[Seminar] Spider mites aid to unravel the interaction between carbon-based and metal-based plant defences

Plants for Life 2017 - Invited Speakers

Title: Spider mites aid to unravel the interaction between carbon-based and metal-based plant defences

Speaker: Sara Magalhães

Affiliation: cE3c: Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa

Host: Paula Duque

Abstract:

High metal concentrations are toxic to most plants. Still, some plant species or populations are able to accumulate metals in their aerial parts and thereby persist in contaminated soils. Such metal accumulation can serve as a defence against herbivores. However, plants also have ‘classical’ carbon-based defences and how these interact with metal-based defences is as yet largely unknown. To shed light on this issue, we used a system composed of two spider mites, Tetranychus urticae and T. evansi, co-occurring on tomato, a cadmium-accumulating plant. Whereas T. urticae upregulates plant defences, T. evansi down-regulates those defences. Hence, if metal-based and carbon-based defences interact, we expect different responses of these mite species on plants with cadmium.

To test this hypothesis, we exposed the two spider mite species to tomato plants with different cadmium concentrations. We found that, as expected, mites had reduced performance at high cadmium concentrations. However, they had increased performance at intermediated cadmium levels, as compared to clean plants. This pattern correlated inversely with sugar contents on the leaves. Importantly, the pattern was similar for the two mite species, suggesting that mite interaction with carbon-based defences do not interfere with their response to metal-based defences. In line with this, we found that patterns of up- and down-regulation remained unaffected by cadmium levels in plants.

We plan to integrate this knowledge to generate predictions concerning the evolutionary dynamics of spider mites on cadmium-accumulating plants. As a first step, we have observed that the evolution of T. urticae on tomato plants without cadmium does not result in a modification of its up-regulation patterns.