Valentín Torres Suheidy, Vargas María M, Godoy-Lutz Graciela, Porch Timothy G, Beaver James S
Department of Biology.
Department of Biology, University of Puerto Rico, Mayagüez, PR 00681-9000.
Plant Dis. 2016 Jul;100(7):1351-1357. doi: 10.1094/PDIS-11-15-1270-RE. Epub 2016 Apr 21.
In common bean (Phaseolus vulgaris L.), Rhizoctonia solani Kühn is an important pathogen causing web blight (WB) in the tropics, and it is also a soilborne pathogen causing root rot (RR) worldwide. This pathogen is a species complex classified into 14 anastomosis groups (AG). AG 1-IA, AG 1-IB, AG 1-IE, AG 1-IF, AG 2-2, and AG 4 have been reported to cause WB of the aboveground structures of the plant, while AG 4 and AG 2-2 have been associated with RR. There is limited information, however, concerning the ability of particular isolates of specific AG to cause both diseases in common bean. Nine R. solani isolates, including three AG 1 and three AG 4 WB isolates and three AG 4 RR isolates collected from both leaves and roots, respectively, of common bean in Puerto Rico, were used to evaluate the response of 12 common bean genotypes to WB inoculated using a detached-leaf method and to RR inoculated using a solution suspension of R. solani mycelia in the greenhouse. All R. solani isolates were able to induce both RR and WB symptoms. RR readings were generally more severe than the WB readings. The RR isolate RR1 (AG 4) produced the most severe RR scores. A few bean lines had mean RR scores ≤4.4 for specific R. solani isolates on a scale of 1 to 9, with 1 representing resistant and 9 highly susceptible. However, all of the bean lines had mean RR scores ≥5.0 when inoculated with the isolates RR1, RR2, and RR3, which were determined to be AG 4 in this study. Significant line-isolate interactions were observed for the WB and RR inoculations for the three planting dates, suggesting a differential response of the common bean lines to the pathogen. This genotypic interaction may require bean breeders and pathologists to monitor the virulence patterns of R. solani in specific growing environments, while the compatibility of specific R. solani isolates to both aerial and root tissue needs to be considered for disease control strategies.
在普通菜豆（Phaseolus vulgaris L.）中，立枯丝核菌（Rhizoctonia solani Kühn）是热带地区引起网斑病（WB）的一种重要病原菌，也是全球范围内引起根腐病（RR）的土传病原菌。该病原菌是一个复合种，分为14个融合群（AG）。据报道，AG 1-IA、AG 1-IB、AG 1-IE、AG 1-IF、AG 2-2和AG 4会导致植物地上部分发生网斑病，而AG 4和AG 2-2与根腐病有关。然而，关于特定AG的特定分离株在普通菜豆中引发这两种病害的能力，相关信息有限。从波多黎各普通菜豆的叶片和根部分别收集了9株立枯丝核菌分离株，包括3株AG 1和3株AG 4网斑病分离株以及3株AG 4根腐病分离株，用于评估12个普通菜豆基因型对采用离体叶片法接种网斑病以及在温室中采用立枯丝核菌菌丝体溶液悬浮液接种根腐病的反应。所有立枯丝核菌分离株都能够诱发根腐病和网斑病症状。根腐病的读数通常比网斑病的读数更严重。根腐病分离株RR1（AG 4）产生的根腐病评分最严重。在1至9的评分尺度上，一些菜豆品系针对特定立枯丝核菌分离株的平均根腐病评分≤4.4，其中1表示抗病，9表示高感。然而，当用本研究中确定为AG 4的分离株RR1、RR2和RR3接种时，所有菜豆品系的平均根腐病评分≥5.0。在三个种植日期的网斑病和根腐病接种中均观察到显著的品系-分离株相互作用，这表明普通菜豆品系对病原菌的反应存在差异。这种基因型相互作用可能需要菜豆育种者和病理学家监测特定生长环境中立枯丝核菌的毒力模式，同时在制定病害控制策略时需要考虑特定立枯丝核菌分离株对地上和根部组织的亲和性。
