In vitro bioproduction and enhancement of moscatilin from a threatened tropical epiphytic orchid, Dendrobium ovatum (Willd.) Kraenzl

Moscatilin, a bibenzyl derivative (stilbenoid), mostly found in one of the largest genera of Orchidaceae; Dendrobium has many therapeutic benefits. Its function as an anticancer agent has been widely demonstrated through many research investigations. However, the compound has not been produced in vitro to date. The present study highlights the development of cultures viz., seedling generation, callus induction and callus regeneration (transformation of callus into plantlets). These cultures were devised to conserve the threatened tropical epiphytic orchid species, Dendrobium ovatum and identify their potential towards moscatilin bioproduction in vitro. Among the three culture platforms, callus-derived plantlets could yield high moscatilin when treated with l-Phenylalanine as a precursor. Tissue differentiation was found to be indispensable for the high production of this polyphenol. These cultures also offer potential commercial benefits as they can serve as appropriate platforms to decode moscatilin biosynthesis and other significant bibenzyl derivatives. Elicitors, such as chitosan, salicylic acid, and methyl jasmonate, were found, causing an enhancement in moscatilin content in the cultures. The seedlings obtained can serve towards ecorestoration and preservation of the studied species. Callogenesis was useful in plantlet regeneration, as callus-derived plantlets could be utilized for the enrichment and commercial scale-up of moscatilin-like chemicals.

Effect of culture media, auxins and genotypes on plantlet regeneration from oil palm (Elaeis guineensis Jacq.) zygotic embryos through somatic embryogenesis

Aim: This study evaluated efficient culture media for the regeneration of elite material through somatic embryogenesis from oil palm zygotic embryos. Methodology: For callus induction, zygotic embryos of four elite genotypes (G1-264T, G2-238DX17P, G3-37DX17P and G4-237T) were cultured on three basal media (Y3, MS and N6) with different auxin 2 mg l-1 (Picloram, 2,4-D and Dicamba) combinations. Subculture was made every month for three passages. It evaluated various callus characters. The embryogenic calli from callus induction media were transferred to the embryo maturation medium and subcultured until the polyembryoids formed. For shoot and root formation, somatic embryo clumps were transferred into regeneration media. In-vitro plantlets with well-grown roots were hardened in pots for six weeks and assessed clonal fidelity using polymorphic SSR primers. Results: Among the treatments, calli from N6+2,4-D, Y3+2,4-D and N6+Picloram showed the highest embryogenic callus potential. G4-237T induced more embryogenic calli (32.982) among genotypes, which was on par with G1-264T (24.196). Embryogenic calli grown on N6 media with Dicamba showed the highest proliferation rate (1.141). After 60 days of culture on regeneration media, the highest number of plantlets per somatic embryogenic clump was obtained from G1-264T on N6 media supplemented with Dicamba. Interpretation: Culture media salt concentration showed a significant difference among media by causing perturbations of auxin flow during somatic embryogenesis affecting callus induction, proliferation and plantlet regeneration. This may be useful for standardizing the genotype-specific regeneration media in oil palm.

Improved Anther Culture Media for Enhanced Callus Formation and Plant Regeneration in Rice (Oryza sativa L.)

Anther culture technique is the most viable and efficient method of producing homozygous doubled haploid plants within a short period. However, the practical application of this technology in rice improvement is still limited by various factors that influence culture efficiency. The present study was conducted to determine the effects of two improved anther culture media, Ali-1 (A1) and Ali-2 (A2), a modified N6 medium, to enhance the callus formation and plant regeneration of japonica, indica, and hybrids of indica and japonica cross. The current study demonstrated that genotype and media had a significant impact (p < 0.001) on both callus induction frequency and green plantlet regeneration efficiency. The use of the A1 and A2 medium significantly enhanced callus induction frequency of japonica rice type, Nipponbare, and the hybrids of indica × japonica cross (CXY6, CXY24, and Y2) but not the indica rice type, NSIC Rc480. However, the A1 medium is found superior to the N6 medium as it significantly improved the green plantlet regeneration efficiency of CXY6, CXY24, and Y2 by almost 36%, 118%, and 277%, respectively. Furthermore, it substantially reduced the albino plantlet regeneration of the induced callus in two hybrids (CXY6 and Y2). Therefore, the improved anther culture medium A1 can produce doubled haploid rice plants for indica × japonica, which can be useful in different breeding programs that will enable the speedy development of rice varieties for resource-poor farmers.

Multiple analyses of various factors affecting the plantlet regeneration of Picea mongolica (H. Q. Wu) W.D. Xu from somatic embryos

Picea mongolica, a native species with excellent industrial wood quality and strong sand-fixing capacity, may be utilized in construction of urban green spaces in arid areas in China. However, now the sustainability of the ecosystems where this species grows is at serious risk due to a lack of natural regeneration. In this study, we developed an efficient regeneration system and comprehensively analyzed various factors affecting somatic embryogenesis (SE) using zygotic embryos as explants. We identified the optimal plant growth regulators (PGRs) performance and the best donor trees (k81) for the generation of somatic embryos (SEMs). Additionally, we confirmed that the positive developmental window of SEMs initiation was at the end of July to early August, which is when zygotic embryos was at the late embryogeny. In this time period, specific transcripts associated with the regulation of epigenetic modifications, plant hormone-related genes, and embryonic development-related transcription factors play important roles for early SEMs initiation. These results may provide a valuable resource for vegetative propagation of Picea mongolica. Our results may help to establish a reliable protocol for plantlet regeneration, which may facilitate urban greening applications and industrialization in arid areas.

Effect of Forchlorfenuron on Somatic Embryo Proliferation and Plantlet Regeneration in Oil Palm SUP-PSU1

In vitro propagation of palm oil is still an obstacle for mass propagation due to the low plant regeneration frequency. The objective of this study was to investigate the effect of N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU) on a somatic embryo (SE) proliferation and plant regeneration of oil palm SUP-PSU1. At an approximate size of 5 mm, SE from chopping with a sharp razor blade at 100 times was cultured on oil palm culture medium (OPCM) with 0.1 mg/L dicamba and different concentrations CPPU. The results showed that 0.3 mg/L CPPU gave the highest SE proliferation at 100 % and the number of SEs at 5.16 embryos/tube after 4 weeks of culture. SE was transferred to Murashige and Skoog (MS) medium supplemented with 0.2M sorbitol, a secondary somatic embryo (SSE), which was induced at 66.67 % with 21.2 embryos/tube after 8 weeks. Furthermore, cultured SSE on PGR-free MS medium for 8 weeks gave the highest germination rate at 65 %, with the number of shoots at 2.29 shoots. Thus, this study provides new information for improving the plantlet regeneration system through somatic embryogenesis in oil palm.

Plantlet regeneration via nucellar embryogenesis in Citrus jambhiri

To produce true-to-type and rapid multiplication micropropagation technique was utilized to the nucellar tissue with ovular halves of C. jambhiri. Nucellar tissues were cultured in a modified MS medium supplemented with different concentrations of 2ip viz. 0.25,0.50 mg l-1 alone and in combination of 0.50 mg l-1 NAA. Initiation of cell division and differentiation of proembryogenic tissue became apparent in first 80 days.These proembryos developed into embryos through subculturing in fresh medium. Low concentration of 0.25 2ip was found more suitable for the development of embryo producing large number of fully developed embryo in comparision to the embryo produced in the high concentration of 2ip (0.50 mg l-1) and in combination of 0.25 2ip and 0.50 mg l-1 NAA. Normally developed embryos in 0.25 2ip showed best germination in the fresh medium supplemented with 0.25 mg l-1 IAA, 100 ME mg l-1 and 5mg mg l-1 amino acids within 30 days as compared to other treatments. These germinated embryos were utilized for producing disease free saplings after hardening and nurturing in laboratory conditions. The disease free saplings thus produced can be used to establish new Citrus orchards within short time.