Garrett K A, Dendy S P, Power A G, Blaisdell G K, Alexander H M, McCarron J K
Department of Plant Pathology, Kansas State University, Manhattan 66506.
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853.
Plant Dis. 2004 May;88(5):574. doi: 10.1094/PDIS.2004.88.5.574B.
The grasses Sorghastrum nutans (Indian grass), Schizachyrium scoparium (little bluestem), Panicum virgatum (switchgrass), and Andropogon gerardii (big bluestem) are four of the most common plant species present in a tallgrass prairie (1). Infection with barley yellow dwarf virus (BYDV, family Luteoviridae) is of interest in these species because of the potential effects of the virus on tallgrass prairie plant communities and the potential for tallgrass prairie to function as a reservoir of the virus for infection in wheat or barley fields. In a previous inoculation experiment, an unidentified strain of BYDV transmitted by the aphid species Rhopalosiphum padi was reported to infect S. scoparium but none of the other three grass species (2). We sampled for the presence of five virus strains in at least 50 blooming plants of each grass species in a natural tallgrass prairie stand in August 2000. Samples were collected in watersheds that were designated 1B, 1D, K1A, 20B, and 20C at Konza Prairie Biological Station in the Flint Hills near Manhattan, KS. To detect the virus, we used enzyme-linked immunosorbent assay (ELISA) with antibodies purchased from Agdia (Elkhart, IN). For the PAV, MAV, RMV, and SGV strains, we used double-antibody sandwich ELISA with alkaline phosphatase label. For Cereal yellow dwarf virus (RPV), we used compound direct ELISA with alkaline phosphatase label. The scoring of ELISA results was based on comparison with infected and uninfected control plants of the same species. Symptoms of infection in the field were difficult to interpret visually, since plants in this natural environment often showed multiple symptoms of stress. None of the five strains were detected in 51 individuals of S. nutans. For 50 individuals of S. scoparium, the incidence of infection by the different strains was 4% for MAV, 0% for PAV, 2% for RMV, 0% for RPV, and 58% for SGV. For 51 individuals of P. virgatum, the incidence of infection was 31% for MAV, 0% for PAV, 0% for RMV, 0% for RPV, and 4% for SGV. For 64 individuals of A. gerardii, the incidence of infection was 59% for MAV, 0% for PAV, 0% for RMV, 0% for RPV, and 3% for SGV. The impact of BYDV on these tallgrass prairie species remains to be determined. The PAV strain is the most commonly reported strain in wheat in Kansas but was not recovered from these grass species. References: (1) C. C. Freeman. The flora of Konza Prairie: A historical review and contemporary patterns. Pages 69-80 in: Grassland Dynamics. A. K. Knapp et al., eds. Oxford, 1998. (2) W. N. Stoner. Plant Dis. Rep. 60:593, 1976.
高粱草（印度草）、柳枝稷（小须芒草）、柳枝稷（柳枝稷）和大须芒草（大须芒草）是高草草原中最常见的四种植物物种（1）。感染大麦黄矮病毒（BYDV，黄症病毒科）在这些物种中备受关注，因为该病毒可能对高草草原植物群落产生影响，并且高草草原有可能成为该病毒在小麦或大麦田中感染的宿主。在之前的接种实验中，据报道，由蚜虫物种禾谷缢管蚜传播的一种未鉴定的BYDV菌株感染了柳枝稷，但未感染其他三种草种（2）。2000年8月，我们在堪萨斯州曼哈顿附近弗林特山的孔扎草原生物站的一个天然高草草原样地中，对每种草种至少50株开花植物进行采样，检测是否存在五种病毒菌株。样本采集于标记为1B、1D、K1A、20B和20C的流域。为了检测病毒，我们使用了从Agdia（印第安纳州埃尔克哈特）购买的抗体进行酶联免疫吸附测定（ELISA）。对于PAV、MAV、RMV和SGV菌株，我们使用了碱性磷酸酶标记的双抗体夹心ELISA。对于谷物黄矮病毒（RPV），我们使用了碱性磷酸酶标记的复合直接ELISA。ELISA结果的评分是基于与相同物种的感染和未感染对照植物进行比较。由于在这种自然环境中的植物经常表现出多种胁迫症状，因此在田间很难通过视觉判断感染症状。在51株高粱草个体中未检测到这五种菌株中的任何一种。对于50株柳枝稷个体，不同菌株的感染率分别为：MAV为4%，PAV为0%，RMV为2%，RPV为0%，SGV为58%。对于51株柳枝稷个体，感染率分别为：MAV为31%，PAV为0%，RMV为0%，RPV为0%，SGV为4%。对于64株大须芒草个体，感染率分别为：MAV为59%，PAV为0%，RMV为0%，RPV为0%，SGV为3%。BYDV对这些高草草原物种的影响仍有待确定。PAV菌株是堪萨斯州小麦中最常报道的菌株，但在这些草种中未检测到。参考文献：（1）C.C.弗里曼。孔扎草原的植物区系：历史回顾与当代模式。载于：《草原动态》。A.K.克纳普等人编。牛津，1998年，第69 - 80页。（2）W.N.斯托纳。《植物病害报告》60:593，1976年。
