About The Trust
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The Sárvári Research Trust (SRT) was set up as a not-for-profit company limited by guarantee and registered in England and Wales in 2002. Our aim is to research late-blight disease of potato and to develop new varieties with high levels of durable blight resistance. The best potential varieties are submitted for U.K. National Listing and are assessed by Sience and Advice for Scottish Agriculture (SASA) and the National Institute of Agricultural Botany (NIAB) for commercial suitability over a two-year period. The Sárvári family in Hungary makes primary selections from their breeding programme and their most promising clones are sent to SRT where we further select the ones which show the highest and most consistent resistance to blight. This is done by growing them in field plots with standard non-Sarpo varieties that have shown some resistance over many years. We conduct trials at many sites within the U.K., in several European countries and sometimes in highland Mexico where the most damaging blight is found. Each clone is assessed over several seasons. Further testing is done in the laboratory by inoculating detached leaflets or potted plants with standardized spore suspensions prepared from a wide range of blight isolates. Standard varieties are also included in these tests to provide a base-line for assessment. In this way we are able to expose our material to as many different populations of the blight pathogen as possible. Those which show high levels of resistance consistently have a high probability of expressing durable resistance into the future. Such clones are said to have broad-spectrum resistance or strain-non-specific resistance. It is essential to find out if clones with good foliage resistance also have good tuber resistance because resistance in the foliage is not always corrlated with resistance in the tuber. Some varieties have good foliage resistance but poor tuber resistance while other varieties have poor foliage resistance and good tuber resistance. Ideally a variety should have good resistance in both foliage and tuber. Accordingly, tubers from blight trials are assessed for the incidence of tuber blight at harvest and again after several weeks in store. We also test tuber resistance in the laboratory by inoculating harvested tubers with standardized spore suspensions from a range of blight isolates. Tubers are scored for tuber blight symptoms after incubation for several weeks. Having selected good resistance to late-blight, it is then necessary to screen clones for a large number of traits which are essential if the clone is to have any chance of success. Included in these assessments are: yield; tuber number, shape and uniformity; resistance to other pests and diseases; foliage maturity and dormancy; cooking and processing quality and taste. The Trust is collaborating with SCRI, Dundee and CSL, York in a study of the evolution of the U.K. population of blight in a project funded by the Potato Council Ltd. In season 2005, SRT fingerprinted isolates collected by the Potato Council and found that the A2 mating type had increased in frequency and that several new genotypes had arisen among A1 and A2 isolates. A new A2 strain, referred to as Blue (later referred to as strain 13 by SCRI) was found to be resistant to the curative fungicide, metalaxyl. Our field trials in 2007 showed that strain Blue-13 was able to overcome formerly resistant varieties including Stirling and Lady Balfour. Similar conclusions concerning the high aggressiveness of strain Blue-13 have been made by SCRI. SRT have studied what happens when A1 and A2 strains were introduced into the same crop enclosed within polythene tunnels. The tunnels have been replanted with fresh seed and the new crops became infected with blight soon after emergence. Samples of the blight were sent to SCRI for microsatellite fingerprinting. Results showed that the parental A1 and A2 genotypes had not survived but that new hybrid strains had been generated. The findings are consistent with the survival of oospores in the soil and germination of oospores to produce hybrid blight which infected the new emerging crop. Four crops have now been planted on the same site and the soil is still infectious, producing blighted plants soon after emergence of the new crop. View PowerPoint Poster (840kb - link opens in a new window).
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