Spider mite egg extract modifies Arabidopsis response to future infestations

Isabel Diaz,Manuel Martinez,Dairon Ojeda-Martinez,M. Estrella Santamaria

doi:10.1038/s41598-021-97245-z

Abstract

Transcriptional plant responses are an important aspect of herbivore oviposition studies. However, most of our current knowledge is derived from studies using Lepidopteran models, where egg-laying and feeding are separate events in time. Little is known regarding plant response to pests where females feed and oviposit simultaneously. The present study characterized oviposition-induced transcriptomic response of Arabidopsis to Tetranychus urticae egg extracts. Transcriptional evidence indicates that early events in plant response to the egg extract involve responses typical to biotic stresses, which include the alteration in the levels of Ca2+ and ROS, the modification of pathways regulated by the phytohormones jasmonic acid and ethylene, and the production of volatiles and glucosinolates as defence mechanisms. These molecular changes affect female fertility, which was significantly reduced when mites fed on plants pre-exposed to the egg extract. However, longer periods of plant exposure to egg extract cause changes in the transcriptional response of the plant reveal a trend to a decrease in the activation of the defensive response. This alteration correlated with a shift at 72 h of exposition in the effect of the mite feeding. At that point, plants become more susceptible and suffer higher damage when challenged by the mite.

Highlights

Research on herbivore oviposition has recently become a topic of great interest, where numerous results are emerging
T. urticae is reared in laboratory conditions, its genome has been sequenced and has the ability to feed on model species such as Arabidopsis thaliana, all of which makes it a good mite model for herbivory studies[17,18]
The accumulation of H2O2 at the leaf deposition site of the egg extract was detected by the brown colour of oxidized 3,3-diaminobenzidine tetrachloride hydrate (DAB) used as substrate in the histochemical assays

Summary

Introduction

Research on herbivore oviposition has recently become a topic of great interest, where numerous results are emerging. Either eggs induce plant defences that directly kill them or act as warning signals to trigger plant responses leading to impaired herbivore performance or to attract natural enemies of the pest. All these responses are determined by specific molecules present in the egg, named egg-associated molecular patterns (EAMP), which have been scarcely studied. Stahl et al.[28] showed that purified phosphatidylcholines from P. brassicae eggs trigger similar defence responses in Arabidopsis than egg extracts These compounds diffuse from inside the eggs to the leaves at concentrations that are sufficient to induce plant responses. Phenotyping assays revealed a significant reduction in female fertility upon feeding on egg extract pre-treated plants, while feeding increased on plants pre-treated for 72 h

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Conclusion