جستجوی مقالات مرتبط با کلیدواژه « melatonin » در نشریات گروه « زراعت »

Production and consumption of button mushroom is increasing in many parts of the world due to their good nutritional value and desirable medicinal properties, but because these types of mushrooms do not have a protective outer coating, they have a short shelf life, and during the postharvest, the quality of button mushrooms decreases due to water reduction, color change, texture change, reduction of taste and nutritional value, which limits its economic value, so the application of postharvest treatments can preserve the nutritional value and improve the shelf life of these mushrooms. Therefore, this study aimed to investigate the effect of postharvest treatments of melatonin and γ-aminobutyric acid (GABA) on the storage life and nutritional quality of fresh cut button mushrooms.

The postharvest treatments used in this experiment included melatonin (10 μM) and GABA (1 mM) and control (distilled water), which the mushrooms were immersed in a solution of these treatments for 5 minutes, and after drying at room temperature (24 ± 1), the mushrooms were placed in sealed containers and stored in a cold store at 4 °C with a relative humidity of 90 ± 5%. The samples were taken on days 0, 5, 10, and 15 days after treatment, and to measure browning index, hydrogen peroxide accumulation, the activity of cell membrane degrading enzymes and antioxidants enzymes were used.

The results showed that postharvest application of melatonin and GABA in fresh cut button mushrooms caused a delay in browning of slices of button mushrooms compared to control mushrooms and on the 15th day of storage, browning index in mushrooms treated with melatonin, GABA, and control was 45.78, 40.01, and 90.5%, respectively. Accumulation of hydrogen peroxide in melatonin and GABA treated mushrooms was significantly reduced compared to control mushrooms due to increased activity of the antioxidant enzymes superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase, and the highest hydrogen peroxide accumulation (51.35 μ mol g-1 FW) was obtained on the 10th day of storage in control samples. Membrane stability increased in melatonin and GABA treated mushrooms due to decreased activity of lipoxygenase and phospholipase D enzymes in these mushrooms. GABA treatment also showed better results than melatonin in most of the studied traits.

In general, according to the results of the present study, melatonin and GABA can used as an effective and safe method in maintaining nutritional quality and improving the shelf life of fresh cut button mushrooms during cold storage. Also, due to the better results provided by GABA in most of the studied traits and its cheapness compared to melatonin, it is recommended to use GABA in fresh cut mushrooms postharvest to maintain the quality of the mushrooms.

Increase in ultraviolet radiation (UV (, especially UV B, as one of the consequences of climate change, can disrupt the growth of plants. UV light influences plant growth and metabolism. Various studies have shown that increasing in UV B can have detrimental effects on physiological processes and overall growth of some plants. The use of exogenous plant growth regulators has mostly been effective in reducing the effects of environmental stresses in plants. The present study was conducted to investigate the effect of UV-A and UV-B and foliar application of melatonin and ascorbic acid (ASC) on growth, biomass and morphological and stomatal characteristics of fenugreek in 2019.

The experiment was performed as a split plot in a completely randomized design in the research greenhouses of the Faculty of Agriculture and Natural Resources, Lorestan University. Ultraviolet radiation was considered in four levels as the first factor (including: control, UV-A, UV-B and UV-A+UV-B) and application of osmolytes was used in four levels (Control, melatonin, ASC and melatonin+ ASC) as the second factor. Finally, Plant height, plant width, number of leaves, leaflet length and width, petiole length, crown diameter, plant fresh weight, plant dry weight, leaf fresh weight, number of internodes, number of lateral branches, stomatal gurad cell length and width, stomatal index, stomatal density, chlorophyll and carotenoid contents were measured. The data obtained from the experiment was analyzed using Minitab software. Mean comparison was performed using LSD test method at 0.05.

The results showed that UV-A increased fresh leaf weight, crown diameter, leafstalk length, leaflet length and width, plant height and width, plant fresh weight (12.17%), plant dry weight, number of internodes and content of chlorophyll a (7.4%) and chlorophyll b (3.5%), but reduced the number of lateral branches (15.63%). In contrast, UV-B and UVA+UVB treatments reduced most of the studied traits including plant height (8.09%), leaflet length and width, leafstalk length, chlorophyll a, chlorophyll b, total chlorophyll, plant fresh and dry weight and leaf fresh weight. However, carotenoid content, the number of lateral branches (6.58%) and stomatal index (11.4%) were increased by UV-B and UV-A+UV-B. Application of ASC and melatonin reduced the negative effects of UV-B on fenugreek. In control and UV-A treatments, ASC foliar application had shown the best effects on the studied traits and the highest plant height, number of lateral branches, number of leaves, leaf length and width, chlorophyll, carotenoids, and stomatal index and density were observed in this treatment. While, simultantious application of melatonin and ASC led to the best results under UV-B and UVA+B treatments. Therefore, it can be concluded that the synergistic effect of these two compounds in modulating the effects of ultraviolet stress on fenugreek was remarkable.

In the present study, UV-B radiation and simultaneous radiation of UV-A and UV-B reduced the growth and development of fenugreek. In contrast, UV-A treatment improved yield and morphological characteristics of the plant. In addition, foliar application of melatonin and ascorbic acid modulated morphological destruction and growth indices caused by ultraviolet-B treatment.

Diosgenin is one of the most important medicinal compounds in the world; however, little information is available on the biosynthetic pathway of this valuable metabolite in fenugreek. Given the importance of increasing the production of diosgenin, the application of various stimulants to enhance its production might be an interesting research topic. The aim of this study was to increase the expression of some genes involved in the biosynthesis pathway of diosgenin in fenugreek plants treated with salinity stress and different levels of melatonin. Treatments in this experiment included different salinity levels (0, 150 and 300 mM), different levels of melatonin (0, 30, 60 and 90 ppm) and a combination of different levels of salinity and melatonin. The expression of Cycloartenol synthase، 26-o-Beta glucosidase ,C4-demethylase in 150 mM and 60 ppm melatonin salinity treatments increased 7, 5 and 4 times compared to the control treatment (no melatonin application and salinity stress), respectively. The expression of C22-hydroxylase and Δ7-reductase genes was less affected by all experimental treatments. Overall, the results of the present study showed that the application of melatonin in fenugreek under salinity stress substantially increases the expression of genes involved in the biosynthesis pathway of diosgenin as a suitable functional stimulus.  The results of this research could be used in the pathway engineering of this valuable medicinal metabolite.