Comparison of the effects of different sa concentrations on senescence in excised rocket (Eruca sativa L.) cotyledons

Abstract

Senescence, accepted as the last phase of growth in plants, is characterized by a series of degenerative events that decrease the metabolic activity and eventually cause the death of cells, tissues and organs. In the present studies the effect of salicylic acid, a phenolic substance that recently came to be defined as plant growth regulator, especially increasing immunity of plants against infections, regulating thermogenesis in Arum flowers, inhibiting ethylene biosynthesis and germination, reversing the effects of abscisic acid and blocking the wound-induced response on the senescence of excised cotyledons of cultivated Eruca sativa L., (Rocket) was examined. Cotyledons of ten-day-seedlings of E. sativa were cut apart from the petiole and.-used as experiment materials. The fresh weight of cut cotyledons were measured and they were then incubated in 3 ml of salicylic acid at 10(-3), 10(-1), 10(-7), 10(-9) M concentrations and in distilled water as control. After 4 hours of light exposure in climatie room (25 +/- 2 degrees C), total chlorophyll amount, total protein content, peroxidase activity and protein analysis with SDS-PAGE method were assayed spectrophotometrically with biochemical methods. Furthermore, the effect of salicylic acid on fresh weights of rocket cotyledons was studied.