The ability of cyanobacteria to produce the phytohormone indole-3-acetic acid (IAA) was demonstrated. A colorimetric (Salkowski) screening of 34 free-living and symbiotically competent cyanobacteria, that represent all morphotypes from the unicellular to the highly differentiated, showed that auxin-like compounds were released by about 38% of the free-living as compared to 83% of the symbiotic isolates. The endogenous accumulation and release of IAA were confirmed immunologically (ELISA) using an anti-IAA antibody on 10 of the Salkowski-positive strains, and the chemical authenticity of IAA was further verified by chemical characterization using gas chromatography-mass spectrometry in Nostoc PCC 9229 (isolated from the angiosperm Gunnera) and in Nostoc 268 (free-living). Addition of the putative IAA precursor tryptophan enhanced IAA accumulation in cell extracts and supernatants. As the genome of the symbiotically competent Nostoc PCC 73102 contains homologues of key enzymes of the indole-3-pyruvic acid pathway, a transaminase and indolepyruvate decarboxylase (IpdC), the putative ipdC gene from this cyanobacterium was cloned and used in Southern blot analysis. Out of 11 cyanobacterial strains responding positively in the Salkowski/ELISA test, ipdC homologues were found in 4. A constitutive and possibly tryptophan-dependent production of IAA via the indole-3-pyruvic acid pathway is therefore suggested. The possible role of IAA in cyanobacteria in general and in their interactions with plants is discussed.

Canola, Brassica napus cv. Westar, was transformed to express a bacterial 1-aminocyclopropane-1-carboxylate (ACC) deaminase (EC 4.1.99.4) gene under the transcriptional control of (a) the constitutive and strong 35S promoter from cauliflower mosaic virus, (b) the root-specific promoter of the rolD gene within the T-DNA from the Ri plasmid of Agrobacterium rhizogenes, and (c) the promoter for the pathogenesis-related prb-1b gene from tobacco. Following the growth of transformed and non-transformed canola plants in the presence of 0-200 mM NaCl, the fresh and dry weights of plants, leaf protein concentration, and leaf chlorophyll contents were measured. The data suggest that the presence of ACC deaminase provides the transgenic canola lines with tolerance to the inhibitory effects of salt stress, compared to the non-transformed canola plants, with the rolD transformants being the most effective. The improved salt tolerance of these transgenic plants is likely the consequence of the decreased synthesis of stress ethylene. This data is consistent with previous studies with transgenic tomato plants expressing bacterial ACC deaminase which showed that lowering ethylene levels partially protected plants against growth inhibition by metals, phytopathogens and flooding.Abbreviation: ACC -1-aminocyclopropane-1-carboxylate

The possible number of chiral and achiral tetrasubstituted [2.2]paracyclophanes possessing different types of symmetry (C(2), C(i), C(s), C(2v), C(2h)) is evaluated and a unified independent trivial naming descriptor system is introduced. The reactivity and regioselectivity of the electrophilic substitution of the chiral pseudo-meta- and achiral pseudo-para-disubstituted [2.2]paracyclophanes are investigated in an approach suggested to be general for the synthesis of bis-bifunctional [2.2]paracyclophanes. The mono- and diacylation of chiral pseudo-meta-dihydroxy[2.2]paracyclophane 14 with acetylchloride occur ortho-regioselectively to produce tri- 22, 23 and symmetrically 21 tetrasubstituted acyl derivatives. The same reaction with benzoylchloride is neither regio-, nor chemoselective, and gives rise to a mixture of ortho-/para-, mono-/diacylated compounds 27-31. The double acylation of pseudo-meta-dimethoxy[2.2]paracyclophane 18 is completely para-regioselective. Electrophilic substitution of pseudo-meta-bis(methoxycarbonyl)[2.2]paracyclophane 20 regioselectively generates the pseudo-gem-substitution pattern. Formylation of this substrate produces the monocarbonyl derivatives 35 only, whereas the Fe-catalyzed bromination may be directed towards mono- 36 or disubstitution 37 products chemoselectively by varying the reactions conditions. The diacylation and dibromination reactions of the respective achiral diphenol 12 and bis(methoxycarbonyl) 40 derivatives of the pseudo-para-structure retain regioselectivities which are characteristic for their pseudo-meta-regioisomers. Imino ligands 26, 25, and 39, which were obtained from monoacyl- 22 and diacyldihydroxy[2.2]paracyclophanes 21, 38, are tested as chiral ligands in stereoselective Et(2)Zn addition to benzaldehyde producing 1-phenylpropanol with ee values up to 76 %.

Two useful approaches to ortho-acylhydroxy[2.2]paracyclophanes, starting from 4-hydroxy[2.2]paracyclophane, have been developed. TiCl 4 -catalyzed Fries rearrangement and direct acylation occur regioselectively (to the ortho position with respect to the hydroxy group), leading to 4-acetyl-5-hydroxy[2.2]paracyclophane (3) and 4-benzoyl-5-hydroxy[2.2]-[a] A. N. Nesmeyanov Institute of Organoelement Compounds, 3295 paracyclophane (4) in high to excellent chemical yields. For compound 4, an X-ray investigation has been performed. ortho-Acylhydroxy[2.2]paracyclophanes 3 and 4 have been obtained in enantiomerically enriched forms (ee 92−99%) and the absolute configurations of their enantiomers have been determined. parative routes to enantiomerically enriched ortho-acylhydroxy[2.2]paracyclophanes were elaborated.

The production of auxins, such as indole-3-acetic acid (IAA), by rhizobacteria has been associated with plant growth promotion, especially root initiation and elongation. Six indole-producing bacteria isolated from the rhizosphere of legumes grown in Saskatchewan soils and identified as Pantoea agglomerans spp. were examined for their ability to promote the growth of canola, lentil and pea under gnotobiotic conditions and for tryptophan (Trp)-dependent IAA production. Five of the isolates enhanced root length, root weight or shoot weight by 15-37% in at least one of the plant species, but isolates 3-117 and 5-51 were most consistent in enhancing plant growth across the three species. Indole concentrations in the rhizosphere of plants grown under gnotobiotic conditions increased in the presence of the rhizosphere isolates and when Trp was added 3 days prior to plant harvest. Isolates 3-117, 5-51 and 5-105 were most effective in increasing rhizosphere indole concentrations. Colony hybridization confirmed that all of the isolates possessed the ipdC gene which codes for a key enzyme in the Trpdependent IAA synthetic pathway.