No abstract

Abiotic stress factors, especially low temperatures, drought, and salinity, represent the major constraints limiting agricultural production in temperate climate. Under the conditions of global climate change, the risk of damaging effects of abiotic stresses on crop production increases. Plant stress response represents an active process aimed at an establishment of novel homeostasis under altered environmental conditions. Proteins play a crucial role in plant stress response since they are directly involved in shaping the final phenotype. In the review, results of proteomic studies focused on stress response of major crops grown in temperate climate including cereals: common wheat (Triticum aestivum), durum wheat (Triticum durum), barley (Hordeum vulgare), maize (Zea mays); leguminous plants: alfalfa (Medicago sativa), soybean (Glycine max), common bean (Phaseolus vulgaris), pea (Pisum sativum); oilseed rape (Brassica napus); potato (Solanum tuberosum); tobacco (Nicotiana tabaccum); tomato (Lycopersicon esculentum); and others, to a wide range of abiotic stresses (cold, drought, salinity, heat, imbalances in mineral nutrition and heavy metals) are summarized. The dynamics of changes in various protein functional groups including signaling and regulatory proteins, transcription factors, proteins involved in protein metabolism, amino acid metabolism, metabolism of several stress-related compounds, proteins with chaperone and protective functions as well as structural proteins (cell wall components, cytoskeleton) are briefly overviewed. Attention is paid to the differences found between differentially tolerant genotypes. In addition, proteomic studies aimed at proteomic investigation of multiple stress factors are discussed. In conclusion, contribution of proteomic studies to understanding the complexity of crop response to abiotic stresses as well as possibilities to identify and utilize protein markers in crop breeding processes are discussed.

We investigated the role of a guiding magnetic field on extreme ultraviolet (EUV) and ion emission from a laser produced Sn plasma for various laser pulse duration and intensity. For producing plasmas, planar slabs of pure Sn were irradiated with 1064 nm, Nd:YAG laser pulses with varying pulse duration (5–15 ns) and intensity. A magnetic trap was fabricated with the use of two neodymium permanent magnets which provided a magnetic field strength ∼0.5 T along the plume expansion direction. Our results indicate that the EUV conversion efficiency do not depend significantly on applied axial magnetic field. Faraday Cup ion analysis of Sn plasma show that the ion flux reduces by a factor of ∼5 with the application of an axial magnetic field. It was found that the plasma plume expand in the lateral direction with peak velocity measured to be ∼1.2 cm/μs and reduced to ∼0.75 cm/μs with the application of an axial magnetic field. The plume expansion features recorded using fast photography in the presence and absence of 0.5 T axial magnetic field are simulated using particle-in-cell code. Our simulation results qualitatively predict the plasma behavior.

The shot to shot variation in perveance of a planar diode with explosive emission graphite cathode in a range of accelerating gaps 3–12 mm is investigated experimentally. The typical electron beam parameters were 200 kV, 12 kA, 100 ns, with a few hundreds of A/cm2 current density. The diode perveance remains less than the Child–Langmuir value, indicating that only a fraction of the cathode take part in the emission process. A simple statistical analysis of the diode perveance shows that the shot to shot variation is more pronounced for the later part of the accelerating pulse. The cathode plasma expansion velocity and the effective initial emission area have been calculated from the perveance data. It was found that the plasma expansion velocity varies from 3 to 6.5 cm/μs. The mean expansion velocity and the standard deviation increase with the increase in the accelerating gap. The initial emission areas also varies randomly on a shot to shot basis and at the beginning of the accelerating pulse only 4%–35% of the cathode area take part in the emission process. The mean initial emission area and the standard deviation also increase with the increase in the accelerating gap. Experimental result indicates that the larger gaps and lower electric fields suggest a path to more uniform emission.