Universitat Hohenheim, Stuttgart, Germany.
Phytopathology. 2012 Jan;102(1):128-34. doi: 10.1094/PHYTO-06-11-0162.
Fusarium head blight (FHB), caused by Fusarium graminearum sensu stricto (s.s.), causes tremendous annual yield losses in wheat worldwide. Variation of aggressiveness of isolates from individual field populations in terms of FHB infection and deoxynivalenol (DON) concentration in the host are important population parameters reflecting parasitic ability. Our main objective was to estimate the variation of both traits within three populations of F. graminearum s.s., each consisting of 30 single-spore isolates collected from small wheat fields in Germany, and to compare it with 11 isolates of a collection (F. graminearum collection) from four countries. The same isolates were characterized using 19 single-sequence repeat markers. All isolates were spray inoculated on a moderately resistant spring wheat cultivar at two field locations over 2 years (i.e., in four environments). The genotypic proportion of phenotypic variance (σ(2)(G)) within populations was significant (P < 0.01) for both traits, and the σ(2)(G) × environment interaction was even more important for mean FHB severity. Ranges in mean FHB severity and DON concentration in the host were only slightly smaller for the field populations than for the F. graminearum collection. Both traits were significantly (P < 0.05) correlated within and across populations. A further partitioning of σ(2)(G) revealed 72% of σ(2)(G) within and 28% of σ(2)(G) across populations for both traits. Molecular variance of the three populations was similarly distributed (73.6% within versus 26.4% between populations). In view of this high within-field variation for traits of parasitic ability and selection, neutral molecular markers, multiple resistance genes of different origin should be employed in wheat breeding programs to obtain a long-term stable FHB resistance.
镰刀菌顶腐病（FHB），由禾谷镰刀菌严格种（s.s.）引起，在全球范围内给小麦造成了巨大的年度产量损失。单个田间种群分离物在宿主中感染赤霉病和脱氧雪腐镰刀菌烯醇（DON）浓度方面的侵袭力变异性是反映寄生能力的重要种群参数。我们的主要目标是估计三个禾谷镰刀菌 s.s. 种群内这两个性状的变异，每个种群由从德国小麦小田块收集的 30 个单孢分离物组成，并与来自四个国家的 11 个分离物（禾谷镰刀菌分离物集合）进行比较。使用 19 个单序列重复标记对所有分离物进行了特征描述。所有分离物在两年内在两个田间地点用喷雾接种在一个中度抗病春小麦品种上（即，在四个环境中）。两个性状在种群内的基因型比例表型方差（σ(2)(G)）均显著（P < 0.01），而 σ(2)(G)×环境互作对于平均赤霉病严重度更为重要。田间种群的平均赤霉病严重度和宿主中 DON 浓度的范围仅比禾谷镰刀菌分离物集合略小。两个性状在种群内和跨种群均显著相关（P < 0.05）。σ(2)(G)的进一步划分显示，两个性状的σ(2)(G)有 72%在种群内，28%在种群间。三个种群的分子方差分布相似（73.6%在种群内，26.4%在种群间）。鉴于这些对寄生能力和选择性状的田间高变异性，应在小麦育种计划中使用中性分子标记和不同来源的多个抗性基因，以获得长期稳定的赤霉病抗性。
