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Two glasshouse experiments were conducted at the Department of Plant Production, University of Helsinki, Finland, to study the effect of foliar application of aqueous 0.1 and 0.3M glycinebetaine on leaf growth of drought-stressed tobacco (Nicotiana tabacum L.) cv. Samsun. Leaf nitrogen and glycinebetaine concentrations were estimated periodically. After 16 days of treatment, leaves were harvested, and fresh and dry weights, and area determined. The number of total and green leaves was also recorded. Significant increases in leaf fresh and dry weights, and area were associated with glycinebetaine application, especially when drought was induced early. The application of 0.3M glycinebetaine reduced leaf area duration. Residual leaf glycinebetaine content remained high 16 days after application. The results indicate that exogenous glycinebetaine has the potential to improve the drought tolerance of leaf tobacco.

The HPLC separation of dansylated amides including mono-, di-, and polyamines from a Peucedanum palustre (L.) Moench plant and an embryogenic cell culture line was studied. The flowers, stems, leaves, and roots of the plant were analyzed separately. The mobile phase was optimized with the "PRISMA" model, which is a multi-solvent optimization system. Twenty-five standard amines were tested, twelve of which were present in the plant samples. The amine concentrations varied considerably in the different organs of the plant. There were also differences in amine concentrations between the wild plant and the embryogenic cell line and plantlets. The "PRISMA" optimization system proved to be a rapid and efficient method in the HPLC analysis of biogenic amines present in plant samples.

The nucleotide sequence of LEU4, a yeast gene encoding alpha-isopropylmalate synthase, has been determined. An open reading frame of 1857 nucleotides specifies a protein of 619 residues whose calculated molecular weight (68,416) and amino acid composition agree well with earlier estimates based on protein data. The 5' flanking region contains three blocks of sequence potentially involved in the general control of amino acid biosynthesis. It also has six blocks of homology in common with the 5' flanking regions of two other LEU structural genes (LEU1 and LEU2). One of these blocks coincides with a palindromic element that has previously been demonstrated to be important for the specific leucine control of LEU2 (Martinez-Arias, A., Yost, H. J., and Casadaban, M. J. (1984) Nature 307, 740-742). Determination of the 5' ends of the LEU4 transcript indicates the existence of four major and several minor potential transcription start sites. Two of the major sites are located downstream from the ATG at the beginning of the long open reading frame. Utilization of these sites would lead to mRNA that could be translated from an in-frame AUG located 90 nucleotides downstream from the first one. The protein thus generated would be 30 amino acid residues shorter than the larger one. This situation might account for the occurrence of two alpha-isopropylmalate synthase-related proteins observed both in cell-free extracts and in in vitro translation mixtures (Hampsey, D. M., Lewin, A. S., and Kohlhaw, G. B. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 1270-1274). The larger of these proteins was incorporated into the mitochondria while the smaller one was not. We conclude that selection of appropriate transcription and translation start sites might control the subcellular localization of the LEU4 gene product. This conclusion is discussed with respect to other examples in yeast of genes that encode two forms of the same protein.

Crop losses caused by environmental stresses might be reduced by applying osmoprotectans to crop canopies. Glycinebetaine is endogenously accumulated by some halophytes under stress conditions and represents such a compound. Glycinebetaine was applied exogenously to barley (Hordeum vulgare L.), oat (Avena sativa L.), spring wheat (Triticum aestwum L.), and summer turnip rape (Brassica rapa ssp. oleifera DC.) canopies and its optimal concentration was monitored in the greenhouse. In field experiments the response of crop plants to betaine applications was assessed by measuring accumulation of above ground biomass, leaf area index (LAI), leaf chlorophyll, and yield. The optimum betaine concentration producing advantageous effects on growth and crop physiology in turnip rape was close to 0.1 M and for wheat 0.3 M. Such concentrations promoted accumulation of betaine similar to that of halophytes under stress conditions [ca. 200 μmol (g DM)−1]. In the 1993 field experiment peak LAIs were recorded in irrigated wheat and barley treated with 17.5 kg ha−1 betaine applied at 300 1 ha−1. Green leaf area was slightly more persistent in wheat treated twice with 1 kg ha−1 betaine applied at 200 1 ha−1 in 1994, although it was not associated with increased grain yield. Our results indicated that betaine has no actual potential in Finland for the principal grain crops but further studies are needed in stress prone environments to assess the potential of betaine treatments for preventing crop failures.