Banca de DEFESA: MARCOS VINICIUS SILVA DE ANDRADE

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARCOS VINICIUS SILVA DE ANDRADE
DATE: 06/05/2022
TIME: 09:00
LOCAL: sala de conferência do programa na plataforma Conferência Web RNP (https://conferenciaweb.rnp.br/web
TITLE:

Seed viability and biochemical and metabolomic profiles of Stevia Rebaudiana (Bert.) Bertoni plants under different photoperiods

KEY WORDS:

Luminosity, Steviol Glycosides, Antioxidant Enzymes, Phenolic Compounds, Bioactive compounds.

PAGES: 100
BIG AREA: Outra
AREA: Tecnologia e Inovação
SUMMARY:

Stevia rebaudiana (Bert.) Bertoni has gained relevance in recent years due to sweetening characteristics provided by the presence of steviol glycosides (SG), mainly in its leaves. Due to its rich nutritional and phytochemical profile, stevia also provides beneficial effects against a multitude of health conditions, thus being of interest as plants with medicinal properties. However, the large-scale cultivation of stevia faces obstacles since it is highly responsive to environmental stimuli, among which the photoperiod is one most relevant, affecting its morphological and biochemical characteristics. Therefore, it is of fundamental importance to understand the mechanisms underlying stevia responses to different light conditions. In this sense, the present study aimed to characterize the morphoanatomical profile of seed germination and seedling antioxidant enzymes, along with biochemical and metabolomic profiles of Stevia rebaudiana plants under different photoperiods. We have initially evaluated the morphophysiology and germinability of the different seeds (achenes) produced by Stevia plants, where we have defined a viability profile based on tetrazolium test. Subsequently, we sought to investigate the profile of antioxidant enzymes in seedlings submitted to different photoperiod conditions (Chapter 1). At this first moment, we observed that antioxidant enzymes can be an important tool for evaluation the physiological state of Stevia seedlings/plants under different light stress conditions, providing very useful information which may be considered for large-scale seed-based cultivation. Subsequently, we performed plant growth under different photoperiods regimes, where we evaluated the SG content and the general Nuclear Magnetic Resonance chemical composition, antioxidant (DPPH and SOD) and antimicrobial activities, as well as total phenolic contents of the extracts obtained from leaf and stem samples (Chapter 2). We have noted that the SG and other bioactive contents produced by Stevia plants can vary in response to different photoperiods, providing important information which may be applied to improve its large-scale cultivation. We have also focused on the extraction and quantification of key SG (Stevioside and Rebaudioside A) via RP-HPLC-UV from leaf and stem samples. As predicted, leaf samples presented higher contents of SGs. However, it’s worth noting that relevant amounts of metabolites were also present in stem samples. According to our results, SG synthesis can be affected by light (Chapter 3). Furthermore, we demonstrate that, in addition to the leaf, the stevia stem can present a series of very important properties for future exploitation.

BANKING MEMBERS:
Externo à Instituição - SILVIO CLAUDIO DA COSTA
Externa à Instituição - SIMONE RIBEIRO LUCHO
Externa à Instituição - DANIELE TAKAHASHI BERNAL
Presidente - 2085555 - RENATO DELMONDEZ DE CASTRO
Externo à Instituição - VALDIR GOMES NETO