In vitro photoautotrophic potential, photosynthetic capacity and 20E accumulation of diploid and synthetic polyploid accessions of Pfaffia glomerata (SPRENG.) Pedersen (Amaranthaceae)

• Ano de defesa: 2014
• Autor(a) principal: Corrêa, João Paulo de Oliveira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Pfaffia glomerata; Ginseng brasileiro; Fitoecdisteróides; Poliploidia; Botânica
• Link de acesso: http://www.locus.ufv.br/handle/123456789/7556

Popularly known as Brazilian ginseng, Pfaffia glomerata (Amaranthaceae) is a medicinal species native to Brazil that produces the phytoecdysteroid 20- hydroxyecdisone (20E) as its main active ingredient. This study aimed to shed light if the in vitro photoautotrophic potential and 20E production of 6 P. glomerata accessions could be related to photosynthetic performance and biomass accumulation under ex vitro conditions and study how these parameters are affected by induced polyploidy. P. glomerata accessions have significantly different photosynthetic capacities, resulting in differential biomass accumulation both in vitro and ex vitro. As hypothesized, the accessions with the highest photoautotrophic potential also showed greater photosynthetic performances and biomass accumulation ex vitro. The same accessions also showed the highest 20E mass per plant ex vitro. 20E production in vitro also varied among accessions, with the highest total mass achieved by accessions 4 and 43, which are also among the best producers ex vitro. Synthetic polyploidization was efficient in producing tetraploid 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 5 independently generated tetraploids tested (P28, P60, P68, P75 and P75), only P28 showed effectively increased growth performance, with higher biomass accumulation in vitro and ex vitro in comparison to diploid plants. Polyploidization did not increase the photosynthetic rates per leaf area, but increased leaf area in P28, what may have resulted in an increased net photosynthesis per plant. 20E accumulation in vitro was higher in diploid plants than in tetraploids. The 20E content ex vitro in the tetraploid P28 was 31% greater than in diploids. In comparison to diploids, P28 showed the double of the total 20E mass produced per plant. The induction of polyploidy and selection of genotypes showed to be effective strategies to achieve an improved P. glomerata production in terms of higher in vitro photoautotrophic potential, biomass accumulation and 20E production ex vitro.