Muhle Anthony A, Palmer Nathan A, Edme Serge J, Sarath Gautam, Yuen Gary, Mitchell Robert B, Tatineni Satyanarayana
United States Department of Agriculture-Agricultural Research Service, University of Nebraska-Lincoln, Lincoln, USA.
Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA.
Arch Virol. 2022 May;167(5):1247-1256. doi: 10.1007/s00705-022-05412-y. Epub 2022 Mar 28.
Panicum mosaic virus (PMV), the type member of the genus Panicovirus in the family Tombusviridae, naturally infects switchgrass (Panicum virgatum L.). PMV and its molecular partner, satellite panicum mosaic virus (SPMV), interact synergistically in coinfected millets to exacerbate the disease phenotype and increase the accumulation of PMV compared to plants infected with PMV alone. In this study, we examined the reaction of switchgrass cvs. Summer and Kanlow to PMV and PMV+SPMV infections at 24°C and 32°C. Switchgrass cv. Summer was susceptible to PMV at both temperatures. In contrast, cv. Kanlow was tolerant to PMV at 24°C, but not at 32°C, suggesting that Kanlow harbors temperature-sensitive resistance to PMV. At 24°C, PMV was readily detected in inoculated leaves, but not in upper uninoculated leaves of Kanlow, suggesting that resistance to PMV was likely mediated by abrogation of long-distance virus transport. Coinfection by PMV and SPMV at 24°C and 32°C in cv. Summer, but not in Kanlow, caused increased symptomatic systemic infection and mild disease synergism with slightly increased PMV accumulation compared to plants infected with PMV alone. These data suggest that the interaction between PMV and SPMV in switchgrass is cultivar-dependent, manifested in Summer but not in Kanlow. However, co-inoculation of cv. Kanlow with PMV+SPMV caused an enhanced asymptomatic infection, suggesting a role of SPMV in enhancement of symptomless infection in a tolerant cultivar. These data suggest that enhanced asymptomatic infections in a virus-tolerant switchgrass cultivar could serve as a source of virus spread and play an important role in panicum mosaic disease epidemiology under field conditions. Our data reveal that the cultivar, coinfection with SPMV, and temperature influence the severity of symptoms elicited by PMV in switchgrass.
黍花叶病毒（PMV）是番茄丛矮病毒科黍病毒属的典型成员，自然感染柳枝稷（Panicum virgatum L.）。PMV及其分子伴侣卫星黍花叶病毒（SPMV）在共同感染的粟类作物中协同作用，与单独感染PMV的植株相比，会加剧病害表型并增加PMV的积累。在本研究中，我们检测了柳枝稷品种Summer和Kanlow在24°C和32°C条件下对PMV以及PMV+SPMV感染的反应。柳枝稷品种Summer在这两种温度下均对PMV敏感。相比之下，品种Kanlow在24°C时对PMV具有耐受性，但在32°C时则不然，这表明Kanlow对PMV具有温度敏感抗性。在24°C时，在接种的叶片中很容易检测到PMV，但在Kanlow未接种的上部叶片中未检测到，这表明对PMV的抗性可能是由长距离病毒运输的阻断介导的。在24°C和32°C条件下，品种Summer中PMV和SPMV共同感染，但Kanlow中未出现这种情况，与单独感染PMV的植株相比，导致症状性系统感染增加以及轻微的病害协同作用，同时PMV积累略有增加。这些数据表明，PMV和SPMV在柳枝稷中的相互作用取决于品种，在Summer中表现明显，而在Kanlow中则不然。然而，用PMV+SPMV共同接种品种Kanlow会导致无症状感染增强，这表明SPMV在耐受性品种无症状感染增强中发挥作用。这些数据表明，病毒耐受性柳枝稷品种中无症状感染增强可能成为病毒传播源，并在田间条件下的黍花叶病流行病学中发挥重要作用。我们的数据表明，品种、与SPMV共同感染以及温度会影响PMV在柳枝稷中引发的症状严重程度。
