Dissecting the role of plant immunity in plant-aphid interactions

Aphids are economically important phloem-feeding insects that cause loss in plant productivity worldwide. This occurs through the removal of photoassimilates and the vectoring of hundreds of plant viruses. Plants possess a complex immune system in order to defend themselves from a range of pathogens including bacteria and fungi. I aimed to discover if this immune system was also involved in defence against aphids. I found that aphids have proteins that trigger plant immune responses. The aphid Myzus persicae contains several protein elicitors with varying molecular weights. These proteins are perceived by the plants Nicotiana benthamiana and Arabidopsis thaliana. In A. thaliana the perception of a 3 to 10 kDa elicitor fraction requires the leucine-rich repeat receptor-like kinase (LRR-RLK) BAK1, as a mutant in this gene was deficient in immune responses activated by this elicitor. Plant recognition of the elicitor is unlikely to depend on a single non-arginine-asparate (non-RD) RLK. In addition, aphids possess the means to modulate the plant immune response. I helped to identify three aphid effectors that modulate plant processes. I then investigated the role of one of these effectors, a M. persicae chemosensory protein (CSP) known as Mp10, in suppressing the immune responses triggered by the aphid elicitors. Mp10 is likely to disrupt the function of plant genes near the top of the immune signalling cascade in N. benthamiana in order to suppress elicitor-triggered immunity. Surprisingly, the homologs of this CSP in other aphids also show the same ability to suppress plant immune responses, suggesting an important role for Mp10 in plant-aphid interactions. This is the first report of a role for elicitor recognition by plants in aphid defence, the use of plant cell surface receptors to detect insects, and aphids’ attempts to suppress plant immunity.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2012

Author dc:creator

• Prince, David

Language dc:language

en