Exogenous application of mycotoxin fusaric acid improve the morphological, cytogenetic, biochemical and anatomical parameters in salt (NaCl) stressed Allium cepa L.

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.

Investigation of the potential role of fusicoccin, a fungal phytotoxin, in mitigating salt stress in onion roots.

Fusicoccin is a diterpene glycoside that plays an important role in the regulation of plant growth and development. Fusicoccin produced by Fusicoccum amydali fungus is known to affect plant growth positively with external applications due to its potential to stimulate the tolerance system of plants under stress conditions. In this study, it was aimed to reduce the negative effects of salt (0.15 M NaCl) stress on the germination and growth of onion (Allium cepa L.) bulbs by external fusicoccin (3 µM) application. For this purpose, the germination percentage, root length, root number, fresh weight, mitotic activity, micronucleus frequency, chromosomal abnormality, antioxidant enzyme activity, osmolyte accumulation, cell membrane damage and root anatomical structure were investigated in the current study. Salt stress caused a statistically significant difference (p < 0.05) in all examined parameters. External application of fusicoccin to onion bulbs germinated under salt stress conditions was found to be promising as a plant growth promoter and mitosis stimulator. In addition, fusicoccin application alleviated the harmful effects of salt stress on the chromosome structure and root anatomical structure and protected the cells from the cytotoxic and genotoxic effects of salt. Moreover, this application contributed to the fight against reactive oxygen species of onion plant and increased salt tolerance by regulating the accumulation of osmolyte substances such as proline and antioxidant enzymes such as superoxide dismutase and catalase, and by minimizing cell membrane damage in root cells. In conclusion, this study showed that exogenous application of 3 µM fusicoccin reduced the damage caused by oxidative stress in onion bulbs and served for healthy germination and growth.

Potential toxicity assessment of mycotoxin fusaric acid with the spectral shift profile on DNA.

In this study, the multiple toxicities induced by three different doses (1, 5, and 10 µM) of fusaric acid (FA), a mycotoxin, was investigated with Allium test. Physiological (percent germination, root number, root length, and weight gain), cytogenetic (micronucleus = MN, chromosomal abnormalities = CAs, and mitotic index = MI), biochemical (proline level, malondialdehyde = MDA level, catalase = CAT activity, and superoxide dismutase = SOD activity), and anatomical parameters were used as indicators of toxicity. Allium cepa L. bulbs were divided into four groups as one control and three applications. The bulbs in the control group were germinated with tap water for 7 days, and the bulbs in the treatment groups were germinated with three different doses of FA for 7 days. As a result, FA exposure caused a decrease in all physiological parameters examined at all three doses. Besides, all FA doses caused a decrease in MI and an increase in the frequency of MN and the number of CAs. FA promoted CAs such as nucleus with vacuoles, nucleus buds, irregular mitosis, bridge, and misdirection in root meristem cells. DNA and FA interactions, which are the possible causes of genotoxic effects, were examined by spectral analysis, and FA could interact with DNA through intercalation, causing bathochromic and hypochromic shifts in the spectrum. FA also causes toxicity by inducing oxidative stress in cells, confirming this; dose-related increases in root MDA and proline levels were measured as a result of FA exposure. In the root SOD and CAT enzyme activities, increases up to 5 µM doses and decreases at 10 µM doses were measured. FA exposure induced anatomical damage such as necrosis, epidermis cell damage, flattened cell nucleus, thickening of the cortex cell wall, and unclear vascular tissue in root tip meristem cells. As a result, FA caused a comprehensive toxicity by showing an inhibitory effect in A. cepa test material, and the Allium test was a very useful test in determining this toxicity.

Protective role of Ginkgo biloba on petroleum wastewater-induced toxicity in Vicia faba L. (Fabaceae) root tip cells.

The Melet is one of Turkey's economically important rivers. Most of the petroleum plants are located at fairly nearby of the river This situation is considered as main source of heavy metal pollution in the river. The present study was designed to evaluate the protective role of Ginkgo biloba (GB) on cytotoxicity induced by petroleum wastewater in Vicia faba root tip cells. For this aim, we used the germination percentage, root length, weight gain and micronucleus (MN) frequency as indicators of cytotoxicity. Additionally to the cytological analysis, lipid peroxidation analyses were also performed in V. faba roots. Heavy metal concentrations in wastewater were measured by atomic absorption spectrophotometer (AAS). The V. faba seeds were divided into six groups. They were treated with petroleum wastewater and 10, 20 and 30 microM doses of GB. As a result, the mean concentrations of heavy metals in wastewater were observed in the order: Pb > A > Ni > Cr > Fe > Cu > Zn > Cd. The highest germination percentage was observed in the seeds of the control and positive control groups (in proportion as 98 and 96%, respectively). Wastewater treatment caused a significant decrease in the germination percentage of Group III (in proportion as 44%). The highest root length and weight gain were observed in the seeds of the control and positive control groups at the end of the experimental period. The least root length and weight gain were observed in the seeds of Group III treated with wastewater alone. In the control group, the final weights of all the seeds increased about 4.08 g according to initial weight. The root lengths of the control seeds were measured as 6.80 cm at the end of the experimental period. The final weights of the seeds exposed to wastewater alone increased about 0.90 g according to initial weight. Besides, there was a significantly increase in the MDA levels of the roots exposed to wastewater. Heavy metals in wastewater significantly affected the MDA production indicating lipid peroxidation. But, GB-treatment caused amelioration in indices of the germination percentage, root length, weight gain, MN frequency and lipid peroxidation when compared with group III. Each dose of GB provided protection against wastewater toxicity and its strongest protective effect observed at dose of 30 microM. In vivo results showed that GB is a potential protector against toxicity induced by petroleum wastewater and its protective role is dose-dependent.

Protective role of Royal Jelly (honeybee) on genotoxicity and lipid peroxidation, induced by petroleum wastewater, in Allium cepa L. root tips.

In the present study, the protective effect of Royal Jelly (RJ) on genotoxicity and lipid peroxidation, induced by petroleum wastewater, in Allium cepa L. root-tip cells was investigated. For this purpose, we used the malondialdehyde (MDA) level, mitotic index (MI), frequency of micronucleus (MN) and chromosomal aberrations (CAs) as indicators of genotoxicity and lipid peroxidation, and correlated these data with statistical parameters. In additional to the genotoxic analysis, we examined changes in the root anatomy of A. cepa seeds treated with the wastewater. Heavy metal concentrations in the wastewater were measured by atomic absorption spectrophotometry. The seeds were divided into six groups as control, wastewater and RJ treatment groups. They were treated with the wastewater alone, RJ alone (25 and 50 microm doses) and RJ + wastewater for 10 consecutive days. As a result, the mean concentrations of heavy metals in the wastewater were observed to be in the order: Pb > Fe > Al > Ni > Cu > Zn > Cr > Cd. The results showed that there was a significant alteration in MI and in the frequency of MN and CAs in the seeds exposed to the wastewater when compared with the controls. The wastewater exposure resulted in a significant increase in CAs and MN formation (P < 0.05). The wastewater also caused a decrease in MI (P < 0.05). Additionally, there was a significant increase in the MDA levels of the roots exposed to the wastewater (P < 0.05). Heavy metals in the petroleum wastewater significantly increased the MDA production, indicating lipid peroxidation. Moreover, light micrographs showed anatomical damages such as an accumulation of chemical compounds in cortex parenchyma, cell death, an unusual form of cell nucleus and unclear vascular tissue. However, the RJ treatment caused amelioration in the indices of lipid peroxidation and MI, and in the frequency of CAs and MN, when compared with the group treated with petroleum wastewater alone (P < 0.05). Also, the RJ application caused the recuperation of anatomical structural damages induced by the petroleum wastewater. Each dose of RJ provided protection against the wastewater toxicity, and the strongest protective effect was observed at dose of 50 microm. In vivo results showed that RJ is a potential protector against toxicity induced by petroleum wastewater, and its protective role is dose-dependent.