β-Cyanoalanine synthase protects mites against Arabidopsis defenses

Abstract

Glucosinolates are antiherbivory chemical defense compounds in Arabidopsis (Arabidopsis thaliana). Specialist herbivores that feed on brassicaceous plants have evolved various mechanisms aimed at preventing the formation of toxic isothiocyanates. By contrast, generalist herbivores typically detoxify isothiocyanates through glutathione conjugation upon exposure. Here, we examined the response of an extreme generalist herbivore, the two-spotted spider mite Tetranychus urticae (Koch), to indole glucosinolates. T. urticae is a composite generalist whose individual populations have a restricted host range but have an ability to rapidly adapt to initially unfavorable plant hosts. Through comparative transcriptomic analysis of mite populations that have differential susceptibilities to Arabidopsis defenses, we identified β-cyanoalanine synthase of T. urticae (TuCAS), which encodes an enzyme with dual cysteine and β-cyanoalanine synthase activities. We combined Arabidopsis genetics, chemical complementation and mite reverse genetics to show that TuCAS is required for mite adaptation to Arabidopsis through its β-cyanoalanine synthase activity. Consistent with the β-cyanoalanine synthase role in detoxification of hydrogen cyanide, we discovered that upon mite herbivory, Arabidopsis plants release hydrogen cyanide. We further demonstrated that indole glucosinolates are sufficient for cyanide formation. Overall, our study uncovered Arabidopsis defenses that rely on indole glucosinolate-dependent cyanide for protection against mite herbivory. In response, Arabidopsis-adapted mites utilize the β-cyanoalanine synthase activity of TuCAS to counter cyanide toxicity, highlighting the mite’s ability to activate resistant traits that enable this extreme polyphagous herbivore to exploit cyanogenic host plants.

Iberverin exhibits antineoplastic activities against human hepatocellular carcinoma via DNA damage-mediated cell cycle arrest and mitochondrial-related apoptosis

“…There is growing evidence from encouraging in vitro and in vivo animal models that ITCs have multiple biological activities including plant defense and benefits to human health (antioxidant, antimicrobial and anticarcinogenic properties) ( Jain et al, 2019 ; Chuang et al, 2020 ; Li et al, 2021 ; Lohning et al, 2021 ; Dixit et al, 2022 ). ITCs have been found to exert anticarcinogenic activity in diverse cancers, such as lung cancer, breast cancer, prostate cancer and bladder cancer ( Psurski et al, 2019 ; Zheng et al, 2019 ; Justin et al, 2020 ; Nguyen et al, 2020 ).…”

Cyanogenesis, a Plant Defence Strategy against Herbivores

“…Likewise, the delivering of dsRNA- TuCAS to mites allowed Arnaiz et al [ 20 , 22 ] to demonstrate the effect of CAS detoxification on mite performance, shown by a significant reduction in the fecundity of treated mites after feeding on Arabidopsis hnl mutant lines and its isogenic control plants. Similarly, combining Arabidopsis genetics, chemical complementation and mite reverse genetics, Dixit et al [ 60 ] showed that CAS was required for mite adaptation to Arabidopsis to counter cyanide toxicity. These examples highlight the pest’s ability to respond to toxic metabolites by activating resistant traits to use cyanogenic plants as hosts.…”

The role of host plant usage and the accumulation of toxic secondary chemical compounds across the life cycle of a passion vine specialist butterfly

“…A diverse group of herbivorous arthropod taxa has evolved mechanisms to detoxify cyanide (CN) in their food including spider mites (Dixit et al, 2022), white flies (Easson et al, 2021) and Lepidoptera larvae (Zagrobelny et al, 2018). Some insect clades have even evolved the ability to defend themselves against natural enemies by incorporating cyanogenic glucosides into their tissues via sequestration and biosynthesis (de Castro et al, 2019; Zagrobelny et al, 2007).…”