Physiological response of common bean (Phaseolus vulgaris L.) seedlings to salinity stress

The effect of salinity stress on five cultivars of common bean: Bassbeer, Beladi, Giza 3, HRS 516 and RO21 were evaluated on a sand/peat medium with different salinity levels (0, 50 and 100 mM NaCl) applied 3 weeks after germination for duration of 10 days. Salinity had adverse effects not only on the biomass yield and relative growth rate (RGRt), but also on other morphological parameters such asplant height, number of leaves, root length and shoot/root weight ratio. Photosynthesis, transpiration rate and stomatal conductance were adversely affected in all cultivars. Leaf osmotic potential and leafturgor varied significantly among cultivars and salt levels. The interaction between cultivars and salt levels for photosynthesis, leaf osmotic potential and leaf turgor was highly significant at day 10 of salttreatment. The Na uptake among the cultivars varied in the order: HRS 51

Influence of Auxins on Rooting of Stem Cuttings of the Small- Leaved White Crossby (Gudaim), Grewia tenax (Forsk)

The small-leaved white crossberry (Gudaim), Grewia tenax (Forsk( Fiori , is a deciduous, tropical shrub or tree valued for its fruit. Being high in iron content, the fruit is considered as a simple safeguard against iron-deficiency anemia. In spite of this, the fruit is exploited from the wild and there have been little or no efforts to domesticate and cultivate this species. Information on the vegetative propagation of this species is not available at the present time. A series of nursery experiments were conducted during March-June 2003 to assess the effects of auxin source ]indole acetic acid (IAA), indole-3-butyric acid (IBA) and -phthalene acetic acid (NAA)], concentration (0, 1000, 1500 and 2000 ppm( duration of exposure (quick dip, one-minute dip and five-minutes dip )and form (liquid versus powder) on adventitious root formation in stem cuttings. Significant stimulation of rooting was observed with IBA at all concentrations and with IAA at 1000 and 1500 ppm. NAA, at all concentrations, was ineffective in promoting root formation. Maximum rooting success with IBA was achieved at 1500 ppm (43%) and with IAA at 1000 ppm (37%). Short-term exposure (quick dip or one-minute dip( of the cut surface to 1500 ppm IBA solution resulted in greater rooting success (57%-61%) than a five-minutes dip (32%). IBA talcum powder worked slightly better than in liquid form (56% versus 52%). It was concluded that application of 1500 ppm IBA as a quick dip in liquid or powder form is the most suitable treatment for rooting of stem cuttings of this species.   &nbsp

Adsorption and desorption of deuterium on partially oxidized Si(100) surfaces

Adsorption and desorption of deuterium are studied on the partially oxidized Si(100) surfaces. The partial oxygen coverage causes a decrease in the initial adsorption probability of D atoms. The observed D2 temperature-programmed-desorption (TPD) spectra comprise of multiple components depending on the oxygen coverage (θO). For θO=0.1ML the D2 TPD spectrum is deconvoluted into four components, each of which has a peak in the temperature region higher than the D2 TPD peaking at 780 K on the oxygen free surface. The highest TPD component with a peak around 1040 K is attributed to D adatoms on Si dimers backbonded by an oxygen atom. The other components are attributed to D adatoms on the nearest or second nearest sites of the O-backbonded Si dimers. D adatoms on the partially oxidized Si surfaces are abstracted by gaseous H atoms along two different abstraction pathways: one is the pathway along direct abstraction (ABS) to form HD molecules and the other is the pathway along indirect abstraction via collision-induced-desorption (CID) of D adatoms to form D2 molecules. The ABS pathway is less seriously affected by oxygen adatoms. On the other hand, the CID pathway receives a strong influence of oxygen adatoms since the range of surface temperature effective for CID is found to considerably shift to higher surface temperatures with increasing θO. Gradual substitution of D adatoms with H atoms during H exposure results in HD desorption along the CID pathway in addition to the ABS one. By employing a modulated beam technique the CID-related HD desorption is directly distinguished from the ABS-related one

Angular distributions of H-induced HD and D2 desorptions from the Si(100) surfaces

We measured angular distributions of HD and D2 molecules desorbed via the reactions H+D/Si 100 →HD abstraction ABS and H+D/Si 100 →D2 adsorption-induced-desorption AID , respectively. It was found that the angular distribution of HD molecules desorbed alongABS is broader than that of D2 molecules desorbed along AID, i.e., the former could be fit withcos2.0±0.2 , while the latter with cos5.0±0.5 . This difference of the angular distributions between thetwo reaction paths suggests that their dynamic mechanisms are different. The observed cos2 distribution for the ABS reaction was reproduced by the classical trajectory calculations over theLondon-Eyring-Polanyi-Sato potential-energy surfaces. The simulation suggests that the HDdesorption along the ABS path takes place along the direction of Si–D bonds, but the apparentangular distribution is comprised of multiple components reflecting the different orientations ofD-occupied Si dimers in the 2 1 and 1 2 double domain structures

Catalytic enantioselective synthesis of carbocyclic and heterocyclic spiranes via a decarboxylative aldol cyclization

The synthesis of a variety of enantioenriched 1,3-diketospiranes from the corresponding racemic allyl β-ketoesters via an interrupted asymmetric allylic alkylation is disclosed. Substrates possessing pendant aldehydes undergo decarboxylative enolate formation in the presence of a chiral Pd catalyst and subsequently participate in an enantio- and diastereoselective, intramolecular aldol reaction to furnish spirocyclic β-hydroxy ketones which may be oxidized to the corresponding enantioenriched diketospiranes. Additionally, this chemistry has been extended to α-allylcarboxy lactam substrates leading to a formal synthesis of the natural product (−)-isonitramine

Catalytic enantioselective synthesis of carbocyclic and heterocyclic spiranes via a decarboxylative aldol cyclization

The synthesis of a variety of enantioenriched 1,3-diketospiranes from the corresponding racemic allyl β-ketoesters via an interrupted asymmetric allylic alkylation is disclosed. Substrates possessing pendant aldehydes undergo decarboxylative enolate formation in the presence of a chiral Pd catalyst and subsequently participate in an enantio- and diastereoselective, intramolecular aldol reaction to furnish spirocyclic β-hydroxy ketones which may be oxidized to the corresponding enantioenriched diketospiranes. Additionally, this chemistry has been extended to α-allylcarboxy lactam substrates leading to a formal synthesis of the natural product (−)-isonitramine

Modulated hydrogen beam study of adsorption-induced desorption of deuterium from Si(100)-3×1:D surfaces

We have studied the kinetic mechanism of the adsorption-induced-desorption (AID) reaction, H + D/Si(100)D2. Using a modulated atomic hydrogen beam, two different types of AID reaction are revealed: one is the fast AID reaction occurring only at the beam on-cycles and the other the slow AID reaction occurring even at the beam off-cycles. Both the fast and slow AID reactions show the different dependence on surface temperature Ts, suggesting that their kinetic mechanisms are different. The fast AID reaction overwhelms the slow one in the desorption yield for 300 KTs650 K. It proceeds along a first-order kinetics with respect to the incident H flux. Based on the experimental results, both two AID reactions are suggested to occur only on the 3×1 dihydride phase accumulated during surface exposure to H atoms. Possible mechanisms for the AID reactions are discussed

Sources of resistance to Fusarium wilt of chickpea in Sudan

A total of 330 chickpea genotypes were screened for resistance to Fusarium wilt caused by Fusarium oxysporum f. sp. ciceris in a wilt-infected plot at Hudeiba Research Station, Ed-Damer, Sudan. The released kabuli cv. Shendi (NEC 2491/ILC 1335) and Jebel Marra-1 (ILC 915), and the widely-grown kabuli cv. Baladi were highly susceptible to Fusarium wilt. Conversely, kabuli cv. ICCV 2 and UC 15, and desi genotypes FLIP 85-20C, FLIP 85- 29C and FLIP 85-30C were highly resistant to the disease with less than 10% wilt incidence. ‘ICCV 2’ matured about 4 to 5 weeks earlier than the other four resistant chickpea genotypes. Two field trials were also conducted to verify the resistance of cv. ICCV 2 and the efficacy of the seed-dressing fungicides Tecto-TM and Quinolate Pro for control of Fusarium wilt. One trial was carried out in the wilt-infected plot and the other in farmers’ fields with a history of high disease incidence. In both trials, cv. ICCV 2 showed a good level of resistance to wilt and produced twice the grain yield of cv. Baladi in farmers’ fields. Both seed-dressing fungicides significantly increased seedling emergence in the wilt-infected plot, but neither significantly decreased the final incidence of dead plants, or increased the grain yield in the infected plot or the farmers’ fields. Results of this study indicate that cv. ICCV 2 is a potential variety for release in the traditional chickpea-producing areas of Sudan where Fusarium wilt and late-season soil moisture stress are major constraints to production

Total synthesis of the antimitotic marine macrolide (-)-leiodermatolide.

Leiodermatolide is an antimitotic macrolide isolated from the marine sponge Leiodermatium sp. whose potentially novel tubulin-targeting mechanism of action makes it an exciting lead for anticancer drug discovery. In pursuit of a sustainable supply, we report a highly stereocontrolled total synthesis (3.2% yield) based on a convergent sequence of palladium-mediated fragment assembly and macrolactonization. Boron-mediated aldol reactions were used to configure the three key fragments 2, 5, and 6 by employing the appropriate enantiomer of the lactate-derived ketone 7.This research was supported by a SCAST postgraduate research scholarship (K.K.-H.N.), the Todd-Raphael Fund (S.W.), and Clare College, Cambridge (S.M.D.). We thank Dr. Amy Wright (HBOI, Florida Atlantic University) for helpful discussions and the EPSRC UK National Mass Spectrometry Facility at Swansea University.This is the final published version. It's also available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/anie.201310164/abstract