Will chemical defenses become more effective against specialist herbivores under elevated CO 2 ?

Atmospheric carbon dioxide (CO 2 ) concentrations are among the chief factors shaping the mode and magnitude of interactions between plants and herbivorous insects. Here, we describe the first global analysis of systemic transcriptomic responses of grapevine Vitis vinifera plants to feeding of European grapevine moth Lobesia botrana larvae at future elevated CO 2 concentrations. The study was conducted on mature, fruit-bearing grapevine plants under ambient and elevated CO 2 concentrations in a grapevine free-air carbon dioxide enrichment (FACE) facility. Grapevine transcriptional response to herbivory was clearly dependent on phenological stage, with a higher number of differentially expressed genes identified at fruit development compared to berry ripening. At fruit development, more transcripts were differentially expressed as a response to herbivory under elevated compared to ambient CO 2 concentrations. Classification of the respective transcripts revealed that in particular genes involved in metabolic pathways, biosynthesis of secondary metabolites and plant-pathogen interactions were significantly enriched. Most of these genes had similar expression patterns under both CO 2 concentrations, with a higher fold-change under elevated CO 2 concentrations. Differences in expression levels of a subset of herbivory responsive genes were further validated by RT-qPCR. Our study indicates that future elevated CO 2 concentrations will affect interactions between grapevine plants and one of its key insect pests, with consequences for future relevance of L. botrana in worldwide viticulture.

Section: Introductionmentioning

confidence: 99%

Elevated atmospheric CO2 concentrations alter grapevine (Vitis vinifera) systemic transcriptional response to European grapevine moth (Lobesia botrana) herbivory

Reineke

Selim

2019

“…These studies generally involve measurements of development, reproduction, and consumption, and they often addresses the effects of elevated CO 2 on herbivores by altering a plant’s primary and secondary metabolism 8 . CO 2 enrichment may also affect herbivore consumption by altering plant hormones 9 , 10 . Although herbivore responses to increased CO 2 have been relatively well-studied given the extensive interpretations reported, they are highly variable and the underlying mechanisms need to be explored further 10 .…”

Section: Introductionmentioning

confidence: 99%

“…CO 2 enrichment may also affect herbivore consumption by altering plant hormones 9 , 10 . Although herbivore responses to increased CO 2 have been relatively well-studied given the extensive interpretations reported, they are highly variable and the underlying mechanisms need to be explored further 10 . Because information regarding the direct effects of elevated CO 2 on herbivory performance is currently lacking, additional data are needed to comprehensively understanding the influence of increased levels of CO 2 on herbivores.…”

Section: Introductionmentioning

confidence: 99%

Effects of elevated CO2 on the fitness and potential population damage of Helicoverpa armigera based on two-sex life table

Liu

Huang

Chi

et al. 2017

We evaluated the direct effects of three different atmospheric CO2 concentrations (380 ppm, 550 ppm and 750 ppm) on the population parameters of the cotton bollworm, Helicoverpa armigera fed an artificial diet. The life history and fitness of H. armigera were analyzed using an age-stage, two-sex life table. Our results showed significantly longer larval durations and lower female pupal weight under elevated CO2 than under ambient CO2. Additionally, the fecundity of H. armigera was lower under elevated CO2 than under ambient CO2. H. armigera reared under elevated CO2 conditions showed lower intrinsic and finite rates of increase but higher net consumption and finite consumption rates than H. armigera reared under ambient CO2 conditions. According to population projections, a much smaller total population size and reduced consumption capacities would be expected in an elevated CO2 atmosphere due to higher mortality and lower growth rate compared with ambient CO2 levels. These results indicate that the fitness of and potential damage caused by H. armigera would be affected by increased CO2 relative to ambient CO2 concentrations. Additional studies on the long-term direct and indirect effects of elevated CO2 levels on H. armigera are still needed.

“…In terrestrial systems, elevation of CO 2 tends to increase the production of plant secondary metabolites, but responses are variable 29 30 . The limited investigations in marine systems suggest that elevated CO 2 decreases phenolics in seagrasses 31 and brown macroalgae 32 or has little effect on terpenes in calcareous algae 33 .…”

mentioning

confidence: 99%

Effects of ocean acidification on the potency of macroalgal allelopathy to a common coral

Mónaco

Hay

Gartrell

et al. 2017

Many coral reefs have phase shifted from coral to macroalgal dominance. Ocean acidification (OA) due to elevated CO 2 is hypothesised to advantage macroalgae over corals, contributing to these shifts, but the mechanisms affecting coral-macroalgal interactions under OA are unknown. Here, we show that (i) three common macroalgae are more damaging to a common coral when they compete under CO 2 concentrations predicted to occur in 2050 and 2100 than under present-day conditions, (ii) that two macroalgae damage corals via allelopathy, and (iii) that one macroalga is allelopathic under conditions of elevated CO 2 , but not at ambient levels. Lipid-soluble, surface extracts from the macroalga Canistrocarpus (=Dictyota) cervicornis were significantly more damaging to the coral Acropora intermedia growing in the field if these extracts were from thalli grown under elevated vs ambient concentrations of CO 2 . Extracts from the macroalgae Chlorodesmis fastigiata and Amansia glomerata were not more potent when grown under elevated CO 2 . Our results demonstrate increasing OA advantages seaweeds over corals, that algal allelopathy can mediate coral-algal interactions, and that OA may enhance the allelopathy of some macroalgae. Other mechanisms also affect coral-macroalgal interactions under OA, and OA further suppresses the resilience of coral reefs suffering blooms of macroalgae.Coral reefs are one of the most diverse and complex ecosystems on the planet and provide livelihoods, food, and important ecosystem services for hundreds of millions of people 1 . However, a large proportion of reefs worldwide are severely degraded, and many reefs are on a trajectory of decline 2,3 . A symptom of decline is a reduced cover of reef-building corals and an increased abundance of upright macroalgae 4,5 . Understanding the drivers of macroalgal increases and the effects of coral-macroalgal interactions on reef degradation and resilience is of critical importance for the conservation of reef ecosystems [6][7][8] .The drivers of coral loss and macroalgal increase are varied and include herbivore loss through overfishing or disease, decreased water quality associated with nutrient enrichment and sedimentation, coral mortality caused by predators, hurricanes and cyclones, bleaching and diseases, algal colonization associated with coral morality, and a failure of juvenile corals and fishes to recruit once reefs become algal dominated 2,9-12 . Problems arising from human-induced ocean acidification, that occurs as atmospheric CO 2 is absorbed by the ocean and lowers pH 13 , have also been suggested as potential drivers of elevated algal populations on reefs [14][15][16] . Elevated seawater CO 2 concentrations may enhance fleshy algal growth rates 15,17,18 , reduce coral growth and calcification rates 19 , and strengthen space competition between macroalgae and corals, with outcomes that favour macroalgae over corals 14,15,20 . Habitats with naturally elevated CO 2 concentrations show increased fleshy macroalgal abundance 21 and decreased coral...