Title: Comparative transcriptomics implicates glutathione as a key regulator of ozone tolerance in legume crops Authors
Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2012
Publication Date: July 20, 2012
Citation: Yendrek, C.R., Koester, R.P., Ainsworth, E.A. 2012. Comparative transcriptomics implicates glutathione as a key regulator of ozone tolerance in legume crops [abstract]. Plant Biology Annual Meeting. Paper No. P23003. Technical Abstract: In the past 100 years, tropospheric ozone concentrations [O3] have more than doubled in response to industrialization. Models indicate that [O3] will continue to rise another 25% by the year 2050, thus exacerbating the strain on agriculture to provide food at a time of rapid population growth. Here, we compare the O3 response of Glycine max, Pisum sativum, Phaseolus vulgaris, Cicer arietinum and Medicago sativa - all commercially relevant crops, important for global food security. When grown in elevated chronic O3, in situ measurements of stomatal conductance (gs) revealed a broad range of O3 sensitivities. The most sensitive species, P. vulgaris and M. sativa, each had decreases in gs of 55%, while the most tolerant species, P. sativum, was not significantly different from ambient-grown plants. G. max and C. arietinum showed an intermediate response, with decreases in gs of 46% and 36%, respectively. This trend continued for measurements of net CO2 assimilation, Rubisco content and activity, and the maximum rate of electron transport. Also consistent with the ranges of O3 sensitivity were whole plant characteristics such as leaf longevity, total plant leaf area and biomass, as well as biochemical markers of antioxidant capabilities such as apoplastic ascorbate. At the transcript level, RNA-seq analysis revealed changes in core metabolic pathways across species and identified several Glutathione S Transferase (GST) genes that were 50-100 times more abundant in P. sativum compared to P. vulgaris and G. max. P. sativum leaves also had a significantly larger pool size of total glutathione that increased in response to elevated O3, whereas glutathione levels in P. vulgaris and G. max were unchanged. Based on these results, it may be feasible to improve the tolerance of sensitive crops by mining the genomic components from O3 tolerant species.