Enhancement Production of Phenolic Compounds in The Cell Suspension Culture of Iberis Amara L.: The Effect of Chitosan Elicitation

Iberis amara L. medicinal herb is well-known for having pharmacological values although its use has been challenged by the low levels of secondary metabolites. To address this issue, this study focused on evaluating the effect of explant, photoperiod, and plant growth regulators (PGRs) to find the optimum medium for inducing callus and establishing cell suspension in I. amara, followed by investigating the chitosan effect on some secondary metabolites. From our observations, the optimum condition for induced callus was achieved from the leaf explants in Murashige and Skoog (MS) media completed with 3 mg L− 1 6-benzylaminopurine(BAP) and 1 mgL− 1 1-naphthalene acetic acid(NAA) under 16-h light/8-h dark photoperiod. The MS enhanced with 3 mgL− 1BAP, 1 mg L− 1NAA, and 2% (w/v) sucrose appeared to be optimum conditions for suspension establishment. Thus, the cells were exposed to different concentrations of chitosan (200, 100, 50, and 0 mg L− 1) in their exponential growth stage from day 8 to 12 and day 12 to 16 following sub-cultures (T1) and sub-cultures (T2), respectively. The results showed that the 50 mgL− 1 chitosan significantly improved the total phenol, flavonoid, flavonol, and anthocyanin content in the I. amara in a dose-dependent manner. The highest malondialdehyde (MDA) amount, as a result of lipid peroxidation, was observed under the 200 ppm chitosan elicitation. Overall, these novel findings demonstrated the possibility of applying the cell suspension of I. amara treated with chitosan as a helpful approach for improving synthesizing phenolic compounds under controlled and sterile conditions without genetic modifications in medicinal herbs.

Effect of pathogen virulence on pathogenicity, host range and reproduction of Plasmodiophora brassicae, the causal agent of clubroot disease

A series of greenhouse experiments was conducted to evaluate the effect of Plasmodiophora brassicae virulence on clubroot development and propagation of resting spores in 86 plant species from 19 botanical families. Plants were artificially inoculated with two isolates of P. brassicae, which were either virulent on clubroot-resistant oilseed rape cv. Mendel (P1 (+)) or avirulent on this cultivar (P1). Clubroot severity and the number of resting spores inside the roots were assessed 35 days post inoculation. Typical clubroot symptoms were observed only in the Brassicaceae family. P1 (+)-inoculated species exhibited more severe symptoms (2 to 10–fold more severe), bigger galls (1.1 to 5.8 fold heavier) and higher number of resting spores than the P1-inoculated plants. Among all Brassica species, Bunias orientalis, Coronopus squamatus and Raphanus sativus were fully resistant against both isolates, while Camelina sativa, Capsella bursa-pastoris, Coincya momensis, Descurainia sophia, Diplotaxis muralis, Erucastrum gallicum, Neslia paniculata, Sinapis alba, S. arvensis, Sisymbrium altissimum, S. loeselii and Thlaspi arvense were highly susceptible. Conringia orientalis, Diplotaxis tenuifolia, Hirschfeldia incana, Iberis amara, Lepidium campestre and Neslia paniculata were completely or partially resistant to P1-isolate but highly susceptible to P1 (+). These results propose that the basis for resistance in these species may be similar to that found in some commercial cultivars, and that these species could contribute to the build-up of inoculum of virulent pathotypes. Furthermore, the pathogen DNA was detected in Alopecurus myosuroides, Phacelia tanacatifolia, Papaver rhoeas and Pisum sativum. It can concluded that the number and diversity of hosts for P. brassicae are greater than previously reported.

Essential Oil Composition, Bioactive Compounds, and Antioxidant Activities in Iberis amara L.

This research was carried out to assess essential oils (EOs), total phenolic content (TPC), total flavonoids (TFD), total flavonols (TFL), total chlorophyll, total carotenoids, total anthocyanins, and different antioxidant activity assays in two plant samples (leaf and bud) of Iberis amara L. The gas chromatography mass spectrophotometry (GC-MS) of the EOs and the head space (HS)-GC-MS of the methanolic leaf extracts identified 34 and 6 different compounds, respectively. The major components of the leaf EOs were carvacrol (9.4%), camphene (6.2%), р-cymene (4.3%), and eugenol (3.8%) respectively, whereas cumin aldehyde (10.4%) was the main component in the bud sample. 1-Butene, 4-isothiocyanate (50%) was identified as the main component in the HS-GC-MS analysis of leaves extract. The highest content of TPC (32.8 ± 0.7 mg GAE/gDW), TFD (28.4 ± 0.7 mg QE/gDW), TFL (11.8 ± 0.06 mg QE/gFW), and anthocyanin (0.4 ±0.02 µmol/g FW) was found in the methanolic extract of leaves. The highest antioxidant activity in the phosphomolibdate assay (628.3 ± 10 µg AAE/gFW) and the least activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay (IC50 = 415 ± 3.1 µg/mL) was found in leaf samples. The high ratio of monoterpene hydrocarbons and oxygenated monoterpenes of the EOs along with the high antioxidant activity propose the application of this medicinal plant for general or specific applications in food industries as a herbal plant.