Biological similarities and differences between Tobacco streak virus and Groundnut bud necrosis virus infecting groundnut (Arachis hypogea).

摘要

Biological differentiation of Groundnut bud necrosis virus (GBNV) and Tobacco streak virus (TSV) is investigated by sap inoculation of both viruses separately using 7-84 days old seedlings of groundnut cv JL24 at weekly intervals. These viruses differed by clearly distinguishable biological parameters such as, incubation period (GBNV: 5-14 days; TSV: 4-12 days), per cent infection in 7-63 days old seedlings (GBNV: 63-100%; TSV: 100%), per cent wilt of seedlings (GBNV: 50-100%; TSV: 25-100%) and period for complete wilting (GBNV: 15-28 days; TSV: 35-65 days). The typical characteristic symptoms induced by GBNV are localized chlorotic spots with concentric rings inside, occasionally localized oak leaf line pattern spots, gradual drying back of sap inoculated leaves including petiole, leaflets showing mosaic mottling having distorted lamina and drooping of quadrifoliates on main stem in younger seedlings. In contrary, the landmark symptoms induced by TSV are localized necrotic spots, presence of continuous necrotic streaks on main stem, general chlorosis of leaflets and pod necrosis. However, both viruses induced certain similar kind of symptoms in sequence such as, necrosis, yellowing and wilting of sap inoculated leaves, necrosis of petiole, top growing bud and stem, axillary shoot proliferation with small leaflets, stunting, pod size reduction and seed discoloration. Similarly, in both viruses, titer from localized infection is inversely proportional to the age of the seedlings upon sap inoculation. However, rapid decrease of titer of GBNV is observed in 7-49 days old seedlings due to quick wilting and severe necrosis as compared to TSV infection.