Vleugels T, Baert J, De Riek J, Heungens K, Malengier M, Cnops G, Van Bockstaele E
Institute for Agricultural and Fisheries Research, Unit Plant, Caritasstraat 21, BE-9090 Melle, Belgium.
Commun Agric Appl Biol Sci. 2010;75(4):649-53.
Since the 16th century, red clover has been an important crop in Europe. Since the 1940s, the European areal of red clover has been severely reduced, due to the availability of chemical fertilizers and the growing interest in maize. Nowadays there is a growing interest in red clover again, although some setbacks still remain. An important setback is the low persistence of red clover crops. Clover rot, caused by the ascomycete fungus Sclerotinia trifoliorum Erikss., is a major disease in Europe and reduces the persistence of red clover crops severely. The fungus infects clover plants through ascospores in the autumn, the disease develops during the winter and early spring and can kill many plants in this period. In early spring, black sclerotia, serving as surviving bodies, are formed on infected plants. Sclerotia can survive up to 7 years in the soil (Ohberg, 2006). The development of clover rot is highly dependent on the weather conditions: a humid fall, necessary for the germination of the ascospores and an overall warm winter with short periods of frost are favourable for the disease. Cold and dry winters slow the mycelial growth down too much and prevent the disease from spreading. Clover rot is difficult to control and completely resistant red clover varieties have yet to be developed. Because of the great annual variation in disease severity, plant breeders cannot use natural infection as an effective means to screen for resistant material. Breeding for resistant cultivars is being slowed down by the lack of a bio-test usable in breeding programs. When applying artificial infections, it is necessary to have an idea of the diversity of the pathogen. A diverse population will require resistance screening with multiple isolates. The objective of this research is to investigate the genetic diversity among isolates from the pathogen S. trifoliorum from various European countries. We assessed diversity using a species identification test based on the sequence of the beta-tubulin gene, vegetative compatibility grouping and AFLP.
自16世纪以来，红三叶草一直是欧洲的重要作物。自20世纪40年代以来，由于化肥的可获得性以及对玉米兴趣的增加，欧洲红三叶草的种植面积大幅减少。如今，人们对红三叶草的兴趣再度上升，尽管仍存在一些挫折。一个重要的挫折是红三叶草作物的持久性较低。由子囊菌核盘菌引起的三叶草腐烂病是欧洲的一种主要病害，严重降低了红三叶草作物的持久性。该真菌在秋季通过子囊孢子感染三叶草植株，病害在冬季和早春发展，在此期间可导致许多植株死亡。早春时，在受感染的植株上会形成黑色菌核，作为存活体。菌核在土壤中可存活长达7年（奥伯格，2006年）。三叶草腐烂病的发生高度依赖天气条件：有利于子囊孢子萌发的潮湿秋季以及总体温暖且有短暂霜冻期的冬季有利于该病发生。寒冷干燥的冬季会使菌丝体生长过于缓慢，从而阻止病害传播。三叶草腐烂病难以防治，且尚未培育出完全抗病的红三叶草品种。由于病害严重程度每年差异很大，植物育种者无法将自然感染作为筛选抗病材料的有效方法。缺乏可用于育种计划的生物测试减缓了抗病品种的培育进程。进行人工感染时，有必要了解病原体的多样性。多样的种群需要用多个分离株进行抗性筛选。本研究的目的是调查来自欧洲不同国家的核盘菌分离株之间的遗传多样性。我们使用基于β-微管蛋白基因序列的物种鉴定测试、营养体亲和群分组和扩增片段长度多态性来评估多样性。
