Elevated ultraviolet-B (UV-B) radiation is potentially deleterious to many organisms specifically crop plants and has become a global challenge. Rice is an exceptionally important staple food which is grown worldwide, and many efforts have been done recently to improve rice varieties against UV-B stress. This current study aims to investigate the effects of exogenous application of β-sitosterol (βSito) on growth improvement and tolerance level of rice plants against prolonged UV-B stress. The physiological and metabolic responses were evaluated in rice plants not supplemented with βSito (Nβ) and those supplemented with βSito (Sβ). The Nβ and Sβ plants were grown under non-stress (ns) and under prolonged UV-B stress (uvs) conditions and termed as Nβns, Sβns and Nβuvs, Sβuvs, respectively. The application of βSito contributes positively under non-stress and specifically to UV-B stress in terms of improving numerous physiological parameters associated with growth and development such as shoot and root length, RWC, whole plant biomass, chlorophyll pigments, and photosynthetic-related parameters (Pn, Gs, Tr, WUEi, Fv/Fm, and NPQ) in Sβ compared with Nβ plants. Moreover, enhanced oxidative stress tolerance of Sβuvs vs. Nβuvs plants under stress was attributed to low levels of ROS and substantial trigger in activities of antioxidant enzymes (SOD, POD, CAT, and APX). Metabolic analysis was performed using GC-TOFMS, which revealed higher accumulation of several key metabolites including organic acids, sugars, amino acids, and others in Sβuvs vs. Nβuvs plants, which were mainly reduced in Nβ plants under stress vs. non-stress conditions. These results provide useful data regarding the important role of βSito on growth maintenance and modulation of several metabolites associated with osmotic and redox adjustments during UV-B stress tolerance in rice plants. Importantly, βSito-regulated plasticity could further be explored specifically in relation to different environmental stresses in other economically useful crop plants.

Phytochromes are plant photoreceptors that have long been associated with photomorphogenesis in plants; however, more recently, their crucial role in the regulation of variety of abiotic stresses has been explored. Chilling stress is one of the abiotic factors that severely affect growth, development, and productivity of crops. In the present work, we have analyzed and compared physiological, biochemical, and molecular responses in two contrasting phytochrome mutants of tomato, namely aurea (aur) and high pigment1 (hp1), along with wild-type cultivar Micro-Tom (MT) under chilling stress. In tomato, aur is phytochrome-deficient mutant while hp1 is a phytochrome-sensitive mutant. The genotype-specific physiological, biochemical, and molecular responses under chilling stress in tomato mutants strongly validated phytochrome-mediated regulation of abiotic stress. Here, we demonstrate that phytochrome-sensitive mutant hp1 show improved performance compared to phytochrome-deficient mutant aur and wild-type MT plants under chilling stress. Interestingly, we noticed significant increase in several photosynthetic-related parameters in hp1 under chilling stress that include photosynthetic rate, stomatal conductance, stomatal aperture, transpiration rate, chlorophyll a and carotenoids. Whereas most parameters were negatively affected in aur and MT except a slight increase in carotenoids in MT plants under chilling stress. Further, we found that PSII quantum efficiency (Fv/Fm), PSII operating efficiency (Fq′/Fm′), and non-photochemical quenching (NPQ) were all positively regulated in hp1, which demonstrate enhanced photosynthetic performance of hp1 under stress. On the other hand, Fv/Fm and Fq′/Fm′ were decreased significantly in aur and wild-type plants. In addition, NPQ was not affected in MT but declined in aur mutant after chilling stress. Noticeably, the transcript analysis show that PHY genes which were previously reported to act as molecular switches in response to several abiotic stresses were mainly induced in hp1 and repressed in aur and MT in response to stress. As expected, we also found reduced levels of malondialdehyde (MDA), enhanced activities of antioxidant enzymes, and higher accumulation of protecting osmolytes (soluble sugars, proline, glycine betaine) which further elaborate the underlying tolerance mechanism of hp1 genotype under chilling stress. Our findings clearly demonstrate that phytochrome-sensitive and phytochrome-deficient tomato mutants respond differently under chilling stress thereby regulating physiological, biochemical, and molecular responses and thus establish a strong link between phytochromes and their role in stress tolerance.

Introduction: Datura, long considered an medicinal plant, represents a prospective source for discovering novel drugs for modern medicine. The Egyptian flora encompasses six Datura genotypes, including D. innoxia, D. ferox, D. metel and three forms of D. stramonium (stramonium, tatula and inermis). However, the taxonomic status of Datura genus remains controversial.Methods: Our study aims to clarify the phylogenetic relationships among Egyptian Datura via contemporary molecular taxonomy techniques, including ISSR, SCoT, CDDP, as well as cytogenetics assessment, and chemical taxonomy, using total- and tropane-alkaloid and UV spectroscopic pattern.Results: Based on our results, the three forms of D. stramonium (stramonium, tatula and inermis) are closely related taxa, although there were some significant differences, suggesting the need to upgrade inermis to level of subspecies (Datura stramonium subsp. Inermis). The GC-MS results identified 31 tropane alkaloids. Out of which, seven were described in a qualitative manner in genus Datura, which enhances these genotypes’ medical and economic value. Expression level of the genes PMT, TR1, TR2, H6H, HDH and AT4 influenced the tropane alkaloids accumulation within the genotypes examined.Discussion: To date, this is the first study to identify the evolutionary relationship of the genus Datura combining molecular and chemical taxonomy, and to quantify the TAs and the genes involved in their biosynthesis among Datura genotypes.Conclusion: This study is significant since drug development strategies and enhanced therapeutic usage of Datura heavily depend on comprehensive knowledge of the species and subspecies’ molecular and phytochemical variability.

Capparis spinosa is a xerophytic shrub that has amazing capacity for surviving in challenging circumstances. Therapeutic and pharmacological benefits of this plant species, and its culinary applications, are of significant interest. Various bioactive constituents discovered throughout several organs contribute to its phytochemical relevance, and its cultivation has significant potential commercial benefit. Furthermore, the broad heterogeneity of C. spinosa has made taxonomic classification challenging, and paucity of genetic investigations has led to uncertainty among numerous authors. Recent study epitomizes dataset regarding C. spinosa encompasses taxonomical, phytochemical and molecular investigation. Three Egyptian endemic varieties of C. spinosa; canescens, deserti, inermis were genetically identified using two marker approaches including inter simple sequence repeat (ISSR) and start codon targeted polymorphism (SCoT). Five primers for each approach totaled ten in total for the analysis. ISSR and SCoT primers generated 28 and 40 bands overall, respectively. Polymorphism levels ranged between 64.28 to 67.50% with ISSR and SCoT examination, respectively. Furthermore, chemo-taxonomic clustering employing UV-spectroscopic analysis besides phenolic content was coupled with unsupervised chemometric tools of Principal Components Analysis (PCA) and Hierarchical Cluster Analysis (HCA). Through molecular and phytochemical investigations, interspecific relationships among canescens and deserti varieties have been verified. Additionally, inermis variety was identified as a monotypic variety. Flavonoid content coincided with the conclusion, which was proved through different expression of phenylpropanoid biosynthetic genes. This research suggests raising var. inermis to the species level, namely Capparis orientalis, demonstrating that chemotaxonomic information can mirror evolutionary connections between caper varieties and sheds light on the need of combining molecular and chemo-taxonomy’s advantages to clarify the evolutionary connections within this species.

Capparis spinosa var. deserti Zohary (Family: Capparaceae), is an edible medicinal plant which is considered as an excellent genetic source of flavonoids. It is a threatened species that is listed among the endangered and unutilized plant species. In an attempt to preserve C. spinosafrom genetic erosion, micropropagation was employed as a useful way to mass propagate this plant due to the high population diversity and problems in traditional propagation methods. Furthermore, molecular and biochemical evaluation was carried out in C. spinosacallus under the influence of different chemical treatments.The best appropriate medium for proliferation of C. spinosashoot tip explants was Murashige and Skoog (MS) medium supplemented with 2.0 mg/l 2iP. An efficient procedure for inducing high frequency direct shoot organogenesis from leaf explants in response to thidiazuron (TDZ) is reported. TDZ at 0.75 mg/l induced shoot organogenesis. The effect of different concentrations of two elicitors; salicylic acid (SA), methyl jasmonate(MeJA) andthe precursor phenylalanine(Phe)on quercetin and rutinbiosynthesis was examined.Metabolic results were confirmed by elevated transcript level of quercetin and rutin biosynthetic genes, 4-coumaroyl CoA ligase and flavonol-3-O-glucoside L-rhamnosyltransferase in C. spinosacallus.This study provides useful data regarding the vital role ofplant growth regulators in conservation and micropropagationof C.spinosavar. deserti. Moreover,these results suggest that quercetin and rutin content in C. spinosa can be enhanced to a significant extent by SA, MeJA, and Phe treatments and the gene expression patterns ofqurecetin and rutin biosynthesis-related genes are regulated by these elicitors.