Spatial epidemiology of a vector-borne plant virus: interactions between landscape, hosts, vectors and an emerging disease of potatoes

Lead Research Organisation: University of St Andrews
Department Name: Biology

Abstract

Potato is the world's third most important staple food and Potato virus Y (PVY) is the most important virus disease in most potato production systems. In the last few decades recombinant strains of PVY have emerged in Europe and more recently in N America that are spreading and are associated with serious tuber damage. Factors responsible for the emergence and spread of these new strains are unknown but PVY is an ideal system to study the ecology and evolution of this infectious disease because all of the components, the virus, the host and the vector, are relatively well characterised. In this project we will investigate genetic, physiological, ecological, evolutionary and environmental factors as a dynamic network of variables affecting disease spread. We will identify the most important variables and how they influence PVY spread within and between potato plants.

This project addresses the significant challenges to agricultural production posed by changes in climate and the limitations on the use of agrochemicals in Europe. Potato production requires high levels of inputs to ensure high yields of crop for consumption as well as high quality of seed tuber planting material. PVY and many other virus diseases are transmitted by aphids and the changing weather patterns with warmer, drier summers and warmer, wetter winters is resulting in increasing aphid populations with the earlier arrival of aphids into the crops. The information gained will be used to develop quantitative and predictive models of disease risk in different agro-ecosystems and devise strategies for targeted intervention with agrochemicals for improved disease control. PVY infects a wide range of other crops including vegetables, tobacco and fruit and the underlying concepts, models and disease management tools developed in the project will have broad applicability in other agricultural systems.

Technical Summary

The UK component will examine mature plant resistance (MPR) to PVY and provide data on aphid phenology. Results will be combined with data collected by the US collaborators on spatial epidemiology and interactions between landscape, hosts and vectors to describe the ecology of this important virus disease and emergence of new strains. MPR has been little studied since the 1980s and while there is evidence that it prevents virus infection in potato tubers in the late growing season and reduces the plants susceptibility, sometimes completely, the mechanism behind MPR remains unknown. Since MPR varies with cultivar and environmental conditions its onset is currently impossible to predict. The main, but poorly tested, hypothesis that we will investigate is that changes in host physiology affect translocation of virus in the phloem from leaves to tubers. We will investigate phloem connections between leaves and tubers, at different stages of development, and the effect of flower and fruit formation on tuber sink strength. The sink/source transition will be manipulated and variation between genotypes will be examined. We will use GFP-tagged virus infectious clones to test whether phloem entry and translocation of PVY varies at different stages or with cultivar. Gene expression in inoculated leaves will be analysed by comparison of microarray data from different virus strains and potato cultivars. Numbers of infected tubers and sprouts of progeny tubers will be tested to assess the potential for transmission to next generation. The goal is to identify physiological and gene expression markers for onset of MPR that can be used in field assays.
Information obtained about virus infection and movement through the plant will help to devise a risk index for different cultivars at key growth stages. Further work in collaboration with other partners will involve validation and optimisation of the markers and their use in predictive models for virus risk.

Planned Impact

not applicable

Publications

10 25 50
 
Description Potato virus Y (PVY) is one of the most serious pathogens of cultivated solanaceous crops worldwide, reducing both yield and quality. New recombinant strains of PVY have emerged and are increasingly found infecting potato in most potato production systems. Natural host resistance, conferred by resistance (R) genes, is considered one of the best strategies to control virus diseases. However, identification and introgression of such R genes into commercial cultivars is not facile and so other strategies are required to achieve disease control. Mature plant resistance (MPR) is a poorly understood phenomenon where older plants become more resistant to infection by plant pathogens. A thorough understanding of MPR would potentially be a valuable component of PVY management in seed potato production. The role of the UK team in this project is to investigate MPR, to understand the mechanism and factors affecting onset. This information will be integrated into other project findings to understand PVY spatial ecology and assist disease management.
The objectives of this project were:
1. Determine the potato growth stage when MPR against PVY occurred in different host genotypes (year 1 and 2).
2. Examining the change in source/sink relationship within plant with respect to solute transport during MPR (year 1 and 2).
3. Studying within-plant virus movement to determine if PVY is prevented from entering the phloem in inoculated leaves during MPR (year 2 to 4).
4. Studying global gene expression change (60K potato array) and other changes in physiology before and after MPR onset to identify key genes involved in MPR (year 3 to 5).
5. Identification and development of diagnostic markers for MPR (year 4 and 5).

Report of Outcomes To Date

1. Experiments on mature plant resistance (MPR) in potatoes showed no systemic movement of PVYO into foliar tissue at the flowering stage in all cultivars tested (Desiree, Atlantic, Maris Piper and Shepody). In addition, resistance was observed against PVYN and recombinant strains (PVYNTN, PVYNWI) in foliar tissues of all cultivars except Shepody. Last year we tested PVY infection in tubers from plants inoculated at flowering stage and found that the recombinant strains can infect tubers of all cultivars. All these experiments were carried out in the glasshouse as per the original research plan. This year we have collaborated with SASA (Scottish government-funded science and advice organization for Scottish Agrigulture) where field experiments have been conducted which corroborate the glasshouse trials; PVYNTN overcomes MPR late in the season while plants become resistant to PVYO around flowering time. This strengthens our conclusion that MPR does not protect tuber infection by recombinant strains.

2. Solute transport studies showed no change in sink-source relationship when potato plants become resistant to PVYO. Furthermore, these studies showed that the majority of solutes move from source leaves to tubers at flowering, thus explaining the lack of movement of PVYNTN and PVYN-Wi to non-inoculated leaves. It also provided evidence that solute transport and unloading in tubers is functional at the flowering stage and acts as a channel for delivery of recombinant PVY strains to tubers. Experiments to study PVYN-GFP movement in inoculated leaves showed that PVYN had unhindered entry into phloem tissues.

3. We previously identified flowering as a simple marker for the onset of MPR, and using FTIR analysis, identified two further biochemical markers; increased oxalate levels in source leaves from tuber-development onwards and reduced nitrate the flowering stage). However, since we have now shown that MPR is not effective against recombinant PVY strains and these recombinants are currently the most prevalent virus strains, the use of these markers for breeding is probably of limited utility. The fact that flowering acts as a marker for the onset of MPR is useful for farmers to know, but only in areas where PVYO is the prevalent strain.

4. Since MPR against recombinant PVY strains was not found in any potato cultivar we decided to determine the molecular mechanism underlying MPR against PVYO and how recombinant strains have managed to overcome MPR. We have now carried out a large-scale microarray experiment to analyse the whole-genome transcript profile of plants after PVY challenge; studying PVYO, PVYNTN and a water control in cultivar Atlantic at two developmental stages (before and after the onset of MPR), sampled at 1, 4 and 8 days after PVY infection. Inoculated leaf samples were transcript profiled using the 60K array of the potato genome. This massive dataset has not been fully mined, but has already provided three key results:

a) Nine genes have been identified which are uniquely expressed and 25 genes have been identified which are upregulated at flowering in response to PVYO. These genes are associated with several diverse metabolic pathways. We therefore have 35 candidate genes responsible for MPR to PVYO.

b) In healthy plants, as development progresses, more genes become differentially expressed. PVYNTN infection leads to a suppression of this effect, reducing the number of differentially expressed genes and maintaining a more 'youthful' gene expression profile. It seems that whatever the plant switches on during development to detect and suppress PVYo may be suppressed by PVYNTN and this functionally prevents MPR against PVYNTN.

c) Pathways associated with lipid remodeling are implicated in MPR. We have taken this information forward in a lipid metabolomics study (see below).

5. Preliminary metabolomics analysis has revealed changes in structural lipids during MPR. One candidate molecule has been identified for future work. Application of the molecule renders plants more resistant to PVY infection and a key gene in this pathway was further studied by VIGS in N. benthamiana. In preliminary studies, silencing of this lipid gene in N. benthamiana rendered plants more resistant to PVY, with an effect on both PVYO and PVYNTN. We are now at the end of year 4 of the project and the UK team has successfully achieved all areas of their objective. We found that MPR varies with virus strain, development stage and cultivar. MPR against PVYO begins to be induced at stolon initiation and is fully effective by the flowering stage. PVYNTN and PVYN-Wi did not readily spread to non-inoculated leaves of plants at flowering, but most progeny tubers were infected with virus showing that MPR is not fully effective against recombinant strains. Although recombinant strain-infected plants may be less important sources of viruses for vector aphids later in the growing season, there is a major risk of tuber infection.

In the final year of the project, the UK group will continue to study the results of the microarray data and write up publications for the data collected in previous years. We will also attempt to find further funding to pursue the candidate resistance genes we have identified.
Exploitation Route The project is still on-going but we have had preliminary discussions with groups in the UK (such as SASA and AHDB Potatoes) interested in aphid forecasting in seed potato crops to discuss how we might take the information and outputs forward to apply to UK crops.
Sectors Agriculture, Food and Drink,Education,Environment

URL http://www.hutton.ac.uk/potato-virus-y
 
Description Findings are currently being written up and we expect to publish three manuscripts. The findings to date have led to the identification of 35 candidate gene involved in mature plant resistance to PVY. They have generated a hypothesis that aspects of lipid metabolism are important in PVY replication and have led to us seeking relevant collaboration with Dr Terry Smith, University of St Andrews. The project partners have developed a model for aphid spread that we will seek further funding to adopt in UK potato systems.
First Year Of Impact 2017
Sector Agriculture, Food and Drink
Impact Types Economic,Policy & public services

 
Description Global challenge research fund
Amount £89,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 09/2016 
End 02/2018
 
Description Global challenges Research fund
Amount £388,276 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 06/2017 
End 06/2019
 
Description Scottish Government RESAS HEI funding from 2016-21 SRP
Amount £100,000 (GBP)
Organisation Government of Scotland 
Department Scottish Government Rural and Environment Science and Analytical Services Division (RESAS)
Sector Public
Country United Kingdom
Start 04/2016 
End 03/2017
 
Title Fourier transform infrared spectroscopy (FTIR) 
Description Fourier Transform-Infrared Spectroscopy (FTIR) is an analytical technique used to identify organic and inorganic materials. This technique measures the absorption of infrared radiation by the sample material versus wavelength. The spectrum collected represents the molecular absorption and transmission, creating a molecular fingerprint of the sample. Like a fingerprint no two unique molecular structures produce the same infrared spectrum. This makes infrared spectroscopy useful for several types of analysis. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact FTIR was used to identify key molecular changes during growth development of potato plants and associated with MPR. We identified two markers that correlate to oxalate levels increase in source leaves from tuber-development stage onwards and reduction of nitrate level at the flowering stage. These markers would be useful to predict MPR to help understand when plants had some protection against PVY-O. 
 
Title Live cell confocal microscopy 
Description An increasing number of investigations are using live-cell imaging techniques to provide critical insight into the fundamental nature of cellular and tissue function, especially due to the rapid advances that are currently being witnessed in fluorescent protein and synthetic fluorophore technology. It is used by scientists to obtain a better understanding of biological functions. 
Type Of Material Physiological assessment or outcome measure 
Provided To Others? No  
Impact Carboxyfluorescein diacetate (CFDA) was used as phloem-mobile fluorescent probe to study solute transport from source leaves to sink tissues using confocal microscopy. This method of study replaces the traditional technique of C-14 labelling of sugars to study solute transport, thus avoiding radiation hazards. 
 
Title Microarray 
Description A microarray is a laboratory tool used to detect the expression levels of large number of genes simultaneously or to genotype multiple regions of a genome. Microarray utilises microscope slides that are printed with thousands of tiny spots in defined positions, with each spot containing a known DNA sequence or gene. Often, these slides are referred to as gene chips. The DNA molecules attached to each slide act as probes to detect gene expression, which is also known as the transcriptome or the set of messenger RNA (mRNA) transcripts expressed by a group of genes. 
Type Of Material Technology assay or reagent 
Year Produced 2017 
Provided To Others? No  
Impact We determined the whole genome transcript profile of Atlantic leaves which were inoculated with PVYNTN, PVYO and sterile water (mock treatment) at 6-leaf (pre-MPR stage) and flowering stages (MPR stage). Inoculated leaf tissue samples were harvested at 1, 4 and 8 dpi and subjected to whole genome transcript profiling using the 60K array of the potato genome. Sequences of the expressed transcripts were received recently and we are starting to analyse the data. We hope to discover MPR-associated genes which are differentially expressed between PVYNTN and PVYO inoculated leaves as well as between the 6-leaf and flowering growth stages. Preliminary analysis after 2-way ANOVA and pairwise comparison (mock vs. each PVY strain) at each time point showed that a large number of genes were differentially expressed in PVYO and PVYNTN treated leaves at the 6 leaf stage compared to the same treatment at the flowering stage. 
 
Description SASA Collaboration 
Organisation Science and Advice for Scottish Agriculture
Country United Kingdom 
Sector Public 
PI Contribution Comparison of glasshouse generated data in the project with field data collected by SASA. Discussion held to investigate potential sources of future funding for the aphid phenology model as applied to UK seed potato crops
Collaborator Contribution Provided field data for discussion
Impact none to date
Start Year 2016
 
Description Spatial Epidemiology of a Vector-Borne Potato Virus: Interactions between Landscape, Hosts and Vectors 
Organisation Cornell University
Country United States 
Sector Academic/University 
PI Contribution see web pages http://www.hutton.ac.uk/research/projects/spatial-epidemiology-vector-borne-potato-virus-interactions-between-landscape
Collaborator Contribution see web pages
Impact ongoing
Start Year 2013
 
Description Spatial Epidemiology of a Vector-Borne Potato Virus: Interactions between Landscape, Hosts and Vectors 
Organisation Rothamsted Research
Country United Kingdom 
Sector Academic/University 
PI Contribution see web pages http://www.hutton.ac.uk/research/projects/spatial-epidemiology-vector-borne-potato-virus-interactions-between-landscape
Collaborator Contribution see web pages
Impact ongoing
Start Year 2013
 
Description Spatial Epidemiology of a Vector-Borne Potato Virus: Interactions between Landscape, Hosts and Vectors 
Organisation University of Wisconsin-Madison
Country United States 
Sector Academic/University 
PI Contribution see web pages http://www.hutton.ac.uk/research/projects/spatial-epidemiology-vector-borne-potato-virus-interactions-between-landscape
Collaborator Contribution see web pages
Impact ongoing
Start Year 2013
 
Description Spatial Epidemiology of a Vector-Borne Potato Virus: Interactions between Landscape, Hosts and Vectors 
Organisation York St John University
Country United Kingdom 
Sector Academic/University 
PI Contribution see web pages http://www.hutton.ac.uk/research/projects/spatial-epidemiology-vector-borne-potato-virus-interactions-between-landscape
Collaborator Contribution see web pages
Impact ongoing
Start Year 2013
 
Description Terry Smith St Andrews 
Organisation University of St Andrews
Country United Kingdom 
Sector Academic/University 
PI Contribution We have provided leaf material for lipid analysis; we also used additional funding from Scottish Government RESAS HEI funding stream to pay for sample analysis
Collaborator Contribution Terry Smith is an expert in lipidomics and has agree to help analyse potato leaves (with and without PVY infection) and provide lipid profiles to assist in identifying candidate genes involved in MPR.
Impact Lipid profiles of infected and non-infected potato cv Atlantic leaves have been obtained that suggest that there are a number of specific changes associated with virus infection and this work is ongoing.
Start Year 2016
 
Description A presentation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Kumar, P., Cowan. G.H., Roberts, A.G., Tobin, A.K. and Torrance, L. Recombinant strains of potato virus Y overcome mature plant resistance in Solanum tuberosum. 20th EAPR Triennial Conference - PVYwide, Versailles, France, July 2017.
Year(s) Of Engagement Activity 2017
 
Description A talk to Indian delegation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Kumar, P., Cowan. G.H., Roberts, A.G., Tobin, A.K. and Torrance, L Mature plant resistance in potato, its implications in PVY dynamics and management". India-Scotland research symposium 2017 at The James Hutton Institute, Dundee, Scotland UK.
Year(s) Of Engagement Activity 2017
 
Description Conference: Advances in plant virology 2015, Birmingham 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Pankaj Kumar (Research Fellow, University of St Andrews) presented a talk titled ;Studies on Mature Plant Resistance Against Potato Virus Y in Solanum tuberosum L.; at Advances in Plant Virology 2015 conference. The conference was organised by Association of Applied Biologists (AAB). This annual conference attracts researchers from all over the world as well as policy makers from other organisations such as Potato Council and SASA, to present and discuss new finding in plant virology. The talk generated lot of interest among audience since MPR is poorly understood phenomenon.
Year(s) Of Engagement Activity 2015
 
Description International Advances in Plant Virology meeting held at University of Greenwich, UK on 7-9 September 2016 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Prof. Lesley Torrance attended International Advances in Plant Virology meeting (in conjunction with Cost Action FA1407), held at University of Greenwich, UK on 7-9 September 2016. During the meeting Prof. Lesley Torrance informally presented and discussed the recent progress and findings of the project with other delegates.
Year(s) Of Engagement Activity 2016
 
Description Meeting at SASA, Edinburgh 2015 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A formal meeting was organized at Science and Advice for Scottish Agriculture (SASA) Edinburgh on 15 January 2015. Researchers from four organizations (Rothamsted Research, SASA, Uni. St Andrews and JHI) were present during the meeting which aimed to exchange information/knowledge regarding PVY incidence in United Kingdom. Pankaj Kumar (Research Fellow, Uni St Andrews) presented findings of MPR onset studies in potatoes. Our work showed that MPR against PVY coincides with flowering stage in potatoes.
Christophe Lacomme (SASA) is interested in MPR as control measure for PVY incidence in Scotland. Also, Christophe Lacomme presented PVY dynamics in Scotland. Jon Pickup (SASA) exchanged 10 yrs data on PVY incidence in Scotland and showed that recombinant PVY strains are increasingly dominating PVY incidence in Scotland. We exchanged information if our results from controlled environment could extrapolated to field conditions.
Year(s) Of Engagement Activity 2015
 
Description Oral presentation at "Taming Plant Viruses - Fundamental Biology to Bionanotechnology", Pitlochry, UK ( 7-10 November 2016) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Dr. Alison Roberts presented a talk titled "The effect of mature plant resistance (MPR) on PVY infection" at the "Taming Plant Viruses - Fundamental Biology to Bionanotechnology" international conference, organised by the Biochemical Society in Pitlochry, Scotland, UK, from 7th - 10th November 2016.
Year(s) Of Engagement Activity 2016
URL https://www.biochemistry.org/Events/tabid/379/View/Programme/Filter/64/InfoID/26715/MeetingNo/SA188/...
 
Description Oral presentation during 8th annual meeting of PVYwide organization (European Association of Potato Research, EAPR) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Pankaj Kumar (Research Fellow, University of St Andrews) presented a talk titled ;Recombinant strains of Potato virus Y overcome mature plant
resistance in Solanum tuberosum L.; at the 16th Triennial Meeting of the Virology Section of the European Association of Potato Research (EAPR) which was combined with the 8th annual meeting of PVYwide organization,. The conference was organised by AEuropean Association of Potato Research (EAPR). This annual conference attracts researchers from all over the world, policy makers from other organisations such as Potato Council and SASA and personnel from private sector, to present and discuss new finding in potato viruses. The audience was first time informed that mature plant resistance against recombinant PVY strains does not exit and probably is the reason for increase in PVY incidence worldwide. The talk generated lot of interest among audience since MPR is poorly understood phenomenon.
Year(s) Of Engagement Activity 2016
 
Description Poster presentation in 13th International Plant Virus Epidemiology Symposium at the University of Avignon, France (6 June to 10 June 2016) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Prof. Lesley Torrance presented a poster titled "RECOMBINANT STRAINS OF POTATO VIRUS Y OVERCOME MATURE PLANT RESISTANCE IN SOLANUM TUBEROSUML." at 13th International Plant Virus Epidemiology Symposium organised by the University of Avignon, France (6 June to 10 June 2016).
Year(s) Of Engagement Activity 2016
URL https://colloque.inra.fr/ipve2016
 
Description Potato Technology workshop; Nairobi Kenya (11.11.2016) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A Potato Technology Workshop part funded by a BBSRC impact accelerator award to the University of St Andrews (with James Hutton attendees part funded by SG) was held in Nairobi, Kenya 11.11.2016. There were 50 attendees from all sectors of the Kenyan potato industry as well as representatives from SASA, JHI and JHL and a potato seed exporter. Discussion focussed on new technologies and varieties with traits that would benefit the Kenyan potato industry helping to secure food security and economic growth. Outcomes were to connect Kenyan potato seed importers with Scottish exporters, connect Kenyan and Scottish plant health officials to fast track importation and NPT of Scottish varieties and to establish a database of attendees to facilitate further interactions.
Year(s) Of Engagement Activity 2016
 
Description Presentation to Potatoes in Practice industry meeting, Balruddery Farm, Perth and Kinross 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Engagement with growers, professional practitioners and potato seed businesses to discuss findings of the project.
Year(s) Of Engagement Activity 2017
URL http://hutton.ac.uk/events/potatoes-practice-2017
 
Description Project meeting 24-25 April 2014, Cornell University 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Personnels involved in the project from UK and US partner labs met to discuss research activity and future plans. Outcomes from 8 months research work since the begining of project were shared. Lesley Torrance (University of St Andrews/JHI) briefed the audience that onset of mature plants resistance (MPR) was studied in four potato cultivars using four PVY strains (PVY-O, PVY-NWi, PVY-N and PVY-NTN). For this, PVY infection in non-inoculated upper leaves was checked at four growth stages of potato plants. Early results showed that PVY-O infection in upper non-inoculated leaves was stopped at tuber bulking stage. However, PVY-NWi infection in upper non-inoculated leaves was stopped at last growth stage i.e.. flowering stage. Solute transport from source leaves to sink tissues was studied to find out any change in phloem transport after MPR onset. These studies were completed until tuber bulking stage and results did not show any change in phloem connection or unloading. Solute transport at flowering stage was not finished.
Year(s) Of Engagement Activity 2014
 
Description Project meeting, Dundee 17-18 September 2015 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Second year project meeting was held at Dundee on 17-18 September 2015. Meeting was attended by personnel from UK and USA collaborator labs. The meeting aimed to discussed research accomplishment and future plans. Richard Harrington of Rothamsted research has now retired and James Bell has taken over on the project and will continue to provide advice and information on aphid phenology data in UK.

Pankaj Kumar (Research fellow) presented the experimental data for the UK team. MPR onset experiments showed no systemic movement of PVY-O into foliar tissue at the flowering stage in all cultivars tested (Desiree, Atlantic, Maris Piper and Shepody). In addition, resistance was observed against PVY-N and recombinant strains (PVY-NTN, PVY-NWi) in foliar tissues of all cultivars except Shepody. However, examination of PVY infection in tubers from plants inoculated at flowering stage showed that the recombinant strains can infect tubers of all cultivars even at the flowering stage. Thus, MPR does not protect tuber infection by recombinant PVY strains. This is the first report MPR study against recombinant PVY strains.
CFDA translocation experiments to study solute transport have backed up and explained the above result. There was no CFDA transport from the inoculated leaves to systemic leaves at the time the plant is flowering, but there was still a (reduced) level of CFDA transport to tubers; sufficient to allow virus infection.
GFP-tagged PVY-N was studied in the inoculated leaves at four developmental stages and was found to enter the phloem at all stages, suggesting that phloem entry is not a limiting step to virus infection, even at flowering when MPR protects foliar tissues.
Furthermore, identification of a marker for the MPR stage was done using FTIR. Two markers were identified that correlate to oxalate levels increase in source leaves from tuber-development stage onwards, and reduction in nitrate level at the flowering stage. These markers would be useful to predict MPR to help understand when plants had some protection against PVY-O. However, since we have now shown that MPR is not effective against recombinant PVY strains and these recombinants are the most prevalent infection pressure today, the use of these markers is probably of limited utility.
Year(s) Of Engagement Activity 2015
 
Description Visit to Xisen Potato Company Ltd 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Visit to Xisen potato company where discussions were held with Dr Xie (R&D director), Dr Hu (Managing director) and Mr Liang (owner). L Torrance gave a talk to company technical staff and visited sites in Shendong province, Inner Mongolia and Beijing.
Year(s) Of Engagement Activity 2017
 
Description Workshop on Potato's technology Nairobi Kenya 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The workshop was held to raise awareness of new innovations in potato technologies (results of research, traits of different potato cvs, pest and disease problems) among Kenyan farmers, plant health officials, seed producers and NGO.
Year(s) Of Engagement Activity 2018