Banca de DEFESA: ROBERTA DÁVILA PEREIRA DE LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ROBERTA DÁVILA PEREIRA DE LIMA
DATE: 15/02/2023
TIME: 16:00
LOCAL: CCAB
TITLE:

Effect of indoleacetic acid on salt stress tolerance in Urochloa brizantha
cultivate piatã

KEY WORDS:

Auxin; ionic homeostasis; oxidative stress

PAGES: 50
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

Urochloa brizantha cultivar piatã is a tropical forage widely cultivated for its nutritive
value and adaptability to low fertility soils. However, the growth of this forage grass is
threatened when soils contain high levels of salts. Salinity alters the ionic balance and
the redox state of the plant, causing alterations that contribute to the loss of plant
productivity. In this sense, reliable methods are needed to mitigate the effects generated
by saline stress, and the application of plant hormones is an efficient way for such
purposes. The aim of this study is to evaluate the salt stress tolerance responses in U.
brizantha when treated with indoleacetic acid (IAA). Initially, experiments were carried
out to select an adequate concentration of the hormone (50, 200 and 800 µM) via foliar
application in plants subjected to saline stress with NaCl at 100 mM. Analysis of growth
by weighing and length measurements of aerial and root tissues, determination of
sodium and potassium contents by flame photometry, and spectrophotometric
methodologies for analysis of chlorophyll, carotenoid, proline and lipid peroxidation
contents were carried out. The results showed that at lower concentrations of AIA there
was a better regulation of Na+ levels, an increase in the content of photosynthetic
pigments and a reduction of proline in stressed plants. Therefore, a second experiment
was developed with the foliar application of AIA at 50 µM in plants subjected to saline
stress with NaCl at 75 mM. In this experiment, the analyzed parameters in previous
experiment were evaluated and it were included the follow analysis: relative water
content, electrolyte leakage, content of hydrogen peroxide and enzyme activity of
catalase (CAT), guaiacol peroxidase (POD) and superoxide dismutase (SOD). POD
enzymatic activity was also evaluated by zymography. The results showed that
treatment with AIA in stressed plants did not promote plant growth and stimulate
enzyme activity, however it was observed a reduction in electrolyte leakage, lipid
peroxidation and hydrogen peroxide, as well as a decrease in sodium levels and
potassium retention in piatã grass leaves, revealing a possible participation of AIA in
the regulation of ionic homeostasis. It is concluded that AIA would induce salt stress
tolerance in U. brizantha by acting on processes that control sodium and potassium
transport to the aerial tissues.

BANKING MEMBERS:
Presidente - JUAN CARLOS ALVAREZ PIZARRO
Externo à Instituição - SÉRGIO LUIZ FERREIRA DA SILVA
Externa à Instituição - AIALA VIEIRA AMORIM.