Early Molecular Responses of Tomato to Combined Moderate Water Stress and Tomato Red Spider Mite Tetranychus evansi Attack.

Vicent Arbona,Félix Ortego,Aurelio Gómez-Cadenas,Miguel González-Guzmán,Miguel G Ximénez-Embún,Marcos Martin-Sánchez,Alberto Echavarri-Muñoz

doi:10.3390/plants9091131

Abstract

Interaction between plants and their environment is changing as a consequence of the climate change and global warming, increasing the performance and dispersal of some pest species which become invasive species. Tetranychus evansi also known as the tomato red spider mite, is an invasive species which has been reported to increase its performance when feeding in the tomato cultivar Moneymaker (MM) under water deficit conditions. In order to clarify the underlying molecular events involved, we examined early plant molecular changes occurring on MM during T. evansi infestation alone or in combination with moderate drought stress. Hormonal profiling of MM plants showed an increase in abscisic acid (ABA) levels in drought-stressed plants while salicylic acid (SA) levels were higher in drought-stressed plants infested with T. evansi, indicating that SA is involved in the regulation of plant responses to this stress combination. Changes in the expression of ABA-dependent DREB2, NCED1, and RAB18 genes confirmed the presence of drought-dependent molecular responses in tomato plants and indicated that these responses could be modulated by the tomato red spider mite. Tomato metabolic profiling identified 42 differentially altered compounds produced by T. evansi attack, moderate drought stress, and/or their combination, reinforcing the idea of putative manipulation of tomato plant responses by tomato red spider mite. Altogether, these results indicate that the tomato red spider mite acts modulating plant responses to moderate drought stress by interfering with the ABA and SA hormonal responses, providing new insights into the early events occurring on plant biotic and abiotic stress interaction.

Highlights

Plant life is continually challenged by different environmental stresses which must be endured by making physiological and metabolic adjustment to continue their life cycle
One of the most established plant responses during a drought stress period is the reduction of plant stomatal conductance to avoid water loss, which leads to a decrease in the photosynthetic activity and the progressive arrest of plant growth when drought stress becomes severe [25]
No significant differences in gs values were observed between control and T. evansi infested plants at any time point, whereas a significant reduction of gs was found in plants under moderate drought stress alone or in combination (Figure 1B), indicating that tomato red spider mite infestation does not affect tomato leaf stomatal conductance at early infestation stages as reported for longer infestation times [32]

Summary

Introduction

Plant life is continually challenged by different environmental stresses which must be endured by making physiological and metabolic adjustment to continue their life cycle. The interaction between plants and several phytophagous pests are going. To face single or combined stresses, plants must synchronize the activation of a set of plant response genes to produce biochemical and metabolic changes, which will allow plant adaptation to the new and specific environmental conditions [4,5]. This genetic reprogramming is achieved through the coordinated action of several phytohormones which may act in different phases of the adaptation and response to the stress combination [5,6]

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