Banca de QUALIFICAÇÃO: EDUARDO SOUZA DE AMORIM

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : EDUARDO SOUZA DE AMORIM
DATE: 22/11/2024
TIME: 13:30
LOCAL: Online
TITLE:

Metabolization and programmed cell death in Conyza sumatrensis with a rapid physiological response to the herbicide 2,4-D

KEY WORDS:

fleabane; Auxin mimickers; Cytochrome P450, Oxidative stress.

PAGES: 23
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Matologia
SUMMARY:

Chemical weed control is one of the most effective and economical control methods, and the herbicide 2,4-D is one of the molecules used. The species Conyza sumatrensis is resistant to five herbicide mechanisms of action, one of which is 2,4-D itself. For the Conyza sumatrensis biotype studied in this work, symptoms indicating a rapid physiological response to the herbicide were observed. These metabolization processes are involved and related to the cytochrome P450 (P450) enzyme complex. Compartmentalization in vacuoles is also observed as an adaptive mechanism in plants that develop resistance to herbicides. The aim of this study is to prove that the rapid physiological response to the herbicide 2,4-D is a process of programmed cell death, and to understand whether metabolization occurs in biotypes resistant to this herbicide. Thus, the F2 seeds of these populations will be germinated in a growth chamber in a controlled environment of 19ºC in germination trays and transplanted into 0.1L plastic pots containing a mixture of 50% soil and 50% substrate. Subsequently, all the plants will be kept in a greenhouse, irrigated daily and fertilized twice a week. The experiment for P450 inhibitors will be conducted in a 2x4 factorial design, with two Conyza sumatrensis biotypes Susceptible and Resistant and 4 treatments, including the herbicide 2,4-D alone and combined with P450 inhibitors (Malathion, verapamil and orthovanadate). The inhibitors will be applied 2 hours before 2,4-D, using a pressurized CO₂ sprayer. Visual control will be assessed at 2, 3, 7, 14, 21, 35 and 42 days after application (DAA), and the dry mass of the aerial part will be measured. The rapid physiological response will be monitored in the first 24 hours, with measurements of α-chlorophyll fluorescence and visual analysis of phytotoxicity in which 0% is the absence of a symptom and 100% is total control of the plant. For enzymatic and H₂O₂ analysis, the plant material will be frozen at -80ºC. The enzyme activities will be measured according to known protocols, for total SOD it will be measured as described by Giannopolitis and Ries (1977), for CAT the protocol of Azevedo-Neto et al. (2006), and for APX activity the method of Nakano and Asada (1981). The statistical analysis of enzyme activity and ROS measurement and of the other experiments will be carried out using the R statistical software. All the data will be subjected to the normality test (Shapiro-Wilk) and analysis of variance (ANOVA p≤0.05) and, if significant, the mean comparison test (Tukey, p≤0.05). The transmission electron microscopy experiment will be carried out in a DIC with 3 treatments, leaves from plants without the application of the herbicide, leaves from plants collected 2h and 4h after the application of the 2,4D herbicide, with three biological replicates for each treatment. Vegetative material will be sent to the Electron Microscopy Center of the Botucatu Biosciences Institute (UNESP), in Botucatu, SP, for processing and obtaining images. It is hoped that this research will make it possible to understand that the rapid physiological response observed in biotypes of buva resistant to the herbicide 2,4-D is related to a process of programmed cell death, triggered by the metabolization of the herbicide.

COMMITTEE MEMBERS:
Interna - 2466219 - CAMILA FERREIRA DE PINHO
Interno - 2181674 - LEONARDO OLIVEIRA MEDICI
Externo à Instituição - JUNIOR BORELLA - FURG