in tomato water T1, Fusarium oxysporum infected T2 plants and also to evaluate the defense-related responses resulting from CU application in either nonT3 and/or T4 infected seedlings at anatomical and molecular levels. Fast and consistent increment in detoxifying enzymes peroxidase, phenylalanine ammonia-lyase, polyphenol oxidase and soluble proteins were recorded in T4 roots. In contrast, tomato roots, T2, T4 showed retard response in catalase activity. T4 accumulate highly significant level (80%) of total free and bound phenolics within its root. Root of T4 SA concomitant with coumarins had significant increment in both free and conjugated phenolic part. Anatomical microscopy shows alterations in T2, T3 as compared to T1 tomato root vascular bundle diameter. Results showed earlier reduction explained as adaptation mechanism in resisting the imposed stress regardless of its type. In contrast, T4 seedlings showed great increase in vascular bundle diameter concomitant with xylem lignin deposition and on epidermis cell walls. Tomato shoot administered CU implicate phenylpropanoid pathway in prime root to F. oxysporum invasion by enhancing innate immunity mechanisms, fast accumulation of H₂O₂ concomitant with cell wall modifications as physical barrier.

Key words: Cross-resistance, signaling, defense mechanism, detoxification enzymes, free and glycoside-phenolics, phenylpropanoid pathway.