Wild and weedy Hesperis matronalis hosts turnip mosaic virus across heterogeneous landscapes in upstate New York

Abstract

Turnip mosaic virus (TuMV) is a widespread and economically important pathogen in agricultural crops and has the widest known host range in the virus family Potyviridae. While management of the virus and its aphid vectors in agricultural fields decreases virus incidence, many alternative wild hosts for TuMV may serve as source populations for crop infection through spillover. Over thirty years ago, research demonstrated that the introduced brassica, Dame's Rocket (Hesperis matronalis) hosts several viruses, including TuMV. Here, we use both enzyme-linked immunosorbent assays (ELISA) and next generation sequencing to document the frequent infection by TuMV of Dame's Rocket, which is common and widespread in disturbed areas around crop fields in upstate New York. Deep sequencing of multiple tissue types of symptomatic hosts indicate that the infection is systemic and causes diagnostic, visible symptoms. In a common garden experiment using host populations from across upstate New York, we found evidence for genetic tolerance to TuMV infection in H. matronalis. Field surveys show that TuMV prevalence varies across populations, but is generally higher in agricultural areas. Examining disease dynamics in this and other common alternative hosts will enhance our understanding of TuMV epidemiology and, more broadly, virus distribution in wild plants.

Keywords: Hesperis matronalis, Wild host plants; Plant virus ecology; Spillover; Tolerance; Turnip mosaic virus; Virus spillover; Wild viruses.

Fig. 1

Distribution of H. matronalis populations across North America (dark grey dots) and locations where visual presence of color breaking flower petals were detected, indicating TuMV presence in H. matronalis individuals (purple dots). Host occurrence data were sourced from online biodiversity repositories.

Fig. 2

Symptomatic host individuals (panels 1, 2, 3 and 4 on the left) were infected with viral contigs that matched to TuMV; asymptomatic control (panel 5) did not yield any virus contigs. Symptomatic phenotypes were defined by leaf mottle (panel B) and color breaking petals (panel D), while asymptomatic individuals had solid pigmentation and regular leaf margins (panels A and C).

Fig. 3

Leaf area estimate at the end of the common garden experiment. Host plant groups inoculated with TuMV are indicated in purple while control plants are in grey.

Fig. 4

Field surveys of TuMV prevalence in H. matronalis in 2018 in upstate New York. Purple indicates results from the Adirondacks and grey represents results from the Finger Lakes. A. TuMV prevalence across sites. Bars represent the standard deviation around the mean (sd=0.06). B Landcover variation between the agricultural Finger Lakes and largely forested.