Role of aphid salivary gland proteins in plant infestation
Lead Research Organisation:
John Innes Centre
Department Name: UNLISTED
Abstract
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Technical Summary
Aphids, like whiteflies, leafhoppers and planthoppers, are hemipteran sap-feeding insects of plants. These insects induce extensive feeding damage, can build up to high population densities, and are the vector of important plant diseases worldwide, including Europe. Aphids have highly developed salivary glands consisting of several lobes that are predicted to produce proteins required for establishing successful interactions with host plants. A recent study showed that some aphid salivary gland proteins suppress plant defences thereby allowing the aphids to freely feed from the plants. Despite the importance of sap-feeding insects in agriculture, few researchers worldwide have focused on gaining a better understanding of the functions of the salivary gland proteins in insect feeding. The goal of this to identify and characterize salivary gland proteins of two aphid species, Myzus persicae (green peach aphid), and Acyrthosiphon pisum (pea aphid), and to elucidate how these proteins enhance aphid feeding and affect host range specificity. We will use a genomics/proteomics approach to identify secreted salivary proteins of M. persicae and A. pisum. Functional characterization will be done using several approaches: 1) Aphids will be micro-injected with siRNA to knock-down the expression of candidate genes. Aphids will then be introduced on (non)host plant species to assess aphid survival and fitness. 2) We will generate transgenic A. thaliana plants that express aphid genes under control constitutive promoter. Transgenic lines will be analyzed for phenotypic changes and assessed for effects of transgene over-expression on aphid survival and fitness. 3) We will use protein interaction assays to identify plant targets of aphid proteins. The project will be an important first step towards understanding how phloem-feeding aphids manipulate plant cell processes and will generate new insights into improvement of plant resistance to these insects.
Planned Impact
unavailable
Organisations
Publications
Bos J
(2011)
Effectors in Plant-Microbe Interactions
Bos J
(2010)
A Functional Genomics Approach Identifies Candidate Effectors from the Aphid Species Myzus persicae (Green Peach Aphid)
in PLoS Genetics
Mugford ST
(2016)
An Immuno-Suppressive Aphid Saliva Protein Is Delivered into the Cytosol of Plant Mesophyll Cells During Feeding.
in Molecular plant-microbe interactions : MPMI
| Description | Introduction Aphids, like whiteflies, leafhoppers and planthoppers, are hemipteran sap-feeding insects of plants. These insects induce extensive feeding damage, can build up to high population densities, and are the vector of important plant diseases worldwide, including Europe. Aphids have highly developed salivary glands consisting of several lobes that are predicted to produce proteins required for establishing successful interactions with host plants. A recent study showed that some aphid salivary gland proteins suppress plant defences thereby allowing the aphids to freely feed from the plants. Despite the importance of sap-feeding insects in agriculture, few researchers worldwide have focused on gaining a better understanding of the functions of the salivary gland proteins in insect feeding. The aim of this project was to identify and characterize aphid salivary gland proteins to elucidate how these proteins enhance aphid feeding. Herein, we specifically focused on the generalist aphid species Myzus persicae. Main results Identification of Myzus persicae candidate effectors using a functional genomics screen We set-up a functional genomics pipeline to identify candidate effectors (secreted salivary proteins that promote aphid infestation on plants by modulating host cell responses) from the aphid M. persicae. Using bioinformatics on publicly available ESTs from aphid salivary glands we identified 46 predicted secreted proteins (candidate effectors). With three of these candidates being polymorphic and two candidates not expressed, we cloned 48 candidate effectors from cDNA into a 35S-expression vector transient expression in Nicotiana benthamiana and stable transformation of Arabidopsis. We initiated functional characterization of the set of 48 candidates. Candidate effector Mp10 induces chlorosis specifically in Nicotiana benthamiana We over-expressed the 48 cloned candidates in N. benthamiana using agroinfiltration assays to determine whether the proteins induce any visible phenotype in plants. One protein, Mp10, induced chlorosis in these assays. Further functional assays with Mp10 showed that this phenotype was specific to N. benthamiana as no chlorosis was observed in N. tabacum or tomato. Using Virus-Induced-Gene-Silencing, we showed that the induction of chlorosis by Mp10 was dependent on the plant protein SGT1 and HSP90, which are involved in plant defense responses mediated by resistance proteins. Candidate effector Mp10 suppresses the flg22 but not the chitin induced oxidative burst Suppression of PTI induced by PAMPs like flg22 and chitin is a common feature of plant pathogen effectors. To determine whether aphid candidate effectors can suppress PTI, we assessed whether any of our 48 candidates suppressed the oxidative burst response induced by the bacterial PAMP flg22. Out of all candidates, Mp10 was found to suppress the flg22-induced oxidative burst. Follow-up assays with the fungal PAMP chitin showed that Mp10 does not suppress the oxidative burst induced by this PAMP. Thus, Mp10 specifically suppresses the oxidative burst induced by the PAMP flg22. Candidate effectors Mp10, Mp42, and MpC002 affect aphid fecundity on N. benthamiana In order to assay the 44 candidate effectors from M. persicae, we developed a method that allows the medium-throughput screening for effects on aphid performance. Using this novel assay, we identified three candidate effectors that affect aphid fecundity. More specifically, Mp10 and Mp42 reduced aphid fecundity when overexpressed in plants and MpC002 increases aphid fecundity. These results support the hypothesis that Mp10 may induce yet unknown plant defence responses. |
| Exploitation Route | The results were shared with agrochemical and seed breeding companies leading to a BBSRC Industry Partnership Award (BB/L002108/1), a full funded project by industry, a BBSRC-LINK award (BB/N009169/1) and an iCASE studentship. |
| Sectors | Agriculture Food and Drink Chemicals Education Environment |
| Description | Hosted colleague from industry for teaching lab technique |
| Geographic Reach | National |
| Policy Influence Type | Influenced training of practitioners or researchers |
| Impact | Taught industrial partner specific lab technique. |
| Description | Progress meeting with industrial collaborator |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | Regular progress meetings with colleagues SESVanderHave to discuss project made with BBSRC-LINK and iCASE projects. |
| Year(s) Of Engagement Activity | 2019 |