Bonde M R, Nester S E, Berner D K, Frederick R D, Moore W F, Little S
United States Department of Agriculture-Agricultural Research Service, Foreign Disease-Weed Science Research Unit, Fort Detrick, MD 21702.
Department of Entomology and Plant Pathology, Mississippi State University, Mississippi State 39762.
Plant Dis. 2008 Jan;92(1):30-36. doi: 10.1094/PDIS-92-1-0030.
Knowledge of the host range of Phakopsora pachyrhizi is important to agriculture in the United States because of the distinct possibility that economic losses could occur to crops other than soybean. Furthermore, it is possible that alternative hosts could provide a means of overwintering of the pathogen, providing inoculum to initiate epidemics in future years. To clarify the potential importance of soybean rust on nonsoybean legumes and their role in overwintering of the disease, multiple accessions of clover, cowpea, pea, kudzu, lima bean, snap bean, and single accessions of coffee senna, Florida beggarweed, hemp sesbania, hyacinth bean, partridge pea, and showy crotalaria were inoculated under greenhouse conditions with urediniospores of P. pachyrhizi; infected soybean plants served as a control. The four criteria used to assess susceptibility were lesion density, proportion of lesions with sporulating uredinia, average number of uredinia per lesion, and average uredinia diameter, each determined 2 weeks following inoculation. Based on lesion densities, percentage of lesions with sporulation, and average numbers of uredinia per lesion, soybean, kudzu, and pea were the most susceptible species, followed by snap bean. However, because infected pea plants defoliated rapidly, urediniospore production presumably was limited, lessening the potential for epidemics on pea. Cultivars of snap bean produced numerous brown to reddish-brown lesions, many of which sporulated, but numbers of uredinia per lesion were lower than on soybean, kudzu, or pea. The presence of both tan (susceptible) and reddish-brown (resistant) lesions on kudzu demonstrated physiological differentiation on that host. Some kudzu plants appeared to be potentially excellent hosts for overwintering of the disease. The average number of uredinia per lesion appeared to be a valid measurement with which to compare host susceptibilities, and may have epidemiological significance. High susceptibility of a host was characterized by numerous uredinia with a wide range of sizes within individual lesions. In contrast, low susceptibility to rust was characterized by no or a few small uredinia.
了解大豆锈病菌（Phakopsora pachyrhizi）的寄主范围对美国农业很重要，因为除大豆外的其他作物极有可能遭受经济损失。此外，替代寄主可能为病原菌提供越冬途径，为未来年份引发病害流行提供接种体。为了阐明大豆锈病对非大豆豆科植物的潜在重要性及其在病害越冬中的作用，在温室条件下，用大豆锈病菌的夏孢子对三叶草、豇豆、豌豆、葛藤、利马豆、菜豆的多个种质以及决明、铺地锦、田菁、扁豆、鹧鸪豆和艳丽猪屎豆的单个种质进行接种；受感染的大豆植株作为对照。接种后2周，用于评估易感性的四个标准为病斑密度、产生具夏孢子堆病斑的比例、每个病斑的平均夏孢子堆数和夏孢子堆平均直径。根据病斑密度、产孢病斑百分比和每个病斑的平均夏孢子堆数，大豆、葛藤和豌豆是最易感的物种，其次是菜豆。然而，由于受感染的豌豆植株迅速落叶，夏孢子产生量可能有限，降低了豌豆上病害流行的可能性。菜豆品种产生大量褐色至红棕色病斑，其中许多产孢，但每个病斑的夏孢子堆数低于大豆、葛藤或豌豆。葛藤上出现了褐色（易感）和红棕色（抗性）两种病斑，表明该寄主存在生理分化。一些葛藤植株似乎可能是该病害越冬的极佳寄主。每个病斑的平均夏孢子堆数似乎是比较寄主易感性的有效指标，可能具有流行病学意义。寄主的高易感性表现为单个病斑内有大量大小各异的夏孢子堆。相比之下，对锈病的低易感性表现为没有或只有少数小的夏孢子堆。
