Atividade de enzimas antioxidantes e inibição do crescimento radicular de feijão caupi sob diferentes níveis de salinidade

Abstract

ABSTRACT(Activities of antioxidant enzymes and root growth inhibition in cowpea seedlings exposed to diff erent salt levels). Phenol peroxidase (POX) is a dual enzyme that is involved with hydrogen peroxide scavenging and lignin biosynthesis, contributing to growth inhibition by secondary wall thickening. In order to relate growth inhibition to salt-induced oxidative modulation, the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and POX were evaluated in cowpea roots under salinity. Four-day-old seedlings of the Pitiúba and Pérola cultivars were exposed to 0, 25, 50, 75 and 100 mM NaCl in germination paper under controlled conditions. Aft er two days of treatment, root length was reduced under 100 mM NaCl by 56 and 26% in Pitiúba and Pérola, respectively, which was associated with enhanced electrolyte leakage and cell death in the root apex. NaCl salinity did not trigger lipid peroxidation, indicating that cell death was probably due to membrane damage instead of oxidative stress. Salt stress reduced the activity of SOD, CAT and APX and increased the POX activity, demonstrating that this enzyme plays a role in oxidative protection in cowpea roots exposed to NaCl salinity. In conclusion, salt-induced growth inhibition in cowpea roots could be attributed, at least in part, to a coordinate action involving an increase in POX activity and a drop in CAT and APX activities. Atividade de enzimas antioxidantes e inibição do crescimento radicular de feijão caupi sob diferentes níveis de salinidade

Azospirillum brasilense affects the antioxidant activity and leaf pigment content of Urochloa ruziziensis under water stress

“…The results obtained in the present study corroborate those found in cowpea grown under saline conditions, in response to increased POD activity (Maia et al 2012). Previous results from hypocotyls of corn seedlings also indicate that proteins were protected by increased CAT activity (Rosa et al 2005).…”

Crescimento e conteúdo de prolina em plântulas de guandu submetidas a estresse osmótico e à putrescina exógena

“…A redução no crescimento das plântulas de guandu pelo aumento da salinidade foi expressivo, mesmo com o incremento observado nos teores de prolina, na parte aérea e nas raízes. A redução do potencial hídrico, induzida pelo PEG ou pelo sal, bem como os efeitos citotóxicos dos íons Na + e Cl -, no caso da salinidade, são responsáveis pela redução no crescimento das plântulas (Gordin et al, 2012;Maia et al, 2012).…”

Crescimento radicular e pigmentos clorofilianos em duas forrageiras submetidas a níveis crescentes de NaCl

“…A redução do potencial hídrico, induzida pelo sal, bem como, os efeitos citotóxicos dos íons Na + e Cl -são responsáveis pela redução na fitomassa e na densidade radicular das plântulas (Gordin et al, 2012;Maia et al, 2012). Esta informação é ratificada por Monteiro et al (2014) ao relatarem que em situações de toxidez por Na + e Cl -, a degradação de compostos celulares e a síntese de metabólitos indesejáveis podem promover redução drástica do crescimento.…”