Banca de DEFESA: LUCILENE RODRIGUES DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUCILENE RODRIGUES DOS SANTOS
DATE: 23/11/2020
TIME: 14:00
LOCAL: Através de chamada por videoconferência
TITLE:

 

HOW BRASSINOSTEROIDS ACT IN SOYBEAN PLANTS SUBMITTED TO THE INADEQUATE ZINC AND IRON SUPPLIES?

KEY WORDS:

Brassinosteroids, Chlorophylls, Liquid photosynthetic rate, Quantum yield of photosystem II, Glycine max

PAGES: 60
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUMMARY:

Global soy production reached the 2017/2018 crop, the second highest production ever recorded thanks to harvests in the United States and Brazil. Among the factors that have contributed to leverage the production and productivity of this commodity, in addition to favorable soil conditions, the availability of nutrients, especially micronutrients, has been a determining factor to be considered. Essential micr-onutrients such as zinc (Zn) and iron (Fe) play a crucial role in soybean production, as they are involved throughout the crop's development cycle. However, inadequate supplies of Zn and Fe have become stress factors for culture due to the deficiency or excess of these elements in the plant. In recent years, strategies and technologies have been developed for the treatment of plants stressed by abiotic factors, among them, the application of plant steroids has been discussed as an effective and less harmful method. From plant steroids, considerable attention has been paid to brassinosteroids (BRs). In this context, the objective was to evaluate the effects of Zn and Fe in the soybean culture exposed to low/high supplies of these elements in the soil, as well as to investigate the physiological and biochemical behavior of BRs in soybean plants submitted to Zn deficiency and excess and Fe and identify the possible benefits caused by the steroid. For this, two experiments were carried out in a greenhouse. Experiment I followed a completely randomized factorial design with two concentrations of 24-epibrassinolide (0 and 100 nM EBR) and three supplies of Zn (0.2, 20 and 2000 μM Zn). Experiment II was carried out in a completely randomized design with four treatments (0 nM EBR + 250 μM Fe, 0 nM EBR + 2.5 μM Fe, 100 nM EBR + 250 μM Fe and 100 nM EBR + 2.5 μM Fe). In general, low supplies of Zn and Fe and high supplies of Zn produced deleterious effects. However, the results revealed that exogenous BRs (100 nM EBR) minimized the damage caused by Zn and Fe deficiency and by toxic Zn levels in soybean plants. In experiment I, EBR alleviated the impact produced by zinc stress on the root system by acting positively on the epidermis, endoderm, cortex, vascular cylinder and metaxylem, intrinsically improving the nutritional status in plants. EBR promoted improvements in the photosynthetic machinery of plants exposed to zinc stress, stimulating the activity of antioxidant enzymes that play crucial roles in the protection of chloroplast membranes, with positive repercussions on chlorophylls, effective quantum yield of PSII photochemistry and transport rate of PSII electrons. In experiment II, EBR maximized the Fe content in the leaf, stem and root, as well as improved the nutrient content and the metal homeostasis, as confirmed by the increased detection of Fe2+/Mg2+, Fe2+/Mn2+ and Fe2+/Cu2+ in plants with Fe deficiency. The steroid also promoted improvements in chloroplastic pigments and increased photochemical efficiency, positively regulating electron transport and reducing the negative impacts associated with PSII photoinhibition.

BANKING MEMBERS:
Presidente - 1803899 - ALLAN KLYNGER DA SILVA LOBATO
Externo à Instituição - FLÁVIO JOSÉ RODRIGUES CRUZ - UFRPE
Externo à Instituição - JOÃO RODRIGO COIMBRA NOBRE - UEPA
Externa ao Programa - 3074669 - RAFAELA CABRAL DOS SANTOS DA TRINDADE
Externo à Instituição - SEIDEL FERREIRA DOS SANTOS - UFPA