Catalase, Peroxidase, and Polyphenoloxidase Activities during Rice Leaf Senescence

Abstract

The activities of catalase, peroxidase, and polyphenoloxidase were studied in attached and detached rice (Oryza satva L. cv. Ratna) leaves. Catalase activity decreased while peroxidase and polyphenoloxidase activities increased during senescence of both attached and detached rice leaves. Kinetic (5 EAM) and benzimidazole (1 1M), which are known to delay the senescence of detached rice leaves, retarded the decrease of catalase activity during detached leaf senescence. On the other hand, these chemicals accelerated the increase of peroxidase and polyphenoloxidase activities over the water control. Total phenoUics accumulated in detached and darkened rice leaves, but in attached leaf senescence in light no accumulation of phenolics was observed.

Calcium application enhances growth and alleviates the damaging effects induced by Cd stress in sesame (Sesamum indicumL.)

“…Fresh leaf sample (0.5 g) was homogenized in a mixture of 50 mM tris-HCl buffer (pH 7.0) containing 3.0 mM MgCl 2 , 1.0 mM ethylenediaminetetraacetic acid (EDTA), 1.0% (w/v) polyvinylpyrrolidone (PVP) and homogenate and was centrifuged at 10,000 rpm for 15 min at 4°C (Kar & Mishra 1976). Supernatant was used as the enzyme source to assess the antioxidant enzymes (peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR)).…”

“…Peroxidase (POD) activity was measured according to the method described by Kar and Mishra (1976). CAT activity was assayed as described by Aebi (1984).…”

Respostas enzimáticas na enxertia de tomateiro

“…A atividade da PPO foi determinada de acordo com Kar & Mishra (1976) expressa em µmol de purpurogalina/min/mg de proteína.…”

Fenóis, peroxidase e polifenoloxidase na resistência do cafeeiro a Meloidogyne incognita

“…Após o volume ser completado a 3,25ml com tampão, a mistura da reação foi incubada a 25°C por 30 minutos e, a reação, interrompida pela adição de 0,5ml de H 2 S0 4 5%. Como branco, substituiu-se 0 extrato por tampão, sendo as leituras de absorbância feitas em 420nm (OLIVEIRA, 1972;DRAETTA & LIMA, 1976;KAR & MISHRA, 1976).…”

“…A incubação foi feita a 30°C por trinta minutos, a reação interrompida pela adição de 0,5ml de H 2 S0 4 5% e as leituras deabsorbância em 420nm. Como branco, substituiu-se o extrato por tampão (OLIVEIRA, 1972;DRAETTA & LIMA, 1976;KAR & MISHRA, 1976).…”