Roles of Arabidopsis WRKY3 and WRKY4 Transcription Factors in Plant Responses to Pathogens

<p>Abstract</p> <p>Background</p> <p>Plant WRKY DNA-binding transcription factors are involved in plant responses to biotic and abiotic responses. It has been previously shown that <it>Arabidopsis WRKY3 </it>and <it>WRKY4</it>, which encode two structurally similar WRKY transcription factors, are induced by pathogen infection and salicylic acid (SA). However, the role of the two WRKY transcription factors in plant disease resistance has not been directly analyzed.</p> <p>Results</p> <p>Both WRKY3 and WRKY4 are nuclear-localized and specifically recognize the TTGACC W-box sequences <it>in vitro</it>. Expression of <it>WRKY3 </it>and <it>WRKY4 </it>was induced rapidly by stress conditions generated by liquid infiltration or spraying. Stress-induced expression of <it>WRKY4 </it>was further elevated by pathogen infection and SA treatment. To determine directly their role in plant disease resistance, we have isolated T-DNA insertion mutants and generated transgenic overexpression lines for <it>WRKY3 </it>and <it>WRKY4</it>. Both the loss-of-function mutants and transgenic overexpression lines were examined for responses to the biotrophic bacterial pathogen <it>Pseudomonas syringae </it>and the necrotrophic fungal pathogen <it>Botrytis cinerea</it>. The <it>wrky3 </it>and <it>wrky4 </it>single and double mutants exhibited more severe disease symptoms and support higher fungal growth than wild-type plants after <it>Botrytis </it>infection. Although disruption of <it>WRKY3 </it>and <it>WRKY4 </it>did not have a major effect on plant response to <it>P. syringae</it>, overexpression of <it>WRKY4 </it>greatly enhanced plant susceptibility to the bacterial pathogen and suppressed pathogen-induced <it>PR1 </it>gene expression.</p> <p>Conclusion</p> <p>The nuclear localization and sequence-specific DNA-binding activity support that WRKY3 and WRKY4 function as transcription factors. Functional analysis based on T-DNA insertion mutants and transgenic overexpression lines indicates that WRKY3 and WRKY4 have a positive role in plant resistance to necrotrophic pathogens and WRKY4 has a negative effect on plant resistance to biotrophic pathogens.</p

Methyl­naltrexone bromide methanol monosolvate

In the title compound [systematic name: (4R,4aS,7aR,12bS)-3-cyclo­propyl­meth­yl-4a,9-hy­droxy-7-oxo-2,3,4,4a,5,6,7,7a-octa­hydro-1H-4,12-methano­benzofuro[3,2-e]isoquinolin-3-ium bromide methanol monosolvate], C21H26NO4 +·Br−·CH3OH, two of the three six-membered rings adopt chair conformations while the third, which contains a C=C double bond, adopts an approximate half-boat conformation. The 2,3-dihydro­furan ring adopts an envelope conformation. In the crystal, the components are linked by O—H⋯O and O—H⋯Br hydrogen bonds. The absolute stereochemistry was inferred from one of the starting materials

Simulation for field emission images of micrometer-long SWCNTs

The electron distribution of open-ended single-walled carbon nanotubes with chirality indexes (7,0) and (5,5) in the field emission conditions was calculated via a multi-scaled algorithm. The field emission images were produced numerically. It was found that the emission patterns change with the applied macroscopic field. Especially, the symmetry of the emission pattern of the (7,0) carbon nanotube is breaking in the lower field but the breaking is less obvious in the higher field. The enlargement factor increases with the applied macroscopic field.Comment: 8 pages, 4 figure

(3S,4R,4aS,7aR,12bS)-3-Cyclo­propyl­meth­yl-4a,9-dihy­droxy-3-methyl-7-oxo-2,3,4,4a,5,6,7,7a-octa­hydro-1H-4,12-methano-1-benzofuro[3,2-e]isoquinolin-3-ium 2,2,2-trifluoro­acetate methanol solvate

In the title compound, C21H26F3NO6 +·CF3COO−·CH3OH or S-MNTX·CF3COO−·CH3OH (MNTX = methyl­naltrexone), the conformation of the polycyclic backbone of the noroxy­morphone skeleton can be simplified in terms of the angles between the least-squares planes of these rings. The dihedral angle between the cyclohexene and piperidine rings is 84.5 (6)°, while the dihedral angles between the planes of cyclohexane ring and the benzene, cyclohexene and piperidine rings, respectively, are 85.8 (6),80.0  (7) and 10.3 (7)°. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds. The trifluoro­acetate F atoms are disordered in a 0.710 (14):0.710 (14) ratio. The absolute stereochemistry was inferred from the use of (4R,4aS,7aR,12bS)-3-(cyclo­propyl­meth­yl)-4a,9-dihy­droxy-2,3,4,4a,5,6-hexa­hydro-1H-4,12-meth­ano­benzofuro[3,2-e]isoquinolin-7(7aH)-one as one of the starting materials

Atomic decoration for improving the efficiency of field electron emission of carbon nanotubes

The field electron emission from the single-walled carbon nanotubes with their open ends terminated by -BH, -NH, and -O has been simulated. The apex-vacuum barrier and the emission current have been calculated. It has been found that -BH and -NH suppress the apex-vacuum barrier significantly and lead to higher emission current in contrast to the -O terminated structure in the same applied field. The calculated binding energy implies that the carbon nanotubes terminated with -BH and -NH are more stable than those saturated by oxygen atoms or by hydrogen atoms.Comment: 8 pages, 9 figures, LaTeX; content changed, typos corrected, references adde