Potassium loss is involved in tobacco cell death induced by palmitoleic acid and ceramide.

Tobacco cell death induced by palmitoleic acid (16:1), ceramide, and KCN was found to possess features associated with program cell death (PCD), including cell volume decrease, loss of membrane integrity, DNA damage, nuclear and plastid disorganization, and chromatin condensation. Cell volume decrease was found to be caused by loss of intracellular K(+). Ba(2+) was able to prevent the K(+) loss and it also protected the cells from death induced by 16:1 and ceramide but not KCN. The results suggest that K(+) loss is a critical step in plant PCD. The inability of Ba(2+) to prevent cell death was most likely due to its other effects of KCN, i.e., inhibition of cytochrome oxidase in the respiratory chain and generation of reactive oxygen species.

cis-3-Hexenal production in tobacco is stimulated by 16-carbon monounsaturated fatty acids.

Transgenic tobacco plants O9 and T16 expressing the yeast acyl-CoA Delta9 desaturase and an insect acyl-CoA Delta11 desaturase, respectively, displayed altered profiles of fatty acids compared to wild-type tobacco plants and marked increases in cis-3-hexenal, a major leaf volatile derived from alpha-linolenic acid (18:3). As expected, O9 and T16 plants had increased levels of the major unsaturated fatty acid products formed by the transgenic desaturases they expressed, viz., palmitoleic acid (16:1(Delta9)) and palmitvaccenic acid (16:1(Delta11)), respectively. In addition, levels of 18:3 lipid declined slightly and the pool of free 18:3, which accounts for about 30% of free fatty acids in wild-type plants, disappeared completely in both transgenics. Both O9 and T16 plants were found to have a two-fold increase in 13-lipoxygenase (13-LOX) activity, which catalyzes the first of two steps leading to hexenal production from 18:3. In O9 and T16 plants, the activity of 9-lipoxygenase and hydroperoxide lyase, the latter catalyzing the formation of cis-3-hexenal from alpha-linolenic acid hydroperoxide, was significantly different from that of the wild-type plants. Although 16:1(Delta9) and 16:1(Delta11) had no direct effects on 13-LOX activity in vitro, cis-3-hexenal production increased in tobacco leaves treated with these fatty acids, suggesting that they may act in vivo by stimulating 13-LOX gene expression.

Quantification of protodioscin and rutin in asparagus shoots by LC/MS and HPLC methods.

A liquid chromatography/mass spectrometry (LC/MS) method with selected ion monitoring was developed and validated to analyze the contents of protodioscin and rutin in asparagus. The distribution of rutin and protodioscin within the shoots was found to vary by location, with the tissue closest to the rhizome found to be a rich source of protodioscin, at an average level of 0.025% tissue fresh weight in the three tested lines, while the upper youngest shoot tissue contained the highest amount of rutin at levels of 0.03-0.06% tissue fresh weight. The lower portions of the asparagus shoots that are discarded during grading and processing should instead be considered a promising source of a new value-added nutraceutical product.

Antifungal constituents from the seeds of Allium fistulosum L.

A new unsaturated fatty acid monoglyceride (1), glycerol mono-(E)-8,11,12-trihydroxy-9-octadecenoate, was isolated from the seeds of Allium fistulosum L. along with five known compounds: tianshic acid (2), 4-(2-formyl-5-hydroxymethylpyrrol-1-yl) butyric acid (3), p-hydroxybenzoic acid (4), vanillic acid (5), and daucosterol (6). The structures of 1-3 were established by interpretation and full assignments of NMR spectroscopic data. Both 1 and 2 were found to inhibit the growth of Phytophtohora capsici on V8 media.