Banca de DEFESA: DIEGO DA SILVA CUNHA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : DIEGO DA SILVA CUNHA
DATE: 30/11/2023
TIME: 10:00
LOCAL: Plataforma Conferênciaweb - https://conferenciaweb.rnp.br/ufba/defesas_qualificacoes_ufba_renorbio
TITLE:

Physiological, biochemical and molecular characterization of castor bean (Ricinus communis L.) seed germination under saline and osmotic stresses.

KEY WORDS:

Ricinus sp., Euphorbiaceae, Bioinformatics, Water restriction, Salinity, Enzymes.

PAGES: 151
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Ricinus communis L. (Euphorbiaceae), known as castor bean, is a species that stands out in the national and international scenario, for the oil produced from its seeds, widely demanded by the biofuels, cosmetics and chemical industries. In addition to its multiple commercial and industrial uses, it has socioeconomic importance in the semiarid regions of Brazil, among other places in the world. However, semiarid regions have adverse environmental conditions such as short periods of rain and soils with saline levels. Conditions that limit water absorption and promote greater generation of reactive oxygen species (ROS), such as superoxide anion-O2, hydroperoxyl-HO2 radical, hydroxyl-OH radical, hydrogen peroxide-H2O2 and singlet oxygen, 1O2, compromising the germinative processes, growth and development of seedlings, reduce productivity and can lead to plant death. During the germination process, the activity of ROS removing enzymes has been reported, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), among others, which constitute efficient detoxification mechanisms during imbibition, these enzymes can be used as molecular markers to elucidate the events that occur during the germination process. Therefore, this proposal provides a better understanding of the mechanisms involved in the response of castor bean to abiotic stresses by water restriction and saline stress at the physiological level, related to antioxidant enzymes by biochemical and molecular studies. A REVIEW was developed where studies were identified on advances in research related to the cultivation of castor under abiotic stresses due to water restriction and salt stress, germination, and early stages of development of seedlings and antioxidant enzymes, highlighting the enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). In CHAPTER 1 we performed the biometric characterization of two R. communis cultivars (BRS Nordestina and BRS Paraguaçu), we noticed that the seeds of Cultivar BRS Paraguaçu are larger than those of BRS Nordestina, which may be related to the higher water absorption observed for the seeds of that cultivar. Through the imbibition studies in water restriction (PEG) and saline (NaCl) we observed that there is a difference in the water restriction capacity for these two solutions at the same osmotic potential, where for the imbibition by PEG at -0.23 MPa there was a drastic decrease in water absorption, inhibiting the cell cycle and the germination process while in NaCl imbibition there was only a slight delay in water absorption compared to the control. The imbibition in light potentials of NaCl (-0.23 MPa) can stimulate a greater activity of the antioxidant enzyme SOD, while for the imbibition in PEG due to severe water restriction, the activity of the SOD enzyme was lower than the control In CHAPTER 2 we performed the characterization of the family of genes that code for the enzyme Ascorbate peroxidase (APX) in castor bean, 6 putative RcAPX genes were found, through phylogenetic analysis we identified the orthologous genes in other angiosperms where we classified the APX genes according to location intracellular (Citosol, plastid and peroxisomes). We observed that the RcAPX genes have a large number of exons/introns in addition to sharing conserved motifs. An increase in the total activity of the APX enzyme was observed after 48 h of imbibition (post-germinative) in the imbibition of water (control) and in NaCl -0.23 MPa (saline restriction) in both cultivars evaluated (Nordestina and Paraguaçu), while that soaking in a -0.23 MPa PEG solution (osmotic restriction) repressed the activity of APX. In CHAPTER 3 we characterized the Catalase (CAT) gene family, we identified 2 putative RcCAT genes predicted for peroxisome intracellular localization, from phylogenetic comparison we found orthologous genes in other angiosperms where we observed the classification into three groups. We found differences in gene structure and motif order for the RcCAT2 gene compared to the angiosperm CAT genes. Through the analysis of regulatory elements in the promoter region of these genes, we identified possible forms of regulation related to biotic and abiotic stresses, as well as plant hormones such as ABA. Finally, the enzymatic activity of catalase was shown to be modulated according to development time, stress during germination and cultivar. The results contribute to a better understanding of the effects of water and saline restriction stresses in castor bean, in addition to the characterization of a family of genes that code for important antioxidant enzymes in seed responses to abiotic stress conditions.

COMMITTEE MEMBERS:
Externa à Instituição - DENISE CUNHA FERNANDES DOS SANTOS DIAS - UFV
Interno - 1919894 - FABIO ALEXANDRE CHINALIA
Externo à Instituição - LIV SOARES SEVERINO
Externo ao Programa - 3768242 - PAULO ROBERTO RIBEIRO DE JESUS - nullExterna à Instituição - RENATA SILVA-MANN - UFS
Interno - 2085555 - RENATO DELMONDEZ DE CASTRO
Externa ao Programa - 1674313 - SUZANA TELLES DA CUNHA LIMA - null