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This symposium was jointly organized by NiÃ°de University and the Republic of Turkey Ministry of Food, Agriculture and Livestock and provided an opportunity for scientists, growers and industry members from around the world to discuss and share information on many aspects of Allium research, including combatting pest and disease. I was given the opportunity to present our work on understanding the genetic control of pathogenicity and resistance for Fusarium oxysporum in onion (funded through the BBSRC HAPI initiative).
What became clear from this symposium is that Fusarium basal rot (caused predominantly by Fusarium oxysporum f. sp. cepae), globally, is the most important onion pathogen. It is a slightly different situation in India where diseases such as Stemphylium leaf blight (Stemphylium vesicarium), purple blotch (Alternaria porri) and anthracnose (Colletotrichum spp.) are more prevalent.
The opening lecture was presented by Prof Mike Havey from the University of Wisconsin who gave his perspectives on 25 years of genetic mapping in onion and his views on future prospects. His group have recently produced a robust set of ~900 SNP markers which provide an excellent genotyping platform; we are using this platform to genotype an onion population segregating for Fusarium resistance. Prof Havey also presented a talk on resistance to Thrips tabaci in onion. On top of the feeding damage caused by thrips, they are also a vector for Iris Yellow Spot Virus (IYSV), a damaging viral pathogen of onion in the USA and some other countries. They found that resistance is related to wax content of the leaves. A glossy phenotype (less wax) confers greater resistance to thrips but also increases susceptibility to fungi and spray damage. A semi-glossy phenotype was found to be less attractive to thrips without any unwanted effects.
Among the Plenary speakers were Dr Colin Eady (Agriseeds, New Zealand), Prof Masayoshi Shigyo (Yamaguchi University, Japan) and Richard Finkers (Wageningen University, Netherlands).
Dr Eady summarised his work (20 years) on genetic engineering technologies for Alliums. Unfortunately, this work has halted due to lack of support for GM crops / technologies. Dr Eady and his team had been working on many traits including herbicide resistance, resistance to IYSV and resistance to Allium white rot (Sclerotiorum cepivorum). Their group is also famous for producing a tearless onion variety using GM technologies.
Prof Shigyo summarised their work on Allium mapping and breeding and discussed his research on resistance to Fusarium oxysporum. Their work has revealed a role for saponins in resistance to Fusarium oxysporum in Shallot. Saponins can be found in Shallot roots and root exudates. In addition, Prof Shigyo presented work on the potential role of 3 effector genes (SIX genes) in Fusarium oxysporum f. sp. cepae. Our group have also proposed a role for these effectors as well as an additional seven putative effectors. It is our plan to work very closely with Prof Shigyo’s group in the future. Richard Finkers presented an excellent talk on SEQUON, an ambitious project to sequence the onion genome. An initial assembly has been produced for the very large (estimated 16Gb) genome and future work will involve longer read sequencing in order to bridge the contigs and reduce the number of contigs.
There were two interesting talks from Universitas Gadjah Mada in Indonesia. Dr Wibowo presented work on moler disease in Shallot. This is a disease caused by a range of Fusarium species (F. acucatum, F. solani and F. oxysporum mainly). It was found that subjecting bulbs to a hot water treatment (50 . C for 30 mins) provides some control of moler disease. Dr Subandiyah presented work on bacterial rot in shallot and identified Pectobacterium carotovorum as one of the main causal agents. An interesting poster was presented by Dr Claudio Garlmarini (Instituto Nacional de Tecnologia Agropecuaria, Argentina) whose group are working on Fusarium basal rot in Argentina.
They found a strong correlation between fusaric acid production and pathogenicity towards onion. We hope to collaborate with Dr Galmarini in a future project. Paolo Pagan (Cora Seeds, Italy) presented an interesting poster which suggested that many important traits in onion (including Fusarium resistance) are maternally inherited.
I would like to thank the BSPP for supporting this trip as well as Ali Fuat Gokce (Nigde University) and his team for all their hard work in organising this meeting.
Dr Andrew Taylor Warwick Crop Centre, University of Warwick