Vleugels T, Baert J, Van Bockstaele E
Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Caritasstraat 21, BE-9090 Melle, Belgium.
Commun Agric Appl Biol Sci. 2011;76(4):583-6.
Sclerotinia trifoliorum causes clover cancer in red clover crops. Clover cancer is difficult to control and completely resistant red clover varieties are not available. Breeding for resistant red clover varieties is being slowed down because little is known about the diversity of European S. trifoliorum populations and because of the lack of bio-tests that are useable in breeding programs. The first objective of this research was to develop a reliable high-throughput bio-test, useable in breeding programs. The second objective was to optimise another bio-test, based on isolated leaves, for more precise studies. First, we optimised a method for ascospore production of S. trifoliorum. Once produced, the ascospores were used to evaluate the effects of climate conditions, ascospore concentration and plant age on the high-throughput bio-test. For the bio-test on isolated leaves, the effects of infection method, incubation conditions, incubation period, ascospore concentration, leaf growth stage and mechanical damage were evaluated. In the high-throughput bio-test, disease levels rose with increasing ascospore concentration up to 20,000 spores/ml. The plant age had a small, yet significant effect on the disease level. For the isolated leaf bio-test, the most effective and most repeatable infection method was spraying of an ascospore suspension. Disease levels continued to increase with rising concentrations and incubation time did not interact with plant susceptibility levels. The youngest completely opened leaf yielded the most repeatable results. Both bio-tests were shown to be correlated and could be valuable instruments for breeding programs and for studying plant-pathogen interactions.
三叶草核盘菌会导致红花草作物患三叶草癌症。三叶草癌症难以控制，且目前尚无完全抗性的红花草品种。抗性红花草品种的培育工作进展缓慢，原因一是对欧洲三叶草核盘菌种群的多样性了解甚少，二是缺乏可用于育种计划的生物测试。本研究的首要目标是开发一种可靠的高通量生物测试方法，用于育种计划。第二个目标是优化另一种基于离体叶片的生物测试方法，以进行更精确的研究。首先，我们优化了三叶草核盘菌子囊孢子生产方法。子囊孢子生产出来后，用于评估气候条件、子囊孢子浓度和植株年龄对高通量生物测试的影响。对于离体叶片生物测试，则评估了感染方法、培养条件、培养时间、子囊孢子浓度、叶片生长阶段和机械损伤的影响。在高通量生物测试中，病害水平随子囊孢子浓度增加而上升，直至达到20,000个孢子/毫升。植株年龄对病害水平有微小但显著的影响。对于离体叶片生物测试，最有效且最可重复的感染方法是喷洒子囊孢子悬浮液。病害水平随着浓度升高持续增加，培养时间与植株易感性水平无相互作用。最幼嫩的完全展开叶片产生了最可重复的结果。两种生物测试均显示具有相关性，并可能成为育种计划以及研究植物与病原体相互作用的宝贵工具。
