Sterilization protocols and the effect of plant growth regulators on callus induction and secondary metabolites production in in vitro cultures Melia azedarach L.

Melia azedarach L. is a valuable source of antioxidants and secondary metabolites. This study is a first extensive report about the effect of different serialization protocols and plant growth regulators (PGRs) on explant disinfection efficiency, callus induction and secondary metabolites production and accumulation in callus cultures of M. azedarach L. In this regard, the effect of plant growth regulators on callus induction and secondary metabolites production were examined. In addition, different sterilization agents were evaluated for disinfection of chinaberry leaf explants. The results showed that the lowest percentage of explant contamination and browning with the highest percentage of callus induction and callus growth obtained with explants pretreated with benomyl (2 g/L) for 2 h and sterilized with 7% H2O2 for 10 min and NaOCl 2% (without pH adjustment) for 12 min. Although adjusting the pH of NaOCl to pH = 7 and 10 significantly reduced the microbial contamination and increased the percentage of contamination-free cultures of M. azedarach L., adversely influenced the explant viability and callus induction and growth. The highest percentage of callus induction obtained on the MS medium containing 3 mg/L NAA/2,4-D and 1 or 3 mg/L Kin/BAP, and the highest callus yield (1804.833 mg/explant) belonged to the MS medium supplemented with 5 mg/L 2,4-D and 5 mg/L Kin. The callus cultures grown on the MS medium supplemented with 3 mg/L NAA and 1 mg/L Kin produced the highest amount of Quercetin (2.06 mg/g fresh weight), Rutin (5.56 mg/g fresh weight) and Kaempferol (1.84 mg/g fresh weight).

Efficient Plant Regeneration via Indirect Organogenesis in Carnation (Dianthus Caryophyllus Semperflorens flore pleno) Cultivars

ABSTRACT Callus induction and plant regeneration are important steps of in vitro plant breeding of ornamental plants. In this study, the effects of different combinations of plant growth regulators (PGRs), promoters, and minerals on callus induction and plant regeneration in different carnation cultivars were studied in a completely randomized design with three replications. For callus induction, 16 different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BA), 1-naphthaleneacetic acid (NAA), and casein hydrolysate (CH) were studied using in vitro leaf explants. The Murashige and Skoog (MS) medium supplemented with 0.2 mg·dm-3 of 2,4-D and 200 mg·dm-3 of CH showed the highest frequency of callus induction. Among the cultivars, ‘Noblesse’ showed the highest rate of callus induction (91.67%). Regarding regeneration, BA, NAA, silver nitrate (AgNO3), and adenine hemisulfate (As) were used in ten different combinations. The ‘Cameron’, ‘Tabasco’, and ‘Noblesse’ cultivars with 95.24% regeneration percentage showed the highest rate of plant regeneration. Generally, in most cultivars, the highest regeneration rate and shoot number per explant were found in the MS medium supplemented with 3 mg·dm-3 of BA, 0.6 mg·dm-3 of NAA, 5 mg·dm-3 of AgNO3, and 40 mg·dm-3 of As. According to the results, the highest regeneration frequency was obtained when 40 mg·dm-3 of As was added to the medium. Finally, the flow cytometry analysis indicated that there were no significant differences between in vitro regenerated and control plants in terms of DNA ratios.

Micropropagation of Feverfew (Tanacetum parthenium) and Quantification of Parthenolide Content in Its Micropropagated and Conventionally Grown Plants

Feverfew (Tanacetum parthenium) is a well-known multi-functional plant with anti-inflammatory, cardiotonic, antiangiogenic, and anticancer effects. The therapeutic value of this plant is due to its phytochemical constitutes, especially parthenolide. Tissue culture techniques have been applied to improve the bioactive components of many herbal plants. Hence, this study, was carried out to establish a protocol for micropropagation of the feverfew plant and to quantify parthenolide content in its micropropagated and conventionally grown plants. To establish an aseptic culture, different concentrations of sodium hypochlorite (NaOCl) were investigated for seed surface sterilization. Besides, the effects of plant growth regulators (PGRs) on the callus induction, shoot organogenesis from callus and in vitro rooting were evaluated. Additionally, the parthenolide yield of the micropropagated and conventionally grown plants was determined by using high-performance liquid chromatography (HPLC). The results showed that surface sterilization of feverfew seeds with 6% NaOCl for 15 min obtained 65.00 ± 2.69% aseptic seeds. Murashige and Skoog (MS) medium supplemented with 0.4 mg/L thidiazuron (TDZ) and 2 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) resulted in 86.00 ± 1.72% callus induction. The highest number of shoots (5.00 ± 0.15) per explant was obtained in the treatment of MS medium supplemented with 5 mg/L zeatin. MS medium fortified with 3 mg/L indole-3-butyric acid (IBA) produced the maximum number of roots per plantlet (8.90 ± 0.35). A total of 90% of the micropropagated plantlets survived when planted in perlite + peat moss (1:1 v/v); the micropropagated plantlets were successfully established in the ex vitro conditions. According to parthenolide analysis, its level was significantly higher in the micropropagated plants than conventionally grown plants. Among different solvents, ethanolic extraction obtained the highest parthenolide content of the feverfew plant. Hence, it can be concluded that micropropagation of feverfew could be applied to produce disease-free planting materials and to improve the parthenolide content of the feverfew plant.

Callus induction of mountain papaya endosperm (Vasconcellea pubescens A. DC) with different combination of 2,4-Dichlorophenoxyacetic acid and Kinetin

Endosperm as a result of double fertilization in Angiospermae shows high level chromosomes and polyploidy. It is also considered as dead tissue that unable to be generated to form plantlet. The aim of this research is to determine the effect of kinetin and 2,4-Dichlorophenoxyacetic acid (2,4-D) in induction of callus formation of mountain papaya. This research used A factorial randomized block design with 18 groups, 1 fruit was used for 1 experimental group. Culture using Murashige and Skog (MS) media with combination of three level of kinetin (0, 2, 4 mgL-1) and six level of 2,4-D (0, 1, 2, 3, 4, 5 mgL-1). Maximum endosperm callus induction (0.88%) was achieved from endosperm explant cultured on MS medium fortified with 2.0 mgL-1 Kinetin and 4.0 mgL-1 2,4-D. The fastest day induction (24,66 day) was observed with 5.0 mg L-1 2,4-D. The maximum number of browning (0,10) was induced by 2.0 mgL-1 Kinetin and 5.0 mgL-1 2,4-D. Combination Kinetin and 2,4-D proved could induces callus formation from mountain papaya endosperm.

The Role of Growth Regulators in The Multiplication of Stevia Rebaudiana Bertoni Shoot and Callus Induction in Vitro

The research was conducted to investigate the effect of plant growth regulators on the vegetative multiplication of the Stevia plant shoot and the induction of callus from it. The results indicated that the interaction between 2.0 mg. L-1 BA with 0.5 mg. L -1 Kin gave the highest rate number of shoot with 6.32 branches and the highest average of leaves number Were 9.60 leaves compared to the lowest average for the number of shoot and leaves Were 1.40 shoot and 3.80 leaves respectively. As for the length of the shoot, the interaction between (1.0 mg. L-1 BA and 0.5 mg. L-1 Kin) gave the highest average shoot length 4.31 cm compared to the control which gave 2.20 cm. in connection with the callus induction, the concentration 3 mg. L-1 of NAA gave the highest percentage of callus induction from leaves 100%, and the lowest mean of days that for callus initiation was 9 days compared to the control which reached to 20 days. As for the wet and dry weights of callus tissue, the interaction between 2.0 mg. L-1 NAA and 0.5 mg. L -1BA gave the highest wet weight rate 3.68 g and the average dry weight was 0.31 g compared to the control which gave the lowest rate 0.95 g, 0.08 g respectively.

Establishment of Tissue Culture Regeneration System for Medicago ruthenica L. cv. ‘Zhilixing’

Background: Medicago ruthenica L. ‘Zhilixing’ is a new variety with superior forage and seed yield compared to the wild type. The cold, drought and salt tolerance of Zhlixing are better than those of alfalfa, suggesting that this variety can serve as a high-quality genetic resource for improving the stress resistance of alfalfa. However, because of the lack of tissue culture regeneration system, it is difficult to perform genetic transformation studies on stress resistance genes. This study aimed to establish an efficient tissue culture regeneration system for Zhilixing variety. Methods: Three types of explants were selected and tested on four types of basal media supplemented with different combinations of auxin and cytokinin for callus induction and differentiation, based on orthogonal tests to select the combinations of auxin and cytokinin suitable for callus induction and differentiation. Two-factor combination method was used to formulate a suitable rooting medium. Result: The hypocotyledonary axis was found to be an excellent explant for callus induction on MS medium. The optimum callus induction medium contained thidiazuron (TDZ, 0.5 mg/L), 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg/L) and naphthaleneacetic acid (NAA, 0.5 mg/L) where the callus induction rate was 93.33%. The differentiation medium was supplemented with TDZ (0.75 mg/L), 2,4-D (0.25 mg/L) and 6-benzyladenine (6-BA, 1.5 mg/L) where the differentiation rate was 63.33%. Thidiazuron played the key role in both processes of callus induction and differentiation. Half-strength MS containing 0.1 mg/L of NAA was the most efficient rooting medium.

Indirect in vitro Regeneration of the Medicinal Plant, Aspilia africana, and Histological Assessment at Different Developmental Stages

The medicinal plant, Aspilia africana, has been traditionally used in several African countries to treat many diseases such as tuberculosis, cough, inflammation, malaria, osteoporosis, and diabetes. In this study, we developed a protocol for in vitro propagation of A. africana using indirect shoot organogenesis from leaf and root explants of in vitro-grown seedlings and assessed the tissues at different developmental stages. The highest callus induction (91.9 ± 2.96%) from leaf explants was in the Murashige and Skoog (MS) medium augmented with 1.0 mg/L 6-Benzylaminopurine (BAP) and 1.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) while from root explants, the highest callus induction (92.6 ± 2.80%) was in the same plant tissue culture medium augmented with 0.5 mg/L BAP and 1.0 mg/L 2,4-D. The best shoot regeneration capacity from leaf-derived calli (i.e., 80.0 ± 6.23% regeneration percentage and 12.0 ± 6.23 shoots per callus) was obtained in medium augmented with 1.0 mg/L BAP and 0.05 mg/L α-Naphthaleneacetic acid (NAA); the best regeneration capacity for root-derived calli (i.e., 86.7 ± 6.24% shoot regeneration percentage and 14.7 ± 1.11 shoots per callus) was obtained in the MS medium augmented with 1.0 mg/L BAP, 0.05 mg/L NAA, and 0.1 mg/L Thidiazuron (TDZ). Regenerated plantlets developed a robust root system in 1/2 MS medium augmented with 0.1 mg/L NAA and had a survival rate of 93.6% at acclimatization. The in vitro regenerated stem tissue was fully differentiated, while the young leaf tissue consisted of largely unorganized and poorly differentiated cells with large intercellular airspaces typical of in vitro leaf tissues. Our study established a protocol for the indirect regeneration of A. africana and offers a basis for its domestication, large-scale multiplication, and germplasm preservation. To the best of our knowledge, this is the first study to develop an indirect regeneration protocol for A. africana and conduct anatomical assessment through the different stages of development from callus to a fully developed plantlet.