Pfaffia glomerata (Spreng.) Pedersen is a medicinal species of great interest because it produces the phytoecdysteroid 20-hydroxyecdysone (20E). Generally, because of atypical growing conditions, in vitro propagated plants function less efficiently as autotrophs and have poorly developed morphological structures. This study analyzed the autotrophic potential of P. glomerata propagated in vitro and evaluated the influence that this has on 20E biosynthesis. Physiological and structural parameters of plants subjected to heterotrophic, photomixotrophic and photoautotrophic growth conditions were evaluated. Levels of 20E were measured by HPLC. Plants were acclimatized in a mixture of soil, sand and substrate, in a greenhouse. Conditions that provided higher carbon input led to an increase in plant growth, and the presence of sucrose was critical, in closure systems without a gas permeable membrane, for normal anatomical development of the micropropagated plants. The absence of sucrose increased photosynthesis and conditions that enhanced photoautotrophy induced greater levels of 20E. The increase of 20E levels by the photoautotrophic system offers new prospects for increasing the commercial production of this species, and for studies that could elucidate the biosynthetic pathway of phytoecdysteroids in plants.

Plant growth regulators play an important role in seed germination. However, much of the current knowledge about their function during seed germination was obtained using orthodox seeds as model systems, and there is a paucity of information about the role of plant growth regulators during germination of recalcitrant seeds. In the present work, two endangered woody species with recalcitrant seeds, Araucaria angustifolia (Gymnosperm) and Ocotea odorifera (Angiosperm), native to the Atlantic Rain Forest, Brazil, were used to study the mobilization of polyamines (PAs), indole-acetic acid (IAA) and abscisic acid (ABA) during seed germination. Data were sampled from embryos of O. odorifera and embryos and megagametophytes of A. angustifolia throughout the germination process. Biochemical analyses were carried out in HPLC. During seed germination, an increase in the (Spd + Spm) : Put ratio was recorded in embryos in both species. An increase in IAA and PA levels was also observed during seed germination in both embryos, while ABA levels showed a decrease in O. odorifera and an increase in A. angustifolia embryos throughout the period studied. The (Spd + Spm) : Put ratio could be used as a marker for germination completion. The increase in IAA levels, prior to germination, could be associated with variations in PA content. The ABA mobilization observed in the embryos could represent a greater resistance to this hormone in recalcitrant seeds, in comparison to orthodox seeds, opening a new perspective for studies on the effects of this regulator in recalcitrant seeds. The gymnosperm seed, though without a connective tissue between megagametophyte and embryo, seems to be able to maintain communication between the tissues, based on the likely transport of plant growth regulators.

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.