Pathogenesis of sugar beets with mixed infections

Abstract

Sugar beet plantations were monitored in agrocenoses of Cherkasy region with both symptoms and no symptoms of viral diseases. Plant diagnostics by polymerase chain reaction was performed. The presence of beet mosaic virus, beet yellows virus, beet necrotic yellow vein virus and the presence in the tissues of leaf hyphae of phytopathogenic fungi, in particular Alternaria tenuissima. The lesion of the fungal disease was accompanied by the characteristic proteolytic destruction of the cell walls, especially intensive destruction of the tissues was observed in the conductive bunches of leaf petioles. The hyphae were found in the xylem vessels and by the nature of their spatial orientation in a series of sections, it is evident that the fungi spread in the tissues of the leaf mainly by conducting bundles. It is also shown that when fungi lesions of the covering tissues of the petiole in cells intensively develops a hypersensitivity reaction of plants, which is accompanied by ligninification and probing of the cell walls of the main parenchyma. It has been shown that under conditions of infection of sugar beet virus with necrotic yellowing of beet veins, in the phloem cells of conductive leaf bundles, the content of peroxidases bound to cell walls decreases against the background of accumulation of free isoenzymes in protoplasts of sieve tubules and cell tubules. The redistribution of peroxidase molecules in cell compartments is accompanied by a significant increase in their activity. In the case of mixed infections in the parenchyma of the sugar beet root, specific middle polar terpenoid compounds have also been identified.  It can be a potential biochemical markers of viral pathogenesis.