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Following a 13 hour flight and 3 hour drive from Shanghai to Hangzhou, we were immediately presented with the first of many banquet meals, and a superb selection of dishes washed down with a very pleasant cabernet sauvignon. And this was to be a feature of the 7th Hangzhou International Symposium on Plant Pathology and Biotechnology – excellent organisation of both the scientific and social aspects of the meeting, great food and great hospitality, for which much of the credit must go to the chairperson of the organising committee, Professor Xueping Zhou.
The Congress itself, which was organised and sponsored by the Institute of Biotechnology, Zhejiang University and held at the Golden River Plaza Hotel was part of a series held every 2-3 years, and was attended by over 100 delegates including an assortment of overseas invited speakers from the US, Canada, Germany, Switzerland, Denmark, Iran, and myself from the UK. Following the opening ceremony, Steve Lommel (North Carolina State University) opened proceedings with a discussion of the methods by which viruses regulate temporal gene expression strictly at the RNA level. He also raised a point that will mean I have to update my plant virology lectures when talking about red clover necrotic mosaic virus, which is apparently a root infecting virus that is actually transferred through the soil without any need for a vector – the plant sheds the virus directly into the soil and it then enters plants through root abrasions – not an infection strategy I was previously aware of.
Steve’s talk was then followed by a couple of interesting talks on rice biotechnology before we returned to the plant pathology theme with Robert Dudler (University of Zurich) talking about syringolin, a secondary metabolite produced by pathovars of Pseudomonas syringae that induces systemic acquired resistance and can be used as both a protectant and an eradicant of powdery mildew when sprayed onto leaves (although it doesn’t appear to control any other pathogens such as rust). Modelling has shown how the syringolin binds to and inhibits proteasomes, and that there are also similar compounds produced by some of the burkholderias that have both antifungal and anti-cancer activity in mammalian systems. Yongping Duan (USDA Fort Pierce) then continued the bacterial theme with a fascinating insight into the Citrus huanglongbing (yellow shoot disease) caused by Liberibacter asiaticus. This bacterium, like the phytoplasmas that I work on, is phloem-limited, unculturable, vector transmitted (psyllids) and has low and uneven distribution in plants. Different subspecies of the bacterium give different disease symptoms, and the bacterium has been causing significant losses in citrus production in Africa, Asia, Brazil, and Florida where it arrived in 2005. The whole genome has now been sequenced, and the bacterium is closely related to the sinorhizobia, but with a much smaller genome (1. 23 Mb) containing no transposable elements, no type III or type IV secretion mechanisms, but a lot of phage and prophage sequences. He also discussed seed transmission of the bacterium and some evidence that seed transmission results in isolates of the bacterium that have lost their pathogenicity, and how molecular diagnostics needs to be developed to be able to differentiate between the virulent and avirulent isolates of the bacterium.
After an excellent lunch, I then gave my talk on phytoplasma diagnostics, including the use of generic and specific real-time PCR diagnostic methods and the loop isothermal amplification (lamp) methods combined with isolation of DNA onto lateral flow device strips that we have recently been developing for rapid (less than 1 hour from plant sample to detection) detection of phytoplasmas. The theme then moved on to biological control, with Sabine Ravnskov (University of Aarhus, Denmark) talking about arbuscullar mycorrhiza and the fact that it is still not possible to be able to predict which Glomus / plant interactions are likely to be successful in disease reduction and which not. Ralf Oelmuller (Friedrich Schiller University of Jena, Germany) then talked about Piriformospora indica and its use in growth promotion and disease control in a range of crop species, and how it stimulates auxin levels in roots and lateral root formation. A number of genes upregulated in roots have been identified and there is also evidence that the fungus can confer drought resistance through antioxidant production. Yang Ching-Hong (University of Wisconsin) then discussed cyclic diguanosine from Dickeya dadantii and its role as a global secondary messenger that regulates biofilm production, motility and virulence through the type III secretion system, and Bin Li (Zhejiang University) took us back to the theme of mycorrhiza and the mechanisms through which they exert their biocontrol affect.
On day 2 (Saturday) the theme switched to talks that were predominantly related to Magnaporthe oryzae and other fungal plant pathogens. Ulrich Schaffrath (University of Aachen) described research to find ems-generated mutants of mlo barley that had enhanced M. oryzae resistance (mlo normally enhances susceptibility). Amongst these mutants, he described emr1 which has reduced epicuticular wax, and he showed from backcross experiments that this wax reduction correlates with resistance. Bo Zhou (Zhejiang University) then described effector proteins from M. oryzae and Zhengyi Wang (also Zhejiang University) discussed G-protein signalling and the role of MoRic8. Ralph Dean (North Carolina State University) then gave an excellent overview on M. oryzae genomics including comparisons between isolates from different parts of the world and also discussed the role of non-coding RNAs. I have to confess to becoming slightly distracted when the street-cleaning truck went past the hotel with its horn blaring out the tune of Scarborough Fair – the Sound of Silence would have been much more appropriate, but noise pollution is very much part of everyday life in city of 7 million people. Won-Bo Shim (Texas A & M) then discussed maize stalk rot and in particular the role of Fusarium verticillioides, and this was followed by Daniel Ebbole (also Texas A & M) talking about transcriptomics and comparison of conidiation mechanisms between different fungi. After lunch, the theme switched again to talks that were largely on fungicide resistance, with talks from Zhonghua Ma (Zhejiang University) and also a number of his PhD students on strobilurin and DMI resistance in both Botrytis cinerea and Fusarium graminearum. Professor Xueping Zhou then gave his closing remarks on the benefits of these symposia particularly to Chinese graduate students for whom travel to overseas conference is often difficult due to costs and visa restrictions.
The conference dinner, which involved yet more excellent food and plenty of toasting, was followed on the Sunday by a day-long tour to the West Lake in Hangzhou (a hugely popular tourist attraction with more than 20 million visitors a year – most of whom appeared to be there that Sunday morning judging from the traffic jams to get there and the throngs of people queuing for the boat trips on the lake!), followed by the a silk museum, a tea plantation and then a recreated Song Dynasty village / theme park. It only remains for me to once again express my thanks to Xueping Zhou and his team for organising such an excellent symposium and such enjoyable cultural activities, and also to the BSPP for helping to fund my first but hopefully not last visit to China.
Matt Dickinson,
University of Nottingham
