Foolad M R, Ntahimpera N, Christ B J, Lin G Y
Department of Horticulture.
Department of Plant Pathology.
Plant Dis. 2000 Sep;84(9):967-972. doi: 10.1094/PDIS.2000.84.9.967.
Twenty-nine tomato genotypes (cultivars, breeding lines, and plant introductions), representing three Lycopersicon species, were evaluated for resistance to early blight (EB) caused by the fungus Alternaria solani. Evaluations were conducted in replicated trials in multiple years under field and greenhouse conditions (with whole plants) and in growth chamber (with detached leaflets). In the field experiments, plants were evaluated for disease symptoms, and area under the disease progress curve (AUDPC) and final percent defoliation were determined. In the greenhouse experiments, plants were evaluated for percent defoliation following spray-inoculation with isolates of A. solani. In the growth chamber experiments, lesion radius, rate of lesion expansion, and final disease severity were determined for individual detached leaflets inoculated with isolates of A. solani. There were significant differences among genotypes in their response to A. solani infection in the field, greenhouse, and growth chamber experiments. In the field and greenhouse experiments, disease response varied from near-complete resistance in some accessions of the wild tomato species L. hirsutum (e.g., PI126445 and LA2099) to complete susceptibility in tomato cultivar New Yorker and breeding line NC84173. The previously developed EB-resistant breeding lines 88B231, 89B21, C1943, NCEBR-1, NCEBR-2, NCEBR-5, NCEBR-6, NC24E, and NC39E exhibited more resistance than New Yorker and NC84173. Field and greenhouse results were comparable across replications and years, and there were great correspondences (r ≈0.71, P < 0.01) between field and greenhouse resistance across genotypes. In contrast, results from the detached-leaflet assays were inconsistent across experiments and not correlated with either greenhouse or field results. The overall results indicate the utility of greenhouse evaluation and the inadequacy of detached-leaflet assay for screening tomatoes for EB resistance.
对代表三个番茄属物种的29个番茄基因型（品种、育种系和植物引种材料）进行了对由真菌链格孢引起的早疫病（EB）的抗性评估。评估在多年的重复试验中进行，试验条件包括田间和温室（整株植物）以及生长室（离体小叶）。在田间试验中，对植株的病害症状进行评估，并测定病害进展曲线下面积（AUDPC）和最终落叶率。在温室试验中，在用链格孢分离株喷雾接种后，对植株的落叶率进行评估。在生长室试验中，对用链格孢分离株接种的单个离体小叶测定病斑半径、病斑扩展速率和最终病害严重程度。在田间、温室和生长室试验中，各基因型对链格孢感染的反应存在显著差异。在田间和温室试验中，病害反应从野生番茄物种多毛番茄的一些材料（如PI126445和LA2099）的近乎完全抗性到番茄品种纽约客和育种系NC84173的完全感病不等。先前培育的抗早疫病育种系88B231、89B21、C1943、NCEBR - 1、NCEBR - 2、NCEBR - 5、NCEBR - 6、NC24E和NC39E比纽约客和NC84173表现出更强的抗性。田间和温室试验结果在各重复和各年份之间具有可比性，并且各基因型的田间和温室抗性之间存在高度相关性（r≈0.71，P < 0.01）。相比之下，离体小叶试验的结果在各试验之间不一致，并且与温室或田间结果均无相关性。总体结果表明温室评估对于筛选番茄早疫病抗性的实用性以及离体小叶试验用于此目的的不足。
