Phenological, morpho-physiological and proteomic responses of Triticum boeoticum to drought stress.

Drought is the most important abiotic stress limiting wheat production worldwide. Triticum boeoticum, as wild wheat, is a rich gene pool for breeding for drought stress tolerance. In this study, to identify the most drought-tolerant and susceptible genotypes, ten T. boeoticum accessions were evaluated under non-stress and drought-stress conditions for two years. Among the studied traits, water-use efficiency (WUE) was suggested as the most important trait to identify drought-tolerant genotypes. According to the desirable and undesirable areas of the bi-plot, Tb5 and Tb6 genotypes were less and more affected by drought stress, respectively. Therefore, their flag-leaves proteins were used for two-dimensional gel electrophoresis. While, Tb5 contained a high amount of yield, yield components, and WUE, Tb6 had higher levels of water use, phenological related traits, and root related characters. Of the 235 spots found in the studied accessions, 14 spots (11 and 3 spots of Tb5 and Tb6, respectively) were selected for sequencing. Of these 14 spots, 9 and 5 spots were upregulated and downregulated, respectively. The identified proteins were grouped into six functional protein clusters, which were mainly involved in photosynthesis (36%), carbohydrate metabolism (29%), chaperone (7%), oxidation and reduction (7%), lipid metabolism and biological properties of the membrane (7%) and unknown function (14%). We report for the first time that MICP, in the group of lipid metabolism proteins, was significantly changed into wild wheat in response to drought stress. Maybe, the present-identified proteins could play an important role to understand the molecular pathways of wheat drought tolerance. We believe comparing and evaluating the similarity-identified proteins of T. boeoticum with the previously identified proteins of Aegilops tauschii, can provide a new direction to improve wheat tolerance to drought stress.

Assessment of changes in growth traits, oxidative stress parameters, and enzymatic and non-enzymatic antioxidant defense mechanisms in Lepidium draba plant under osmotic stress induced by polyethylene glycol.

Lepidium draba is a weed with the medicinal properties which few researches have been done on it. In this study, some traits, related to the osmotic stress, in 14-day-old L. draba sprouts that were grown 9 days in the presence of various doses of polyethylene glycol 6000 (PEG 6000) including 0, 3, 6, 9, and 12%, with different osmotic potentials (- 0.04, - 0.12, - 0.23, - 0.34, and - 0.48 MPa, respectively) were investigated. Based on our results, germination percentage besides stem and root lengths decreased with increasing the concentrations of PEG. The contents of electrolyte leakage, malondialdehyde, other aldehydes, total protein, free amino acids, total soluble carbohydrate as well as free proline increased with increasing the concentrations of PEG. Also, for the first time, our results have proven that under osmotic stress, there is an adverse relationship between hydrogen peroxide content and the activity of catalase, peroxidase, ascorbate peroxidase, and guaiacol peroxidase enzymes, such that hydrogen peroxide content decreased with induction of PEG up to 6% and after that increased, while the activity of catalase, peroxidase, ascorbate peroxidase, and guaiacol peroxidase enzymes increased up to 6% PEG and after that decreased. The expression levels of catalase, peroxidase, ascorbate peroxidase, and guaiacol peroxidase genes showed the same pattern as was seen for these enzyme activities. According to the results of this study, it can be deduced that decreasing H2O2 content cannot be the main reason for other oxidative stress parameters to decrease. In this study, P5CS and P5CR gene expression levels increased with increasing levels of PEG up to 12% which was completely similar to free proline content. Based on our results, L. draba can be considered as a semi-tolerant plant to osmotic stress.

Morpho-physiological and proteomic responses of Aegilops tauschii to imposed moisture stress.

Moisture stress is the most important limitation of wheat production in the worldwide. Among the tribe Triticeae, Aegilops tauschii is one of the most valuable gene sources of resistance to abiotic stresses. In order to identify the most tolerant accession to moisture stress, and to understand its adaptive mechanisms at the molecular level, the present experiment was carried out on ten Ae. tauschii accessions under normal (95% soil pot capacity) and moisture stress (45% soil pot capacity) conditions. At the start of the heading time, the expanded flag leaves of treated and untreated plants were sampled for two-dimensional electrophoresis (2-DE) based on proteomics approach. A19 accession was less affected by the imposed moisture stress; therefore, it was used for the proteomics experiment. Among 252 protein spots which were reproducibly detected in each given 2-DE gels, 25 spots showed significant differences between the two moisture treatments; 17 spots were upregulated and 8 spots were downregulated. The identified proteins by MALDI-TOF/TOF, were allocated to seven functional protein groups, which were mainly involved in photosynthesis/respiration (28.5%), carbohydrate metabolism (14.2%), energy metabolism (7.1%), chaperone (14.2%), protein translation and processing (14.2%), repair and stability of the genome (7.1%) and unknown function (14.2%). We report this for the first time that RMI2 protein (in the group of repair and stability of the genome) was significantly changed in wheat in response to moisture stress. We believe that, the identified proteins could play important roles in acclimation and tolerance to moisture stress and provide the genetic pathways for improving tolerance to moisture stress in wheat.