University of Hohenheim, State Plant Breeding Institute, Fruwirthstr. 21, 70599, Stuttgart, Germany.
Present Address: Department of Plant Cell Biology, Schwann-Schleiden Centre, Georg-August-University Goettingen, Julia-Lermontowa-Weg 3, 37077, Goettingen, Germany.
BMC Genomics. 2021 Aug 30;22(1):630. doi: 10.1186/s12864-021-07931-5.
Fusarium culmorum is an important pathogen causing head blight of cereals in Europe. This disease is of worldwide importance leading to reduced yield, grain quality, and contamination by mycotoxins. These mycotoxins are harmful for livestock and humans; therefore, many countries have strict regulatory limits for raw materials and processed food. Extensive genetic diversity is described among field populations of F. culmorum isolates for aggressiveness and production of the trichothecene mycotoxin deoxynivalenol (DON). However, the causes for this quantitative variation are not clear, yet. We analyzed 92 isolates sampled from different field populations in Germany, Russia, and Syria together with an international collection for aggressiveness and DON production in replicated field experiments at two locations in two years with two hosts, wheat and rye. The 30x coverage whole-genome resequencing of all isolates resulted in the identification of 130,389 high quality single nucleotide polymorphisms (SNPs) that were used for the first genome-wide association study in this phytopathogenic fungus.
In wheat, 20 and 27 SNPs were detected for aggressiveness and DON content, respectively, of which 10 overlapped. Additionally, two different SNPs were significantly associated with aggressiveness in rye that were among those SNPs being associated with DON production in wheat. Most of the SNPs explained only a small proportion of genotypic variance (p), however, four SNPs were associated with major quantitative trait loci (QTLs) with p ranging from 12 to 48%. The QTL with the highest p was involved in DON production and associated with a SNP most probably located within the Tri4 gene.
The diversity of 92 isolates of F. culmorum were captured using a heuristic approach. Key phenotypic traits, SNPs, and candidate genes underlying aggressiveness and DON production were identified. Clearly, many QTLs are responsible for aggressiveness and DON content in wheat, both traits following a quantitative inheritance. Several SNPs involved in DON metabolism, among them the Tri4 gene of the trichothecene pathway, were inferred as important source of variation in fungal aggressiveness. Using this information underlying the phenotypic variation will be of paramount importance in evaluating strategies for successful resistance breeding.
串珠镰刀菌是一种重要的病原菌，可引起欧洲谷类作物的穗枯病。这种疾病在全球范围内都很重要，会导致产量、谷物质量和霉菌毒素污染降低。这些霉菌毒素对牲畜和人类都有害；因此，许多国家对原材料和加工食品都有严格的监管限制。在串珠镰刀菌分离株的田间种群中，已描述了广泛的遗传多样性，包括侵袭性和产脱氧雪腐镰刀菌烯醇（DON）等三萜烯霉菌毒素。然而，这种数量变化的原因尚不清楚。我们分析了 92 株从德国、俄罗斯和叙利亚不同田间种群中采集的分离株，以及一个国际分离株，这些分离株在两年内在两个地点的两个宿主（小麦和黑麦）上进行了重复田间实验，以评估其侵袭性和 DON 产量。对所有分离株进行了 30x 覆盖的全基因组重测序，共鉴定出 130389 个高质量的单核苷酸多态性（SNP），这是在这种植物病原真菌中进行的首次全基因组关联研究。
在小麦中，分别检测到 20 个和 27 个 SNP 与侵袭性和 DON 含量有关，其中 10 个 SNP 重叠。此外，在黑麦中还检测到两个与侵袭性显著相关的不同 SNP，这些 SNP 与小麦中 DON 产量相关。大多数 SNP 仅解释了一小部分基因型方差（p），然而，有四个 SNP 与主要数量性状位点（QTL）相关，p 值范围为 12%至 48%。与 DON 产量相关的 QTL 与一个 SNP 关联程度最高，该 SNP 最有可能位于 Tri4 基因内。
使用启发式方法捕获了 92 株串珠镰刀菌分离株的多样性。确定了侵袭性和 DON 产量的关键表型特征、SNP 和候选基因。显然，小麦中的侵袭性和 DON 含量都有许多 QTL 负责，这两个性状都遵循数量遗传。推测参与 DON 代谢的几个 SNP，包括三萜烯途径的 Tri4 基因，是真菌侵袭性变异的重要来源。利用这些与表型变异相关的信息，对于评估成功抗性育种的策略至关重要。
