Plant Pathology and Plant-Microbe Biology Section, Cornell University, Geneva, NY 14456.
Phytopathology. 2023 Jul;113(7):1289-1300. doi: 10.1094/PHYTO-11-22-0417-R. Epub 2023 Sep 1.
Apple is an important fruit crop of temperate regions. The narrow genetic base of commercially cultivated apples has resulted in its vulnerability to a large number of fungal, bacterial, and viral pathogens. Apple breeders are always seeking new sources of resistance within the cross-compatible species that can be deployed into elite genetic backgrounds. We have evaluated resistance to two major fungal diseases of apples: powdery mildew and frogeye leaf spot, using a germplasm collection of 174 accessions to identify novel sources of genetic resistance. In 2020 and 2021, we evaluated these accessions for the incidence and severity of powdery mildew and frogeye leaf spot diseases at Cornell AgriTech, Geneva, New York, in a partially managed orchard. The severity and incidence of powdery mildew and frogeye leaf spot, as well as weather parameters were recorded in June, July, and August. Total incidence of powdery mildew and frogeye leaf spot infections increased from 33 to 38%, and 56 to 97% in 2020 and 2021, respectively. Our analysis showed that relative humidity and precipitation correlate with powdery mildew and frogeye leaf spot susceptibility. The predictor variables with highest impact to the variability of powdery mildew were accessions and relative humidity in May. A total of 65 accessions were found to be resistant to powdery mildew, and only one accession showed moderate resistance to frogeye leaf spot. Several of these accessions belong to hybrid species and domesticated apples and can therefore be potential sources of novel resistance alleles for apple breeding.
苹果是温带地区重要的水果作物。商业种植的苹果品种遗传基础狭窄，容易受到大量真菌、细菌和病毒病原体的侵害。苹果育种家一直在杂交相容的物种中寻找新的抗性来源，可以将其部署到优良的遗传背景中。我们使用 174 个种质资源评估了苹果的两种主要真菌病害：白粉病和蛙眼病的抗性，以确定新的遗传抗性来源。在 2020 年和 2021 年，我们在纽约日内瓦的康奈尔农业技术中心的半管理果园中评估了这些种质对白粉病和蛙眼病的发病率和严重程度。在 6 月、7 月和 8 月记录了白粉病和蛙眼病的严重程度和发病率以及天气参数。2020 年和 2021 年，白粉病和蛙眼病总发病率分别从 33%增加到 38%，从 56%增加到 97%。我们的分析表明，相对湿度和降水与白粉病和蛙眼病的易感性相关。对白粉病变异性影响最大的预测变量是 5 月的品系和相对湿度。共有 65 个品系对白粉病表现出抗性，只有一个品系对白蛙眼病表现出中度抗性。这些品系中有几个属于杂交种和栽培苹果，因此可以成为苹果育种的新抗性等位基因的潜在来源。
