THE HIGH PLAINS VIRUS

A NEWLY EMERGING PROBLEM OF MAIZE AND WHEAT WITH WORLD WIDE IMPLICATIONS.

Stanley G. Jensen, USDA-ARS. Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583

The high plains virus (HPV) was first found in 1993 infecting susceptible maize and winter wheat in several High Plains states of the central and western USA. The virus has a characteristic 32 kDa protein which is associated with the nucleic acid. An antiserum has been prepared against the protein and is available for diagnosis. Five species of ds-RNA have been extracted from the nucleoprotein, cloned and partially sequenced. The partial sequence of RNA #3 which directs for the synthesis of the 32 kDa protein has been deposited in the Genebank under the accession # V60141. PCR also works well for diagnosis. HPV is not mechanically transmitted and the Eriophyid mite, Aceria tosichella Kiefer, which is the obligate vector for HPV also transmits wheat streak mosaic virus (WSMV) and plants may be doubly infected. Both WSMV and A. tosichella may be world wide in distribution. HPV has a relatively large host range and can cause severe or lethal symptoms on susceptible maize, wheat, barley, and several grasses. There is evidence that HPV may be seed transmitted in maize at very low levels.

Electron microscopy of infected cells reveals large spherical to ovoid double membrane bound particles (DMP) 150 -200 nm in diameter. HPV is a member of a group of pathogens that are all transmitted by Eriophyid mites, produce large DMP, and cause diseases with viral-like symptoms. This group includes wheat spot mosaic virus (WSpMV) (which is similar to HPV but no cultures of WSpMV exist), fig mosaic, thistle mosaic, rose rosette, and redbud yellow ringspot. HPV has been found in some areas in the USA for four consecutive years. The virus has been confirmed from maize and wheat tissue samples from more than 100 counties in a geographic area extending from eastern Nebraska to western Idaho and from the Texas panhandle to central South Dakota. The virus has also been found in winter sweet corn production fields in southern Florida. Samples of maize, testing serologically positive for HPV, have also been received from three foreign countries on two continents. The virus is probably distributed worldwide and thus I am putting this information and photographs on the WWW. A bibliography is attached for further reading on HPV and related pathogens. For additional information on HPV contact Stanley G. Jensen at sjensen@unlinfo.unl.edu.

SYMPTOMS OF THE HIGH PLAINS VIRUS IN MAIZE

Symptom expression of the High Plains virus (HPV) is extremely variable. This may reflect different genotype reactions, differences in environment, differences in time of infection or differences in the complex of infecting viruses. The limited set of photographs shown below was chosen to depict a range of plant ages and a range of reactions but they do not portray all possible combinations of symptoms. Chlorotic spots due to HPV always occur in a pattern associated with veins and are never sunken or watersoaked.

Maize screening trial all planted the same time. Row on left is a very susceptible commercial hybrid. Plants are severely stunted and chlorotic but no red or purple pigment develops on this genotype. Many plants are dead, others are dying, symptoms are on all leaves from the top to the bottom. The middle row is moderately susceptible. Plants show some stunting, purple leaf tips and margins and numerous chlorotic spots. Symptoms are most severe on lower leaves and progressively milder up the plant, top leaves look relatively healthy. The right row is a resistant hybrid with few or no symptoms on any leaves.

Closeup view of a young plant showing characteristic chlorotic spots. Spots on lower leave are scattered, becoming more frequent on upper leaves until they fuse to produce a general chlorosis. Note particularly that the spots tend to form along vascular bundles in linear arrays. This is characteristic of HPV. This plant has been overtaken by severe symptoms, is stunted and will probably soon die.

This is a young plant showing severe leaf symptoms. Note the chlorotic spot symptoms as described in photograph #2 and in addition one leaf is turning purple. It is severely chlorotic and almost white. Necrosis will start at the tip of the lower leaf and progress rapidly up the plant. When plants die they fall over and do not remain standing as dead stubs. See photo #1 for an illustration.

These are characteristic symptoms on a leaf from an older plant. Chlorotic spots while tending to be linear are almost random in distribution. The purple color develops first on the tips of the lower leaves, spreading along the leaf margins toward the base. Purpling is followed by necrosis. Symptoms progress upward rapidly on a young plant until the plant is overtaken by symptoms and then it may die. If the plants are older at infection, symptom development is slower.

Symptoms on a middle leaf of a mature plant showing spots in various stages of development and purpling along the leaf margin. Even with just a few spots, some spots form streaks or linear arrays. Spots never have margins or distinctive centers, they may be yellow or nearly white or there may be yellow, white and dead spots mixed on the same leaf. Spots or leaf margins are never sunken or water soaked. Necrotic spots are a uniform light brown to tan.

Five leaves from the top (left) to near the bottom (right) of a single HPV infected maize plant. Note that the symptoms are worse on the lower leaves and progressively less severe up the plant. In this genotype the symptoms are expressed as definite sectors or streaks of spots. In some genotypes the sectors are very sharply defined by the vascular bundles and may be very uniform in color. The color of the sectors may vary from light green to yellow to nearly white.

This is an electron micrograph of an HPV infected wheat cell. A portion of the nucleus with dark staining chromatin is in one corner. Four mitochondria are near the center of the micrograph. Large (150-200 nm diameter), darkly stained, double membrane bound spherical or ovoid particles are seen scattered throughout the cytoplasm. These particles are characteristic of HPV and of this group of mite transmitted pathogens.

SELECTED REFERENCES ON HPV AND RELATED PATHOGENS IN CHRONOLOGICAL ORDER. PAPERS IN PRESS SHOULD BE AVAILABLE IN SIX MONTHS OR LESS AFTER JULY 1996.

Slykhuis, J.T. 1956. Wheat spot mosaic, caused by a mite transmitted virus associated with wheat streak mosaic virus. Phytopathology 46:682-687.

Bradfute, O.E., and Nault, L.R.. 1969. Ultrastructure of Gramineae leaf tissue infected by a mite-borne virus-like agent. Phytopathology 59:1019 (Abstract)

Nault, L.R., Styer, W.E., Gordon, D.T., Bradfute, O.E., Lafever, H.N., and Williams, L.E. 1969. An eriophyid-borne pathogen from Ohio, and its relation to wheat spot mosaic virus. Pl. Dis. Reptr. 54:156-160.

Bradfute, O.E., Whitmoyer, R.E., and Nault, L.R. 1970. Ultrastructure of plant leaf tissue infected with mite-borne viral-like pathogens. Proc. Electron Microscope Soc. of Amer. 28:178-179.

Nault, L.R., and Styer, W.E. 1970. Transmission of an Eriophyid-borne wheat pathogen by Aceria tulipae. Phytopathology 60:1616-1618.

Slykhuis, J.T. 1980. Mites. in Vectors of Plant Pathogens. ed Kerry F. Harris and Karl Maramorosch. Academic Press, New York.

Borodina, E.E., Sukhareva, S.I., Shtien-Margolina, V.A., Evgrafova, L.P., and Krylov, A.V. 1982. Biological hosts of the agent of spot mosaic--a new viral disease of grasses. Mikrobiol. Ztl. 44(3): 38-41. (in Russian)

Gergerich, R.C., and Kim, K.S. 1983. A description of the causal agent of rose rosette disease. Arkansas Farm Research 32(3): 7.

Hiruki, C., Chen, M.H. 1988. Triple natural infection of wheat with the wheat spot mosaic agent, wheat streak mosaic and wheat striate mosaic viruses in Alberta. Phytopathology 78:1536. (Abstract)

Hiruki, C. 1989. Characterization of the disease agent of wheat spot mosaic disease in western Canada. Can. J. Plant. Path. 11: 190 (Abstract)

Zaychuk, K.S., and Hiruki, C. 1991. Further studies on wheat spot mosaic disease and the associated double membrane bodies. Can. J. Plant. Path. 13: 288.(Abstract)

Ahn K.-K., Kim, K.S., Gergerich, R.C., and Anderson, E.J. 1993. A virus-like agent associated with thistle mosaic disease. Phytopathology 83: 1402. (Abstract)

Jensen, S.G., and Lane, L.C. 1994. Observations on a mite transmitted disease of maize and wheat in the high plains. Rose Rosette International Symposium Proceedings p 43-45. Iowa State University, May 19-21, 1994. A. Epstein and J. Hill Editors

All papers in the Proceedings of the International Symposium: Rose Rosette and other Eriophyid mite-transmitted plant disease agents of uncertain etiology. May 19-21, 1994. Iowa State University, Ames, Iowa. A. H. Epstein and J. H. Hill Editors.

Brown, W.M. Jr., French, R.C., Hammond,R.W., and, Jensen, S.G. 1994. Occurrence and distribution of wheat viruses in Colorado. Phytopathology 84:1167. (Abstract)

Jardine, D.J., Bowden, R.L., Jensen, S.G., and Seifers, D.L. 1994 A new virus of corn and wheat in western Kansas. Phytopathology 84:1117-1118. (Abstract)

Jensen, S.G., and Lane, L.C. 1994. A new viral disease of corn and wheat in the high plains. Phytopathology 84:1158. (Abstract)

Jensen, S.G. 1994. The high plains virus - a new threat to corn and wheat production in the west. Proceedings of the 49th annual corn and sorghum industry research conference 1994. pp 156-164. Chicago, Ill. Publisher, American Seed Trade Association, Washington D.C.

Ahn, K. -K., Jensen, S.G., Anderson, E.J., Gergerich, R.C., and Kim, K.S. 1995. A virus-like disease of corn and wheat in the high plains: Ultrastructural aspects. Phytopathology 85:1183 (Abstract)

Jensen, S.G. 1995. The high plains virus, what is it? Where did it come from? Proceedings of the High Plains Virus Symposium. Amarillo, TX. October 19-20, 1995. J. Michels and C. Rush editors. (in press)

Jensen, S.G. and Hall, J.S. 1995. Molecular characterization of a viral pathogen infecting maize and wheat in the high plains. Phytopathology 85:1211. (Abstract)

Marcon, A., Jensen, S.G., and Kaeppler, S.M. 1995. High plains virus in maize: Symptomatology and genetic differences among inbreeds for disease response. Report of the NCR-167 - Corn Breeding and NCR-25 - Corn and Sorghum Diseases, Bettendorf, IA, Febr. 22-23, 1995.

Marcon, A., Jensen,S.G., and Kaeppler, S.M. 1995. Inheritance of tolerance to the high plains virus (HPV) complex in corn. Agronomy Abst. pp 175-176. (Abstract)

Rodriguez-Ballesteros, O.R., Marcon, A., Frederiksen, R.A., Rush, C.M., Heidel, G. Jeffers, D. Kaeppler, S.M., and Jensen, S.G. 1995. Genetics of resistance to high plains disease in maize. Proceedings of the High Plains Virus Symposium. Amarillo, TX. October 19-20, 1995. J. Michels and C. Rush editors. (in press)

All Papers in the Proceedings of the High Plains Virus Symposium. October 19-20, 1995. Amarillo, Texas. J. Michels and C. Rush editors. (in press).

Rush, C.M., and Michels, G.J. 1995. Studies of a new disease of corn of unknown etiology in the Texas panhandle. Phytopathology 85:1193. (Abstract)

Ahn, K.-K., Kim, K.S., Gergerich, R.C., Jensen, S.G., and Anderson, E.J.199_. Comparative ultrastructure of double membrane-bound particles and inclusions associated with eriophyid mite-borne plant diseases of unknown etiology : a potentially new group of plant viruses. Journal of Submicroscopic Cytology and Pathology: (in press)

Forester, R.L.,Strausbaugh, C.A., Jensen, S.G., Harvey, T., Seifers, D.L. 1996. Investigation of seed transmission of the high plains disease in sweet corn. Proceedings of the International Seed Trade Association Symposium, Cambridge England, 1996. (in press).

Jensen, S.G., Lane, L.C., and Seifers, D.L. 199_. A new disease of maize and wheat in the high plains. Plant Disease: (in press)

Marcon, A., Kaeppler, S.M., and Jensen, S.G. 1996. Resistance in Maize to the High Plains Virus. 7TH Interregional Corn Conference. Bettendorf, IA pp 26. (Abstract)

Marcon, A., Kaeppler, S.M. Jensen, S.G. and Hall, J.S. 1996. Characteristics of the High Plains Virus (HPV) and breeding for resistance in maize. Proceedings of the Latin American Workshop on Maize Diseases. Sete Lagoas, MG, Brazil May 20-24, 1996. Publisher EMBRAPA, E. de Oliveira Editor. (in press).

	Maize screening trial all planted the same time. Row on left is a very susceptible commercial hybrid. Plants are severely stunted and chlorotic but no red or purple pigment develops on this genotype. Many plants are dead, others are dying, symptoms are on all leaves from the top to the bottom. The middle row is moderately susceptible. Plants show some stunting, purple leaf tips and margins and numerous chlorotic spots. Symptoms are most severe on lower leaves and progressively milder up the plant, top leaves look relatively healthy. The right row is a resistant hybrid with few or no symptoms on any leaves.
	Closeup view of a young plant showing characteristic chlorotic spots. Spots on lower leave are scattered, becoming more frequent on upper leaves until they fuse to produce a general chlorosis. Note particularly that the spots tend to form along vascular bundles in linear arrays. This is characteristic of HPV. This plant has been overtaken by severe symptoms, is stunted and will probably soon die.
	This is a young plant showing severe leaf symptoms. Note the chlorotic spot symptoms as described in photograph #2 and in addition one leaf is turning purple. It is severely chlorotic and almost white. Necrosis will start at the tip of the lower leaf and progress rapidly up the plant. When plants die they fall over and do not remain standing as dead stubs. See photo #1 for an illustration.
	These are characteristic symptoms on a leaf from an older plant. Chlorotic spots while tending to be linear are almost random in distribution. The purple color develops first on the tips of the lower leaves, spreading along the leaf margins toward the base. Purpling is followed by necrosis. Symptoms progress upward rapidly on a young plant until the plant is overtaken by symptoms and then it may die. If the plants are older at infection, symptom development is slower.
	Symptoms on a middle leaf of a mature plant showing spots in various stages of development and purpling along the leaf margin. Even with just a few spots, some spots form streaks or linear arrays. Spots never have margins or distinctive centers, they may be yellow or nearly white or there may be yellow, white and dead spots mixed on the same leaf. Spots or leaf margins are never sunken or water soaked. Necrotic spots are a uniform light brown to tan.
	Five leaves from the top (left) to near the bottom (right) of a single HPV infected maize plant. Note that the symptoms are worse on the lower leaves and progressively less severe up the plant. In this genotype the symptoms are expressed as definite sectors or streaks of spots. In some genotypes the sectors are very sharply defined by the vascular bundles and may be very uniform in color. The color of the sectors may vary from light green to yellow to nearly white.
	This is an electron micrograph of an HPV infected wheat cell. A portion of the nucleus with dark staining chromatin is in one corner. Four mitochondria are near the center of the micrograph. Large (150-200 nm diameter), darkly stained, double membrane bound spherical or ovoid particles are seen scattered throughout the cytoplasm. These particles are characteristic of HPV and of this group of mite transmitted pathogens.