The drought response of landraces of wheat from the northern Negev Desert in Israel

Summary Diverse landraces of wheat, collected from the semi-arid (150 to 250 mm of total annual rainfall) Northern Negev desert in Israel were considered as a potential genetic resource of drought resistance for wheat breeding. These materials were therefore evaluated for their reponses to drought stress in agronomical and physiological terms. Up to 68 landraces, comprising of Triticum durum, T. aestivum, and T. compactum were tested in two field drought environments, in one favourable field environment, under post-anthesis chemical plant desiccation which revealed the capacity for grain filling from mobilized stem reserves, under a controlled drought stress in a rainout shelter and in the growth chamber under polyethylene glycol (PEG)-induced water stress. Biomass, grain yield and its components, harvest index, plant phenology, canopy temperatures, kernel weight loss by chemical plant desiccation, growth reduction by PEG-induced drought stress and osmotic adjustment were evaluated in the various experiments.Landraces varied significantly for all parameters of drought response as measured in the different experiments, which was in accordance to their documented large morphological diversity. Variation in grain yield among landraces under an increasing drought stress after tillering was largely affected by spike number per unit area. Kernel weight contributed very little to yield variation among landraces under stress, probably because these tall (average of 131 cm) landraces generally excelled in their capacity to support kernel growth by stem reserve mobilization under stress. Yield under stress was reduced with a longer growth duration of landraces only under early planting but not under late planting. Landraces were generally late flowering but they were still considered well adapted phenologically to their native region where they were always planted late.Landraces differed significantly in canopy temperature under drought stress. Canopy temperature under stress in the rainout shelter was negatively correlated across landraces with grain yield (r=0.67^**) and biomass (r=0.64^**) under stress. Canopy temperature under stress in the rainout shelter was also positively correlated across landraces (r=0.50^**) with canopy temperature in one stress field environment. Osmotic adjustment in PEG-stressed plants was negatively correlated (r=–0.60^**) with percent growth reduction by PEG-induced water stress. It was not correlated with yield under stress in any of the experiments. In terms of yield under stress, canopy temperatures and stem reserve utilization for grain filling, the most drought resistant landrace was the Juljuli population of T.durum.     

Mass selection of wheat for grain filling without transient photosynthesis

Summary Post-anthesis chemical desiccation of wheat (Triticum aestivum L.) plants in the field eliminates transtent photosynthesis by killing all green tissues, thus revealing the plant's capacity for grain filling from stored stem reserves, as the case is for post-anthesis stress such as drought or leaf diseases. This study was conducted to investigate whether mass selection for large kernels under chemical desiccation would lead to the improve ment of grain filling in the absence of transient photosynthesis.Six crosses of common spring wheat were subjected to three cycles of mass selection from F₂ through F₁ when selection was performed for large kernels by sieving grains from plants that were erther chemically desiccated after anthesis, or not (controls). The resulting 36 bulks (six crosses by three selection cycles by two selection environments) were compared with their respective F₂ base populations, when tested with and without chemical desiccation.Selection for large kernels under potential conditions (without chemical desiccation) did not improve kernel weight under potnetial conditions, evidently because these materials were lacking in genetic variation for kernel weight under potential conditions. In four of the crosses, 3rd cycle selection for large kernels under potential conditions decreased kernel weight under chemical desiccation. On the other hand, selection for large kernels under chemical desiccation was effective in improving kernel weight and test weight under chemical desiccation, depending on the cross and the selection cycle, with no genetic shift in mean days to heading or mean plant height. Selection for large kernels under chemical desiccation was also effective in some cases in increasing kernel weight under potential conditions. The results are interpreted to show that selection under potential conditions and under chemical desiccation operate on two different sources for grain filling, namely transient photosynthesis and stem reserve utilization, respectively. In order to expose genetic variability for stem reserve utilization to selection pressure, transient photosynthesis must be eliminated, as done by chemical desiccation in this study.     

Host resistance to lung infection mediated by major vault protein in epithelial cells

The airway epithelium plays an essential role in innate immunity to lung pathogens. Ribonucleoprotein particles primarily composed of major vault protein (MVP) are highly expressed in cells that encounter xenobiotics. However, a clear biologic function for MVP is not established. We report here that MVP is rapidly recruited to lipid rafts when human lung epithelial cells are infected with Pseudomonas aeruginosa, and maximal recruitment is dependent on bacterial binding to the cystic fibrosis transmembrane conductance regulator. MVP was also essential for optimal epithelial cell internalization and clearance of P. aeruginosa. These results suggest that MVP makes a substantial contribution to epithelial cell-mediated resistance to infection.     

The Grain Quality of Landraces of Wheat as Compared with Modern Cultivars

Landraces of tetraploid and hexaploid wheat from the Northern Negev in Israel were evaluated over two years for their grain quality attributes. Twenty-one populations of tetraploid wheat (Triticum durum, represented by 56 accessions) and 8 populations of hexaploid wheat (T. aestivum and T. compactum, represented by 13 accessions) were compared with 3 and 4 modern improved Israeli cultivars of tetraploid and hexaploid reheat, respectively. This comparison allowed to estimate the progress made in the improvement of gram quality m present-day cultivars. Except for grain protein content in the hexaploids, significant variation was revealed among landraces in kernel weight, protein content (tetraploids), sedimentation, mixograph score and carotin content. The best modern cultivars were comparable to the best landraces in kernel weight and carotin content (tetraploids), indicating that modern wheat breeding maximized kernel weight and carotin content, as compared with the tested landraces. Gram protein content and/or quality was not maximized in modern cultivars and its improvement was deemed possible by introgression from the best landraces in this respect.     

First report on Bursaphelenchus sexdentati (Nematoda: Aphelenchoididae) in Israel

This is the first report and characterization of Bursaphelenchus sexdentati and the first official report of the presence of the genus Bursaphelenchus in Israel. This species was isolated from Orthotomicus erosus (Coleoptera: Scolytinae) found on Pinus halepensis in the Judean foothills in Israel. Nematodes collected from insect galleries were reared on fungal cultures and identified based on morphological diagnostic characters for the genus Bursaphelenchus. Sequencing analyses of the Internal Transcribed Spacer (ITS) region, small subunit (SSU) and large subunit (LSU) of ribosomal DNA confirmed the identification of this nematode species collected from wood and directly from the insect body.     

Strategies and priorities in field collections for ex situ conservation: the case of the Israel Plant Gene Bank

The ex situ collection of the Israel Plant Gene Bank (IGB) aims to encompass the rich local flora and its genetic diversity with an emphasis on crop wild relatives. However, to properly establish a core collection, collection efforts must be prioritized and strategized. We previously classified local plant genetic resources into four priority groups that assisted in strategizing the collection activities. The following years of intensive collection activity yielded over 4200 banked accessions. However, these do not necessarily represent the distribution range of the target species for collection (TSC) and consequently, their genetic diversity. To best cover the latter, the collecting area was divided into botanical districts and the magnitude of the collection was determined according to prioritization group, e.g., a wild relative of an agricultural crop with a vast distribution range should be represented by a larger number of banked accessions than one with a smaller range. Continuous evaluation of specific needs shapes the collection scheme of the IGB to maximize collection efforts, better represent the presumed genetic diversity of TSC, and establish its core collection.     

Experimental handling stress as infection-facilitating factor for the goldfish ulcerative disease

Experimental handling stress (EHS) was applied to clinically asymptomatic farmed goldfish (Carassius auratus L.). EHS affected the gills and skin integrity of the fish and was accompanied by increased levels of plasma glucose, cortisol and interleukin-10 (IL-10). EHS application was followed by highly significant enhancement of the rate of infection with a virulent Aeromonas salmonicida isolate. Cumulative ulceration at the initial phase of the ensuing goldfish ulcerative disease (GUD) evidenced a facilitating role of EHS in the onset of GUD. Host susceptibility to the pathogen increased from 40% in unstressed fish to 90% in the stressed fish. A. salmonicida could be reisolated from the early-stage skin lesions only, whereas opportunistic strains, other than A. salmonicida (A. sobria and A. hydrophila), were recovered from progressive-stage ulcers. The implication of these findings in fish aquaculture is discussed.     

Effect of potassium on growth and the electrophoretic pattern of leaf proteins of sunflower supplied with ammonium or nitrate

Sunflower (Helianthus annuus L.) was grown on liquid medium containing either nitrate, ammonium or ammonium + nitrate, with or without potassium. The growth of plants supplied with nitrate or ammonium + nitrate in the presence of potassium (5 mmol/l) was comparable. Plants grown on ammonium‐N only showed significantly lower growth. Dry matter and organic nitrogen content in plants supplied with ammonium + nitrate (total nitrogen 10 mmol/1) in the presence of potassium (5 mmol/l) was higher than in nitrate grown plants. Leaf protein pattern on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) was not affected by the nitrogen source provided in the medium.

Potassium deficiency led to reduced growth, necrotic spots on the leaves and specific alterations in leaf protein pattern, expressed by an increase or decrease in several polypeptides. This was common to all the nitrogen forms tested. A most pronounced change was the increased expression of polypeptides of molecular weight 60 and 62 kilodaltons.     

Effect of ascorbic acid on soybean seedlings grown on medium containing a high concentration of copper

The detoxifying effect of ascorbic acid on soybean seedlings grown on copper (Cu)‐containing medium is reported. The effect was due mainly to prevention of entry of Cu into plant roots. Short term exposure of the seedlings to high concentrations of Cu in the presence of ascorbic acid did not lead to Cu toxicity signs.     

Mass Transfer of Carbaryl from Pure Water to Salt Aqueous Solution: Result Comparison Between Sea and Lab-Made Water

It is well known that mass transfer of a solid compound into a liquid phase is characterized by mutual properties of both sides. Solubilization capacity of the liquid phase is primary affected by its composition in inorganic species inducing salting in/out effect evaluated by Setschenow constant, generally defined at 298.15 K. On the other hand, the equilibrium process is highly influenced by polar compatibility issue. Therefore, the study of such transfer is essential in order to set the role of each party participating in the solid–liquid equilibrium. Thus, a comparison of transfer magnitude and feasibility of carbaryl from pure water, to seawater, and lab-made seawater was held. To do so, solubility of the compound was experimented at different temperature in multiple media. Solubility determination is based on the saturation of a specific heated fluid passing through a saturation cell. The solute transported is subsequently trapped in a specific extraction column. Back flashing method is then applied to dissolve the compound. After validation, aqueous solubility of carbaryl was studied as function of temperature ranging from (273.15 to 318.15 K) at atmospheric pressure. In addition, solubility was determined in pure, seawater, and corresponding lab-made water, thus solubility values ranged from 3.57E-06 to 3.49E-05 in pure water, from 3.04E-06 to 2.53E-05 in seawater and from 6.51E-06 to 3.61E-05 in lab-made water. As a result, thermophysical properties of transfer and usage of lab-made water on the mass transfer properties divergence was spotted. The Salting out phenomenon observed for carbaryl was interpreted by the internal pressure theory that suggests the reduction of internal cavities in the presence of salt, making solubilization process more difficult to achieve. Thus, showing an overall endogenic process with a positive Gibbs free energy of transfer that is highly affected by the magnitude of salting out effect and the temperature. The molar entropy of transfer increases versus temperature caused by the disorder of solvent molecules due to the dissolution process.