Proteome-level differences between auxinic-herbicide-susceptible and -resistant wild mustard (Sinapis arvensis L.)

To identify proteins that may be involved in mediating auxinic herbicide resistance (i.e., resistance to dicamba, picloram, 2,4-D), we compared the proteomes of an auxinic-herbicide-susceptible (S) and -resistant (R) wild mustard (Sinapis arvensis L.) biotype at different developmental stages. Using two-dimensional electrophoresis and mass spectrometry, we identified 11 seedling and leaf proteins that showed reproducible differences in expression between the S and the R wild mustard biotype following application of dicamba. Our proteome-level studies revealed the increased expression of the enzyme peptidylprolyl cis-trans isomerase (PPIase), which has recently been implicated in auxin signal transduction. Juglone, an inhibitor of PPIase, interfered with the normal ability of R seeds to germinate in the presence of dicamba, whereas S seeds did not germinate in the presence of dicamba or dicamba plus juglone. When R and S plants (3-4 leaf stage) were treated with dicamba, S showed typical auxinic herbicide effects (e.g., epinasty) whereas R did not. However, the concomitant application of dicamba and juglone to greenhouse-grown R plants produced morphological changes that were consistent with known auxinic-herbicide-induced symptoms. This is the first report suggesting the potential involvement of differential expression of PPIase in mediating auxinic herbicide resistance.

Linking fluorescence induction curve and biomass in herbicide screening

A suite of dose-response bioassays with white mustard (Sinapis alba L) and sugar beet (Beta vulgaris L) in the greenhouse and with three herbicides was used to analyse how the fluorescence induction curves (Kautsky curves) were affected by the herbicides. Bentazone, a photosystem II (PSII) inhibitor, completely blocked the normal fluorescence decay after the P-step. In contrast, fluorescence decay was still obvious for flurochloridone, a PDS inhibitor, and glyphosate, an EPSP inhibitor, which indicated that PSII inhibition was incomplete. From the numerous parameters that can be derived from OJIP-steps of the Kautsky curve the relative changes at the J-step [Fvj = (Fm - Fj)/Fm] was selected to be a common response parameter for the herbicides and yielded consistent dose-response relationships. Four hours after treatment, the response Fvj on the doses of bentazone and flurochloridone could be measured. For glyphosate, the changes of the Kautsky curve could similarly be detected 4 h after treatment in sugar beet, but only after 24 hs in S alba. The best prediction of biomass in relation to Fvj was found for bentazone. The experiments were conducted between May and August 2002 and showed that the ambient temperature and solar radiation in the greenhouse could affect dose-response relationships. If the Kautsky curve parameters should be used to predict the outcome of herbicide screening experiments in the greenhouse, where ambient radiation and temperature can only partly be controlled, it is imperative that the chosen fluorescence parameters can be used to predict accurately the resulting biomass used in classical bioassays.

Microcystin-LR alters the growth, anthocyanin content and single-stranded DNase enzyme activities in Sinapis alba L seedlings

Seedlings of the white mustard (Sinapis alba L.) are sensitive to the cell-free extracts of a toxigenic strain of Microcystis aeruginosa and to microcystin-LR. Fresh mass of plants, plant length, including hypocotyl and root length and lateral root formation is inhibited in microcystin-LR treated seedlings. The decrease of anthocyanin content is obtained in microcystin treated mustard cotyledons. The tissue necrosis of cotyledons is a characteristic consequence of microcystin treatment. Microcystin-LR induces an increase in single stranded deoxyribonucleases (ssDNases) activity of S. alba seedlings as shown by spectrophotometric assays and by ssDNase activity polyacrylamide gels. The significance of this phenomenon is discussed in relation to general stress responses in plants. We conclude that microcystin-LR affects the whole physiology and the growth of plants.

Synthesis of some triazolyl-benzofuranamine derivatives

The synthesis of some triazoly-benzofuranamine derivatives starting from 2-chloro-N-(5-substituted-2,3-dihydro-3-benzofuryl)acetamides and 3-(aryloxyalkyl)-4-ethyl/phenyl-5-mercapto-1,2,4-triazoles is described. The chemical structures of the compounds were elucidated. The prepared compounds were tested for herbicidal activity.