Identification strains of Bean Yellow Virus potyvirus (BYMV) on bean Phaseolus vulgaris in Iraq

Abstract

everal methods were used to identify the virus, such as indicator plants, physical properties, manners transmission by aphids and ELISA test and among indicator plants two strains of BYMV were identified. The first one was showed a necrotic local lesion on bean while the second one was showed strong epinasty, veinal necrosis in inoculated leaves then it caused top necrosis at last severe systemic mottle. This two different symptoms gives a positive reaction at ELISA test and this test was indicated that the two symptoms is belong for two strains of bean yellow mosaic virus ( BYMV).The physical properties for the first strain about the Thermal Inactivating point (TIP) was 50-55ْc while the second strain was 60ْc and the dilution end point (DEP)for the first strain was 10-2 but it was 10-2 -10-3 for the second one and the longevity in vitro (LIV) for the first strain 48 hrs at room temperature and the main transmission by insect was achieved by several species of aphids.The double immunodiffution test in agar have been showed meeting of two precipitin line without cross in this two lines when used antiserum of the first strain of virus against the two sap of infected plants with both strains of virus and this test was used in the second strain against sap of the both infected plants too with the two strains of the virus and this test was additional indication that the two symptoms in bean were belonged to a two different strains to the same virus.