Abstract
Thaxtomin A (TA) is a cellulose biosynthesis inhibitor synthesized by the soil actinobacterium Streptomyces scabies, which is the main causal agent of potato common scab. TA is essential for the induction of scab lesions on potato tubers. When added to Arabidopsis thaliana cell cultures, TA induces an atypical programmed cell death (PCD). Although production of reactive oxygen species (ROS) often correlates with the induction of PCD, we observed a decrease in ROS levels following TA treatment. We show that this decrease in ROS accumulation in TA-treated cells is not due to the activation of antioxidant enzymes. Moreover, Arabidopsis cell cultures treated with hydrogen peroxide (H2O2) prior to TA treatment had significantly fewer dead cells than cultures treated with TA alone. This suggests that H2O2 induces biochemical or molecular changes in cell cultures that alleviate the activation of PCD by TA. Investigation of the cell wall mechanics using atomic force microscopy showed that H2O2 treatment can prevent the decrease in cell wall rigidity observed after TA exposure. While we cannot exclude the possibility that H2O2 may promote cell survival by altering the cellular redox environment or signaling pathways, our results suggest that H2O2 may inhibit cell death, at least partially, by reinforcing the cell wall to prevent or compensate for damages induced by TA.
Highlights
Reactive oxygen species (ROS) are involved in several plant physiological processes, including growth and development, stress and defense responses, tissue differentiation, and senescence
Measurements of cell surface mechanics using atomic force microscopy (AFM)-based force microscopy showed that, while thaxtomin A (TA) treatment decreased cell wall stiffness, the addition of H2 O2 alone or in combination with TA increased cell wall rigidity. This suggests that ROS may, at least partially, inhibit TA-induced programmed cell death (PCD) by preventing or compensating for cell wall damages induced by TA
We first evaluated the level of ROS production before and after TA-treatment in the Arabidopsis suspension cultures used in the present study
Summary
Reactive oxygen species (ROS) are involved in several plant physiological processes, including growth and development, stress and defense responses, tissue differentiation, and senescence. Plant cells can produce ROS enzymatically to fulfill specialized function or in response to a wide variety of stimuli. ROS production can occur non-enzymatically, during photosynthesis and respiration, through electron transport chain reactions occurring in chloroplasts and mitochondria [1,3,4]. While basal ROS levels are essential to maintain normal cell functions, stress conditions can greatly enhance their accumulation up to toxic levels and cause important oxidative damage to cells. To maintain an adequate redox balance and prevent ROS-mediated damage, plant cells have evolved different anti-oxidative strategies involving various non-enzymatic and enzymatic ROS scavengers [2,3,5]
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