Understanding and improving global crop response to ozone pollution

Abstract

Concentrations of ground-level ozone ([O ]) over much of the Earth's land surface have more than doubled since pre-industrial times. The air pollutant is highly variable over time and space, which makes it difficult to assess the average agronomic and economic impacts of the pollutant as well as to breed crops for O tolerance. Recent modeling efforts have improved quantitative understanding of the effects of current and future [O ] on global crop productivity, and experimental advances have improved understanding of the cellular O sensing, signaling and response mechanisms. This work provides the fundamental background and justification for breeding and biotechnological approaches for improving O tolerance in crops. There is considerable within-species variation in O tolerance in crops, which has been used to create mapping populations for screening. Quantitative trait loci (QTL) for O tolerance have been identified in model and crop species, and although none has been cloned to date, transcript profiling experiments have identified candidate genes associated with QTL. Biotechnological strategies for improving O tolerance are also being tested, although there is considerable research to be done before O -tolerant germplasm is available to growers for most crops. Strategies to improve O tolerance in crops have been hampered by the lack of translation of laboratory experiments to the field, and the lack of correlation between visual leaf-level O damage and yield loss to O stress. Future efforts to screen mapping populations in the field and to identify more promising phenotypes for O tolerance are needed.

Tropospheric Ozone Assessment Report: Present-day tropospheric ozone distribution and trends relevant to vegetation

“…Here, ozone impacts on ecosystems will include direct plant toxicity and cell damage, indirect effects mediated by changes in individual organisms and their ecological interactions, and changes in the rate and nature of chemical and biological processes (Ainsworth, 2016;Ainsworth et al, 2012;Ashmore, 2005). Ozone effects on vegetation are species-and cultivar-specific (Büker et al, 2015;Hayes et al, 2007;Mills et al, 2007a, b).…”

“…Excessive ozone uptake can cause altered physiology (photosynthesis, respiration, carbon allocation, stomatal functioning and emissions of volatile organic compounds), reduced growth (both above-and below-ground), reduced seed production, altered phenology, increased senescence and/or altered sensitivity to other biotic and abiotic stresses (e.g. Ainsworth, 2016;Ainsworth et al, 2012;Hoshika et al, 2015). Prolonged ozone uptake by vegetation may lead to changes in gene expression and species composition, the functioning of ecosystems, water economy and carbon sequestration (Bassin et al, 2007;Harmens and Mills, 2012;McLaughlin et al, 2007;Sitch et al, 2007;Sun et al, 2012).…”

“…Plants are vulnerable to ozone episodes where levels are high on several consecutive days as well as to longterm cumulative effects of absorbed ozone over one or several growing seasons (Ainsworth, 2016). Ozone exposure can result in visible leaf injury (leaf stipple, pale yellow or bronze lesions), which can alter the economic value of leafy vegetables (Fumagalli et al, 2001), whilst long-term exposure tends to be associated with growth or yield reductions and altered sensitivity to other abiotic and biotic stresses.…”

Physiological and Morphological Responses to Ozone Exposure of Coleus (Solenostemon scutellarioides (L.) Codd)

“…In many cropping and natural vegetation plants, to study varieties within the species is a standard way to generate susceptible and resistant varieties [31]. It is vital to obtain the resistant varieties to cultivate more yield, and therefore the agriculture sector can alter or stabilize production under ambient ozone that increases day by day [27]. Nonetheless, apart from cropping plants study and findings of different responses to ozone exposure among cultivars still in a low number.…”

“…Research into the changes in the physiological and biochemical state of ozone-affected plants is crucial and needs to be conducted on a broader range of plants than before [27]. Research needs to be done on the role of anthocyanin and how it responds to ozone [11].…”