Suppression of the HOS1 Gene Affects the Level of ROS Depending on Light and Cold

Abstract

The E3 ubiquitin-protein ligase HOS1 is an important integrator of temperature information and developmental processes. HOS1 is a negative regulator of plant cold tolerance, and silencing HOS1 leads to increased cold tolerance. In the present work, we studied ROS levels in hos1Cas9 Arabidopsis thaliana plants, in which the HOS1 gene was silenced by disruption of the open reading frame via CRISPR/Cas9 technology. Confocal imaging of intracellular reactive oxygen species (ROS) showed that the hos1 mutation moderately increased levels of ROS under both low and high light (HL) conditions, but wild-type (WT) and hos1Cas9 plants exhibited similar ROS levels in the dark. Visualization of single cells did not reveal differences in the intracellular distribution of ROS between WT and hos1Cas9 plants. The hos1Cas9 plants contained a high basal level of ascorbic acid, maintained a normal balance between reduced and oxidized glutathione (GSH and GSSG), and generated a strong antioxidant defense response against paraquat under HL conditions. Under cold exposure, the hos1 mutation decreased the ROS level and substantially increased the expression of the ascorbate peroxidase genes Apx1 and Apx2. When plants were pre-exposed to cold and further exposed to HL, the expression of the NADPH oxidase genes RbohD and RbohF was increased in the hos1Cas9 plants but not in WT plants. hos1-mediated changes in the level of ROS are cold-dependent and cold-independent, which implies different levels of regulation. Our data indicate that HOS1 is required to maintain ROS homeostasis not only under cold conditions, but also under conditions of both low and high light intensity. It is likely that HOS1 prevents the overinduction of defense mechanisms to balance growth.

Reactive oxygen species: Multidimensional regulators of plant adaptation to abiotic stress and development

“…tolerance by targeting INDUCER OF CBF EXPRESSION 1 (ICE1) for degradation, while silencing HOS1 leads to increased expression of APX1 and APX2 and decreased ROS levels (Gorpenchenko et al, 2023), suggesting that HOS1mediated negative regulation of cold tolerance is at least partially associated with ROS homeostasis (Figure 8).…”

“…Melatonin, a natural antioxidant molecule, efficiently alleviates cold stress in plants by modulating ROS levels and upregulating the expression of CBFs , CORs , ZAT10 , and ZAT12 (Bajwa et al, 2014; Qari et al, 2022). The E3 ubiquitin‐protein ligase HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (HOS1) negatively regulates cold tolerance by targeting INDUCER OF CBF EXPRESSION 1 (ICE1) for degradation, while silencing HOS1 leads to increased expression of APX1 and APX2 and decreased ROS levels (Gorpenchenko et al, 2023), suggesting that HOS1‐mediated negative regulation of cold tolerance is at least partially associated with ROS homeostasis (Figure 8).…”

Isolation and Characterization of Extracellular Vesicles from Arabidopsis thaliana Cell Culture and Investigation of the Specificities of Their Biogenesis

“…Western Blotting Proteins isolated from callus-derived ELVs were Western blotted using rabbit polyclonal antibodies against TET8 and HSP70 as primary antibodies (PHY1490S and PHY0167, respectively, PhytoAB, San Jose, CA, USA). Immunoreactive bands were detected with the anti-rabbit goat IgG conjugated with alkaline phosphatase (ab97048, Abcam, Cambridge, UK) followed by CDP-Star™ Substrate (T2146, Thermo Fisher Scientific, Waltham, MA, USA) detection reagent as described previously [85].…”