Plant Viruses Can Alter Aphid-Triggered Calcium Elevations in Infected Leaves.

Christiane Then,Martin Drucker,Fanny Bellegarde,Alexandre Martinière,Geoffrey Schivre,Tou Cheu Xiong,Jean-Luc Macia

doi:10.3390/cells10123534

Abstract

Alighting aphids probe a new host plant by intracellular test punctures for suitability. These induce immediate calcium signals that emanate from the punctured sites and might be the first step in plant recognition of aphid feeding and the subsequent elicitation of plant defence responses. Calcium is also involved in the transmission of non-persistent plant viruses that are acquired by aphids during test punctures. Therefore, we wanted to determine whether viral infection alters calcium signalling. For this, calcium signals triggered by aphids were imaged on transgenic Arabidopsis plants expressing the cytosolic FRET-based calcium reporter YC3.6-NES and infected with the non-persistent viruses cauliflower mosaic (CaMV) and turnip mosaic (TuMV), or the persistent virus, turnip yellows (TuYV). Aphids were placed on infected leaves and calcium elevations were recorded by time-lapse fluorescence microscopy. Calcium signal velocities were significantly slower in plants infected with CaMV or TuMV and signal areas were smaller in CaMV-infected plants. Transmission tests using CaMV-infected Arabidopsis mutants impaired in pathogen perception or in the generation of calcium signals revealed no differences in transmission efficiency. A transcriptomic meta-analysis indicated significant changes in expression of receptor-like kinases in the BAK1 pathway as well as of calcium channels in CaMV- and TuMV-infected plants. Taken together, infection with CaMV and TuMV, but not with TuYV, impacts aphid-induced calcium signalling. This suggests that viruses can modify plant responses to aphids from the very first vector/host contact.

Highlights

Introduction iationsPlants sense their environment and respond to abiotic and biotic cues and stresses by installing defences
The transgenic Arabidopsis thaliana line expressing the cytosolic calcium reporter YC3.6NES under control of the constitutive ubiquitin 10 promoter [21] was grown under controlled conditions at 20/17 ◦ C day/night and 60% relative humidity with an 8/16 h day/night
Comparison between Our Results and Those Obtained by Vincent et al Here we show that calcium signals could be monitored upon aphid punctures on detached leaves infected with viruses

Summary

Introduction

Plants sense their environment and respond to abiotic and biotic cues and stresses by installing defences. This includes responses against infestation by phloem feeders such as aphids. Plant defences against aphids seem to follow classical pathogen-associated molecular pattern-induced pathways (for example, [1,2]), analogous to responses against fungi and bacteria [3], but the genes and effectors involved remain largely unknown [4]. After having landed on a potential new host plant, they first insert their needle-like stylets into the tissue. By puncturing epidermis and mesophyll cells, aphids test the plant for suitability and locate the phloem

Methods

Results

Conclusion