Specific patterns of changes in wheat gene expression after treatment with three antifungal compounds

Abstract

The two fungicides azoxystrobin and fenpropimorph are used against powdery mildew and rust diseases in wheat (Triticum aestivumL). Azoxystrobin, a strobilurin, inhibits fungal mitochondrial respiration and fenpropimorph, a morpholin, represses biosynthesis of ergosterol, the major sterol of fungal membranes. Although the fungitoxic activity of these compounds is well understood, their effects on plant metabolism remain unclear. In contrast to the fungicides which directly affect pathogen metabolism, benzo(1,2,3) thiadiazole-7-carbothioic acid S-methylester (BTH) induces resistance against wheat pathogens by the activation of systemic acquired resistance in the host plant. In this study, we monitored gene expression in spring wheat after treatment with each of these agrochemicals in a greenhouse trial using a microarray containing 600 barley cDNA clones. Defence-related genes were strongly induced after treatment with BTH, confirming the activation of a similar set of genes as in dicot plants following salicylic acid treatment. A similar gene expression pattern was observed after treatment with fenpropimorph and some defence-related genes were induced by azoxystrobin, demonstrating that these fungicides also activate a defence reaction. However, less intense responses were triggered than with BTH. The same experiments performed under field conditions gave dramatically different results. No gene showed differential expression after treatment and defence genes were already expressed at a high level before application of the agrochemicals. These differences in the expression patterns between the two environments demonstrate the importance of plant growth conditions for testing the impact of agrochemicals on plant metabolism.

Dehydrogenases, urease and phosphatases activities of soil contaminated with fungicides

“…Other authors studied the effects of fungicides containing such active substances as strobilurins (Ray et al 2004, Ruske et al 2004, Pasquer et al 2005, epoxiconazole (Benton andCobb 1995, Ray et al 2004) and cyprodinil (Ray et al 2004), and found that all of them positively affected crop yields when applied at recommended doses. This meets the expectations of both producers and farmers.…”

“…Pesticides enable to achieve higher crop yields (Ray et al 2004, Pasquer et al 2005, Valenciano et al 2006), but at the same time negatively affect natural environment, including the soil environment, disturbing its homeostasis.…”

Characterization of a wheat transcription factor, TaWRKY45, and its effect on Fusarium head blight resistance in transgenic wheat plants

“…BTH is a functional analog of SA and one of the so-called plant activators, which all induce the same characteristic set of systemic acquired resistance (SAR) genes; this function of BTH has also been observed in wheat (Görlach et al 1996, Pasquer et al 2005. Prior research has indicated that BTH induces acquired resistance in wheat, including resistance to powdery mildew (Erysiphe graminís), leaf rust (Puccinia recondite), and leaf spot (Septoria spp.)…”

Oxidative Stress Defence Response of Carica papaya Challenged by Nitric Oxide, Papaya meleira virus and Saccharomyces cerevisiae

“…Systemic resistance has already been successfully induced in other plants against viruses, and because no transgenic techniques are employed it should be more commercially acceptable. However, it should be borne in mind that some concern has been expressed about the applicability of induced resistance in the field compared to the laboratory or glasshouse, as plants may already be at or near their limit from pre-existing stresses [67,68]. Another consideration is that the applicability of this technique is likely to be cultivar dependent, as has been found in tomatoes [69].…”