Banca de QUALIFICAÇÃO: JOSUÉ VALENTE LIMA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE: JOSUÉ VALENTE LIMA
DATA: 20/12/2016
HORA: 09:00
LOCAL: Auditório do PPAGRO/UFRA
TÍTULO:

Brassinosteroids improve photosystem II efficiency, gas exchange, antioxidant enzymes and growth of cowpea plants exposed to water deficit

PALAVRAS-CHAVES:

Antioxidant system ● Brassinosteroids ● Net photosynthetic rate ● Quantum yield of photosystem II ● Vigna unguiculata ● Water deficiency

PÁGINAS: 48
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitotecnia
ESPECIALIDADE: Fisiologia de Plantas Cultivadas
RESUMO:

Water deficit is considered the main abiotic stress that limits agricultural production worldwide. Brassinosteroids (BRs) are natural substances that play roles in plant tolerance against abiotic stresses, including water deficit. This research aims to determine whether BRs can mitigate the negative effects caused by water deficiency, revealing how BRs act and their possible contribution to increased tolerance of cowpea plants to water deficit. The experiment was a factorial design with the factors completely randomised, with two water conditions (control and water deficit) and three levels of brassinosteroids (0, 50 and 100 nM 24-epibrassinolide; EBR is an active BRs). Plants sprayed with 100 nM EBR under the water deficit presented significant increases in ΦPSII, qP and ETR compared with plants subjected to the water deficit without EBR. With respect to gas exchange, PN, E and gs exhibited significant reductions after water deficit, but application of 100 nM EBR caused increases in these variables of 96, 24 and 33%, respectively, compared to the water deficit + 0 nM EBR treatment. To antioxidant enzymes, EBR resulted in increases in SOD, CAT, APX and POX, indicating that EBR acts on the antioxidant system, reducing cell damage. The water deficit caused significant reductions in Chl a, Chl b and total Chl, while plants sprayed with 100 nM EBR showed significant increases of 26, 58 and 33% in Chl a, Chl b and total Chl, respectively. This study revealed that EBR improves photosystem II efficiency, inducing increases in ΦPSII, qP and ETR. This substance also mitigated the negative effects on gas exchange and growth induced by the water deficit. Increases in SOD, CAT, APX and POX of plants treated with EBR indicate that this steroid clearly increased the tolerance to the water deficit, reducing reactive oxygen species, cell damage, and maintaining the photosynthetic pigments. Additionally, 100 nM EBR resulted in a better dose-response of cowpea plants exposed to the water deficit.

MEMBROS DA BANCA:
Presidente - 1803899 - ALLAN KLYNGER DA SILVA LOBATO
Externo ao Programa - 1125368 - LEILA SOBRAL SAMPAIO
Externo ao Programa - 388486 - ROBERTO CEZAR LOBO DA COSTA
Externo à Instituição - FLÁVIO JOSÉ RODRIGUES CRUZ - UNESP