Bove Federica, Bavaresco Luigi, Caffi Tito, Rossi Vittorio
Department of Sustainable Crop Production, DI.PRO.VE.S., Università Cattolica del Sacro Cuore, Piacenza, Italy.
Centro di Ricerca sulla Biodiversità e sul DNA Antico, Università Cattolica del Sacro Cuore, Piacenza, Italy.
Front Plant Sci. 2019 Nov 27;10:1559. doi: 10.3389/fpls.2019.01559. eCollection 2019.
Grapevine varieties showing partial resistance to downy mildew, caused by , are a promising alternative to fungicides for disease control. Resistant varieties are obtained through breeding programs aimed at incorporating loci controlling the quantitative resistance into genotypes characterized by valuable agronomic and wine quality traits by mean of crossing. Traditional phenotyping methods used in these breeding programs are mostly based on the assessment of the resistance level after artificial inoculation of leaf discs in bioassays, by using the visual score proposed in the 2nd Edition of the International Organization of Vine and Wine (OIV) Descriptor List for Grape Varieties and species (2009). In this work, the OIV score was compared with an alternative approach, not used for the grapevine-downy mildew pathosystem so far, based on the measurement of components of resistance (RCs); 15 grapevine resistant varieties were used in comparison with the susceptible variety 'Merlot'. OIV scores were significantly correlated with infection frequency (IFR), the latent period for the downy mildew (DM) lesions to appear (LP50), and the number of sporangia produced per lesion (SPOR), so that when the OIV score increased (i.e., the resistance level increases), IFR and SPOR decreased, while LP50 increased. The relationship was linear for LP50, monomolecular for IFR and hyperbolic for SPOR. No significant correlation was found between OIV score and DM lesion size, sporangia produced per unit area of lesion, length of infectious period, and infection efficiency of the sporangia produced on DM lesions. The correlation between OIV score and area under the disease progress curve (AUDPC) calculated by using the RCs and a simulation model was significant and fit an inverse exponential function. Based on the results of this study, the measurement of the RCs to in grapevine varieties by means of monocyclic, leaf disc bioassays, as well as their incorporation into a model able to simulate their effect on the polycyclic development of DM epidemics in vineyards, represents an improved method for phenotyping resistance level.
对由[病原菌名称未给出]引起的霜霉病表现出部分抗性的葡萄品种，是用于病害防治的杀菌剂的一种有前景的替代物。抗性品种通过育种计划获得，这些计划旨在通过杂交将控制数量抗性的基因座整合到具有宝贵农艺和葡萄酒品质性状的基因型中。这些育种计划中使用的传统表型分析方法大多基于在生物测定中人工接种叶盘后，根据国际葡萄与葡萄酒组织（OIV）葡萄品种和[物种名称未给出]描述符列表第2版（2009年）中提出的视觉评分来评估抗性水平。在这项工作中，将OIV评分与一种迄今未用于葡萄 - 霜霉病病理系统的替代方法进行了比较，该方法基于抗性成分（RCs）的测量；使用了15个葡萄抗性品种与感病品种‘梅洛’进行比较。OIV评分与[病原菌名称未给出]感染频率（IFR）、霜霉病（DM）病斑出现的潜伏期（LP50）以及每个病斑产生的孢子囊数量（SPOR）显著相关，因此当OIV评分增加（即抗性水平提高）时，IFR和SPOR降低，而LP50增加。LP50的关系是线性的，IFR是单分子的，SPOR是双曲线的。在OIV评分与DM病斑大小、病斑单位面积产生的孢子囊、侵染期长度以及DM病斑上产生的孢子囊的感染效率之间未发现显著相关性。通过使用RCs计算的OIV评分与病害进展曲线下面积（AUDPC）之间的相关性显著，且符合反指数函数。基于本研究结果，通过单循环叶盘生物测定法测量葡萄品种对[病原菌名称未给出]的RCs，并将其纳入能够模拟其对葡萄园DM流行病多循环发展影响的模型中，代表了一种改进的抗性水平表型分析方法。
