Early signaling components in ultraviolet‐B responses: distinct roles for different reactive oxygen species and nitric oxide

Abstract

The nature and origin of the reactive oxygen species (ROS) involved in the early part of Ultraviolet-B (UV-B)-induced signaling pathways were investigated in Arabidopsis thaliana using a range of enzyme inhibitors and free radical scavengers. The increase in PR-1 transcript and decrease in Lhcb transcript in response to UV-B exposure was shown to be mediated through pathways involving hydrogen peroxide (H(2)O(2)) derived from superoxide (O(2)(&z.rad;-)). In contrast, the up-regulation of PDF1.2 transcript was mediated through a pathway involving O(2)(&z.rad;-) directly. The origins of the ROS were also shown to be distinct and to involve NADPH oxidase and peroxidase(s). The up-regulation of Chs by UV-B was not affected by ROS scavengers, but was reduced by inhibitors of nitric oxide synthase (NOS) or NO scavengers. Together these results suggest that UV-B exposure leads to the generation of ROS, from multiple sources, and NO, through increased NOS activity, giving rise to parallel signaling pathways mediating responses of specific genes to UV-B radiation.

Retracted: Nitric oxide enhances plant ultraviolet‐B protection up‐regulating gene expression of the phenylpropanoid biosynthetic pathway

“…Interestingly, it has been shown that: (1) the induction of CHS expression may be co-ordinately regulated by UV-B and nitric oxide (NO) (Mackerness et al 2001); and (2) NO regulates the binding of the AtMYB2 TF to DNA in vitro (Serpa et al 2007). NO is a ubiquitous bioactive molecule, produced in plants by enzymatic and nonenzymatic routes (see Wilson, Neill & (Beligni & Lamattina 2000).…”

Role and Interrelationship of Gα Protein, Hydrogen Peroxide, and Nitric Oxide in Ultraviolet B-Induced Stomatal Closure in Arabidopsis Leaves

“…With regard to the enzymatic source of H 2 O 2 mediating UV-B-induced stomatal closure, our previous study has provided pharmacological evidence that 0.8 W m 22 UV-B-induced H 2 O 2 generation in broad bean guard cells depends on peroxidases but not NADPH oxidases (He et al, 2011a). However, UV-B is reported to stimulate mRNA transcript levels and the activity of NADPH oxidases (Rao et al, 1996;A-H-Mackerness et al, 2001;Casati and Walbot, 2003), and mutants in the Arabidopsis AtrbohD and AtrbohF genes show reduced H 2 O 2 accumulation in response to UV-B (Kalbina and Strid, 2006), suggesting that NADPH oxidases are also potential sources of H 2 O 2 induced by UV-B. To explore whether different doses of UV-B can activate distinct sources of H 2 O 2 to induce stomatal closure, we examined H 2 O 2 sources during stomatal closure induced by 0.5 and 0.7 W m 22 UV-B.…”

Peroxisomes Are Required for in Vivo Nitric Oxide Accumulation in the Cytosol following Salinity Stress of Arabidopsis Plants

“…This plant has been used in many plant studies to determine the involvement of NO in seed germination (Beligni and Lamattina, 2000;Batak et al, 2002;Bethke et al, 2006), biotic stress (Delledonne et al, 1998(Delledonne et al, , 2001), abiotic stress (Mackerness et al, 2001;Huang et al, 2004), programmed cell death (Clarke et al, 2000;Zhang et al, 2003), stomatal closure (Garcia-Mata et al, 2003;Desikan et al, 2004), iron metabolism (Murgia et al, 2004;Perazzolli et al, 2004), flowering (He et al, 2004;Simpson, 2005), and the protein S-nitrosylation (Feechan et al, 2005;Lindermayr et al, 2005), among others. Using the DAF-FM DA as a fluorescence probe, our results provide a detailed picture of the overall distribution of NO during the early development of 3-to 11-d-old Arabidopsis seedlings.…”