Transcription factor TGA2 is essential for UV-B stress tolerance controlling oxidative stress in Arabidopsis

Abstract

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 ROSprocessing 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 GSTU7complemented 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. 2 KeywordsArabidopsis, glutathione transferase, GSTU7, photooxidative stress, redox-signaling, ROS, TGA class II, TGA2, transcription factor, UV-B stress Running TitleTGA2 factor controls oxidative stress in UV-B stress Highlight:Arabidopsis TGA2 transcription factor is part of the redox-signaling network controlling ROS levels and oxidative damage in tolerance response to UV-B and photooxidative stress, via activation of antioxidant GSTU genes.

Transcriptomic Changes in Internode Explants of Stinging Nettle during Callogenesis

“…GSTU7 from thale cress (corresponding to nettle contig_10747 and contig_3454) was shown to antagonize the oxidative stress caused by methyl viologen [56], while GSTU9 (contig_7301 and contig_4735) was up-regulated in Arabidopsis overexpressing a plastidial glycolate oxidase (where H 2 O 2 is produced in chloroplasts) [57]. Among the TFs induced in C1, it is worth mentioning TGA2 (contig_10732, log2FC 34D vs. 0D = 1.07), which mediates the response to UV-B and methyl viologen-triggered ROS and induces GSTU7, -8 and -25 expression by binding to their promoters [58]. The observed induction of GSTU genes in nettle at 34D of callogenesis confirms the involvement of ROS in transdifferentiation to callus.…”

Does the egg capsule protect against chronic UV-B radiation? A study based on encapsulated and decapsulated embryos of cuttlefish Sepia officinalis

“…Oxidative stress may also activate heat shock proteins (HSPs), especially the HSP70, which play vital roles in protein quality control and in repairing denatured proteins and provide a protective mechanism after exposure to stress [19,20]. Herrera-Vásquez et al [21] and Zhou et al [22] suggest that HSPs and GSTs support ROS processing systems initiated by antioxidant enzymes such as SOD, playing an essential role in the control of ROS levels and oxidative damage in the tolerance response to UVB light and photooxidative stress.…”

“…The eggs are attached to natural or artificial support in the intertidal area, where they are subject at low tide to large variations in temperature, low humidity and high amounts of sunshine (irradiance). The embryonic development of S. officinalisis within the egg involves 30 developmental stages grouped into five different phases: cleavage (stages 1-9), gastrulation (stages 10-13), organogenesis, flat stage (stages 14-18), organogenesis, extension stage (stages [19][20][21][22] and organogenesis, growth stage (stages [23][24][25][26][27][28][29][30] when the embryo has the general adult conformation [9]. The light sensitivity of S. officinalis has been demonstrated in the later stages [growth stage (stages [23][24][25][26][27][28][29][30]] of development [10,11].…”

“…Herrera-Vásquez et al . [ 21 ] and Zhou et al [ 22 ] suggest that HSPs and GSTs support ROS processing systems initiated by antioxidant enzymes such as SOD, playing an essential role in the control of ROS levels and oxidative damage in the tolerance response to UVB light and photooxidative stress.…”

TGA factors promote plant root growth by modulating redox homeostasis or response

“…Among all TGA genes, Clade II members have been most extensively studied and their central role in defense responses is well documented (Gatz, 2013). Clade II genes TGA2 , 5 , and 6 are multifunctional; they are not only required for salicylic acid and jasmonic acid/ethylene‐induced defense (Zhang et al, 2003; Zander et al, 2010), but also involved in ultraviolet (UV)‐B stress tolerance (Herrera‐Vásquez et al, 2020). Clade I genes TGA1 and 4 also have a role in defense responses but act in a different pathway.…”