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Report on the 2nd Joint Conference of The International Working Groups on Legume and Vegetable Viruses
Fort Lauderdale, Florida, 10-14th April 2005
This stimulating international conference was held on April 10-14th in the Riverside Hotel in Fort Lauderdale, Florida. It was the Second Joint Conference of the International Working Groups on Legume and Vegetable Viruses. It marked the last stage in the merger of the two groups to form the new International Working Group on Legume and Vegetable Viruses (IWGLVV), this merger being ratified by a vote at the conference. The conference was attended by 45 participants from 15 different countries from five continents. There were 17 talks on vegetable viruses, nine on legume viruses and one that addressed both. There were also 17 posters on legume or vegetable virus topics.
Presentations ranged from basic and molecular to ecological and applied, and there was a major emphasis on new and emerging plant viruses.
The programme commenced on Sunday 10th April with registration and a welcoming reception in the poolside area of the hotel, and on Monday 4th April with introductory comments by the principal symposium organiser, Gail Wisler, Chairperson of the Plant Pathology Department, University of Florida, Gainsville. Scientific papers were presented on Monday 4th April, Tuesday 5th April and Thursday 7th April, with sessions on virus detection, molecular genomics, new and emerging viruses, and virus resistance. Wednesday 6th April was devoted to a full day excursion.
There were three general presentations. Piero Caciagli (Italy) provided a short history of the International Working Group on Vegetable Viruses, and Roger Jones (Australia) did the same for the International Working Group on Legume Viruses. The third general talk by Andrew Schuerger (USA) reflected the proximity to the Cape Canaveral Space Centre! He spoke on “Cross contamination of microbes between earth and Mars – is there a risk”.
Highlights of the conference included the following contributions: 1) Two papers from Joe Vettens’ group at Braunschweig (Germany) on emerging legume viruses in Africa. Using monoclonal antibodies and sequencing to differentiate them from Faba bean necrotic yellows virus, two new Nanovirus species tentatively named Faba bean necrotic stunt virus and Faba bean yellows virus were reported. Both new viruses occur in Ethiopia and the first of them also in Morocco. A new Polerovirus, Chickpea stunt virus, was found infecting cool season legume crops. It was transmitted by Aphis craccivora, distantly related serologically to Beet western yellows virus (BWYV) and had 70-78% sequence homology with BWYV and Groundnut assistor virus. It existed in two clades, clade I found so far in Ethiopia and Sudan, and clade II in Syria, Egypt and Morocco. These findings are undubtedly just the ‘tip of the iceberg’ as regards presence of additional nanoviruses and luteoviruses in Africa and elsewhere.
2) Papers by Rene Van Der Vlugt (The Netherlands) and Kai-shu Ling (USA) comparing the sequences of numerous Pepino mosaic virus isolates from Europe and the Americas. This damaging virus on tomato spread recently throughout the Americas and Europe through movement of contamination of tomato seed between different countries, becoming a significant concern for quarantine authorities worldwide. Two groups of isolates from Chile and the USA have CP sequences that are most divergent not only from each other but also from the European ones which are all very similar.
3) Two papers on emerging Begomoviruses of cucurbits by Judith Brown (USA) and Yeheskel Antignus (Israel). Antignus described the diseases caused by two Begomoviruses from cucurbits, Squash leaf curl virus (SLCV) and Watermelon necrotic stunt virus. Both are damaging new world (bipartite) Begomoviruses that have now spread outside the Americas. Brown described the properties of four new world Begomoviruses in the SLCV clade, SLCV itself, Squash mild leaf curl virus, Cucurbit leaf curl virus and Melon chlorotic leaf curl virus. They all infect Cucurbitaceae and Phaseolus vulgaris. SLCV seems to be the ancestor of the clade.
4) An interesting study on cucurbit viruses in the Sudan, the centre of origin of melon and watermelon presented by Herve Lecoq (France). Ten years of surveys revealed five viruses to be common, Watermelon chlorotic stunt virus (a Begomovirus), Cucurbit aphid-borne yellows virus (a Polerovirus), Squash mosaic virus (a Comovirus), and the Potyviruses Zucchini yellow mosaic virus and Moroccan watermelon mosaic virus. Four other viruses that often infect cucurbits elsewhere were found at lower incidences. In addition, an ancestral melon species contained a new Sobemovirus, Snake melon asteroid mosaic virus, which had 71% amino acid sequence identity with Rice yellow mottle virus. This virus infected melon and watermelon but did not systemically infect pumpkin, squash and zucchini, which originated elsewhere in the world. Interestingly, another common cucurbit virus, Watermelon mosaic virus, was not found in the centre of origin of watermelon (the Sudan). In another paper, Lecoq provide evidence that this cucurbit Potyvirus actually arose by recombination between two legume-infecting Potyviruses, Bean common mosaic virus and Soybean mosaic virus.
5) Several papers and posters by John Walsh (UK), Christian Obermeier (UK) and Rainer Kramer (Germany) that described recent progress with virus diseases of Brassicas. Obermeier described investigations on the genomics of plant virus coevolution in wild Brassica oleracea and B. rapa populations. Competition experiments suggested that local Turnip mosaic virus isolates have greater fitness in their original wild hosts than non-local ones. Walsh discussed mapping resistance genes to TuMV in the Brassica genome and identifying viral determinants of virulence. To date, eight TuMV resistance genes have been mapped and determinants of virulence for six Brassica resistance genes identified. Cross protection was being investigated as a TuMV control strategy in cabbage.
Effects of TuMV, BWYV and Cauliflower mosaic virus (CaMV) on stored cabbage were described. BWYV induced leaf tip burn and TuMV induced cigar burn (internal necrosis). Mixed infection with CaMV and storage both exacerbated the symptoms caused by the other two viruses. Kramer used intergeneric somatic hybridization between B. oleraceus and B. sativus to transfer TuMV resistance into Raphanobrassica hybrids to show that it was possible to generate new donors with durable resistance to different TuMV pathotypes in vegetable Brassicas.
The Scientific Excursion on Wednesday 13th April was very informative. It included visits to commercial fields of tomato devastated by multiple infection with different Begomoviruses, seeing naturally-infected weed hosts with bright yellow symptoms caused by Begomoviruses, inspection of an impressive field trial on control of Begomviruses in Phaseolus vulgaris using host resistance, and a guided tour demonstrating virus research underway at a cyclone-damaged field station. The research station improves tropical crops grown in the southernmost part of Florida. Its research included impressive plantations of papaya with transgenic resistance to Papaya ringspot virus. Picnic lunch even included delicious transgenic papaya! The excursion passed by pristine areas of the Florida everglades, and finished with a tour of an extensive botanical garden full of tropical plants from around the world.
On Tuesday 12th April, participants enjoyed a “Jungle Queen Dinner Cruise” along the Fort Lauderdale canal system, which is lined by some of the most opulent mansions and seagoing pleasure cruisers and yachts to be seen anywhere in the world.
At the end of the final oral session, it was announced that the next conference, the first of the newly combined Working group, would be in Ljubljana, Slovenia in September 2008 at the time of the next International Congress of Plant Pathology in Italy. Membership of the five-person transitional steering committee of the merged Group was also agreed, with Piero Caciagli (Italy) as the president and Ko Verhoeven (the Netherlands) the secretary.
Presentations were made to Gail Wisler to thank her for all her hard work in organising such a successful symposium.
I thank the British Society for Plant Pathology for providing a travel grant that helped me attend this most enjoyable and informative conference.
Data on the effect of insect vectors, different virus inoculum levels and climate variability on the incidence and severity of SPVD was collected from farmers’ fields at six different locations in the Great Lakes region of East Africa. The findings were used to guide decision making over which control measures to recommend against SPVD.
One of the important features of the symposium not mentioned above was the large number of interesting posters, more than 35 in total on a very diverse array of topics. The four poster sessions were held after the afternoon sessions and provided a good opportunity to engage in further discussions.
At the end of the final oral session, presentations were made to Pamela Anderson, Francisco Morales and Luis Salazar to thank them for all their hard work in organising such a successful symposium and to Martha Huanes and her team for their invaluable conference support. At the conference dinner that followed, participants were treated to a delicious multiple course meal + the local “Pisco sour” drink and a choice of wines, followed by a most entertaining display of typical folk dancing from different regions of Peru including audience participation. An excellent evenings’ entertainment was had by all.
It successfully maintained the high standards set by past meetings of the IPVE. The attractive setting of the “El Pueblo” Hotel with its well maintained lawns and garden, extensive sports facilities, and delightful cafe + outdoor restaurant secluded within a its surrounding ‘horseshoe of hills’ all helped to provide an ideal ‘backdrop’ to the event. The Director General of CIP and her staff are to be congratulated warmly over a job well done.
I thank the British Society for Plant Pathology for their support towards my travel expenses to attend this symposium.