Plants' use of different nitrogen forms in response to crude oil contamination.

In this study, we investigated Phragmites australis' use of different forms of nitrogen (N) and associated soil N transformations in response to petroleum contamination. 15N tracer studies indicated that the total amount of inorganic and organic N assimilated by P. australis was low in petroleum-contaminated soil, while the rates of inorganic and organic N uptake on a per-unit-biomass basis were higher in petroleum-contaminated soil than those in un-contaminated soil. The percentage of organic N in total plant-assimilated N increased with petroleum concentration. In addition, high gross N immobilization and nitrification rates relative to gross N mineralization rate might reduce inorganic-N availability to the plants. Therefore, the enhanced rate of N uptake and increased importance of organic N in plant N assimilation might be of great significance to plants growing in petroleum-contaminated soils. Our results suggest that plants might regulate N capture under petroleum contamination.

[Identification of four medicines of Panax L. revealed by mitochondrial nad 1 gene b/c intron].

OBJECTIVE: To study the identification method and phylogenetic relationships of four medicines of Panax L genus: Panax ginseng C. A. Meyer, P. quinquefolicum L. , P. notoginseng (Burk.) F. H. Chen and P. japonicus C. A. Meyer. METHODS: The mitochondrial nad 1 gene was amplified. Their sequence differences were analyzed after sequencing and alignment. RESULTS: The sequence lengths of P. ginseng (including Chinese transplanted ginseng and Korean ginseng), P. japonicus were 1 290 bp, and those of P. quinquefolicum and P. notoginseng were 1 269 bp and 1 522 bp respectively. The main difference among these sequences was in nad 1 gene b/c intron. The NJ phylogenetic tree showed that P. ginseng was most closely related to P. japonicus, next was closer to P. quinquefolicum, and P. notoginseng was comparatively distantly related to P. ginseng. CONCLUSION: P. quinquefolicum and P. notoginseng can be identified from the 4 medicines of Panax L. based on the sequence difference in mitochondrial nad 1 gene. The mitochondrial nad 1 gene b/c intron can provide some evolutionary information, therefore, it is useful to identify and phylogenetically analyse for the medicines of Panax L. genus.

Do plants modulate biomass allocation in response to petroleum pollution?

Biomass allocation is an important plant trait that responds plastically to environmental heterogeneities. However, the effects on this trait of pollutants owing to human activities remain largely unknown. In this study, we investigated the response of biomass allocation of Phragmites australis to petroleum pollution by a ¹³CO2 pulse-labelling technique. Our data show that plant biomass significantly decreased under petroleum pollution, but the root-shoot ratio for both plant biomass and ¹³C increased with increasing petroleum concentration, suggesting that plants could increase biomass allocation to roots in petroleum-polluted soil. Furthermore, assimilated ¹³C was found to be significantly higher in soil, microbial biomass and soil respiration after soils were polluted by petroleum. These results suggested that the carbon released from roots is rapidly turned over by soil microbes under petroleum pollution. This study found that plants can modulate biomass allocation in response to petroleum pollution.

Genetic characterization and phytochemical analysis of wild and cultivated populations of Scutellaria baicalensis.

Scutellaria baicalensis was collected from four wild and four cultivated populations from different locations in China. Forty-two samples were analyzed using random amplification of polymorphic DNA (RAPD) techniques for genetic profiling, and high performance liquid chromatography (HPLC) techniques to determine the flavonoid content. The selected 23 RAPD primers yielded a total of 838 clear and reproducible bands of which 237 were found to be polymorphic. The wild population exhibited higher polymorphism than that of the cultivated population. The dendrogram generated by the UPGMA method via Nei's genetic distance revealed three distinct genotypes from the cultivated populations and several branches from the wild populations. The contents of baicalin and wogonoside in dried roots of the samples ranged from (w/w) 8.63 to 17.84%, and from 1.99 to 4.21%, respectively, whereas their aglycones, baicalein and wogonin, were within the range of only 0.04-0.23%. The total content of the four flavonoids varied from 9.45 to 26.24%. Comparatively, the cultivated populations contained much higher levels of baicalin and total flavonoids than those in the wild populations. The results from genetic characterization and phytochemical analysis demonstrated that the quality variation of this drug was mainly determined by extrinsic environmental or agricultural factors, rather than by genetic differences. Our findings can be used for the commercial production and germplasm management of this medicinal plant.

[Determination of lignin content in tiny Panax ginseng by UV spectrophotometry].

OBJECTIVE: To establish the UV spectrophotometry for determining lignin content in tiny Panax ginseng powder. METHODS: Classical Klason method and UV spectrophotometry were used. RESULTS: The lignin contents measured by UV spectrophotometry were higher, more repeatable and accurate as comparison with the Klason method. The specific absorptance peak of ginseng lignin appeared at 260 nm. The acetyl bromide treatment of the UV spectrophotometry was processed for ginseng powder at 70 degrees C for 30 minutes. It is also concluded that the lignin contents were obvious different among various ginsengs. CONCLUSION: UV spectrophotometry is simple, accurate and just need a little materials. It is especially suitable to determine the lignin content for ginseng and other precious Chinese traditional medicines.

Antioxidative flavanone glycosides from the branches and leaves of Viscum coloratum.

Two new flavanone glucosides, (2S)-homoeriodictyol 7,4'-di-O-beta-D-glucopyranoside (4) and (2R)-eriodictyol 7,4'-di-O-beta-D-glucopyranoside (5) were isolated from the branches and leaves of Viscum coloratum (KOMAR) NAKAI (Loranthaceae), along with three known flavanone glucosides: (2S)-homoeriodictyol 7-O-beta-D-glucopyranoside (1), (2S)-eriodictyol 7-O-beta-D-glucopyranoside (2), and (2S)-naringenin 7-O-beta-D-glucopyranoside (3). The structures of these compounds were elucidated using spectroscopic methods. The antioxidant activities of these isolated compounds were evaluated by colorimetric methods based on their scavenging effects on hydroxyl radicals and superoxide anion radicals, respectively. All the compounds showed potent albeit varied degrees of antioxidative activities and the structure-activity relationship is discussed.

Fitness estimation through performance comparison of F1 hybrids with their parental species Oryza rufipogon and O. sativa.

BACKGROUND AND AIMS: Introgression of crop genes into populations of wild relatives has important implications for germplasm conservation as well as for the persistence of novel transgenes in wild populations. Studies of hybrid fitness can be used to evaluate the potential for introgression to occur following episodes of interspecific hybridization. METHODS: This study estimated relative fitness of interspecific hybrids through performance comparison of F(1) hybrids with their parental species, a cultivated rice (Oryza sativa) Minghui-63 and perennial common wild rice (O. rufipogon) under the cultivation conditions. KEY RESULTS: Compared with their parents, the hybrids had the lowest values of seedling survival ability, pollen viability and seed production; intermediate values of seed germination, spikelet production and flag leaf areas; and the highest values of plant height, number of tillers and panicles. The hybrids performed poorly at the stage of sexual reproduction, although they had a slightly higher hybrid vigour at the vegetative growth stage and better tillering ability than their wild parent. There were no significant differences in composite fitness across the whole life-history between the hybrids and their wild parental species. CONCLUSIONS: Rice genes, including transgenes, might persist in wild rice populations through vegetative and sexual reproduction. Further studies are needed to examine whether the extent of gene flow from rice is sufficiently significant to influence genetic diversity in wild populations of O. rufipogon, a species that has become endangered in some regions of south-east Asia.