Effects of Elevated CO₂and Temperature on Pathogenicity Determinants and Virulence ofPotato virus X/Potyvirus-Associated Synergism

Abstract

Infections of plants by multiple viruses are common in nature and may result in synergisms in pathologies. Several environmental factors influence plant-virus interactions and act on virulence and host defense responses. Mixed viral infections may be more frequent under environmental conditions associated with global warming. Here, we address how changes in the two main parameters behind global warming, carbon dioxide concentrations ([CO₂]) and temperature, may affect virulence of Potato virus X (PVX)/potyvirus-associated synergism compared with single infections in Nicotiana benthamiana. Elevated [CO₂] resulted in attenuated virulence of single infection by PVX, which correlated with a lower accumulation of virus. In contrast, virulence of PVX/potyvirus-associated synergism was maintained at elevated [CO₂]. On the other hand, elevated temperature decreased markedly both virulence and virus titers in the synergistic infection. We also show that the HR-like response elicited by transient coexpression of PVX P25 together with the potyviral helper component-proteinase protein was significantly enhanced by elevated temperature, whereas it was reduced by elevated [CO₂]. Both proteins are main pathogenicity determinants in PVX-associated synergisms. These findings indicate that, under environmental conditions associated with global warming, virulence of PVX/potyvirus-associated synergisms is expected to vary relative to single infections and, thus, may have pathological consequences in the future.

Virulence determines beneficial trade‐offs in the response of virus‐infected plants to drought via induction of salicylic acid

“…Current climate prediction models indicate a gradual increase in CO 2 levels and an enhancement of the frequency and amplitude of heat and drought episodes (IPCC ). Moreover, changing environmental conditions may affect the incidence and severity of plant diseases and influence the further co‐evolution of plants and their pathogens (Eastburn et al ; Aguilar et al ).…”

“…Compared with single infections, co‐infection of Nicotiana benthamiana plants with PVX and Plum pox virus (PPV) resulted in increased virulence that led to necrotic symptoms in the newly emerging leaves. Furthermore, the expression of the P25 protein of PVX by a PPV vector was sufficient to induce an increase of PPV virulence that resembled that of the PPV/PVX synergistic interaction (Aguilar et al ,b).…”

Exploring how viruses enhance plants' resilience to drought and the limits to this form of viral payback

“…These concerns have stimulated research on the effects on plants of multiple abiotic and pathogenic stresses (Malmstrom & Alexander, ). Recent research in this area has shown, for example, that increased CO 2 levels can affect the outcome of single or mixed virus infections (Aguilar et al, ). Another interesting phenomenon discovered from studies of stressed plants, is that virus‐infected plants can display increased resilience to cold and drought (Xu et al, ; Davis et al, ).…”

Virus infection induces resistance to Pseudomonas syringae and to drought in both compatible and incompatible bacteria–host interactions, which are compromised under conditions of elevated temperature and CO2 levels

“…Baulcombe (University of Cambridge). The infectious cDNA clone of PVX carrying PPV HC-Pro (PVX-HC) sequences under the control of the PVX duplicated coat protein (CP) promoter was described before [24,33] . PPV expressing either PVX P25 ( PPV-P25) or GFP ( PPV-GFP) sequences in the viral polyprotein were described before [24].…”