Further studies on turnip yellow mosaic tymovirus isolates from an endemic Australian <i>Cardamine</i>

Abstract

Native and introduced species of Cardamine and other brassicas were collected from various parts of south‐eastern Australia and tested for sap‐transmitted viruses. Isolates of turnip yellow mosaic virus (TYMV‐Cd) were obtained from a robust sward‐forming (SF) species, C. lilacina , that is an endemic species and restricted to the high glacial cirques of the Kosciusko alpine area. At two sites (Blue Lake and Club Lake) 22% of the plants were infected. An undescribed species of flightless pill beetle, Pedilophorus (Byrrhidae), was found on the C. lilacina SF plants. They preferred feeding on leaf discs infected with TYMV‐Cd rather than on virus‐free leaf discs and transmitted the virus for 48 h to seedlings of C. lilacina SF (2.5%) or Chinese cabbage (10%). The pattern of distribution of TYMV‐Cd and its close association with Pedilophorus suggested that it is not a recent migrant to the area. The possible time of its arrival is discussed. A carlavirus was isolated from up to 4% of three other native highland Cardamine species.