Glutaredoxins are small heat-stable oxidoreductases that transfer electrons from glutathione (GSH) to oxidized cysteine residues, thereby contributing to protein integrity and regulation. In Arabidopsis thaliana, floral glutaredoxins ROXY1 and ROXY2 and pathogen-induced ROXY19/GRX480 interact with bZIP transcription factors of the TGACG (TGA) motif-binding family. ROXY1, ROXY2, and TGA factors PERIANTHIA, TGA9, and TGA10 play essential roles in floral development. In contrast, ectopically expressed ROXY19/GRX480 negatively regulates expression of jasmonic acid (JA)/ethylene (ET)-induced defense genes through an unknown mechanism that requires clade II transcription factors TGA2, TGA5, and/or TGA6. Here, we report that at least 17 of the 21 land plant-specific glutaredoxins encoded in the Arabidopsis genome interact with TGA2 in a yeast-two-hybrid system. To investigate their capacity to interfere with the expression of JA/ET-induced genes, we developed a transient expression system. Activation of the ORA59 (OCTADECANOID-RESPONSIVE ARABIDOPSIS AP2/ERF-domain protein 59) promoter by transcription factor EIN3 (ETHYLENE INSENSITVE 3) was suppressed by co-expressed ROXY19/GRX480. Suppression depended on the L**LL motif in the C-terminus of ROXY19/GRX480. This putative protein interaction domain was recently described as being essential for the TGA/ROXY interaction. Ten of the 17 tested ROXY proteins suppressed ORA59 promoter activity, which correlated with the presence of the C-terminal ALWL motif, which is essential for ROXY1 function in flower development. ROXY19/GRX480-mediated repression depended on the GSH binding site, suggesting that redox modification of either TGA factors or as yet unknown target proteins is important for the suppression of ORA59 promoter activity.

Two phenolic compound parameters (total phenolic and flavonoid contents) and 5 antioxidant parameters (DPPH [2, 2-diphenyl-1-picrylhydrazyl] radical scavenging activity, HRSC (hydroxyl radical scavenging capacity), FRAP (ferric ion reducing antioxidant power), CUPRAC (cupric ion reducing antioxidant capacity), and MCA (metal chelating activity) were measured in bulbs and bolts of 43 garlic cultivars. The bulbs of cultivar ‘74-x’ had the highest phenolic content (total phenolic, flavonoids) and the strongest antioxidant capacity (DPPH, FRAP, and CUPRAC), followed by bulbs of cultivar ‘Hanzhong purple’; the bulbs of cultivar ‘Gailiang’ had the lowest phenolic content and antioxidant capacity (FRAP, CUPRAC, MCA). The bolts of ‘Hanzhong purple’ also had higher phenolic content. Principal components analysis (PCA) separated the cultivars into 3 groups according to phenolic and flavonoid contents and strength of antioxidant activity. The first group had higher HRSC, FRAP, and flavonoid content; the second group had higher total phenolic content and MCA; some cultivars in the third group had higher HRSC and FRAP. All 8 test garlic bulb extracts successfully prevented Human Vascular Endothelial Cell death and significantly prevented reactive-oxygen species (ROS) formation in oxidative stress model, in which cultivar ‘74-x’ had highest protection capability, following by cultivar ‘Hanzhong purple’, and the bulbs of cultivar ‘No. 105 from Korea’ had the lower protection capability against cell death and ROS formation. The protection capability in vivo of these garlic cultivars was consistent with their phenolic content and antioxidant capacity.

A single-nucleotide insertion resulted in a premature stop codon that is responsible for white immature fruit color in cucumber. Despite our previous progress in the mapping of the gene controlling white color in immature cucumber fruit and the identification of candidate genes, the specific gene that governs chlorophyll metabolism and its regulatory mechanism remains unknown. Here, we generated a mapping population consisting of 9497 F2 plants to delimit the controlling gene to an 8.2-kb physical interval that defines a sole candidate gene, APRR2. Sequencing the full-length DNA and cDNA of APRR2 allowed for identification of an allele, aprr2, encoding a truncated 101-amino acid protein due to a frameshift mutation and a premature stop codon. Gene structure prediction indicated that these 101 residues are located in a domain necessary for the function of the protein. The expression patterns of APRR2 were entirely consistent with the visual changes in green color intensity during fruit development. A microscopic observation of the fruit pericarp revealed fewer chloroplasts and a lower chloroplast chlorophyll storage capacity in Q24 (white) than in Q30 (green). A single-base insertion in the white color gene w, which leads to a premature stop codon, is hypothesized to have disabled the function of this gene in chlorophyll accumulation and chloroplast development. These findings contribute to basic research and the genetic improvement of fruit color.

Background Astrocytes have been shown to produce several pro- and anti-inflammatory cytokines to maintain homeostasis of microenvironment in response to vast array of CNS insults. Some inflammation-related cytokines are responsible for regulating such cell events. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that can be inducibly expressed in the lesioned spinal cord. Unknown is whether MIF can facilitate the production of immunosuppressive factors from astrocytes to tune milieu following spinal cord injury. Methods Following establishment of contusion SCI rat model, correlation of PGE 2 synthesis-related protein levels with that of MIF was assayed by Western blot. ELISA assay was used to detect production of PGE 2 , TNF-α, IL-1β, and IL-6. Immunohistochemistry was performed to observe colocalization of COX2 with GFAP- and S100β-positive astrocytes. The primary astrocytes were treated by various inhibitors to validate relevant signal pathway. Results The protein levels of MIF and COX2, but not of COX1, synchronously increased following spinal cord injury. Treatment of MIF inhibitor 4-IPP to the lesion sites significantly reduced the expression of COX2, mPGES-1, and as a consequence, the production of PGE 2 . Astrocytes responded robustly to the MIF interference, by which regulated MAPK/COX2/PGE 2 signal pathway through coupling with the CD74 membrane receptor. MIF-induced production of PGE 2 from astrocytes was able to suppress production of TNF-α, but boosted production of IL-1β and IL-6 in LPS-activated macrophages. Conclusion Collectively, these results reveal a novel function of MIF-mediated astrocytes, which fine-tune inflammatory microenvironment to maintain homeostasis. These suggest an alternative therapeutic strategy for CNS inflammation. Electronic supplementary material The online version of this article (10.1186/s12974-019-1468-6) contains supplementary material, which is available to authorized users.

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