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Author: search.filters.author.Ciftci, Yelda OzdenSubject: search.filters.subject.Gene expression

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    Determination of Physiological, Biochemical and Molecular Interactions Between Fraser's Photinia (Photinia x fraseri Dress.) and Its Endophytic Bacterium PGB_invit
    (2022) Turkolmez, Nil; Karakaya, Merve; Ekinci, Muhammed Hamit; Lucas, Stuart James; Akkaya, Ozlem; Seker, Mine Gul; Kayihan, Ceyhun; Ciftci, Yelda Ozden
    An endophytic beneficial bacterium was isolated and characterized from in vitro grown microshoots of Fraser's Photinia (Photinia x fraseri Dress.) in our previous studies. This bacterium, which is nominated as PGB_invit and determined as a member of Pseudorhodoplanes sp., has ability to fix nitrogen and produce plant growth promoting regulators such as indole acetic acid and gibberellic acid. Due to its beneficial traits, this specific bacterium promotes in vitro proliferation of Fraser's Photinia microshoots and enables microshoots to be conserved at 25 +/- 2oC for up to 16 months without requiring periodic subculture. Thus, the aim of the study is to identify physiological, biochemical and molecular influences of this bacterium together with determination of its localization in plant tissues. Our results showed that the optimum inoculum concentration of PGB_invit is 10(6) cfu ml(- 1) and the optimum incubation period is 60 days. Also, this study provides clear microscopic evidence of the endopyhtic bacterial colonization of GFP-labeled bacteria detected by confocal microscopy in Fraser's Photinia. Proline content was significantly enhanced in response to bacterial treatment whereas cellular H2O2 content was decreased. An increase in catalase activity was also detected, indicating that the results were consistent with the decrease in H2O2 content. Moreover, RNA sequencing (RNA-Seq) was also used to assess gene expression patterns and differential expression of five genes (predicted "MID1-Complementing Activity 1", Ubiquitin-conjugating enzyme E2, predicted "E3 ubiquitin-protein ligase RHA1B-like", 4-coumarate-CoA ligase-like 9, and methionine aminopeptidase 2B-like) between active and inactive form of the bacterium was confirmed by qRT-PCR. Among them, ubiquitin-conjugating enzyme E2 and predicted "E3 ubiquitin-protein ligase RHA1B-like genes which play important roles in plant immunity and stress were down-regulated in plant samples inoculated with bacteria which may demostrate that PGB_invit does not evoke plant immune system and has a positive effect on reducing stress on Fraser's Photinia. Key message PGB_invit (Pseudorhodoplanes sp.) has a positive impact on plants growth and development with several mechanisms. Besides its shown that PGB_invit is not act as a stress factor, as it does not cause a severe oxidative stress and thus can be used as a biofertilizer.
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    Regulation of boron toxicity responses via glutathione-dependent detoxification pathways at biochemical and molecular levels in Arabidopsis thaliana
    (2019) Kayihan, Doga Selin; Kayihan, Ceyhun; Ciftci, Yelda Ozden; 0000-0002-9799-3648; Y-6244-2018
    The fine-tuned regulation of the Halliwell-Asada cycle (ascorbate-glutathione pathway) in Arabidopsis thaliana under boron (B) toxicity was shown in our previous report. In this study, we investigated the expression levels of some members of the glutathione S-transferase (GST) superfamily, such as phi (GSTF2, GSTF6, GSTF7, and GSTF8), tau (GSTU19), and zeta (GSTZ1) classes in Arabidopsis thaliana that were exposed to 1 mM boric acid (1B) and 3 mM boric acid (3B). Additionally, the expression levels of genes for glutathione (GSH) and phytochelatin biosynthesis as well as miR169 and miR156 were evaluated in Arabidopsis thaliana exposed to 1B and 3B. Moreover, changes in the levels of total GST activity; GSH; and total, protein-bound, and nonprotein thiols were spectrophotometrically determined. GSH levels and nonprotein thiol content did not change significantly following both B-toxicity conditions. Expression levels of GSH1 and GSH2 stayed stable under 1B toxicity; however, GSH1 expression increased significantly under 3B conditions in Arabidopsis thaliana. The expression levels of four genes from phi class members of GST were not dramatically changed under B-toxicity conditions. However, the transcript levels of miR169, ATGSTU19, and ATGSTZ1 were significantly increased after 1B and 3B exposure. These GST genes may have a role in the dramatic increase of total GST activity under toxic B. To the best of our knowledge, this is the first report displaying an integrative view of high-B-induced regulation of GSH-dependent enzymatic machinery at different biological organization levels in Arabidopsis thaliana.