Expansin protein is a component of the cell wall generally accepted to be the key regulator of cell wall extension during plant growth. Expansins loosen the cell wall in a pH-dependent manner. In this study transgenic AtEXPB2 plants were investigated in normal growth condition. Subsequently some of their physiological, biochemical and molecular traits were measured. Plant materials were transgenic lines; L3, l4, l9 and wide type plant as control. Seeds of three transgenic lines and control were cultured in selective MS and MS medium, respectively. Then transgenic seedlings were grown in greenhouse. Transgenic plants had better antioxidant enzymatic activity of catalase, glutathione peroxidase and polyphenol oxidase as well as higher photosynthetic pigments and proline content. Control plant had higher membrane phospholipid peroxidation and electrolyte leakage. Result of relative expression of AtEXPB2 revealed that this transformed gene was being expressed in transgenic lines. Generally transgenic lines had better performance in comparison to wild type plant.

Objective(s): The purpose of this study was to investigate cytotoxicity and membrane toxicity effects induced by Mesobuthus eupeus venom (MEV) on the HT-29 cell line. Materials and Methods: To determine the in vitro cytotoxicity via MTT assays, HT-29 (as cancer cell line) and Hek-293T (as normal cell) were treated through different concentrations of MEV, and cytotoxicity effects were then measured through assessment of mitochondrial membrane potential (Δ Ψ m), reactive oxygen species (ROS) generation, and apoptosis induction. The colony formation assay was performed to measure the antiproliferative effect of MEV on HT-29 cells. Nuclei alterations were also observed during apoptosis following DAPI staining. Besides, atomic force microscopy (AFM) was used to detect alterations in morphology and ultrastructure of the cells at a nanoscale level. Results: According to MTT and clonogenic assays, MEV caused a significant decrease in cell viability and proliferation of HT-29 cells while it did not have any impact on normal cells and the IC50 value was found to be 10 μ g/ml. Induction of apoptosis was also confirmed by flowcytometric analysis in HT-29 cells. Moreover, the results indicated that MEV had led to a suppression of proliferation and induction of apoptosis through increased ROS and depolarization of mitochondria. Furthermore, AFM imaging demonstrated apoptosis cell death after being treated with MEV in HT-29 cells. Conclusion: This study showed that MEV had an antiproliferative effect on HT-29 cells by inducing apoptosis through the mitochondria signaling pathway. These findings suggested that MEV could be used as a promising natural remedy for cancer treatment.

In the current study, the effect of water deficit stress or drought on relative water content and cell membrane stability of dragonhead (Dracocephalum moldavica) was studied in a greenhouse experiment carried out at Islamic Azad University, Jiroft branch, in 2009. It was a split plot experiment based on Randomized Complete Block Design with three replications, in which vertical factor included three levels of drought stress (irrigation when soil moisture reached 75% of field capacity [mild stress], irrigation when soil moisture reached 50% of field capacity [moderate stress] and irrigation when soil moisture reached 25% of field capacity [severe stress]). The results showed that the effect of water deficit stress was significant on relative water content at 5% level and on cell membrane stability at 1% level. Water stress significantly decreased relative water content from 77.69% under mild stress under severe stress. Relative water content increased as manure level increased. As the stress was intensified, the electrolyte leakage increased, but it started to decrease under severe stress. The manure treatment of 40 t/ha had the greatest electrolyte leakage (328.89 dS.m-1).

In order to study the effect of salinity and silicon application on biomass of shoots and root of fenugreek (Trigonella foenum- graceum L.), a greenhouse experiment was conducted at Research Greenhouse of Ferdowsi University of Mashhad using completely randomized desgin with ten replications. Employed two factors consisted of four levels of salinity using NaCl (0.0, 60, 120 and 180 mM) and two levels of silicon (0.0 and 1.5 mM sodium silicate). Shoot and fruit and root biomass and K content in shoots significantly decreased with increasing salinity, while Na content significantly increased with increasing salinity. Application of silicon imposed a positive effect on preventing high accumulation of Na and increased K content in shoots.

The low temperature is one of the most important factors limiting the growth, production and geographical distribution of plants. This stress may occur as chilling, freezing, and late spring low temperature. In spring, simultaneously with the beginning of wheat growth, tolerance to low temperatures is reduced and may be faced with decreasing temperature at any stage of its growth and damaged. This type of sudden temperature drop in spring is known as late spring frost. This investigation evaluated cell membrane stability in selected cultivars of bread wheat that affected by late spring low temperature, in 50-68 Zadoks codes. The experiment was carried out in a randomized complete block design with two factors, 13 cultivars and three late spring low temperature treatments including+8 (control), 0, and -2°C. membrane lipid peroxidation and electrolyte leakage were analyzed as the most cell membrane stability indices. Regarding to significant differences at the 5% probability level for genotype × stress interactions in traits, comparison of means showed that there were various responses among the cultivars. Finally, based on the results, cv. Pishgam was assessed as resistant and cv. Sivand susceptible to late spring low temperature according to the amounts of measured indices.

Under drought stress conditions, increase of the active oxygen specieses causes damage to the major cell macromolcules such as lipids, proteins and carbohydrates. Some enzymatic systems have a critical role in scavenging cells from these active oxygen species. Changes of catalase and peroxidase activities and their effects on chlorophyll and membrance stability were investigated in tolerant (Azadi, Roshan and M-79-4), Semi-tolerant (M-79-17 and Karaj I) and susceptible (Kavir and Marvdasht) wheat cultivars. Peroxidase activiy increased in Azadi, M- 79-4 and M-79-17 under drought stress. Although, peroxidase activity didn't increased in Roshan, this cutlivar showed the highest level of this enzyme activity under both drought and control conditions. The activity of catalase remained constant or decreased in all cultivars under drought stress, and there wasn't a clear relationship between catalase activity and drought tolerance. Azadi, Roshan, M-79-4 and Karaj 1 showed the highest chlorophyll stability index. Also, M-79-17 and Roshan showed the highest while Kavir showed the lowest cell membrane stability under drought stress. Under drought stress condition there was a positive correlations between peroxidase activity and yield and chlorophyll b stability index but, catalase activity didn't show positive correlation with yield. Also, there was a negative correlation between peroxidase activity and cell membrane injury during drought stress. Our results suggested that peroxidase activity under drought stress resulted in cell membrane and chlorophyll stability and is closely associated with cultivars' tolerance to drought stress.