Journal of Plant Physiology and Breeding
Volume:5 Issue: 1, Winter-Spring 2015

This experiment was carried out to determine the effects of proline and ascorbic acid on chilling injury, electrolyte leakage, lipid peroxidation, peroxide hydrogen and antioxidant enzymes activity of Thompson grape (Vitis vinifera L.) fruit. Grape fruits were treated by 0 (control), 250 and 500 µM proline and 0 (control), 2 and 4% ascorbic acid and their combinations, then stored at 1°C and 90-95 % relative humidity for 28 days. Grapes treated with 500 µM proline and its combination with 2 and 4% ascorbic acid had the lowest amount of lipid peroxidation and peroxide hydrogen and lower chilling injury and electrolyte leakage than non-treated fruits. Moreover, grapes treated with 500 µM proline and its combination with 2 and 4% ascorbic acid significantly increased ascorbate peroxidase, superoxide dismutase, catalase and peroxidase enzyme activity. The present study can be regarded as the first evidence that proline and ascorbic acid enhance grape fruit tolerance to cold stress and therefore fruit quality.

A sub-sample of lentil (Lens culinaris Medik. cv. Kimia) seeds was kept as bulk (S1) and another sample was separated to large (S2) and small (S3) seeds. A sub-sample of each size was kept as control or high vigor seed lot (A1) and the two other sub-samples were artificially aged for 2 and 4 days (A2 and A3، respectively). Field performance and some physiological traits of plants from these seeds were evaluated during 2011. Relative water content (RWC)، ground cover and grain yield per unit area significantly decreased with decreasing water availability، but mean leaf temperature and proline content increased as water stress severed. Seed aging reduced RWC، MSI، ground cover and consequently grain yield per unit area. The superiority of plants from large seeds in ground cover and grain yield was increased with increasing seed aging and water limitation. It was، therefore، concluded that planting large seeds may reduce the deleterious effects of water stress and seed aging on field performance of lentil.

In recent years some research results have appeared that exogenous salicylic acid provided significant mitigation effect against salinity induced injuries in plants. An experiment was conducted to investigate the effects of salt stress and salicylic acid on radish (Raphanus sativus L.) plants. After appearing first leaves، plants were treated by salicylic acid (0. 2 mM) for 3 days and NaCl (180 mM) applied 48 hours after first treatment of salicylic acid. Results showed that salt stress decreased fresh weight of shoots and roots، chlorophyll a، chlorophyll b، anthocyanins and flavonoids contents of leaves. In opposite، this stress increased amount of leaves carotenoids، and both leaves and roots phenolic compounds، hydrogen peroxide، proline and lipid peroxidation content. Salicylic acid had similar effects on these factors. Applying salicylic acid in the saline condition decreased fresh weight of shoot and root، chlorophyll a، chlorophyll b، flavonoids، membrane stability index and increased amount of anthocyanins، carotenoids of leaves، phenolic compounds، proline، hydrogen peroxide، lipid peroxidation of leaves and root. We concluded that benefit of exogenous salicylic acid can be dose dependent and salinity plus salicylic acid، at concentrations applied in this study، were established potent secondary oxidative stress in plants.

To assay the effect of acetylsalicylic acid pretreatment on enhancement of yield and yield components of barley (Reihan-03) under water stress condition، an experiment was conducted as a spilt-plot arrangement based on randomized complete block design with four replications at the Research Field of Shahid Bahonar University of Kerman، Iran، in 2012-2013. Irrigation condition was arranged in main plots (normal irrigation and withholding irrigation at flowering) and acetylsalicylic acid (0، 0. 5، 1 mM) in sub-plots. Water stress caused a significant reduction in relative water content، fertile spike/m2، kernels per spike، 1000 kernel weight، grain yield and biomass and increased electrolyte leakage of plasma membranes، proline content، catalase and also guaiacol peroxidase enzymes activity of flag leaf. Results showed that acetylsalicylic acid application brought on the increased levels of water stress tolerance in barley. Acetylsalicylic acid pretreatment increased antioxidant enzymes activity، relative water content، grain yield، biomass as well as proline content of flag leaf and reduced electrolyte leakage. The concentration of 1 mM acetylsalicylic acid was more effective. In conclusion، seed priming with acetylsalicylic acid increased the tolerance of barley to water stress condition via maintaining cellular membrane integrity and neutralizing or scavenging of reactive oxygen species.

An investigation was undertaken to ascertain the influence of hydro-alcoholic solutions on plant growth as well as quality attributes of strawberry fruits. The mother plants of strawberry (Fragaria ananasa cv. Gaviota) were subjected to various aqueous solutions of ethanol (15, 30%), methanol (15, 30%) and the mixture of ethanol + methanol (15 or 30%) plus the control (water only) as foliar spraying or via irrigation. Application of alcoholic solutions affected the majority of the characters under investigation. The highest amount of leaf chlorophylls, carotenoids, fruit sucrose and total yield were recorded on the plants treated with combination of 15% ethanol and methanol. The maximum fruit weight and the lowest acidity were found in plants treated with 15% methanol or in combination with 15% ethanol. The foliar spraying was superior in most of the traits over the irrigation method. Further experimentations are required to suggest the results of the present study in a commercial scale to the strawberry growers.

The purpose of this research was to transform two economically important cultivars of strawberry with P5CS gene، which encodes Δ1-pyrroline-5-carboxylate synthetase (P5CS)، the key enzyme in proline biosynthesis. Shoots were obtained on MS basal medium supplemented with 2% glucose and 4 mg/l TDZ for Camarosa and Kurdistan cultivars. For genetic transformation، a binary vector PBI121 containing P5CS gene under control of the 35SCaMV promoter was used. Transformed cells (explants) were regenerated on the selective regeneration medium containing 75 mg/l kanamycin and 500 mg/l cefotaxime after five days of pre-incubation and 72 h of co-cultivation with Agrobacterium، while control explants failed to grow in the same medium. The presence of the transgene in the plant genome was confirmed by PCR. The morphology of the transgenic plants was normal as controls. Drought stress was applied using polyethylene glycol (PEG) 6000 at concentrations equal to 0، -5 and -7 Bar، respectively. Proline content was four times higher in the transformed leaves compared to that of the untransformed plants while the proline content in the roots was similar in both transgenic and wild-type plants. Overproduction of P5CS also increased chlorophyll content، shoot length، shoot fresh and dry weight in the transgenic plants under drought-stress conditions.