A family tree of the multifunctional proteins, glutathione transferases (GSTs, EC 2.5.1.18) was created in Solanum lycopersicum based on homology to known Arabidopsis GSTs. The involvement of selected SlGSTs was studied in salt stress response of tomato primed with salicylic acid (SA) or in un-primed plants by real-time qPCR. Selected tau GSTs (SlGSTU23, SlGSTU26) were up-regulated in the leaves, while GSTs from lambda, theta, dehydroascorbate reductase and zeta classes (SlGSTL3, SlGSTT2, SlDHAR5, SlGSTZ2) in the root tissues under salt stress. Priming with SA exhibited a concentration dependency; SA mitigated the salt stress injury and caused characteristic changes in the expression pattern of SlGSTs only at 10(-4) M concentration. SlGSTF4 displayed a significant up-regulation in the leaves, while the abundance of SlGSTL3, SlGSTT2 and SlGSTZ2 transcripts were enhanced in the roots of plants primed with high SA concentration. Unexpectedly, under high salinity the SlDHAR2 expression decreased in primed roots as compared to the salt-stressed plants, however, the up-regulation of SlDHAR5 isoenzyme contributed to the maintenance of DHAR activity in roots primed with high SA. The members of lambda, theta and zeta class GSTs have a specific role in salt stress acclimation of tomato, while SlGSTU26 and SlGSTF4, the enzymes with high glutathione conjugating activity, characterize a successful priming in both roots and leaves. In contrast to low concentration, high SA concentration induced those GSTs in primed roots, which were up-regulated under salt stress. Our data indicate that induction of GSTs provide a flexible tool in maintaining redox homeostasis during unfavourable conditions.

Wheat diseases present a constant and evolving threat to food security. We have little understanding as to how increased atmospheric carbon dioxide levels will affect wheat diseases and thus the security of grain supply. Atmospheric CO exceeded the 400 ppmv benchmark in 2013 and is predicted to double or even treble by the end of the century. This study investigated the impact of both pathogen and wheat acclimation to elevated CO on the development of Fusarium head blight (FHB) and Septoria tritici blotch (STB) disease of wheat. Here, plants and pathogens were cultivated under either 390 or 780 ppmv CO for a period (two wheat generations, multiple pathogen subcultures) prior to standard disease trials. Acclimation of pathogens and the wheat cultivar Remus to elevated CO increased the severity of both STB and FHB diseases, relative to ambient conditions. The effect of CO on disease development was greater for FHB than for STB. The highest FHB disease levels and associated yield losses were recorded for elevated CO -acclimated pathogen on elevated CO -acclimated wheat. When similar FHB experiments were conducted using the disease-resistant cultivar CM82036, pathogen acclimation significantly enhanced disease levels and yield loss under elevated CO conditions, thereby indicating a reduction in the effectiveness of the defence pathways innate to this wheat cultivar. We conclude that acclimation to elevated CO over the coming decades will have a significant influence on the outcome of plant-pathogen interactions and the durability of disease resistance.

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