Kürşat Çavuşoğlu’s research while affiliated with Süleyman Demirel University and other places

Using the Allium test, the various toxicities caused by three distinct dosages (10, 50, and 100 mM) of the hazardous non-protein amino acid L-canavanine (L-CAN) were examined in this work. Indicators of toxicity included cytogenetic [micronucleus (MN) frequency, chromosomal abnormalities (Cas), mitotic index (MI)], physiological [germination percentage (GP), root number (RN), root length (RL), and fresh weight (FW)], biochemical [free proline (PR) level, malondialdehyde (MDA) level, catalase (CAT) activity, and superoxide dismutase (SOD) activity], and anatomical parameters. Four sets of Allium cepa L. bulbs were created: one for control (C) and three for treatments. For 7 days, the bulbs in the treatment groups were germinated with three different doses of L-CAN, whereas the bulbs in the C group were germinated with tap water. Consequently, at all three levels, exposure to L-CAN resulted in a reduction in every physiological parameter measured. In addition, every L-CAN dosage resulted in a rise in the frequency of MN and CAs together with a decrease in MI. L-CAN produced CAs such as notched nuclei, micronuclei accumulation, bilobulated and trilobulated nuclei with bud, C-metaphase, chromosomal stickiness, vagrant chromosome, and chromatid bridge in the root meristem cells. Through the induction of oxidative stress in the cells, L-CAN also produced toxicity. L-CAN exposure resulted in dose-related increases in the levels of free PR, MDA, CAT, and SOD in the root. L-CAN exposure induced anatomical harms such as deformations of the epidermal cells, development of micronucleus, accumulation of certain chemical substances, abnormal position of the epidermal cell nucleus, giant cell nucleus, and vacuole formation in the nucleus of the root tip meristem cells. Due to its inhibitory impact on Allium cepa L. test material, L-CAN induced comprehensive toxicity; the Allium test proved to be a valuable tool in identifying this toxicity.

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.

Salinity is one of the most important abiotic stress factors that negatively affect plant growth and development. In contrast, fusaric acid (FA), a mycotoxin produced by Fusarium and Giberella fungal genera, has biological and metabolic effects in various plants. In this study, it was aimed to investigate the protective effect of externally applied FA (0.1 nM) against the damage caused by salt (0.15 M NaCl) stress in onion (Allium cepa L.) plant. Salt stress resulted in an increase in the chromosomal aberrations (CAs) and micronucleus (MN) frequency, a decrease in the mitotic index (MI), fresh weight, root number, germination percentage, and root length. It promoted CAs such as irregular mitosis, bilobulated nuclei, chromosome loss, bridge, unequal seperation of chromosome, vagrant chromosome and polar slip in root meristem cells. In addition, salt stress caused a enhancement in free proline (PR), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) contents in the roots of onion plant. Moreover, it revealed damage and changes that include the accumulation of some chemical substances such as proline and sugars in epidermis and cortex layer cells, epidermal cell injury, flattening of the cell nucleus, wall thickening in cortex cells, necrotic areas and indistinct transmission tissue in the anatomical structure of onion roots. On the other hand, FA application promoted bulb germination and mitotic activity, strengthened the antioxidant defense system, and reduced chromosome and anatomical structure damages. In conclusion; it has been revealed that exogenous FA application may have a positive effect on increasing the resistance of onion plants to salt stress.