Browsing by Author "Holuigue Barros, Loreto"

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    TGA class II transcription factors are essential to restrict oxidative stress in response to UV-B stress in Arabidopsis
    (2021) Herrera Vásquez, Ariel Esteban; Fonseca Cárdenas, Alejandro Alfredo; Ugalde Valdivia, José Manuel; Lamig Giannini, Liliana Andrea; Seguel Avello, Aldo Luis; Moyano Yugovic, Tomás Custodio; Gutiérrez Ilabaca, Rodrigo Antonio; Salinas, Paula; Vidal, Elena A.; Holuigue Barros, Loreto
    Plants possess a robust metabolic network for sensing and controlling reactive oxygen species (ROS) levels upon stress conditions. Evidence shown here supports a role for TGA class II transcription factors as critical regulators of genes controlling ROS levels in the tolerance response to UV-B stress in Arabidopsis. First, tga256 mutant plants showed reduced capacity to scavenge H2O2 and restrict oxidative damage in response to UV-B, and also to methylviologen-induced photooxidative stress. The TGA2 transgene (tga256/TGA2 plants) complemented these phenotypes. Second, RNAseq followed by clustering and Gene Ontology term analyses indicate that TGA2/5/6 positively control the UV-B-induced expression of a group of genes with oxidoreductase, glutathione transferase, and glucosyltransferase activities, such as members of the glutathione S-transferase Tau subfamily (GSTU), which encodes peroxide-scavenging enzymes. Accordingly, increased glutathione peroxidase activity triggered by UV-B was impaired in tga256 mutants. Third, the function of TGA2/5/6 as transcriptional activators of GSTU genes in the UV-B response was confirmed for GSTU7, GSTU8, and GSTU25, using quantitative reverse transcription–PCR and ChIP analyses. Fourth, expression of the GSTU7 transgene complemented the UV-B-susceptible phenotype of tga256 mutant plants. Together, this evidence indicates that TGA2/5/6 factors are key regulators of the antioxidant/detoxifying response to an abiotic stress such as UV-B light overexposure.
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    Transcription factor TGA2 is essential for UV-B stress tolerance controlling oxidative stress in Arabidopsis
    (2020) Herrera Vásquez, Ariel Esteban; Fonseca Cárdenas, Alejandro Alfredo; Ugalde Valdivia, José Manuel; Lamig Giannini, Liliana Andrea; Seguel Avello, Aldo Luis; Moyano Yugovic, Tomás Custodio; Gutiérrez Ilabaca, Rodrigo Antonio; Salinas, Paula; Vidal, Elena A.; Holuigue Barros, Loreto
    Plants possess a diversity of Reactive Oxygen Species (ROS)-processing enzymes involved in sensing and controlling ROS levels under basal and stressful conditions. There is little information on the transcriptional regulators that control the expression of these ROS-processing enzymes, particularly at the onset of the defense response to abiotic stress. Filling this gap, this paper reports a critical role for Arabidopsis TGA class II factors (TGA2, TGA5, and TGA6) in the tolerance response to UV-B light and photooxidative stress, by activating the expression of genes with antioxidative roles. We identified two clusters of genes responsive to UV-B and activated by TGA2/5/6 were identified using RNAseq and clustering analysis. The GSTU gene family, which encodes glutathione transferase enzymes from the Tau subclass, was overrepresented in these clusters. We corroborated the TGA2-mediated activation in response to UV-B for three model genes (GSTU7, GSTU8, and GSTU25) using RT-qPCR and ChIP analyses. Interestingly, using tga256 mutant and TGA2- and GSTU7-complemented mutant plants, we demonstrated that TGA2-mediated induction of GSTU genes is essential to control ROS levels and oxidative damage after UV-B and MeV treatments. This evidence positions TGA class II factors, particularly TGA2, as a key players in the redox signaling network of Arabidopsis plants.