Host plant selection and virus transmission by Rhopalosiphum maidis are conditioned by potyvirus infection in Sorghum bicolor

Peter Klein,C Michael Smith

doi:10.1007/s11829-020-09783-4

Abstract

Many plant viruses are significant pathogens that are able to utilize arthropod vectors to infect a vast range of host plants, resulting in serious economic damage to world food crops. One such crop is Sorghum bicolor, grain sorghum, which is the fifth most important global cereal crop, it is grown for human consumption, animal feed, and biofuel. In this study, the Potyviruses Johnsongrass mosaic virus (JGMV), Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), and Sorghum mosaic virus (SRMV) were tested for their rates of transmission into tissues of S. bicolor by the corn leaf aphid, Rhopalosiphum maidis. In addition, virus infected and non-infected S. bicolor plants were assessed for their effects on R. maidis host plant selection behavior. Further, the propagation of each virus (viral ssRNA copy number) in infected plants was determined using qPCR amplification of viral coating protein gene fragments. The mean rate of JGMV transmission into S. bicolor plants by R. maidis was significantly lower than transmission of MDMV, SCMV, and/or SRMV. Sorghum bicolor plants infected with MDMV, SCMV or SRMV also attract significantly more R. maidis than non-infected plants. JGMV-infected plants do not effect a similar change in R. maidis plant choice preference. The preference of non-viruliferous R. maidis toward S. bicolor plants infected with MDMV, SCMV or SRMV, and lack of such attraction by JGMV-infected plants may play a role in virus transmission strategy and efficiency by the vector.

Highlights

The earliest fossilized evidence of stylet feeding arthropods was produced roughly 300 million years ago during the Carboniferous period (Labandeira 2013)
R. maidis exhibited a significant preference for S. bicolor plants infected with Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV) or Sorghum mosaic virus (SRMV) compared to mock-inoculated control plants by the end of the bioassay period (Fig. 2)
The mean numbers of R. maidis on plants infected with MDMV, SCMV or SRMV were significantly (P < 0.05) greater than those exposed to mock-inoculated S. bicolor plants

Summary

Introduction

The earliest fossilized evidence of stylet feeding arthropods was produced roughly 300 million years ago during the Carboniferous period (Labandeira 2013). Intense plant–arthropod interactions have resulted in the evolution of more than 4000 species of phloem-feeding Aphididae (aphids) (Jaouannet et al 2014), consisting of ~ 100 economically relevant species (Adams et al 2005) present on the vast majority of the global landmass (Macfadyen and Kriticos 2012) Due to their global distribution on ~ 25% of all plants and immense reproductive rates (Dedryver et al 2010), aphid-related losses to global. Around 75% of all known plant viruses are transmitted via a non-persistent mode of transmission In this process the virus acquired by feeding on an infected host plant retains in the stylet of the vector without entering other tissues or propagation.

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