Environmental conditions modulate plant virus vertical transmission and survival of infected seeds.

Abstract

Seed transmission is a major mode for plant virus persistence and dispersal, as it allows virus survival within the seed in unfavorable conditions and facilitate spread when they become more favorable. To access these benefits, viruses require infected seeds to remain viable and germinate in altered environmental conditions, which may be also advantageous for the plant. However, how environmental conditions and virus infection affect seed viability, and whether these effects modulate seed transmission rate and plant fitness, are unknown. To address these questions, we utilized turnip mosaic virus (TuMV), cucumber mosaic virus (CMV) and Arabidopsis thaliana as model systems. Using seeds from plants infected by these viruses, we analyzed seed germination rates, as a proxy of seed viability, and virus seed transmission rate under standard and altered temperature, CO2 and light intensity. With this data, we developed and parameterized a mathematical epidemiological model to explore the consequences of the observed alterations on virus prevalence and persistence. Altered conditions generally reduced overall seed viability and increased virus transmission rate as compared to standard conditions, which indicated that under environmental stress infected seeds are more viable. Hence, virus presence may be beneficial for the host. Subsequent simulations predicted that enhanced viability of infected seeds and higher virus transmission rate may increase virus prevalence and persistence in the host population under altered conditions. This work provides novel information on the influence of the environment in plant virus epidemics.