Navarro Barbara Ludwig, Campos Raphael de Araújo, Gasparoto Maria Cândida de Godoy, von Tiedemann Andreas
Department of Crop Sciences, Division of Plant Pathology and Crop Protection, Georg-August-Universität Göttingen, Grisebachstraße 6, 37077 Göttingen, Germany.
UNESP-São Paulo State University, Campus of Registro, Av. Nelson Brihi Badur, 430, Registro 11900-000, Sao Paulo, Brazil.
Pathogens. 2021 Feb 2;10(2):154. doi: 10.3390/pathogens10020154.
Northern Corn Leaf Blight (NCLB) is a fungal leaf disease in maize caused by . NCLB occurs worldwide, from tropical to temperate zones raising the question about plasticity of temperature adaptation of local isolates of the pathogen. Seven isolates of originating from South America and seven from Europe were compared for their response to temperature variations in vitro and in vivo between 15 and 30 °C. In vitro, isolates originating from Europe and South America significantly differed in mycelial growth rate at 30 °C and in sporulation at 25 °C and 30 °C. Aggressiveness of isolates was evaluated on three susceptible maize cultivars (maize lines B37, Sus1 and the German hybrid Niklas) under different day/night temperature regimes (15/10 °C, 20/15 °C, 25/20 °C, or 30/25 °C) with a photoperiod of 14 h. Aggressiveness, recorded as area under the disease progress curve (AUDPC), of South American isolates was higher than for European isolates at 15 °C, 20 °C and 25 °C, and for sporulation in vivo in all temperatures. In general, aggressiveness components were most influenced by temperature. Therefore, multivariate analysis was performed with aggressiveness component data at 30 °C, which expressed the highest number of variables with significant differences between isolate origins. According to their aggressiveness, European and South American isolates can be grouped separately, demonstrating that South American isolates are better adapted to higher temperatures and display a higher level of aggressiveness under similar conditions than European isolates from a cool climate. It is concluded that plasticity of temperature adaptation in populations is relatively large and allowed to follow the recent expansion of maize cultivation into cool climate zones in Europe. However, our data suggest that adaptation to higher temperature is likely to increase aggressiveness of NCLB on maize in cooler climate zones when experiencing further climate warming. This plasticity in adaptation to environmental conditions of may also hamper the success of breeding programs as it may decrease the durability of resistance.
玉米大斑病（NCLB）是一种由[病原体名称缺失]引起的玉米真菌叶部病害。玉米大斑病在全球范围内均有发生，从热带到温带地区都有，这引发了关于该病原菌本地分离株温度适应性可塑性的问题。比较了7株源自南美洲的[病原体名称缺失]分离株和7株源自欧洲的分离株在体外和体内对15至30°C温度变化的反应。在体外，源自欧洲和南美洲的分离株在30°C时的菌丝生长速率以及在25°C和30°C时的产孢情况存在显著差异。在不同的日/夜温度条件（15/10°C、20/15°C、25/20°C或30/25°C）、光周期为14小时的情况下，在三个易感玉米品种（玉米品系B37、Sus1和德国杂交种Niklas）上评估了[病原体名称缺失]分离株的致病力。以病害进展曲线下面积（AUDPC）记录的致病力，在15°C时，南美洲分离株高于欧洲分离株；在20°C和25°C时也是如此，并且在所有温度下南美洲分离株在体内的产孢情况也更好。总体而言，致病力成分受温度影响最大。因此，对30°C时的致病力成分数据进行了多变量分析，此时该温度下分离株来源之间具有显著差异的变量数量最多。根据致病力，欧洲和南美洲的分离株可以分别分组，这表明南美洲分离株更适应较高温度，并且在类似条件下比来自凉爽气候的欧洲分离株表现出更高的致病力水平。得出的结论是，[病原体名称缺失]群体的温度适应可塑性相对较大，这使得[病原体名称缺失]能够跟随近期玉米种植向欧洲凉爽气候区的扩展。然而，我们的数据表明，当经历进一步的气候变暖时，对较高温度的适应可能会增加玉米大斑病在较凉爽气候区对玉米的致病力。这种对环境条件的适应可塑性也可能会阻碍育种计划的成功，因为它可能会降低抗性的持久性。
