Cloning and Expression Analysis of bZIP Transcription Factor from Finger Millet (Eleusine coracana L.) Under Abiotic Stress Conditions

Basic leucine zipper (bZIP) transcription factors comprise one of the largest gene families in plants. They play a key role in almost every aspect of plant growth and development and also in biotic and abiotic stress tolerance. In this study, we were attempted to study characterization of bZIP, a transcription factor from a climate smart cereal finger millet (Eleusine coracana L.). Seeds of Eleusine coracana (finger millet) was purchase from local market and were grown under field conditions drought and salt stress conditions. In this study, EcbZIP gene was isolated from finger millet, cloned into DH5α cells, screened by using colony PCR and expression analysis in response to two abiotic stresses was carried out by using qRT PCR. EcbZIP coding DNA sequence and protein sequence were retrieved from NCBI Nucleotide Database and Genpept of Accession number KP033192.1 and AJP67539.1 and validated by using SMART (simple modular architecture tool) Domain Tool. Cloning and expression studies were carried out using standardized molecular biology protocol. Results depicted that EcbZIP transcription factor showed significant upregulation under both salt and drought stress conditions, indicating that it plays an important role in tolerance towards these stresses. In conclusion, expression analysis of bZIP gene from finger millet seed cultivar ML-365 showed 5-fold upregulation to salt stress to drought stress and 8-fold upregulation to salt stress. Hence, it can serve as a candidate gene for improving abiotic stress tolerance and can be helpful in enhancing the crop productivity under stress conditions.

Transcriptome and HPLC Analysis Reveal the Regulatory Mechanisms of Aurantio-Obtusin in Space Environment-Induced Senna obtusifolia Lines

Senna obtusifolia is a famous medicinal plant that is widely used in Asian countries. Its seed plays an important role in the treatment of many diseases because it contains various anthraquinones and flavonoids. Our previous studies have indicated that three space environment-induced S. obtusifolia lines (SP-lines) i.e., QC10, QC29, and QC46, have higher seed yield and aurantio-obtusin (AO) content. However, the underlying mechanism of higher AO content in SP-lines is still unknown. Herein, transcriptome sequencing and HPLC were employed to analyze the differences between SP-lines and ground control (GC3) and elucidate the regulatory mechanisms of AO accumulation in SP-lines. The results show that 4002 differentially expressed genes (DEGs) were identified in SP-lines versus (vs.) GC3. DEGs in the QC10 vs. GC3, QC29 vs. GC3, and QC46 vs. GC3 comparisons were classified into 28, 36, and 81 GO terms and involved in 63, 74, and 107 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. KEGG pathway and gene expression analysis revealed that DEGs involved in anthraquinone pathways were significantly elevated in QC10 and QC46. Integrating the results of GO annotation, KEGG enrichment, and gene expression analysis, we propose that the elevated genes such as DAHPS, DHQS, and MenB enhance the metabolic flux in the anthraquinone pathway and promote AO content in QC10 and QC46. Taken together, this study elucidated the mechanism of AO content in SP-lines and provides valuable genetic information for S. obtusifolia. In addition, to the best of our knowledge, this study presents the first transcriptome analysis of environment-induced medicinal plants and paves the way to select elite S. obtusifolia varieties in the future.