Two allelic mutations, ore14-1 and 14-2, caused a highly significant delay in all senescence parameters examined, including chlorophyll content, the photochemical efficiency of photosystem II, membrane ion leakage, and the expression of senescence-associated genes. A delay of senescence symptoms was also observed under various senescence-accelerating conditions, where detached leaves were treated with darkness, phytohormones, or oxidative stress. These results indicate that the gene defined DNA-PK inhibitor by these

mutations might be a key regulatory genetic component controlling functional leaf senescence. Map-based cloning of ORE14 revealed that it encodes ARF2, a member of the auxin response factor (ARF) protein family, which modulates early auxin-induced gene expression in plants. The ore14/arf2 mutation also conferred an increased sensitivity to exogenous auxin in hypocotyl growth inhibition, thereby demonstrating that ARF2 is a repressor of auxin signalling. Therefore, the ore14/arf2 lesion appears to cause reduced repression of auxin signalling with increased auxin sensitivity, leading Selleckchem GDC 941 to delayed senescence. Altogether, our data suggest that ARF2 positively regulates leaf senescence in Arabidopsis.”
“We report on first-principles studies to investigate the zone-centre optical phonons and polaron properties

in zinc-blende AlxGa1-xN alloys over the whole compositional range. The calculations are performed GSK2879552 concentration using ab initio pseudopotential approach based on the density functional perturbation theory under the virtual crystal approximation. Features such as phonon frequencies, dielectric constants, Frohlich coupling constant, Debye temperature, effective polar field, deformation potential, and polaron effective mass have been determined. Reasonable agreement is obtained between our computed values and data available in the literature. Other case, our results are predictions. The phonon modes are broadened upon

alloying and their frequencies display a blueshift with increasing Al content. The dependence of the studied parameters on Al concentration is found to be monotonic. (c) 2010 American Institute of Physics. [doi: 10.1063/1.3517065]“
“The objective of the present study is to predict Young’s modulus of polymer-layered silicate nanocomposites (PLSNs) containing fully intercalated structures. The particular contribution of this article is to consider the changes in structural parameters of different intercalated morphologies in vicinity of each other. These parameters include aspect ratio of intercalated stacks, number of silicate layers per stack, d-spacing between the layers, modulus of the gallery phase, and volume fraction of each intercalated morphology. To do this, the effective particle concept has been employed and combined with the Mori-Tanaka micromechanical model.