Fen Edebiyat Fakültesi / Faculty of Letters and Science
Permanent URI for this collectionhttps://hdl.handle.net/11727/1396
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Item The involvement of the induction of anthocyanin biosynthesis and transport in toxic boron responsive regulation in Arabidopsis thaliana(2021) Kayihan, Ceyhun; 0000-0003-1684-4147; AAW-8352-2021Recently, boron (B) has been found to form a complex with anthocyanin, which could be evidence for the B tolerance mechanisms that reduce free B in the leaf tissues of plants. However, the molecular mechanism of anthocyanin biosynthesis and transport has not been satisfactorily elucidated in plants exposed to toxic B. Therefore, the changes in expression levels of some of the phenylpropanoid pathway genes, early and late flavonoid biosynthetic genes, and transcription factors related to anthocyanin biosynthesis and transport were determined in Arabidopsis thaliana under B toxicity. Accordingly, 1 mM boric acid treatment did not cause any significant change in the expression levels of anthocyanin biosynthesis genes such as PAL1, PAL2, C4H, 4CL3, CHS, ANS and transcription factors such as MYBD and TT8 in Arabidopsis thaliana. However, 3 mM boric acid treatment induced the expression levels of anthocyanin biosynthesis genes such as C4H, 4CL3 and transcription factors including MYB75, MYB114 and anthocyanin transporter genes such as TT13 and TT19. In addition to B-anthocyanin, B-anthocyanins conjugated with glutathione (GSH) complexes can also participate in the internal B tolerance mechanism in plants. Therefore, the direct role of the B-anthocyanin complex without GSH conjugation needs to be determined. For this purpose, anthocyanin accumulation was determined in slim1 mutant Arabidopsis thaliana exposed to excess B because SLIM1 transcription factor activates sulfate acquisition for S assimilation, which generates cysteine, the substrate for GSH. Accordingly, it was gradually increased through increasing toxic B levels in both wild type (WT) and slim1 mutant plants. slim1 mutant had more anthocyanin accumulation than WT under control and all toxic B conditions. In conclusion, increases in expression levels of MYB75, MYB114, TT13, TT19 and in anthocyanin level in slim1 mutant in response to increased toxic B levels showed that anthocyanins may play a primary role in B tolerance in plants.Item Identification and expression profiling of toxic boron-responsive microRNAs and their targets in sensitive and tolerant wheat cultivars(2021) Kayihan, Doga Selin; Aksoy, Emre; Kayihan, Ceyhun; 0000-0003-1684-4147; AAW-8352-2021Post transcriptional gene regulation in wheat cultivars caused by boron (B) toxicity has not been reported to date. In this study, two wheat cultivars Bolal-2973 (B-tolerant) and Atay-85 (B-sensitive) were compared with regard to the transcriptional regulation of miR319, miR172 and miR398 and their plausible target genes in order to address differences in their performances under high B levels. The expression levels of Cu/ZnSOD gene were found to be greater in Atay exposed to toxic B compared to Bolal, as verified by stable expression level of miR398. In wheat cultivars, both toxic B concentrations might cause an induction of leaf senescence mechanism due to stable level of JA and ethylene-related miRNAs, miR172 and miR319. miR172 targeting transcription factor TOE1 was only induced under B toxicity in sensitive cultivar Atay. However, MY133 as target of miR319 was significantly upregulated under toxic B in both cultivars. Also, computational prediction of these miRNA targets in wheat was performed and their orthologs in Arabidopsis thaliana were determined. Functional protein association networks of proteins encoded by miRNA targets and gene ontology enrichment analyses of these genes were identified. We identified new sets of genes that are targets of miR172, miR319 and miR398 in T. aestivum. In addition, miR172, miR319 and miR398 are responsive to different nutrient deficiencies or toxicities such as Fe, P, B, S and Cu, suggesting crosstalk between the post-transcriptional regulatory mechanisms involving miRNAs in plants.Item The role of microRNAs in recovery rates of Arabidopsis thaliana after short term cryo-storage(2020) Ekinci, Muhammad Hamit; Kayihan, Doga Selin; Kayihan, Ceyhun; Ciftci, Yelda Ozden; 0000-0003-1684-4147; Q-4515-2016Key message The alteration of expression levels of cold- and oxidative stress-induced genes related-miRNAs play a crucial role in development of successful cryopreservation protocols. Cryopreservation is a safe and cost-effective long-term storage technique which helps to conserve plant germplasm in liquid nitrogen (LN). However, up to now, the molecular regulatory mechanisms that effect survival after cryopreservation have not been satisfactorily elucidated in plants. Thus, the aim of the study concerned to reveal out microRNA (miRNA)-based post-transcriptional regulations during different stages of cryopreservation in 48-h and 72-h in vitro germinated Arabidopsis thaliana since miRNAs not only regulate gene expression in developmental process of plants, but also control transcription in stress conditions by post-transcriptional degradation. Among the screened 10 miRNAs and their selected target genes, differential expression levels were detected in two tested germination time according to exposure of cryopreservation stages, as 6 miRNAs (miR393, miR397, miR398, miR159, miR169 and miR172) showed a mixed pattern in 48-h germinated seedlings while 6 miRNAs (miR397, miR398, miR159, miR169, miR172 and miR408) were significantly down-regulated in OD (Osmoprotection-Dehydration) and LD (Liquid nitrogen-Dilution) samples in comparison to control in 72-h germinated ones. The most striking expression change was obtained in miR393 as it was up-regulated 15-fold in LN treated 48-h seedlings while relatively lower amount induction (twofold) was recorded in cryopreserved 72-h seedlings. The concominant down-regulation of its target TIR1 and HOS1 expression and up-regulation of CBF1 and CBF3 and their downstream genes (COR15 and COR47) were also observed in cryopreserved 48-h germinated seedlings. Thus, the alteration of expression levels of cold-induced genes related-miRNAs plays a crucial role for successful cryopreservation.Item Moderate level of toxic boron causes differential regulation of microRNAs related to jasmonate and ethylene metabolisms in Arabidopsis thaliana(2019) Kayihan, Doga Selin; Kayihan, Ceyhun; Ciftci, Yelda Ozden; 0000-0003-1684-4147; Q-4515-2016Earlier our colleagues detected that the genes related to jasmonate (JA), ethylene, and cell wall modification were significantly regulated under boron (B) toxicity in wheat. Determination of regulation mechanisms of these novel genes under B toxicity is very important in Arabidopsis thaliana as a model plant. As key regulators, the microRNAs (miRNAs) regulate gene expression at the posttranscriptional level and respond to numerous abiotic stresses in plants. In this study, expression levels of miRNAs such as miR159, miR172, miR319, and miR394 targeting JA and ethylene-related transcription factors and also miR397 targeting laccase were determined in Arabidopsis thaliana under toxic B conditions. Stem-loop quantitative reverse transcription polymerase chain reaction was used to amplify mature miRNAs for expression analyses. Expression levels of miRNAs targeting transcription factors related to JA and ethylene metabolisms were induced remarkably in moderate B toxicity (condition 1B) but not in severe B toxicity (condition 3B). Most remarkable regulations were obtained in miR172 and miR319 in Arabidopsis thaliana. Expression level of miR397 did not remarkably change under B toxicity, indicating a lack of posttranscriptional regulation of laccase related to cell wall modification. Moreover, miRNAs targeting transcription factors related to JA and ethylene metabolisms might be oxidative stress-adaptive responses of Arabidopsis to B toxicity.