Differential ozone responses identified among key rust susceptible wheat genotypes

Authors: MASHAHEET, ALSAYED - Damanhour University; Burkey, Kent; SAITANIS, COSTAS - Agricultural University Of Athens; ABDELRHIM, ABDELRAZEK - Minia University; RAFIULLAH, RAFIULLAH - University Of Swabi; Marshall, David

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2020
Publication Date: 11/25/2020
Citation: Mashaheet, A., Burkey, K.O., Saitanis, C., Abdelrhim, A., Rafiullah, R., Marshall, D.S. 2020. Differential ozone responses identified among key rust susceptible wheat genotypes. Agronomy. 10:1853. https://doi.org/10.3390/agronomy10121853.
DOI: https://doi.org/10.3390/agronomy10121853

Interpretive Summary: Ground level ozone is formed by the action of sunlight on volatile hydrocarbons and nitrogen oxides produced during combustion of carbon-based fuels. Although frequently considered an urban problem, ozone pollution is much broader in scope because weather systems transport the pollutants into agricultural areas. Ozone is toxic to plants, causing visible injury to foliage and a reduction in the growth and yield of sensitive crops such as wheat. Estimates suggest that current ambient ozone levels are sufficient to reduce wheat yields on the order of 10% or more with greater yield losses anticipated if tropospheric ozone concentrations continue to rise. In the absence of international efforts to control air pollution, future wheat productivity may depend on breeding ozone-tolerant varieties. A first step in developing improved cultivars is identification of ozone-tolerant germplasm. In this study, an international team of scientists from Egypt, Greece, Pakistan, and USDA-ARS at Raleigh, North Carolina tested the ozone response of a set of wheat genotypes commonly used by wheat breeders to evaluate rust diseases. A wide range of ozone sensitivity was found with the genotype ‘Chinese Spring’ identified as ozone tolerant and the genotype ‘Thatcher’ as ozone sensitive with the other lines showing intermediate responses. The results suggest that simultaneous breeding for leaf rust and/or stem rust resistances and ozone tolerance may be possible.

Technical Abstract: The increasing ambient ozone (O3) concentrations and the resurgent rust diseases are two concomitant limiting factors to wheat production worldwide. Breeding resilient wheat cultivars bearing rust resistance and O3 tolerance, while maintaining high yield is critical for global food security. This study aims at identifying ozone tolerance among key rust susceptible wheat genotypes [Rust near-universal susceptible genotypes (RnUS)], as a first step towards achieving this goal. Tested RnUS included seven bread wheat genotypes (Chinese Spring, Line E, Little Club, LMPG 6, McNair 701, Morocco and Thatcher), and one durum wheat line (Rusty). Plants were treated with five O3 concentrations (CF, 50, 70, 90 and 110 ppb), in two O3 exposure systems (CSTR and OPEC), at 21-23 Zadoks decimal growth stage. Visible injury and biomass accumulation rate were used to assess O3 responses. Visible injury data showed consistent order of genotype sensitivity (Thatcher, LMPG 6 > McNair 701, Rusty > Line E, Morocco, Little Club > Chinese Spring). Additionally, leaves at different canopy positions showed differential O3 responses. Biomass accumulation under O3 stress showed similar result for the bread wheat genotypes. However, the durum wheat line ‘Rusty’ had the most O3-sensitive biomass production, providing a contrasting O3 response to the tolerance reported in durum wheat. Chinese Spring was the most tolerant genotype based on both parameters and could be used as a source for O3 tolerance, while sensitive genotypes could be used as sensitive parents in mapping O3 tolerance in bread wheat. The suitability of visible symptoms and biomass responses in high-throughput screening of wheat for O3 tolerance was discussed. The results presented in this research could assist in developing future approaches to accelerate breeding wheat for O3 tolerance using existing breeding materials.