Phytopathology. 2007 May;97(5):584-91. doi: 10.1094/PHYTO-97-5-0584.
ABSTRACT A marked-isolate, release-recapture experiment was conducted to assess the relative contributions of seed-transmitted (released isolates) versus all other inocula to foliar and grain populations of Phaeosphaeria nodorum in winter wheat rotated with nonsusceptible crops in New York and Georgia, United States. Seed infected with two distinct groups of marked isolates of P. nodorum containing rare alleles (identified by amplified fragment length polymorphisms [AFLPs]) and balanced for mating type were planted in experimental field plots in two locations in each state. Recapture was done by isolating P. nodorum from leaves showing necrotic lesions at spring tillering and flowering stages, and mature grains from spikes showing glume blotch. Isolates from these samples were genotyped by AFLPs and categorized as released or nonreleased to infer sources of inoculum. Both infected seed and other sources of the pathogen contributed significant primary inocula to populations recovered from leaves and harvested grain. Seed-transmitted genotypes accounted for a total of 57% of all isolates recovered from inoculated plots, with a range of 15 to 90% of the populations of P. nodorum collected over the season in individual, inoculated plots at the four locations. Plants in the noninoculated control plots also became diseased and 95% or more of the isolates recovered from these plots were nonreleased genotypes. Although other potential sources of P. nodorum within and adjacent to experimental plots were not ruled out, nonreleased genotypes likely were derived from immigrant ascospores potentially from sources at a considerable distance from the plots. Our results suggest that, although reduction of seedborne inoculum of P. nodorum may delay foliar epidemics, this strategy by itself is unlikely to result in high levels of control in eastern North America because of the additional contribution from alternative sources of inoculum.
摘要 在美国纽约州和佐治亚州，进行了一项明显分离株的释放-再捕获实验，以评估种子传播（释放分离株）与其他所有接种体对小麦轮作中感染叶枯病和赤霉病的小麦的叶部和籽粒群体的相对贡献。感染有两组不同的标记 P. nodorum 分离株的种子，这些分离株含有稀有等位基因（通过扩增片段长度多态性 [AFLPs] 鉴定），且交配型平衡，在每个州的两个地点的实验田块中种植。在春季分蘖和开花期出现坏死性病斑和穗部出现颖斑的时期，从叶片中分离出 P. nodorum ，从显示颖斑的成熟穗粒中分离出赤霉病，进行再捕获。通过 AFLPs 对这些样本中的分离株进行基因型分析，并将其归类为释放或未释放，以推断接种体的来源。受感染的种子和病原体的其他来源都为从叶片和收获的谷物中回收的种群提供了重要的初始接种体。种子传播的基因型共占从接种田块中回收的所有分离株的 57%，在四个地点的四个接种田块中，在整个季节内，每个接种田块中采集的 P. nodorum 群体的范围为 15%至 90%。未接种对照田块中的植物也发病，从这些田块中回收的分离株中 95%或更多是非释放基因型。虽然未排除实验田块内和周围的其他潜在 P. nodorum 来源，但非释放基因型可能源自距离田块相当远的来源的入侵子囊孢子。我们的结果表明，尽管减少 P. nodorum 的种子传播接种体可能会延迟叶部流行，但由于来自其他接种体来源的额外贡献，这种策略本身不太可能在北美东部实现高水平的控制。
