Interaction of Rosmarinus officinalis L. with UV-A radiation by preserving its morphological traits and modifying its phenolic composition.

This study investigated the effects of supplemental ultraviolet-A (UV-A) radiation on phenolic compounds, antioxidant properties, and agro-morphological characteristics of Rosmarinus officinalis L. Greenhouse plants were exposed to UV-A for 1, 2, and 4 h daily, 40 days. Based on the results, UV-A radiation had no significant effect on agro-morphological traits, while it remarkably altered chlorophyll content, total phenolic and flavonoid contents, as well as radical scavenging activity. Plants exposed to UV-A (4h) had the highest total phenolic and flavonoid contents, antioxidant activity, as well as the content of rosmarinic, carnosic, vanillic, and caffeic acids, and naringin. Conversely, carnosol, cirsimaritin, and hispulin levels decreased in treated plants. Overall, UV-A radiation had a positive effect on the medicinal aspects of R. officinalis L., which is important in the pharmaceutical industry. Therefore, it is suggested application of UV-A emitting LEDs for commercial purposes, with a lower risk level than UV-B and UV-C.

Exogenous melatonin delays strawberry fruit ripening by suppressing endogenous ABA signaling.

Ripening as a physico-chemical change is part of a continuous developmental process and hormones play a major role in this processes. The present study was carried out to investigate the effect of external melatonin (0 and 10 µM) injection at the light green stage on the ripening of strawberry fruit. The fruit was sampled for morphological, biochemical, and gene expression analysis during (0, 5, 10, and 15 days after treatment). The results showed a lower accumulation of anthocyanin content was observed in fruits treated with 10 µM. The injection of 10 µM melatonin caused a lower total soluble solid content and fruit color, and higher titratable acidity and softening. The total phenol content was higher in fruit treated with 10 µM melatonin, accompanied by increased PAL enzyme activity and gene expression, increased DPPH scavenging capacity, and higher content of quercetin, gallic, caffeic, and chlorogenic acids. The delay in fruit ripening was associated with suppression of H2O2 level and endogenous ABA accumulation caused by lower expression of NCEDs genes. In general, it is concluded that activating the melatonin ROS scavenging cascade might be responsible for the delayed ripening and development of strawberry fruit. Therefore, our study demonstrates that the exogenous application of 10 µM melatonin can slow the ripening of strawberry fruit.

Identifying conserved genes involved in crop tolerance to cold stress.

Low temperature is a limiting factor for crop productivity in tropical and subtropical climates. Cold stress response in plants involves perceiving and relaying the signal through a transcriptional cascade composed of different transduction components, resulting in altered gene activity. We performed a meta-analysis of four previously published datasets of cold-tolerant and cold-sensitive crops to better understand the gene regulatory networks and identify key genes involved in cold stress tolerance conserved across phylogenetically distant species. Re-analysing the raw data with the same bioinformatics pipeline, we identified common cold tolerance-related genes. We found 236 and 242 commonly regulated genes in sensitive and tolerant genotypes, respectively. Gene enrichment analysis showed that protein modifications, hormone metabolism, cell wall, and secondary metabolism are the most conserved pathways involved in cold tolerance. Upregulation of the abiotic stress (heat and drought/salt) related genes [heat shock N -terminal domain-containing protein, 15.7kDa class I-related small heat shock protein-like, DNAJ heat shock N -terminal domain-containing protein, and HYP1 (HYPOTHETICAL PROTEIN 1)] in sensitive genotypes and downregulation of the abiotic stress (heat and drought/salt) related genes (zinc ion binding and pollen Ole e 1 allergen and extensin family protein) in tolerant genotypes was observed across the species. Almost all development-related genes were upregulated in tolerant and downregulated in sensitive genotypes. Moreover, protein-protein network analysis identified highly interacting proteins linked to cold tolerance. Mapping of abiotic stress-related genes on analysed species genomes provided information that could be essential to developing molecular markers for breeding and building up genetic improvement strategies using CRISPR/Cas9 technologies.

Meta-analysis of transcriptomic responses to cold stress in plants.

Transcriptomic analyses are needful tools to gain insight into the molecular mechanisms underlying plant responses to abiotic stresses. The aim of this study was to identify key genes differentially regulated in response to chilling stress in various plant species with different levels of tolerance to low temperatures. A meta-analysis was performed using the RNA-Seq data of published studies whose experimental conditions were comparable. The results confirmed the importance of ethylene in the hormonal cross-talk modulating the defensive responses against chilling stress, especially in sensitive species. The transcriptomic activity of five Ethylene Response Factors genes and a REDOX Responsive Transcription Factor 1 involved in hormone-related pathways belonging to ethylene metabolism and signal transduction were induced. Transcription activity of two genes encoding for heat shock factors was enhanced, together with various genes associated with developmental processes. Several transcription factor families showed to be commonly induced between different plant species. Protein-protein interaction networks highlighted the role of the photosystems I and II, as well as genes encoding for HSF and WRKY transcription factors. A model of gene regulatory network underlying plant responses to chilling stress was developed, allowing the delivery of new candidate genes for genetic improvement of crops towards low temperatures tolerance.

Phenolics diversity among wild populations of Salvia multicaulis: as a precious source for antimicrobial and antioxidant applications.

The genus Salvia L. belongs to the Lamiaceae family including several known species rich in natural compounds that are extensively used in pharmaceutical, food, and cosmetic industries. Salvia multicaulis populations contain a broad diversity of flavonoids and phenolic acids. The present study aimed to explore biological and pharmacological effects including antimicrobial and antioxidant activities of nineteen S. multicaulis populations (SMPs) grown in Iran for the first time. High content of rosmarinic acid (RA) in SMP12 (Gazan) (5.65 ± 0.33 mg/g DW) caused high antimicrobial activity against two bacteria (Staphylococcus aureus, Escherichia coli) and the fungus Candida albicans, while methanolic extract of SMP1 (Taleghan) showed high antioxidant activity due to high content of salvianolic acid A (SAA) and quercetin (0.53 ± 0.04 and 0.49 ± 0.12 mg/g DW, respectively). Altogether these results can be considered for further commercial exploitations to meet the demands of the food and pharmaceutical industries.[Formula: see text].

Triterpenic and phenolic acids production changed in Salvia officinalis via in vitro and in vivo polyploidization: A consequence of altered genes expression.

The induction of polyploidy is an efficient technique for creating a diversity of genetic, phenotypic, and phytochemical novelties in plant taxa. Sage (Salvia officinalis L.) is a well-known medicinal plant rich of valuable bioactive molecules such as triterpenic and phenolic acids. In the present study, the effect of in vitro and in vivo polyploidization on morphological characteristics, anatomical structures, phytochemical traits, and expression level of the genes involved in the biosynthesis of major triterpenic acids (ursolic, betulinic, and oleanolic acids) of the plant was studied. The sterile seeds treated with different concentrations (0, 0.05, 0.1, and 0.2%) of colchicine for 24 and 48 h were considered for polyploidy induction. Flow cytometry and chromosome counting were used to confirm the ploidy level of diploid (2n = 2x = 14, 2C DNA = 1.10 pg) and tetraploid (2n = 4x = 28, 2C DNA = 2.12 pg) plants after seven months. The highest polyploidy induction was obtained by applying 0.1% (w/v) colchicine for 48 h with an efficiency of 19.05% in vitro tetraploidy. Polyploids showed differences in leaf shape and color, leaf and stem thickness, trichrome density, root length, plant height, and number of leaves compared to diploid plants. There was also a significant decrease in rosmarinic acid content in polyploid (plants) as compared to diploid plants. Although a significant decrease in ursolic acid content was observed in polyploids, betulinic acid content associated with the expression levels of genes encoding enzymes being active in triterpene biosynthesis such as squalene epoxidase (SQE) and lupeol synthase (LUS). The expression of SQE and LUS was significantly increased in in vitro tertaploids (2.9-fold) and in vivo mixoploids (2.4-fold). The results confirm the idea that induced polyploidy can randomly alter breeding traits of plants as well as the content of bioactive compounds.