Protecting potato plants against PVX and PVY viral infections by the application of native and chemically modified legume proteins

Abstract

Methylated soy and chickpea proteins (MSP and MCP, respectively), and 11S globulin (a soy protein fraction), are characterized by net positive charges and a more hydrophobic nature, nominating them as antiviral proteins. Under greenhouse conditions, potato plants (cv. Spunta) mechanically infected with potato virus Y (PVY) and potato virus X (PVX) were treated with MSP, MCP, and 11S globulin at different concentrations, after ten days of infection. The three tested substances inhibited the viral propagation, where the concentration 500 µg ml−1 produced the maximum antiviral action. This influence was further augmented by applying the material twice 10 and 20 days after the viral infection. Assessing the viral load by a double antibody sandwich ELISA (DAS-ELISA), dot-blot hybridization, and reverse transcription-polymerase chain reaction (RT-PCR) confirmed the viral inhibition, in the following order: MSP > MCP > 11S globulin. Bringing the virus in contact with MCP produced deformed TEM (transmission electron microscope) viral micrographs referring to a potential direct action of the substance on the virus. The tested materials' antiviral activity at 500 µg ml−1 was positively reflected on the growth and yield of PVY or PVX-infected potato plants cultivated under open field conditions in January. Considerably high increases in the tuber yield of either PVY-infected (68, 42, and 36%) or PVX-infected plants (52, 41 and 30%), were produced by the treatment with MSP, MCP and 11S (500 µg ml−1), respectively.