Papyriflavonol A, a new prenylated flavonol from Broussonetia papyrifera

A new prenylated flavonol, papyriflavonol A, was isolated from the root barks of Broussonetia papyrifera. The structure of this compound was elucidated as 5,7,3',4'-tetrahydroxy-6,5'-di-(gamma,gamma-dimethylallyl)-flavonol (1) by spectroscopic analysis.     

Carbon dioxide enrichment improves growth, water relations and survival of droughted honey mesquite (Prosopis glandulosa) seedlings

Low water availability reduces the establishment of the invasive shrub Prosopis on some grasslands. Water deficit survival and traits that may contribute to the postponement or tolerance of plant dehydration were measured on seedlings of P. glandulosa Torr. var. glandulosa (honey mesquite) grown at CO(2) concentrations of 370 (ambient), 710, and 1050 micro mol mol(-1). Because elevated CO(2) decreases stomatal conductance, the number of seedlings per container in the elevated CO(2) treatments was increased to ensure that soil water content was depleted at similar rates in all treatments. Seedlings grown at elevated CO(2) had a greater root biomass and a higher ratio of lateral root to total root biomass than those grown at ambient CO(2) concentration; however, these seedlings also shed more leaves and retained smaller leaves. These changes, together with a reduced transpiration/leaf area ratio at elevated CO(2), may have contributed to a slight increase in xylem pressure potentials of seedlings in the 1050 micro mol mol(-1) CO(2) treatment during the first 37 days of growth (0.26 to 0.40 MPa). Osmotic potential was not affected by CO(2) treatment. Increasing the CO(2) concentration to 710 and 1050 micro mol mol(-1) more than doubled the percentage survival of seedlings from which water was withheld for 65 days. Carbon dioxide enrichment significantly increased survival from 0% to about 40% among seedlings that experienced the lowest soil water content. By increasing seedling survival of drought, rising atmospheric CO(2) concentration may increase abundance of P. glandulosa on grasslands where low water availability limits its establishment.     

Diallyl disulfide and diallyl trisulfide up-regulate the expression of the pi class of glutathione S-transferase via an AP-1-dependent pathway

Garlic organosulfur compounds are recognized as potential chemopreventive compounds. This protection is related to the induction of phase II detoxification enzymes. We previously reported that diallyl disulfide (DADS) and diallyl trisulfide (DATS) up-regulate the gene expression of the pi class of glutathione S-transferase (GSTP) and that an enhancer element named GPE I is required for this induction. In the present study, we further investigated the signal pathway involved in DADS and DATS up-regulation of this detoxification enzyme in Clone 9 cells. Cells were cultured with 25-200 micromol/L of DADS or DATS for 24 h. Western and Northern blots showed that both garlic allyl sulfides concentration dependently induced GSTP protein and mRNA expression, respectively. Changes in GST activity toward ethacrynic acid were consistent with the increase in GSTP expression (P < 0.05). Electromobility gel shift assay showed that the DNA binding activity of nuclear activator protein-1 (AP-1) is concentration-dependently increased in the presence of DADS and DATS as compared with that of the control cells. The phosphorylation of c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), but not of p38, was stimulated in the presence of both garlic allyl sulfides. Pretreatment with SP600125 and PD98059, which are JNK and ERK inhibitors, respectively, abolished the increase in AP-1-DNA binding activity and also the induction of GSTP protein by either allyl sulfide. Our results indicate that the effectiveness of DADS and DATS on GSTP expression is likely related to the JNK-AP-1 and ERK-AP-1 signaling pathways and, thus, that DADS and DATS enhance the binding of AP-1 to GPE I.     

肟菌酯·己唑醇对水稻病害的防效试验

为了明确45%肟菌酯•己唑醇水分散粒剂在水稻病害上的防治效果,开展45%肟菌酯•己唑醇防治水稻病害的药效试验。结果表明,45%肟菌酯•己唑醇对水稻纹枯病、稻曲病等病害有较好的防效,值得推广应用。