Plant Pathology Group, ETH Zurich, Universitatstrasse 2, 8092 Zurich, Switzerland.
Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
Fungal Genet Biol. 2020 Aug;141:103398. doi: 10.1016/j.fgb.2020.103398. Epub 2020 May 1.
Evolution favors the emergence of locally-adapted optimum phenotypes that are likely to differ across a wide array of environmental conditions. The emergence of favorable adaptive characteristics is accelerated in agricultural pathogens due to the unique properties of agro-ecosystems. We performed a Q - F comparison using 164 strains of Parastagonospora nodorum sampled from eight global field populations to disentangle the predominant evolutionary forces driving population divergence in a wheat pathogen. We used digital image analysis to obtain quantitative measurements of growth rate and melanization at different temperatures and under different fungicide concentrations in a common garden experiment. F measures were based on complete genome sequences obtained for all 164 isolates. Our analyses indicated that all measured traits were under selection. Growth rates at 18 °C and 24 °C were under stabilizing selection (Q < F), while diversifying selection (Q > F) was the predominant evolutionary force affecting growth under fungicide and high temperature stress. Stabilizing selection (Q < F) was the predominant force affecting melanization across the different environments. Melanin production increased at 30 °C but was negatively correlated with higher growth rates, consistent with a trade-off under heat stress. Our results demonstrate that global populations of P. nodorum possess significant evolutionary potential to adapt to changing local conditions, including warmer temperatures and applications of fungicides.
进化有利于出现局部适应的最优表型，这些表型可能因广泛的环境条件而异。由于农业生态系统的独特性质，农业病原体中有利适应性特征的出现得到了加速。我们使用来自八个全球田间种群的 164 株 Parastagonospora nodorum 菌株进行了 Q-F 比较，以厘清在小麦病原体中驱动种群分化的主要进化力量。我们使用数字图像分析在一个共同花园实验中获得了在不同温度和不同杀菌剂浓度下的生长速率和黑化的定量测量值。F 度量基于为所有 164 个分离物获得的完整基因组序列。我们的分析表明，所有测量的性状都受到选择。18°C 和 24°C 的生长速率受到稳定选择（Q<F），而在杀菌剂和高温胁迫下影响生长的主要进化力量是多样化选择（Q>F）。稳定选择（Q<F）是影响不同环境中黑化的主要力量。黑色素的产生在 30°C 时增加，但与更高的生长速率呈负相关，这与热应激下的权衡一致。我们的研究结果表明，P. nodorum 的全球种群具有显著的进化潜力，可以适应不断变化的当地条件，包括更高的温度和杀菌剂的应用。
