Growth Parameters and Resistance against Drechslera teres of Spring Barley (Hordeum vulgare L. cv. Scarlett) Grown at Elevated Ozone and Carbon Dioxide Concentrations

Abstract

Spring barley ( Hordeum vulgare L. cv. Scarlett) was grown at two CO2 levels (400 vs. 700 ppm) combined with two ozone regimes (ambient vs. double ambient) in climate chambers for four weeks, beginning at seedling emergence. Elevated CO2 concentration significantly increased aboveground biomass, root biomass, and tiller number, whereas double ambient ozone significantly decreased these parameters. These ozone-induced reductions in growth parameters were strongly overridden by 700 ppm CO2. The elevated CO2 level increased C : N ratio of the leaf tissue and leaf starch content but decreased leaf protein levels. Exposure to double ambient ozone did not affect protein content and C : N ratio but dramatically increased leaf starch levels at 700 ppm CO2. Resistance against Drechslera teres (Sacc.) Shoemaker was increased in leaves grown at double ambient ozone but was less obvious at 700 ppm than at 400 ppm CO2. Constitutive activities of beta-1,3-glucanase and chitinase were significantly higher in leaves grown at double ambient ozone compared to ambient ozone levels. The sum of methanol-soluble and alkali-released cell wall-bound aromatic metabolites (i.e., C-glycosylflavones and several structurally unidentified metabolites) and lignin contents did not show any treatment-dependent differences.

Advances in understanding CO2 responsive plant metabolomes in the era of climate change

“…Scarlett) grown under ambient (400 ppm) and elevated (700 ppm) CO 2 conditions in combination with two ozone regimes (ambient and double ambient) exhibited differences in methanol-soluble and alkali-released cell wall-bound aromatic metabolites (e.g., glycosylflavones and other unknown metabolites). However, lignin contents were treatment-independent (Plessl et al 2005). Interestingly, anthocyanins synthesized via the same phenylpropanoid pathway were not affected by high CO 2 either in maize (Zea mays L.) (Prins et al 2011).…”

Climate Change Effects on Plant Disease: Genomes to Ecosystems

“…Elevated CO 2 and ozone also have the potential to influence the effectiveness of host resistance (114,115). Pangga et al (106) report that high levels of CO 2 may prevent induced resistance as plants grow more rapidly.…”

Implications of climate change for diseases, crop yields and food security

“…Elevated ozone can have a similar range of effects (Plazek et al 2001;Plessl et al 2005), such as a 3-to 5-fold increase in rust infection on poplar, but this response is reduced by elevated CO 2 (Karnosky et al 2002). However, wheat stem rust was found to be strongly inhibited by ozone but unaffected by CO 2 (Tiedemann and Firsching 2000).…”

“…In rice, enhanced susceptibility to Magnaporthe oryzae under elevated CO 2 was attributed to lower leaf silicon content (Kobayashi et al 2006). Elevated CO 2 also reduced expression of induced resistance (Pangga et al 2004) or affected expression of resistance more directly (Plazek et al 2001;Plessl et al 2005), but in resistant cultivars it also enhanced resistance by boosting phytoalexin production (Braga et al 2006). In soybean elevated CO 2 increased Septoria brown spot but reduced downy mildew (Eastburn et al 2010).…”

“…In soybean elevated CO 2 increased Septoria brown spot but reduced downy mildew (Eastburn et al 2010). Pathogen-specific effects are common, and different stages of infection can be affected differentially with the cumulative effects resulting in changed disease levels (Plazek et al 2001;Plessl et al 2005). These cumulative effects may be due to specific differential responses to climate change at different stages of infection (Hibberd et al 1996).…”