No abstract

Effects of interactions between high temperature and chromium (Cr(VI)) and copper (Cu) on wheat (Triticum aestivum L. cv. Dagdas 94) seedlings were investigated. High concentrations of Cr and Cu at 40°C decreased the root and shoot length and dry weight. The total chlorophyll content was decreased at 30 µM Cr + 40°C. At the high Cr and Cu concentrations, carotenoid content was increased compared to that of control groups. Heavy metal treatment increased proline content but decreased that of soluble protein. In addition, chromium showed greater toxic effects on growth and biochemical parameters than that of Cu.

In this study, the effect of heat and chromium (Cr) heavy metal interactions on wheat seedlings (Triticum aestivum L. cv. Ç-1252 and Gun91) was investigated by measuring total chlorophyll and carotenoid levels, catalase (CAT) and ascorbate peroxidase (APX) antioxidant enzyme activities, and MYB73, ERF1 and TaSRG gene expression. Examination of pigment levels demonstrated a decrease in total chlorophyll in both species of wheat under combined heat and heavy metal stress, while the carotenoid levels showed a slight increase. APX activity increased in both species in response to heavy metal stress, but the increase in APX activity in the Gun91 seedlings was higher than that in the Ç-1252 seedlings. CAT activity increased in Gun91 seedlings but decreased in Ç-1252 seedlings. These results showed that Gun91 seedling had higher resistance to Cr and Cr + heat stresses than the Ç-1252 seedling. The quantitative molecular analyses implied that the higher resistance was related to the overexpression of TaMYB73, TaERF1 and TaSRG transcription factors. The increase in the expression levels of these transcription factors was profound under combined Cr and heat stress. This study suggests that TaMYB73, TaERF1 and TaSRG transcription factors regulate Cr and heat stress responsive genes in wheat.

The effects of waterlogging (WL) and WL plus nitric oxide (WL+NO) were investigated in seedlings of one wheat cultivars (Triticum aestivum cv. Dogankent) and one wheat line (Triticum aestivum cv. Ducula-4). Under WL conditions, catalase activity was greater in Ducula-4 than in Dogankent. Glutathione reductase activity increased in Ducula-4 seedlings under WL+NO conditions, especially at 48 and 72 hours of treatment. Myb2 expression increased during the early hours of treatment in both wheat varieties exposed to WL, with 40-fold higher levels in Ducula-4, gradually decreasing to control levels. Under WL+NO treatment, Myb2 expression increased 44-fold at 12 hours and high levels of expression were still observed at 72 hours. When Ducula-4 seedlings were subjected to WL+NO treatment, PDPK expression increased approximately 15-fold at 3 hours and decreased to control levels at 72 hours. Under the same conditions, SST1 expression increased 3-fold at 3 and 12 hours and reached control levels during the subsequent hours. Among the genes studied, the highest level of expression was observed for Myb2. Moreover, gene expression was altered most by waterlogging in Ducula-4 seedlings.

In this study, effects of heavy metals which are lead (Pb), zinc (Zn) and cadmium (Cd), alone, and their interactions with abscisic acid (ABA) and gibberellin (GA 3) hormones on soluble proteins, soluble phenolics and the amount of free proline have been investigated with respect to time (5th and 10th) days in wheat seedlings. At seedlings on which heavy metals and heavy metals + hormones applied, the amount of free proline and soluble phenolics have increased. Amount of soluble protein has increased at the seedlings on which Pb and Cd applied but has decreased at the 10th day samples of the seedlings on which Zn, Zn + GA 3, Cd + ABA and Cd + GA 3 were applied. Among the parameters worked with, Cd has shown the most toxic effects and lead and zinc followed.