Article

UV-B signaling pathways and fluence rate dependent transcriptional regulation of ARIADNE12.

Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria.
Physiologia Plantarum (Impact Factor: 3.66). 12/2011; 145(4):527-39. DOI: 10.1111/j.1399-3054.2011.01561.x
Source: PubMed

ABSTRACT ARI12 belongs to a family of 'RING between RING fingers' (RBR) domain proteins with E3 ligase activity (Eisenhaber et al. 2007). The Arabidopsis genome codes for 14 ARI genes and two pseudogenes (Mladek et al. 2003). Under standard growth conditions ARI12 is predominantly expressed in roots. In addition, ARI12 is strongly induced in leaves following exposure to ultraviolet (UV)-B radiation at dosages similar to those in areas under a reduced ozone layer. With quantitative reverse transcription polymerase chain reaction analyses and promoter:reporter constructs we show that the expression of ARI12 peaks 2-4 h after UV-B radiation exposure. To test if ARI12's transcriptional activation depends on key players of the UV-B signaling pathway, ARI12 expression was quantified in mutants of the ELONGATED HYPOCOTYL5 (HY5), HY5 HOMOLOG (HYH) and the UV RESISTANCE LOCUS8 (UVR8) genes. ARI12 transcription was reduced by 50-70% in hy5, hyh and hy5/hyh double mutants, but not in uvr8 mutants. However, under low fluence rate UV-B conditions ARI12 is not induced in these mutants. Our results show that ARI12 represents a downstream target of the low fluence rate UVR8/HY5/HYH UV-B signaling pathway while under high fluence rates its expression is regulated by the two bZIP transcription factors HY5 and HYH in an UVR8-independent manner.

0 Bookmarks
 · 
232 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: RBR (RING1-IBR-RING2) proteins play an important role in protein ubiquitination and are involved in many cellular processes. Recent studies showed plant RBR genes were induced by abiotic and biotic stresses. However, detailed studies on RBR genes in the important oil crop, soybean (Glycine max (L.) Merr.), is still lacking. Here we performed a genome-wide search and identified 24 RBR domain-containing genes from the soybean genome sequence and cloned 11 of them. Most soybean RBR proteins contain a highly conserved RBR supra-domain. Phylogenetic analyses indicated all 24 soybean RBR proteins are most related to the RBR proteins from Phaseolus vulgaris, and could be classified into seven groups including Ariadne A, Ariadne B, ARA54, Plant IIA, Plant IIB, Plant IIC, and Helicase. Tandem duplication and block duplication were found among the Ariadne B and Plant IIC group of soybean RBR genes. Despite the conserved RBR supra-domain, there are extensive variations in the additional protein motifs and exon-intron structures between different groups, which indicate they might have diverse functions. Most soybean RBR proteins are predicted to localize in nucleus, and four of them were experimentally confirmed by GFP fusion proteins. Soybean RBR genes are broadly expressed in many tissue types with a little more abundant in the roots and flowers than leaves, stems, and seeds. The expression of GmRTRTP3 (Plant IIB) and GmRTRTP5 (Plant IIC) are induced by NaCl treatment, which suggests these RBR genes might be involved in soybean response to abiotic stresses.
    PLoS ONE 01/2014; 9(1):e87282. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sunlight provides the necessary energy for plant growth via photosynthesis but high light and particular its integral ultraviolet (UV) part causes stress potentially leading to serious damage to DNA, proteins, and other cellular components. Plants show adaptation to environmental stresses, sometimes referred to as "plant memory." There is growing evidence that plants memorize exposure to biotic or abiotic stresses through epigenetic mechanisms at the cellular level. UV target genes such as CHALCONE SYNTHASE (CHS) respond immediately to UV treatment and studies of the recently identified UV-B receptor UV RESISTANCE LOCUS 8 (UVR8) confirm the expedite nature of UV signaling. Considering these findings, an UV memory seems redundant. However, several lines of evidence suggest that plants may develop an epigenetic memory of UV and light stress, but in comparison to other abiotic stresses there has been relatively little investigation. Here we summarize the state of knowledge about acclimation and adaptation of plants to UV light and discuss the possibility of chromatin based epigenetic memory.
    Frontiers in Plant Science 01/2014; 5:474. · 3.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Crops and other plants in natural conditions are routinely affected by several stresses acting simultaneously or in sequence. In areas affected by drought, plants may also be exposed to enhanced UV-B radiation (280-315nm). Each of these stress factors differently affects cellular metabolism. A common consequence of plant exposure to the separate action of water deficit and UV-B radiation is the enhanced generation of reactive oxygen species (ROS) causing damage to proteins, lipids, carbohydrates and DNA. Despite this destructive activity, ROS also act as signalling molecules in cellular processes responsible for defence responses. Plants have evolved many physiological and biochemical mechanisms that avoid or tolerate the effects of stress factors. Water deficit avoidance leads to stomatal closure, stimulation of root growth, and accumulation of free proline and other osmolytes. Secondary metabolites (flavonols, flavones and anthocyanins) that accumulate in epidermal cells effectively screen UV-B irradiation and reduce its penetration to mesophyll tissue. The coordinated increased activity of the enzymatic antioxidant defence system such as up-regulation of superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase and glutathione reductase is an important mechanism of tolerance to water deficit and UV-B radiation. The accumulation of low molecular antioxidants (proline, glycine betaine, ascorbate and glutathione) can also contribute to tolerance to water deficit. Polyamines, tocopherol, carotenoids, alkaloids, flavonoids and other secondary metabolites participate in the removal of ROS under conditions of increased UV-B radiation. The combination of water deficit and UV-B radiation induces responses that can be antagonistic, additive or synergistic in comparison with the action of single stresses. UV-B radiation may enhance resistance to water deficit and vice versa. Hydrogen peroxide, nitric oxide (NO), abscisic acid (ABA), jasmonic acid, ethylene, and salicylic acid participate in the activation of defence mechanisms. The involvement of these molecules in cross-resistance may rely on activation of enzymatic and non-enzymatic antioxidant systems, enzymes of flavonoid biosynthesis and the accumulation of low-molecular-weight osmolytes as well as regulation of stomatal closure. However, under the conditions of prolonged action of stressors or in the case where one of them is severe, the capacity of the defence system becomes exhausted, leading to damage and even death.
    Plant Science 12/2013; 213:98-105. · 4.11 Impact Factor

Full-text

Download
209 Downloads
Available from
May 19, 2014

Similar Publications