Regulatory role of phenols in flower development and senescence in the genus Iris

Abstract

The mechanism of flower development and senescence involves a lot of biochemical and molecular changes. These changes are governed by various external (temperature, light and humidity) and internal factors, viz., protein turnover, protease activity, antioxidant activity, phenols and plant growth regulators. The role of proteins, growth regulators, changes in various antioxidant enzymes and protease activity has been studied to a great extent; however the contribution of phenols in flower development and senescence is still elusive. Generally, flower senescence is thought to be associated with a decrease in the total phenolic content, but the present study on various species of the genus Iris revealed that total phenolic content showed diverging trends, varying from species to species within the same genus. The total phenolic content has been shown to decrease during senescence in Iris versicolor and Iris japonica, but an increase in total phenolic content was registered in Iris germanica, Iris kashmiriana and Iris ensata. Fresh mass, dry mass and water content was shown to increase towards flower anthesis (stages I–IV) and a significant decrease was observed at V and VI stages of flower senescence in all the species of Iris under study. The ascorbate peroxidase activity during the various stages of flower development and senescence indicated that phenols have a more contributory role than just being free radical scavengers in regulating flower senescence of various species of the genus Iris.