The Establishment of an Efficient Callus Induction System for Lotus (Nelumbo nucifera)

Study on the structure and lipid-lowering activity of different components of lotus root polysaccharides

Lotus root is a widely popular aquatic vegetable with edible and medicinal values. Here we report the structure and lipid-lowering activity of two lotus root polysaccharides LRW (lotus root polysaccharide by water extraction) and LRA (lotus root polysaccharide by alkali extraction), that were extracted by aqueous and alkaline solution respectively. The results showed that the yield of polysaccharide from lotus root could be significantly improved by alkali extraction. Basic composition and structural characterization showed that the total sugar contents of LRW and LRA were 96.83 % and 73.66 %, and the molecular weights were 2.464 × 105 Da and 1.727 × 105 Da, respectively. LRW and LRA had the similar structure that the main backbone consisted of →4)-α-D-Glcp-(1→ with branches at C-6 site. Both LRW and LRA could scavenge DPPH and hydroxyl radicals effectively, and have strong adsorption capacity to cholate salts in a concentration-dependent manner. In HepG2 cells, LRW and LRA inhibited the accumulation of lipid droplets induced by oleic acid, and increased the activity of T-SOD and CAT, meanwhile, reduced the level of MDA, TC and TG, showing good lipid-lowering activity. In comparison, the lipid-lowering effect of LRA was better than that of LRW. In addition, gene sequencing and RT-PCR showed that AMPK, ACC, PPARα and CPT-1 were essential for LRA to exert a lipid-lowering effect. This study provides a theoretical basis for the extraction and lipid-lowering application of lotus root polysaccharides.

Sonication-assisted Rhizobium radiobacter-mediated genetic transformation of Indian Lotus (Nelumbo nucifera Gaertn.)

This study aimed to develop a reliable and efficient genetic transformation method for the ornamental Indian Lotus (Nelumbo nucifera Gaertn.) using the sonication-assisted Rhizobium radiobacter-mediated transformation technique. To conduct the transformation, shoot apical meristem explants were infected with Rhizobium radiobacter (synonym Agrobacterium tumefaciens) strain LBA 4404 containing a binary vector pBI121 that harbours the GUS reporter gene (uidA) and kanamycin resistance gene nptII for plant selection. To improve the transformation efficiency, we optimized parameters such as bacterial cell density, sonication duration, infection time, co-cultivation duration, acetosyringone concentration, cefotaxime, and kanamycin concentrations. Sonication treatment at 42 kHz for 90 s recorded the highest transformation efficiency. The selection of regenerated plantlets was performed on a kanamycin-supplemented selection medium. The putative transformants showed GUS expression in the leaves and petioles. The presence of the GUS gene was also confirmed in the putative transformants through PCR, with the appearance of the expected amplicon size of 520 bp. The presence of nptII was confirmed by PCR in the putatively transformed plants with an amplicon size of 530 bp. The maximum regeneration frequency obtained was 72.66%, and the highest transformation efficiency achieved was 9.0% in the Indian Lotus.

The effects of different hormone combinations on the growth of Panax notoginseng anther callus based on metabolome analysis

Panax notoginseng saponins (PNS), the primary active components of Panax notoginseng (Burk.) F.H.Chen, a traditional and precious Chinese medicinal herb, are mainly derived from the roots of the plant. However, due to the long cultivation period and specific environmental requirements, the PNS supply is often limited. And, callus cultures of P. notoginseng, which grow rapidly, have short production cycles, and can be cultured under controlled conditions, provide a more efficient source for the quick acquisition of saponins. In this study, anthers of P. notoginseng were used as explants, and twelve hormone combinations were tested to induce callus formation. Eight kinds of hormone combinations successfully induced P. notoginseng anther callus. Among these, callus induced by combinations 5 and 7 had the highest saponin content, while those induced by combinations 1 and 3 exhibited the highest relative growth rates. Metabolomic analysis of these four callus types revealed that there were a total of 99 differential metabolites between combinations 5 and 7, 30 between combinations 1 and 3, 123 between combinations 3 and 7, and 116 between combinations 1 and 5. Further analysis showed that the tricarboxylic acid (TCA) cycle metabolites in callus induced by combinations 1 and 3 were significantly upregulated, with corresponding genes showing high expression levels, increased ATP accumulation, and low responses of the auxin response factor PnARF-3 and cytokinin response factor PnCRF-3. The abundance of metabolites in the PNS biosynthesis pathway in callus induced by combinations 5 and 7 increased significantly, with related genes showing high expression levels, increased IPP accumulation, and high responses of PnARF-3 and PnCRF-3. Overexpression of PnARF-3 and PnCRF-3 in callus induced by combination 3 promoted the production of IPP and saponins while reducing ATP production. In conclusion, different hormone combinations affect the distribution of Acetyl-CoA through PnARF-3 and PnCRF-3, resulting in the relative growth rate and saponin of P. notoginseng anther callus differences.

Establishment of callus induction and plantlet regeneration systems of Peucedanum Praeruptorum dunn based on the tissue culture method

BACKGROUND

Peucedanum praeruptorum Dunn has typical stacked umbels and medicinal value; however, the lack of an effective tissue culture system for P. praeruptorum has limited the large-scale propagation of its seedlings.

RESULTS

We systematically established an in vitro regeneration system for P. praeruptorum using young leaves and stems as explants. Tissue culture plantlets were successfully obtained within 123 and 90 d of somatic embryogenesis and organogenesis, respectively. Combined plant growth regulators (PGRs) were optimized to promote efficient plant regeneration at each stage of the culture process. Specifically, embryogenic callus induction was superior in Murashige and Skoog (MS) medium supplemented with 0.5 mg/L 6-benzyladenine (BA) and 2.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D). For somatic embryonic development, the highest differentiation rates were achieved using BA, 2,4-D, and 6-furfuryl aminopurine (6-KT). Induction of organogenesis resulted in the highest differentiation rates and proliferation coefficients of buds in MS medium supplemented with BA and α-naphthaleneacetic acid (NAA). Moreover, regeneration of P. praeruptorum seedlings was achieved by adjusting the BA and indole-3-butyric acid (IBA) concentrations in 1/2 MS medium.

CONCLUSION

Our results provide a technical system for the rapid propagation of P. praeruptorum, which can facilitate germplasm improvement, resource conservation, and further genetic transformation of Peucedanum species.

Metabolite profiling and screening of callus browning-related genes in lotus (Nelumbo nucifera)

Callus browning is a major drawback to lotus callus proliferation and regeneration. However, the underlying mechanism of its formation remains largely unknown. Herein, we aimed to explore the metabolic and molecular basis of lotus callus browning by combining histological staining, high-throughput metabolomics, and transcriptomic assays for lotus callus at three browning stages. Histological stained brown callus cross sections displayed severe cell death symptoms, accompanied by an obvious accumulation of polyphenols and lignified materials. Widely targeted metabolomics revealed extensively decreased accumulation of most detected flavonoids and benzylisoquinoline alkaloids (BIAs), as well as a few phenolic acids, amino acids and their derivatives in callus with browning symptoms. Conversely, the contents of most detected tannins were significantly increased. Subsequent comparative transcriptomics identified a set of differentially expressed genes (DEGs) associated with the biosynthesis and regulation of flavonoids and BIAs in lotus. Notably, callus browning was coupled with significantly up-regulated expression of two polyphenol oxidase (PPO) and 17 peroxidase (POD) encoding genes, while the expression of ethylene associated genes remained at marginal levels. These results suggest that lotus callus browning is primarily controlled at the level of metabolism, wherein the oxidation of flavonoids and BIAs is crucially decisive.

Establishment of an efficient regeneration and Agrobacterium transformation system in mature embryos of calla lily (Zantedeschia spp.)

Calla lily (Zantedeschia spp.) have great aesthetic value due to their spathe-like appearance and richness of coloration. However, embryonic callus regeneration is absent from its current regeneration mechanism. As a result, constructing an adequate and stable genetic transformation system is hampered, severely hindering breeding efforts. In this research, the callus induction effectiveness of calla lily seed embryos of various maturities was evaluated. The findings indicated that mature seed embryos were more suitable for in vitro regeneration. Using orthogonal design experiments, the primary elements influencing in vitro regeneration, such as plant growth regulators, genotypes, and nanoscale materials, which was emergent uses for in vitro regeneration, were investigated. The findings indicated that MS supplemented with 6-BA 2 mg/L and NAA 0.1 mg/L was the optimal medium for callus induction (CIM); the germination medium (GM) was MS supplemented with 6-BA 2 mg/L NAA 0.2 mg/L and 1 mg/L CNTs, and the rooting medium (RM) was MS supplemented with 6-BA 2 mg/L NAA 0.7 mg/L and 2 mg/L CNTs. This allowed us to verify, in principle, that the Agrobacterium tumefaciens-mediated genetic transformation system operates under optimal circumstances using the GUS reporter gene. Here, we developed a seed embryo-based genetic transformation regeneration system, which set the stage for future attempts to create new calla lily varieties.

Efficient shoot regeneration of medicinal plant Haplophyllum tuberculatum by direct and indirect organogenesis and genetic fidelity assessment using Inter Simple Sequence Repeats markers

In vitro plant cell and tissue cultures are potent tools to propagating germplasm resources in conserving and managing plant genetic resources. A reliable micropropagation protocol was developed for efficient callus proliferation and direct and indirect shoot regeneration of Meseika (Haplophyllum tuberculatum). With the applied sterilization procedure, immature, unopened H. tuberculatum seed pods can be identified as a potent explant with high viability and low contamination percentage. Multiple shoots were regenerated from leaf and stem explants through direct organogenesis on Murashige and Skoog's (MS) + 3% sucrose medium amended with BAP. Indirect regeneration of several shoots was achieved on 1/2 MS + 1% sucrose media amended with 2 and 4 mg/l BAP. An efficient callus proliferation from both explants can be achieved by supplementing the MS media with NAA and BAP. All the cultures were incubated in a controlled growth chamber under 5/19 h light/dark photoperiod, temperature (25 ± 2°C), and 60% relative humidity (RH).10 ISSR (Inter Simple Sequence Repeat) markers were screened to test the genetic fidelity of regenerated H. tuberculatum shoots. Callus development was observed after 15 days and shoot regeneration was occurred after 30 days after callus initiation. 10 ISSR primers produced a total of 39 clear, distinct amplicons. 75, 60, 40, and 16% polymorphism percentages were recorded by the ISSR primer 11, 7, 5, and 4, respectively. The developed micropropagation protocol is appropriate for rapid in-vitro multiplication of H. tuberculatum shoots and callus.

Endorsement and phylogenetic analysis of some Fabaceae plants based on DNA barcoding

Background

DNA barcoding have been considered as a tool to facilitate species identification based on its simplicity and high-level accuracy in compression to the complexity and subjective biases linked to morphological identification of taxa. MaturaseK gene (MatK gene) of the chloroplast is very vital in the plant system which is involved in the group II intron splicing. The main objective of this study is to determine the relative utility of the “MatK” chloroplast gene for barcoding in 15 legume as a tool to facilitate species identification based on their simplicity and high-level accuracy linked to morphological identification of taxa.

Methods and Results

MatK gene sequences were submitted to GenBank and the accession numbers were obtained with sequence length ranging from 730 to 1545 nucleotides. These DNA sequences were aligned with database sequence using PROMALS server, Clustal Omega server and Bioedit program. Maximum likelihood and neighbor-joining algorithms were employed for constructing phylogeny. Overall, these results indicated that the phylogenetic tree analysis and the evolutionary distances of an individual dataset of each species were agreed with a phylogenetic tree of all each other consisting of two clades, the first clade comprising (Enterolobium contortisiliquum, Albizia lebbek), Acacia saligna, Leucaena leucocephala, Dichrostachys Cinerea, (Delonix regia, Parkinsonia aculeata), (Senna surattensis, Cassia fistula, Cassia javanica) and Schotia brachypetala were more closely to each other, respectively. The remaining four species of Erythrina humeana, (Sophora secundiflora, Dalbergia Sissoo, Tipuana Tipu) constituted the second clade.

Conclusion

Moreover, their sequences could be successfully utilized in single nucleotide polymorphism or as part of the sequence as DNA fragment analysis utilizing polymerase chain reaction in plant systematic. Therefore, MatK gene is considered promising a candidate for DNA barcoding in the plant family Fabaceae and provides a clear relationship between the families.

Genome Estimation and Phytochemical Compound Identification in the Leaves and Callus of Abrus precatorius: A Locally Endangered Plant from the Flora of Saudi Arabia

Abrus precatorius is considered to be a valuable source of natural products for the development of drugs against various diseases. Herein, the genome size and phytochemical compounds in the leaves and callus of A. precatorius were evaluated. The endangered A. precatorius was collected from the Al-Baha mountains, Saudi Arabia and identified based on the phylogenetic analysis of a DNA sequence amplified by ITS1 and ITS4 primers. The callus was induced by the culture of stem explants onto Murashige and Skoog medium (MS) supplemented with various combinations of 2,4-dichlorophenoxyacetic acid (2,4D) and 6-Benzylaminopurine (BAP). The callus with the highest fresh weight (2.03 g) was obtained in the medium containing 0.5µM BA and 5 µM 2,4-D after 8 weeks of culture; thus, the callus of this combination was selected for the genome estimation and phytochemical compound extraction. The genetic stability of the leaves from the donor as well as in the regenerated callus was analyzed by flow cytometry with optimized tomato (2C = 1.96 pg) as an external reference standard. The 2C DNA content was estimated to 1.810 pg ± 0.008 and 1.813 pg ± 0.004 for the leaves and callus, respectively. Then, the total phenol and total flavonoid contents in the methanol extract of the callus and leaves were measured using a spectrophotometer and the High-performance liquid chromatography (HPLC ) methods. The results showed that the methanolic extract of the leaves was higher in total phenols and total flavonoids than the callus extract. Finally, the extracts of callus and leaves were analyzed for phytochemical compound through the Gas chromatography and Mass spectroscopy (GC-MS). A total of 22 and 28 compounds were detected in the callus and leaves, respectively. The comparative analysis showed that 12 compounds of the secondary metabolites were present in both extracts.

Micropropagation of pokeweed (Phytolacca americana L.) and comparison of phenolic, flavonoid content, and antioxidant activity between pokeweed callus and other parts

BACKGROUND

Pokeweed (Phytolacca americana L.) is regarded as an invasive plant in many parts of the world but possesses therapeutic characteristics used for antitumor and rheumatism treatment. This study investigated the effects of auxins and four explants on pokeweed callus induction. The effects of cytokinins and combinations between cytokinins and NAA on shoot and root induction were also studied. TPC, TFC and antioxidant activity of calli were screened and compared with other pokeweed plant parts.

METHODS

Four explants were used to induce callus using 2,4-D and IBA at 1, 2, 3 and 4 mg/l for each auxin. Direct shoot organogenesis from nodal explants was investigated using BAP, kinetin and TDZ (1, 2 and 4 mg/l for each cytokinin). Combined effects between cytokinins and NAA at 0.1, 0.2 and 0.3 mg/l were further simultaneously estimated with root induction. Calli derived from the leaves were compared with other plant parts for TPC, TFC and antioxidant activity using the Folin-Ciocalteu, AlCl₃ colorimetric assay and DPPH assays, respectively.

RESULTS

Results showed that MS medium containing 2 mg/l 2,4-D induced callus formation on leaf explants that provided highest fresh and dry weights. Three types of synthetic cytokinins as kinetin, TDZ and BAP were used for direct shoot organogenesis from pokeweed nodes. MS medium containing 2 mg/l kinetin was effective in stimulating normal shoots, with the largest number of shoots and leaves and the longest shoots. The combination between cytokinins and NAA showed no positive effect on shoot and root induction from pokeweed nodal explants. For TPC and TFC determination, pokeweed seeds and leaves possessed the highest phenolic and flavonoid contents, respectively. Highest phenolic content of pokeweed seeds led to lowest IC₅₀ by DPPH assay. Phenolic content was higher than flavonoid content.

CONCLUSION

Results suggested promising conditions for callus induction. Leaf explants cultured on MS medium with 2 mg/l 2,4-D and nodal explants cultured on MS medium with 2 mg/l kinetin provided the largest number of normal shoots and leaves. NAA did not show positive effects on shoot and root induction when combined with cytokinins. Chemical constituent screening indicated that seeds and leaves provided highest TPC and TFC, respectively, while pokeweed calli contained higher phenolic than flavonoid content. This is the first report describing chemical constituent screening and antioxidant activity of calli and other parts of the pokeweed plant. Results provided significant information to further enhance bioactive compound contents of pokeweed calli using elicitation methods.