Jacobs Daniel C, Revord Ronald S, Capik John M, Mehlenbacher Shawn A, Molnar Thomas J
Department of Plant Biology, Rutgers University, New Brunswick, NJ, United States.
Center for Agroforestry, School of Natural Resources, University of Missouri, Columbia, MO, United States.
Front Plant Sci. 2024 Jul 24;15:1419265. doi: 10.3389/fpls.2024.1419265. eCollection 2024.
Eastern filbert blight (EFB), caused by , is the primary limiting factor for hazelnut ( sp.) production in the United States. In this study, 82 cultivars and selections shown to be resistant or tolerant to EFB in Oregon were field planted in New Jersey in 2017 and 2019 and evaluated for their EFB response under high disease pressure. The trees carry known single resistance (R) genes with most mapped to their respective linkage groups (LG), including LG2, LG6, and LG7, or they express quantitative resistance (QR, horizontal resistance). Disease incidence and severity was documented, stem cankers counted and measured, and the proportion of diseased wood calculated. The EFB disease response of some cultivars/selections varied considerably between New Jersey and Oregon while others were consistent. Trends were observed in relation to resistance source origin and LGs, which provide insight into durability and usefulness of resistance. In striking contrast to Oregon, nearly all selections with R-genes mapped to LG6, including those carrying the 'Gasaway' resistance allele, exhibited severe EFB infections (232 of 266 [87%]). This finding is of consequence since the U.S. hazelnut industry currently relies solely on LG6 resistance for EFB resistance. Further, for the first time, EFB was observed on several selections carrying LG7 resistance, specifically offspring of 'Ratoli' from Spain. Interestingly, selections carrying LG7 resistance from origins other than 'Ratoli' remained free of EFB, with one exception, all selections carrying LG2 (n=9) resistance also remained free from EFB. Interestingly, the EFB responses of selections expressing QR (n=26) more closely resembled the disease phenotypes they exhibited in Oregon. Overall, the divergence in EFB response between Oregon and New Jersey, where pathogen populations differ, supports the presence of pathogenic variation in and highlights potential limitations of using single R-genes to manage the disease. Results also suggest trees expressing QR may be more stable across pathogenic populations.
由[病原菌名称未给出]引起的东部榛树疫病（EFB）是美国榛树（[榛树属未给出具体种名]）生产的主要限制因素。在本研究中，2017年和2019年在新泽西州对俄勒冈州表现出对EFB具有抗性或耐受性的82个品种和选系进行了田间种植，并在高病害压力下评估它们对EFB的反应。这些树携带已知的单个抗性（R）基因，大多数已定位到各自的连锁群（LG），包括LG2、LG6和LG7，或者它们表现出数量抗性（QR，水平抗性）。记录了病害发生率和严重程度，统计并测量了茎溃疡，计算了患病木材的比例。一些品种/选系对EFB的病害反应在新泽西州和俄勒冈州之间有很大差异，但其他一些则较为一致。观察到了与抗性来源起源和连锁群相关的趋势，这为抗性的持久性和实用性提供了见解。与俄勒冈州形成鲜明对比的是，几乎所有R基因定位到LG6的选系，包括携带“Gasaway”抗性等位基因的选系，都表现出严重的EFB感染（266个中有232个[87%]）。这一发现具有重要意义，因为美国榛树产业目前仅依靠LG6抗性来抵御EFB。此外，首次在几个携带LG7抗性的选系上观察到EFB，特别是来自西班牙的“Ratoli”后代。有趣的是，除一个例外，来自“Ratoli”以外其他来源且携带LG7抗性的选系未感染EFB，所有携带LG2抗性的选系（n = 9）也未感染EFB。有趣的是，表现出数量抗性的选系（n = 26）对EFB的反应与它们在俄勒冈州表现出的病害表型更为相似。总体而言，在病原菌群体不同的俄勒冈州和新泽西州之间EFB反应的差异，支持了[病原菌名称未给出]存在致病变异，并突出了使用单个R基因来管理该病害的潜在局限性。结果还表明，表现出数量抗性的树木在不同致病群体中可能更稳定。
