Banca de QUALIFICAÇÃO: LUCAS RÊGO MENDONÇA MARINHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUCAS RÊGO MENDONÇA MARINHO
DATE: 11/10/2023
TIME: 09:00
LOCAL: Sala 4 - IA/DFITO
TITLE:

PHYSIOLOGY AND BIOCHEMISTRY OF PLANTS UNDER THE ACTION OF THE GLUFOSINATE AMMONIUM HERBICIDE

KEY WORDS:

A. thaliana, ROS, GLN1, GLN2, glu1, GS/GOGAT.

PAGES: 48
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Matologia
SUMMARY:

Inhibition of the enzyme glutamine synthetase (GS), crucial in nitrogen assimilation, is known as the primary mechanism of action of glufosinate ammonium, but the rapid controlling effect appears to be associated with the generation of reactive oxygen species resulting from the inhibition of processes such as photosynthesis and/or photorespiration. However, gaps persist in the detailed understanding of the effect of glufosinate ammonium on these processes. The hypothesis is that the action of glufosinate depends exclusively on the inhibition of the chloroplast isoform of GS, inhibiting the GS/GOGAT cycle and leading to the death of plants due to oxidative stress. This project aims to investigate the causes of the differential effectiveness of glufosinate ammonium in plants. To achieve this objective, A. thaliana mutants deficient in GS (GS1 and GS2) and Fd-GOGAT will be studied, as well as mutants for overexpression of the GLN2 gene (GS2). The mutant plants, including non-transformed plants (WT) will be subjected to treatment with glufosinate ammonium (504 g a.i. ha-1) + soy methyl ester (0.5%) and maintained under three different irradiance levels. The tests will be conducted in a growth chamber, adopting a completely randomized design (DIC) and a 7x2 factorial scheme, in which factor A will be composed of mutants for knockout of the GLN1.1, GLN1.2, GLN1.3 and GLN2 genes, with addition of the mutant for overexpression of GLN2, reduced expression of the glu1 gene and control plants (WT). And factor B will be the application or not of the herbicide glufosinate ammonium. Chlorophyll a fluorescence will be evaluated, allowing an understanding of the dynamics of energy transfer throughout the chloroplast ETC. The CO2 assimilation rate will also be evaluated. In addition, analyzes of reactive oxygen species will be conducted, including hydrogen peroxide (H2O2) and superoxide anion (O2•−), as well as the quantification of metabolites such as glutamine, glutamate and glyoxylate. The study will also cover the analysis of the activity of enzymes involved in CO2 assimilation, such as ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase, enzymes associated with the nitrogen assimilation cycle, such as glutamine synthetase (GS) and glutamate synthetase (GOGAT), and antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD). The results are expected to observe the differential efficacy of glufosinate ammonium on A. thaliana mutants, as well as understanding the biochemical and physiological bases for the differences in control with the herbicide.

COMMITTEE MEMBERS:
Presidente - 2466219 - CAMILA FERREIRA DE PINHO
Interno - 2181674 - LEONARDO OLIVEIRA MEDICI
Externa à Instituição - NATALIA DA SILVA GARCIA