Banca de DEFESA: Ivonaldo Reis Santos

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Ivonaldo Reis Santos
DATE: 27/01/2023
TIME: 08:30
LOCAL: Meio virtual
TITLE:

USE OF BIOTECHNOLOGICAL AND NANOTECHNOLOGICAL TOOLS FOR THE CONTROL OF THE PHYTOPATOGENIC BACTERIA Xanthomonas campestris pv. campestris

KEY WORDS:

Concentrated metabolites, black rot, defense response, Xanthomonas campestris pv. campestris and antimicrobial activity

PAGES: 154
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

In order to control the black rot of brassicas caused by Xanthomonas campestris pv. campestris (Xcc), biotechnological and nanotechnological tools were used in this study. In the first stage of this study, concentrated metabolites extracted from Rhizobium tropici (CM-RT) were used in the induction of defense-related genes. The cabbage plants were cultivated in a greenhouse and 21 days after sowing they were sprayed with a 1% CM-RT solution on the leaves or roots. The aerial and root parts were collected separately on day 0 (control condition), 24 and 48 h after treatment (hat) and submitted to RNA extraction for RT-qPCR analysis of 8 defenserelated genes. The results showed that CM-RT applied to the leaves has a more lasting and systemic protective effect on the plant. The results obtained in this study emphasize the biotechnological potential of the use of CM-RT acting as an elicitor of active defense responses in plants, which can significantly contribute to the control of black rot in brassica. In the second stage of this study, the green synthesis of silver nanoparticles (AgNPs) was carried out using aqueous extracts of cabbage leaves, Arabidopsis, neem, and noni, in addition to aqueous extracts of parts of the noni fruit (peel or pulp/seed), as reducing and stabilizing agents. AgNPs synthesis reactions were performed in 6 different concentrations of extracts in aqueous solutions of silver nitrate (AgNO3), at 1 mM final, totaling 42 samples, of which 14 samples of AgNPs were selected, according to their hydrodynamic diameter (HD), polydispersity index (PdI) and Zeta potential (ZP) and then tested in vitro to assess their antibacterial activities against Xcc. The AgNPs that showed the highest antibacterial activity at a concentration of 64 µM, had the lowest HD, such as those synthesized with aqueous extract of noni fruit peel (AEPFN) at a concentration of 60 mg/mL. In addition, plants with susceptible genotypes of B. oleracea were treated with AEPFN-AgNPs, and positive modulation of defense-related biomarker genes was obtained by qRT-PCR. Plants treated with AEPFN-AgNPs at 64 µM when challenged with Xcc showed a more tolerant phenotype, highlighting that the application of AgNPs seems to trigger an effective plant defense response. The present study reveals the potential of AgNPs to direct antibacterial activity and improve plant crop defense and, finally, proposes an interesting alternative approach to combat black rot, potentially extensible to other pathosystems. In the third stage of this study, a proteomic analysis was performed to understand the mechanisms of action of AgNPs in Xcc treated with AgNPs (32 µM), AgNO3 (32 µM), or without treatment (control condition). Subsequently, the extraction of total proteins was performed and the samples were submitted to proteomic analysis. In total, 352 differentially abundant proteins were identified. In samples treated with AgNPs, 134 proteins were differentially abundant, including 107 increased and 27 decreased proteins, in samples treated with AgNO3, there were 14 differentially abundant proteins, including 10 increased and 4 decreased proteins, when compared to the control condition. Finally, when samples treated with AgNPs were compared with samples treated with AgNO3, the results showed 204 differentially abundant proteins, including 75 increased and 129 decreased proteins. Gene ontology analysis revealed that most upregulated proteins were involved in important biological processes such as metal ion homeostasis, detoxification, membrane organization, amino acid and carbohydrate metabolic process, lipid metabolic process, proteolysis, transmembrane transport and others. The results obtained bring important contributions to a better understanding of the mechanisms of action of AgNPs in Xcc and may contribute to the development of strategies to control Xcc in brassica.

BANKING MEMBERS:
Externo à Instituição - LEONARDO LIMA PEPINO DE MACEDO - EMBRAPA
Externa à Instituição - ANA CAROLINA MENDES BEZERRA - EMBRAPA
Externa à Instituição - CINTHIA CAETANO BONATTO - EMBRAPA
Presidente - 804.882.851-00 - LUCIANO PAULINO DA SILVA - EMBRAPA
Interna - 1122620 - SONIA MARIA DE FREITAS