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The changes in lipid peroxidation, H2O2, proline, protein and the involvement of the different antioxidant system (catalase, gayacoule peroxidase, ascorbate peroxidase) and callus-related traits were investigated in relation to salt stress in the callus of two different ploidy levels of Brassica including B. juncea and B. oleracea. The calluses of B. juncea genotypes were less sensitive to NaCl stress than that of B. oleraceae by increasing concentrations of NaCl from 0 to 200 mM.Tetraploid genotype (B. juncea cr3356) showed significant increase in the contents of protein and proline, and also activity of giacle peroxidase and catalase enzymes at higher salinity levels. Also, a significant decrease in the amount of H2O2 and malondialdehyde occurred with increasing the salinity intensity. Diploid cultivar (B. oleracea bra 2828) had the lowest enzymatic activities and the highest content of H2O2 and malondialdehyde with an increase in the salinity level. Therefore, this genotype was identified as the most sensitive cultivar to the salinity stress. The difference in the salinity resistance between diploid and amphidiploid species may be due to differences in the ploidy level of these species. This result suggests that tetraploid genome of B. oleraceae could be considered as a suitable candidate for production under salinity conditions by maintaining higher activities of antioxidant enzymes.

A significant sesquiterpene lactone used as a drug is artemisinin. It is definitely an anti-parasitic drug isolated from field-grown Artemisia annua L. a plant from Asteraceae family. It is the best treatment for Plasmodium falciparum malaria. Unfortunately, artemisinin content in A. annua is extremely low (0.01-0.8% dry weight). So, some researchers focused on enhancing artemisinin content either in tissue/cell culture or the whole plant of A. annua sp. The aims of the current study were the effect of plant growth regulators on callus production and improvement of artemisinin content in cell suspension culture of A. annua, an alternative to the whole plant using abiotic elicitors. For callus induction, an experiment was laid out as a factorial experiment with three factors (explant type, different concentrations of BAP and 2,4-D) based on completely randomized design with three replications. The maximum frequency of callus induction (100%) was found in leaf explant on MS medium with a combination of 2, 4-D (3 mg/l) and BAP (1.5 mg/l). Therefore, the best calli were used for cell suspension culture and the effects of GA3 and ABA as abiotic elicitors were evaluated on the improvement of artemisinin production. The results indicated that both ABA and GA3 increased artemisinin content (2.02 fold and 1.67 fold in comparison to control respectively) in cell suspension culture.

High temperature stress, especially on the early season of plant growth stages, is an agricultural problem in many areas in the world. A temporary or continually high temperature leads to a set of morphological, biochemical and physiological changes in plants, which consequently reduces the plant growth and development and finally may cause a severe reduction in economic yield. The main goal of this study was to assess plant response to high temperature stress (HTS) in early seedling of canola. This study is the first experiment on the effect of heat stress on proteome of canola. In the present research, a proteomics approach was used to evaluate the effects of high temperature stress, including 45 °C day/34 °C night for 2, 6 and 12 hour, on early seedling stage (2-day old) of canola. Proteins were isolated from hypocotyl and separated by two-dimensional polyacrylamide gel electrophoresis. Out of 381 protein spots, 28 and 34 proteins were significantly down- and up-regulated, respectively. The trend of mRNA expression for sucrose binding protein, a scorbate peroxidase and triosephosphateisomerase, was in accordance with their trend at translation level. Results of this study suggest that the up-regulation of proteins involved in cellular traffic, energy and metabolism, and down-regulation of some proteins involved in disease and defense, protein synthesis and signal transduction could be the main reason of physiological and morphological responses to high temperature stress. The observed increases in the level of ascorbate peroxidase protein and mRNA expression in canola hypocotyl in response to HTS suggests that ascorbate peroxidase is a short term high temperature stress response protein and is thus a candidate for gene modification strategies aimed at producing high temperature canola varieties. These results also suggest that the up regulation of protein involved in energy and metabolism in response to the heat stress can use most of nutritive reserves in seedling of canola and might explain the reduced growth of canola in heat stress conditions.

Rapeseed (Brassica napus L.), which is the third leading source of vegetable oil, is sensitive to drought stress during the early vegetative growth stage. To investigate the initial response of rapeseed to drought stress, changes in the protein expression profiles of drought-sensitive (RGS-003) and drought-tolerant lines (SLM-003), and their F1 hybrid, were analyzed using a proteomics approach. Seven-day-old rapeseed seedlings were treated with drought stress by restricting water for 7 days, and proteins were extracted from roots and separated by two-dimensional polyacrylamide gel electrophoresis. In the sensitive rapeseed line, 35 protein spots were differentially expressed under drought stress, and proteins related to metabolism, energy, disease/defense, and transport were decreased. In the tolerant line, 32 protein spots were differentially expressed under drought stress, and proteins involved in metabolism, disease/defense, and transport were increased, while energy-related proteins were decreased. Six protein spots in F1 hybrid were common among expressed proteins in the drought-sensitive and -tolerant lines. Notably, tubulin beta-2 and heat shock protein 70 were decreased in the drought-sensitive line and hybrid F1 plants, while jasmonate-inducible protein and 20S proteasome subunit PAF1 were increased in the F1 hybrids and drought-tolerant line. These results indicate that (1) V-type H(+) ATPase, plasma-membrane associated cation-binding protein, HSP 90, and elongation factor EF-2 have a role in the drought tolerance of rapeseed; (2) The decreased levels of heat shock protein 70 and tubulin beta-2 in the drought-sensitive and hybrid F1 lines might explain the reduced growth of these lines in drought conditions.

An efficient method for producing doubled haploid plants of oilseed rape (Brassicanapus L.) was established using in vitro colchicine treatment of haploid embryos. Haploid embryos in the cotyledonary stage were treated with one of four colchicine concentrations (125, 250, 500 and 1,000 mg/L); for one of three treatment durations (12, 24 and 36 h) at one of the two temperatures (8 and 25°C) and were compared to control embryos (without colchicine treatment). The number of chromosomes, seed recovery, size and density of leaf stomata, and pollen grain size from regenerated plants were determined. No doubled haploid plants were regenerated from control embryos; however, the doubled haploid plants were regenerated from colchicine-treated embryos. A high doubling efficiency, 64.29 and 66.66% of regenerated plants, was obtained from 250 mg/L colchicine treatment for 24 h and 500 mg/L colchicine treatment for 36 h, respectively, at 8°C. Following 500 mg/L colchicine treatment for 36 h, a few plants regenerated (9 plants). At the higher colchicine concentration (1,000 mg/L), no plant regenerated. These results indicate that the colchicine treatment of embryos derived from microspores can induce efficient chromosome doubling for the production of doubled haploid lines of oilseed rape.

Changes in protein levels in drought-stressed soybean seedlings were analyzed using a proteomics approach. Three-day-old soybean seedlings were subjected to drought stress or treated with 10% polyethylene glycol (PEG) as osmotic stress. After treatment, the proteins were extracted from the leaf, hypocotyl, and root and separated using two-dimensional polyacrylamide gel electrophoresis. The root was the most drought-responsive organ, with the levels of 32, 13, and 12 proteins changing in response to drought stress, PEG treatment, and both, respectively. In the leaves of PEG-treated and drought-stressed seedlings, metabolism-related proteins increased and energy production- and protein synthesis-related proteins decreased. For 3 proteins present in all organs in drought-stressed plants, mRNA was differentially regulated: heat shock protein 70 and actin isoform B were upregulated, and methionine synthase was downregulated. mRNA expression patterns reflected those of protein levels, suggesting transcriptional regulation of these proteins. Western blot analysis confirmed the increase in ascorbate peroxidase in drought-stressed plants. The downregulation of mRNA and decreased protein levels of methionine synthase in the leaves, hypocotyl, and roots of drought-stressed plants, but not in other treatments, indicated that methionine synthase is a drought response protein. These results also suggest that the decreased methionine synthase in response to drought stress can impair the soybean seedling growth.