The influence of flask sealing and explant source on the in vitro morphogenesis of pepper, were evaluated in Capsicum annuum. Seeds were sterilized and inoculated in Murashige and Skoog media supplemented with vitamins, myo-inositol, sucrose, and agar. Gas exchange was evaluated in the germination stage by comparing 3 flask-sealing systems: rigid polypropylene lids (PLs) without vents, PLs with 1 vent, and PLs with 2 vents covered with membranes. In the regeneration stage, cotyledon and hypocotyl segments were transferred to the organogenesis-inducing media, being the different sealing types also tested in a factorial scheme. Photosynthetic pigments, morphological and hystological analyses were conducted for each treatment. Plants maintained in glass flasks capped with vented lids showed more vigorous growth and differentiated anatomical structures. These treatments resulted in taller plants, higher numbers and more expanded leaves, higher fresh and dry weights, and an increase in photosynthetic pigments. Cultivation of C. annuum in flasks with reduced gas exchange was more effective on callus induction. During the regeneration stage, hypocotyls were more effective than cotyledons. Sealing type influenced the morphogenic responses of pepper, demonstrating that an increase in gas exchange has a positive effect on biomass production and acclimatization of the plantlets.

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Flask sealing on in vitro seed germination and morphogenesis of two types of ornamental pepper explants

The combination of different colors from light-emitting diodes (LEDs) may influence growth and production of secondary metabolites in plants. In the present study, the effect of light quality on morphophysiology and content of 20-hydroxyecdysone (20E), a phytoecdysteroid, was evaluated in accessions of an endangered medicinal species, Pfaffia glomerata, grown in vitro. Two accessions (Ac22 and Ac43) were cultured in vitro under three different ratios of red (R) and blue (B) LEDs: (i) 1R:1B, (ii) 1R:3B, and (iii) 3R:1B. An equal ratio of red and blue light (1R:1B) increased biomass accumulation, anthocyanin content, and 20E production (by 30-40%). Moreover, 1R:1B treatment increased the size of vascular bundles and vessel elements, as well as strengthened xylem lignification and thickening of the cell wall of shoots. The 1R:3B treatment induced the highest photosynthetic and electron transport rates and enhanced the activity of oxidative stress-related enzymes. Total Chl content, Chl/Car ratio, and NPQ varied more by accession type than by light source. Spectral quality affected primary metabolism differently in each accession. Specifically, in Ac22 plants, fructose content was higher under 1R:1B and 1R:3B treatments, whereas starch accumulation was higher under 1R:3B, and sucrose under 3R:1B. In Ac43 plants, sugars were not influenced by light spectral quality, but starch content was higher under 3R:1B conditions. In conclusion, red and blue LEDs enhance biomass and 20E production in P. glomerata grown in vitro.

Blue and red light affects morphogenesis and 20-hydroxyecdisone content of in vitro Pfaffia glomerata accessions.

Hydroalcoholic extract of Pfaffia glomerata alters the organization of the seminiferous tubules by modulating the oxidative state and the microstructural reorganization of the mice testes.

The present study aimed to verify the effects of induced polyploidization on Pfaffia glomerata regarding its 20-hydroxyecdysone (20E) production both in vitro and under greenhouse conditions, its in vitro photoautotrophic potential, and its ex vitro biomass accumulation and photosynthetic performance. Synthetic polyploidization efficiently produced individuals with increased in vitro photoautotrophic potential and ex vitro biomass accumulation, although photosynthetic rates per leaf area did not vary between diploids and tetraploids. Among the five tetraploids tested (P28, P60, P68, P74, and P75), P28 showed significantly increased biomass both in vitro and ex vitro when compared with diploid plants, whereas the other tetraploids did not differ significantly from the diploids in terms of biomass accumulation. Although photosynthetic rates per unit leaf area remained constant among all the plants tested, P28 showed a significantly greater total leaf area, which may have resulted in an increase in net photosynthesis on a whole-plant basis. Under greenhouse conditions, the 20E content in the tetraploid P28 was 31% higher than that in diploid plants, and the final 20E mass per plant produced by P28 ex vitro was approximately twice that produced by diploid plants. Accumulation of 20E in vitro did not follow the same pattern observed among the plants ex vitro; instead, greater accumulation was observed in diploid plants. The induction of polyploidy in P. glomerata appears to be a promising strategy for producing plants with higher biomass accumulation and 20E production ex vitro, in addition to its higher in vitro photoautotrophic potential.

Induced polyploidization increases 20-hydroxyecdysone content, in vitro photoautotrophic growth, and ex vitro biomass accumulation in Pfaffia glomerata (Spreng.) Pedersen

Pfaffia glomerata has potential pharmacological and medicinal properties due to the production of a secondary metabolite known as the phytoecdysteroid 20-hydroxyecdysone (20E). There have been increasing efforts for massive in vitro propagation of Pfaffia plants due to high extractivism and overharvesting of this species. Research on the species has shown that photoautotrophic cultivation can improve the production of 20E. In addition, other abiotic factors such as the formulations of culture media can influence the morphophysiological behavior of the plants in vitro. Therefore, the objective of this study was to analyze the morphological and physiological performances of P. glomerata plants in different formulations of culture media, under photoautotrophic and photomixotrophic propagation conditions. Six medium formulations, the Driver and Kuniyuki medium (DKW), Correia et al. medium (JADS), Murashige and Skoog medium (MS), Quoirin and Lepoivre medium (QL), Rugini medium (OM), and Woody Plant medium (WPM), all supplemented with DKW vitamins, 100 mg L−1 myo-inositol, 6.5 g L−1 agar, and with or without 3% (w/v) sucrose, were evaluated. Cultures were maintained at 25 ± 2°C, with a 16 h-photoperiod under 60 μmol m−2 s−1 of irradiance under a fluorescent lamp for 50 d. Results showed that the presence or absence of sucrose, and the different nutritional formulations influenced growth, photosynthetic pigment content, endogenous levels of sugars, leaf morphology, levels of 20E, and transport of water and minerals in P. glomerata. Notably, OM, DKW, QL, and WPM media promoted higher production of 20E under photomixotrophic growth conditions.

Morphophysiological in vitro performance of Brazilian ginseng (Pfaffia glomerata (Spreng.) Pedersen) based on culture medium formulations

This study aimed to investigate whether the in vitro photoautotrophic potential and 20 hydroxyecdysone (20E) production of six Pfaffia glomerata accessions could be correlated to photosynthetic performance and biomass accumulation under ex vitro conditions in a greenhouse environment. Our results showed that P. glomerata accessions displayed varying photosynthetic rates that may have resulted in differential biomass accumulation both in vitro and ex vitro. Accessions A4, A13 and A43 showed the highest dry weight under in vitro photoautotrophic conditions, coinciding with the higher photosynthetic rates of the same accessions in greenhouse. They also showed the highest 20E mass per plant ex vitro. Production of 20E in vitro also varied among accessions, with the highest total mass achieved by accessions A4 and A43. In addition to having the potential for optimizing propagation by reducing the duration of the in vitro culture stage and lessening death rate during acclimatization, the use of these genotypes with higher in vitro photoautotrophic potential can guarantee highly productive plants ex vitro because the biomass accumulation pattern observed in vitro matched that under greenhouse conditions.

Jéssica Fernanda Laísca Azevedo

Papers

In vitro photoautotrophic potential and ex vitro photosynthetic competence of Pfaffia glomerata (Spreng.) Pedersen accessions