Virus infection improves drought tolerance

Abstract

Summary• Viruses are obligate intracellular symbionts. Plant viruses are often discovered and studied as pathogenic parasites that cause diseases in agricultural plants. However, here it is shown that viruses can extend survival of their hosts under conditions of abiotic stress that could benefit hosts if they subsequently recover and reproduce.• Various plant species were inoculated with four different RNA viruses, Brome mosaic virus (BMV), Cucumber mosaic virus (CMV), Tobacco mosaic virus and Tobacco rattle virus. The inoculated plants were stressed by withholding water. The onset of drought symptoms in virus-infected plants was compared with that in the plants that were inoculated with buffer (mock-inoculated plants). Metabolite profiling analysis was conducted and compared between mock-inoculated and virus-infected plants before and after being subjected to drought stress.• In all cases, virus infection delayed the appearance of drought symptoms. Beet plants infected with CMV also exhibited significantly improved tolerance to freezing. Metabolite profiling analysis showed an increase in several osmoprotectants and antioxidants in BMV-infected rice and CMV-infected beet plants before and after drought stress.• These results indicate that virus infection improves plant tolerance to abiotic stress, which correlates with increased osmoprotectant and antioxidant levels in infected plants.

Evidence for additive effects of virus infection and water availability on phytohormone induction in a staple crop

“…The role of SA in promoting systemic acquired resistance in plants following challenge with pathogens is well established (Vasyukova and Ozeretskovkaya, 2007). Both SA and ABA were shown to be responsive to virus infection in multiple study systems (Whenham et al, 1986;Xu et al, 2008). The multiple roles of phytohormones suggest they are associated with or can account for virus infection effects on drought and stress tolerance.…”

“…Similarly, in a tropical panic grass (Dichanthelium lanuginosum), association with specific virus-infected fungal endophytes imparts heat tolerance (Márquez et al, 2007). However, despite these apparently widespread and complex ecological associations, the underlying mechanisms driving differential plant responses to stress following virus infection are seldom explored (Xu et al, 2008).…”

“…For example, genetic stock of certain crop species has been inadvertently selected by breeders for infection with vertically transmitted viruses, presumably because of yield advantages imparted by infection (e.g., Capsicum annuum L., Okada et al, 2011;Roossinck, 2012a). In beets (Beta vulgaris L.), infection with Cucumber mosaic virus (CMV) enhances plant thermal and water-stress tolerance (Xu et al, 2008). Similarly, in a tropical panic grass (Dichanthelium lanuginosum), association with specific virus-infected fungal endophytes imparts heat tolerance (Márquez et al, 2007).…”

Move Over, Bacteria! Viruses Make Their Mark as Mutualistic Microbial Symbionts

“…Viruses can directly impact plants under abiotic stress as well. Several acute plant viruses conferred drought tolerance on a number of plants in greenhouse studies, and in at least one instance, virus infection also improves tolerance to cold (14) (Fig. 1).…”

Disease in Natural Plant Populations, Communities, and Ecosystems: Insights into Ecological and Evolutionary Processes

“…We also must remember that a pathogen is not a species but a particular ecological role (C. M. Malmstrom, personal communications), and that many microbes can vary in their effects on plants. For example, recent work suggests that viral infection may be common in asymptomatic plants (90) in nature and that viruses may sometimes have positive effects on plant hosts (139). A current focus in research considers disease in the context of diverse symbiotic interactions (mutualism to parasitism), and postulates that coevolutionary trajectories may relate to the complexity and productivity of the environment (128).…”