Evaluation with physiological, cytogenetic, biochemical and anatomical aspects of dose-dependent inhibitory activity of jasmonic acid, a lipidderived growth regulator, in onion root tip cells

Abstract

The effects of different doses of exogenous jasmonic acid (JA), were investigated on physiological parameters such as germination percentage, root length, root number and fresh weight, cytogenetic parameters such as mitotic index (MI), micronucleus (MN), frequency and chromosome aberration (CA), biochemical parameters as such superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and proline (PR) contents of Allium cepa L., known as onion. In addition, the changes in the root anatomical structures of the bulbs were examined under the microscope by taking cross-sections. Onion bulbs were divided into four groups as one control (C) and three treatments. The bulbs of the C group were kept in cuvettes containing tap water for 7 days and the bulbs of the treatment groups were kept in cuvettes containing 100 µM, 250 µM and 500 µM JA. JA administration caused a decrease in all physiological parameters examined, an increase in the frequency of MN and CA, and a reduce in MI compared to group C. In addition, the mentioned application caused a dosedependent increase in CAT and SOD activities and MDA and PR contents compared to group C. Moreover, 500 µM JA, the highest application dose, caused quite significant damages such as giant cell nucleus, unclear vascular tissue, binuclealar cell and accumulation of some substances in the cells of the epidermis/cortex in root anatomical structure of the bulbs. In summary, it was concluded that JA is a chemical with inhibitory functions and the Allium cepa test is a useful bioindicator for monitoring these effects.