The role of calcium signalling in plant-aphid interactions

• Main Author: Vincent, Thomas
• Published: University of East Anglia 2016
• Subjects: 632
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705151

Myzus persicae is one of the most successful insects on the planet. It is the world’s most pesticide-resistant insect, feeds on hundreds of plant species and acts as a vector for over 100 viruses. Upon perception of M. persicae feeding, plants activate pattern-triggered immunity (PTI), a pivotal part of which is believed to be calcium signalling. The aim of this thesis is to uncover the role that calcium signalling might be playing in the interaction between M. persicae and one of its hosts: the model plant Arabidopsis. Using a fluorescent calcium sensor (GCAMP3), in vivo imaging of calcium dynamics was performed on leaves infested with M. persicae. There is a rapid and highly localised calcium burst around the feeding site in the epidermal and mesophyll cells, making it as one of the first plant responses to aphid attack. This calcium burst is triggered after perception of the aphid by the defence co-receptor BRASSINOSTEROID INSENSITIVE-ASSOCIATED KINASE 1 (BAK1), establishing it as part of PTI. Calcium is released from the extracellular space into the cell by GLUTAMATE-LIKE RECEPTORS 3.3 and 3.6 (GLR3.3 and GLR3.6), in combination with the release of intracellular calcium from the vacuole by TWO-PORE CHANNEL 1 (TPC1). Loss of BAK1, GLR3.3/GLR3.6 or TPC1 significantly attenuates the aphid-induced calcium burst and has an effect on the induction of anti-aphid defence responses. Downstream of the burst, CBL-INTERACTING PROTEIN KINASES 3, 9, 23 and 26 are activated by calcium and together mediate plant resistance to aphid attack. Furthermore, the M. persicae effector Mp10 partially suppresses the feeding site calcium burst, suggesting that the aphid is manipulating this pathway as part of its successful colonisation of the plant. Together, the data presented in this thesis provide evidence for the significant involvement of calcium signalling in the plant response to aphid attack.