Banca de QUALIFICAÇÃO: SANDY SANTOS DA FONSECA
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.DISCENTE : SANDY SANTOS DA FONSECA
DATA : 20/11/2019
HORA: 14:30
LOCAL: Auditório central da UFRA/Paragominas
TÍTULO:
Brassinosteroids positively modulate epiderm, epicuticular wax and trichomes confering tolerance in rice plants under simulated acid rain
PALAVRAS-CHAVES:
24-epibrassinolide ● acid rain ● photosynthesis ● rice ● trichomes
PÁGINAS: 67
RESUMO:
Acid rain is one of the most frequent abiotic stresses in rice, affecting mainly its development and growth, with negative effects on its productivity. Brassinosteroids (BRs) are known to mediate cell expansion, stimulate improvements in the antioxidant system and tolerance to abiotic stress. The aim of this study was to investigate whether exogenous treatment with 24-epibrassinolide (EBR, an active form of BR) can mitigate the negative effects of Simulated Acid Rain (SAR), and provide tolerance to plants exposed to acid water. Next, we evaluate the possible implications on chlorophyll fluorescence, gas exchange, antioxidant system, oxidant system and anatomical characteristics. The experiment was randomized with four treatments, being two simulated acid rain (0 and 0.5 M H2SO4, described as – SAR and + SAR, respectively) and two concentrations of brassinosteroids (0 and 100 nM EBR, described as – EBR and + EBR, respectively). The results showed that plants exposed to SAR but treated with EBR improved chlorophyll fluorescence by relieving photoinhibition, dissipating excess heat energy, protecting plants from damage caused by excess reactive oxygen species (ROS), in the leaf area. Additionally, EBR promoted beneficial changes in gas exchange in stomatal regulation, which facilitated photosynthetic apparatus activity, improving stomatal regulation and circulation of CO2 in intercellular spaces. The research revealed that EBR attenuated the negative effects of SAR by increasing the activity of the antioxidant enzymes superoxide dismutase, catalase, ascorbate peroxidase and peroxidase, which influenced the reduction of membrane damage tilacoid, confirmed by increases in chlorophyll a, b, total and carotenoid contents. Finally, the attenuating effects of EBR observed in plants under SAR showed that steroids mediated important leaf protection modulations, which suffered the greatest SAR impacts. These modulations included increases in the external leaf protection layer, which is quite hydrophobic, consisting of trichomes, epicuticular wax and epidermis. These results provide evidence that EBR is able to confer tolerance on rice plants exposed to SAR.
MEMBROS DA BANCA:
Presidente - 1803899 - ALLAN KLYNGER DA SILVA LOBATO
Externo ao Programa - 3074669 - RAFAELA CABRAL DOS SANTOS DA TRINDADE
Externo à Instituição - DOUGLAS JOSÉ MARQUES - UFU
Externo à Instituição - ALESSANDRA JACKELINE GUEDES DE MORAES - UEPA