Effects of chicken feather protein hydrolysate application on cold stress tolerance of wheat (Triticum aestivum L.)

In this study, it was aimed to investigate the effects of protein hydrolysate from chicken feather on cold stress tolerance in plants. For this aim, two varieties of wheat (Triticum aestivum L.) susceptible to cold (Altındane) and resistant (Bezostaya) were used as plant material. After chicken feathers were subjected to hydrolysis, neutralization and filtration processes with strong acids and bases, water-soluble Chicken Feather Protein Hydrolysate (CFPH) was obtained. The amino acid content of CFPH was determined and then its three different concentrations (0.05, 0.075 and 0.1%) were applied to the leaves of 11 day-old wheat seedlings growing under the controlled conditions. After 6 hours from the treatment, a portion of the treated and non-treated (control) seedlings were transferred to cold conditions (5/2°C). Three days later, the seedlings was harvested for use in physiological and biochemical analyzes. In the seedlings, root-stem lengths, fresh-dry weights and freezing injury parameters were determined first. In addition, the level of lipid peroxidation (LPO) and reactive oxygen species (ROS), the activity of antioxidant enzymes and the content of non-enzymatic antioxidants were examined. The changes in contents of protein, chlorophyll, proline and total sugar, the activity of Rubisco were also assessed in the seedlings. According to our findings, the total protein yield of CFPH was 72% and it contained 19 amino acids which were proteinic. Cold application alone reduced the root-stem length and the fresh weight in both varieties, but increased the freezing injury. CFPH applied before cold stress (CFPH+C) increased the fresh weight with root-stem lengths, and decreased the freezing injury, by alleviating the adverse effect of the cold application on these parameters. Statistically significant results were not obtained regarding the differences in dry weight. The cold application reduced the content of pigments (chlorophyll and carotenoid) and the activity of Rubisco in both varieties, but CFPH+C significantly increased both the parameters, as compared to control. On the other hand, cold stress caused a significant increase in the contents of protein, sugar and proline in both varieties. Whereas, CFPH+C application increased proline content in both varieties while it increased the content of protein and sugar in Altındane and Bezostaya, respectively. In the two varieties, while cold application increased LPO level and the contents of O2.- and H2O2 these three parameters were significantly decreased by CFPH+C application. The cold decreased glutathione and ascorbate content, and increased phenolic content, but the application of CFPH+C reversed this situation. Cold increased superoxide dismutase, ascorbate peroxidase and glutathione reductase activities in the cultivars studied, while CFPH+C more increased the activities of these. However, increased catalase and peroxidase activities by cold were decreased at a significant level by CFPH+C application. In general, the most effective concentration of CFPH was 0.075% in improving the parameters affected by cold stress. The findings were discussed mutually