Wheat with virus-like symptoms (extracts containing a 33-kDa protein in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, negative in enzyme-linked immunosorbent assay to wheat streak mosaic virus, and not infectious in a backassay to other wheat) reacted positively to antiserum made against a protein purified from symptomatic corn infected with the High Plains virus (HPV), indicating a serological relationship between the corn and wheat pathogens. The wheat curl mite (WCM, Aceria tosichella Keifer) was identified as the vector of the virus and caused persistent infection of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) in greenhouse experiments. The HPV was recovered in the field from naturally infected wheat where the number of HPV-infected plants decreased with increasing distance from the WCM source in volunteer wheat.

In 2006, a mechanically-transmissible and previously uncharacterized virus was isolated in Kansas from wheat plants with mosaic symptoms. The physiochemical properties of the virus were examined by purification on cesium chloride density gradients, electron microscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), sequencing of the nucleotides and amino acids of the coat protein, and immunological reactivity. Purified preparations contained flexuous, rod-shaped particles that resembled potyviruses. The coat protein was estimated from SDS-PAGE to have a mass of approximately 35 kDa. Its amino acid sequence, as deduced from DNA sequencing of cloned, reverse-transcribed viral RNA and separately determined by time-of-flight mass spectrometry, was most closely related (49% similarity) to Sugarcane streak mosaic virus, a member of the Tritimovirus genus of the family Potyviridae. The virus gave strong positive reactions during enzyme-linked immunosorbent assays using polyclonal antibodies raised against purified preparations of the cognate virus but gave consistent negative reactions against antibodies to Wheat streak mosaic virus (WSMV), other wheat potyviruses, and the High Plains virus. When the virus was inoculated on the WSMV-resistant wheat cv. RonL, systemic symptoms appeared and plant growth was diminished significantly in contrast with WSMV-inoculated RonL. Taken together, the data support consideration of this virus as a new potyvirus, and the name Triticum mosaic virus (TriMV) is proposed.

ABSTRACT1). PI 222655 is the only source in Table 1 reduced the incidence of WSM (Martin et al., 1984; vented with eight, 12-mm-diam. openings that were covered Harvey and Martin, 1988;Harvey et al., 1990; Conner with nylon mesh with16-m-diam. openings (3-35/16xx; H.R.

High Plains virus (HPV) isolates from Colorado, Idaho, Kansas, Texas, and Utah were serologically related, had similar relative molecular masses (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) for the 32-kDa diagnostic HPV protein, and were transmissible and maintained free of Wheat streak mosaic virus (WSMV) by vascular puncture inoculation. Collections of wheat curl mites (Aceria tosichella Keifer; WCM) from Kansas, Montana, Nebraska, South Dakota, and Texas differentially transmitted these isolates. For collections from South Dakota and Texas, little or no HPV transmission occurred, whereas WCM from Nebraska and Montana transmitted all five isolates. The collection from Kansas mostly transmitted only one HPV isolate. Aviruliferous or viruliferous WSMV Nebraska WCM transmitted HPV at similar rates and aviruliferous Montana WCM transmitted HPV at lower levels than viruliferous Montana WCM.

No abstract

To diversify the genetic base of resistance in wheat (Triticum aestivum L.) to the wheat curl mite (WCM), Aceria tosichella Keifer, resistance to this pest was transferred from the dipolid goatgrass Aegilops taushcii (Coss.). Schmal. to the hard red winter wheat germplasm KS96WGRC40 by backcrossing to the cultivar TAM 107. KS96WGRC40 has WCM resistance derived from both Ae. tauschii and rye (Secale cereale L.). The objectives of this study were to determine if a unique WCM resistance gene was transferred from Ae. tauschii to KS96WGRC40 and to determine the chromosome and linkage map locations of the WCM resistance genes in the germplasm. The rye‐derived WCM resistance gene in TAM 107 and KS96WGRC40, designated Cmc3, is present on wheat–rye translocation T1AL·1RS. Marker analysis of a segregating F2 population revealed that the rye‐specific microsatellite marker SCM09 can be used to select wheat lines carrying the 1RS segment and Cmc3 Allelism tests indicated that the Ae. tauschii‐derived WCM resistance gene in KS96WGRC40, designated Cmc4, segregated independently of the Cmc1 gene previously transferred from this species. Molecular and cytogenetic analyses located Cmc4 distally on chromosome 6DS flanked by markers Xgdm141 (4.1 centimorgans, cM) and XksuG8 (6.4 cM). The linked markers may be used in wheat breeding programs for the selection of lines resistant to WCM and for gene pyramiding.

Triticum mosaic virus (TriMV) is a newly discovered virus found infecting wheat (Triticum aestivum) in Kansas. This study was conducted to determine if the wheat curl mite (WCM, Aceria tosichella) and the bird cherry oat aphid (Rhopalosiphum padi) could transmit TriMV. Using different sources of WCM and two different isolates of TriMV, we were able to show the WCM is the vector of TriMV. Field analysis by enzyme-linked immunosorbent assay (ELISA) demonstrated natural infection patterns of wheat infected with TriMV, Wheat streak mosaic virus (WSMV), or both TriMV and WSMV, putatively infected by viruliferous WCM from a volunteer source growing adjacent to the wheat. Moreover, by single WCM transfers using WCM obtained from different wheat plants naturally infected with TriMV and WSMV and naturally infested with WCM, we showed that these WCM also transmitted TriMV only to wheat or transmitted both TriMV and WSMV to wheat. The infection rates of wheat with TriMV only using WCM transmission was low in both laboratory and field analyses. However, field analyses by ELISA showed that levels of infection of wheat by both TriMV and WSMV were high. No transmission of TriMV to wheat by R. padi occurred in our studies.

Wheat streak mosaic virus (WSMV) infection reduces seed yield and quality in wheat. These losses can be alleviated significantly by exploiting genetic host plant resistance. A new source of temperature-sensitive resistance to WSMV, KS03HW12, and its parental lines (KS97HW29/ KS97HW131//KS96HW100-5) were evaluated in both greenhouse and field conditions. Parental wheat lines were exposed to WSMV pressure under different temperatures in growth chambers to determine the stability of the resistance, and 2 years of field yield trials were conducted to confirm effectiveness. To determine the effectiveness of its resistance against a spectrum of isolates, KS03HW12 was tested against six different WSMV isolates of different geographic origins. Among the three pedigree parents, only one, KS97HW29, was resistant. The parental lines of KS97HW29 are not available for testing; therefore, the presumed origin of the resistance could not be further confirmed. None of the six tested WSMV isolates systemically infected KS03HW12 at 18°C. Yield of KS03HW12 in field tests was not different from healthy controls. Thus, the elite winter wheat KS03HW12 appears to be a stable and effective source of temperature-sensitive resistance to WSMV and should be useful for wheat breeding programs.