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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #92121
Title: CHARACTERIZATION OF SUNFLOWER MOSAIC VIRUS FROM TEXAS WILD SUNFLOWERS

Author
item Gulya Jr, Thomas
item ISAKEIT, T. - TEXAS A&M AGR. EXT. SER.
item FREEMAN, T. - NDSU - DEPT PLANT PATHOLO

Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: 1/30/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Virus diseases of sunflower are fairly rare worldwide, and in the United States there have been only two published reports: one from Beltsville, MD and one from Texas in 1967. When wild sunflowers in southern Texas were observed with apparent virus symptoms in 1997, this presented a unique opportunity to gain more information on a rare, little studied disease. Confirmation of a virus causing the "mosaic" or yellow mottling of the leaves was made by electron microscope, which showed the virus as long, flexuous rods. Further examination revealed the presence of unusual structures in sunflower cells called pinwheel bodies, which are characteristic of a group called potato Y or "poty" viruses. It was possible to transmit the virus by rubbing sap onto other plants. Many commercial sunflower hybrids were susceptible, but a few USDA inbreds were found to be quite resistant. In tests of over 50 different genera of crops and weeds, it was found that the host range of the virus was very narrow, producing mosaic symptoms only on sunflower, zinnia and pepper. If the virus is truly limited to southern Texas, it does not pose a threat to U.S. sunflower production. Further work with a cooperating virologist from Idaho is in progress to purify the virus and then determine its exact relationship with other potyviruses.

Technical Abstract: There are only two reports of a naturally-occurring virus diseases of sunflower in the United States, so the observation of mosaic symptoms on wild sunflower in southern Texas in 1997 presented a unique opportunity to gather more information on a rare disease. EM observations of leaf dips revealed long, flexuous rods which confirmed the symptoms were viral in origin. Mechanical transmission of the virus was successful, which allowed us to do a host range and other studies. Most of the sunflower hybrids and inbreds tested were totally susceptible, but four inbreds and one hybrid appeared to be quite resistant. Over 80 species of crop and weed plants were inoculated, but only sunflower, zinnia, and pepper developed systemic mosaic symptoms, while Chenopodium quinoa produced chlorotic local lesions. In EM studies, the presence of pinwheel inclusion bodies, along with the long, flexuous nature of the virion, confirm that the virus is a member of the potato virus Y group (potyvirus). Purification of the virus is in progress, and a cooperating virologist is attempting to sequence the coat protein to determine the relationship of sunflower mosaic virus with other potyviruses.