Characterization of Bacteria in the Rhizosphere Soils of Polygonum Pubescens and Their Potential in Promoting Growth and Cd,Pb, Zn Uptake by Brassica napus

Microbe-enhanced phytoremediation has been considered as a promising measure for the remediation of metal-contaminated soils. In this study, two bacterial strains JYX7 and JYX10 were isolated from rhizosphere soils of Polygonum pubescens grown in metal-polluted soil and identified as of Enterobacter sp. and Klebsiella sp. based on 16S rDNA sequences, respectively. JYX7 and JYX10 showed high Cd, Pb and Zn tolerance and increased water-soluble Cd, Pb and Zn concentrations in culture solution and metal-added soils. Two isolates produced plant growth-promoting substances such as indole acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and solubilized inorganic phosphate. Based upon their ability in metal tolerance and solubilization, two isolates were further studied for their effects on growth and accumulation of Cd, Pb, and Zn in Brassica napus (rape) by pot experiments. Rapes inoculated with JYX7 and JYX10 had significantly higher dry weights, concentrations and uptakes of Cd, Pb, Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg^?1), Pb (200 mg kg^?1) or Zn (200 mg kg^?1). The present results demonstrated that JYX7 and JYX10 are valuable microorganism, which can improve the efficiency of phytoremediation in soils polluted by Cd, Pb, and Zn.     

Modelling field emergence patterns in arable weeds

A model was developed to simulate weed emergence patterns after soil cultivation. In the model, the consecutive processes of dormancy release, germination and pre-emergence growth were modelled in separate modules. Input variables of the model were: date of soil cultivation, soil temperature and soil penetration resistance. Output variables of the model were: seedling density and timing of seedling emergence. The model was parameterized for Polygonum persicaria , Chenopodium album and Spergula arvensis with data from previous field and laboratory experiments. The model was evaluated with data from an experiment, in which emergence of P. persicaria , C. album and S. arvensis was monitored in field plots that were cultivated once only, at one of five dates in the spring. At the same time as the field observations on seedling emergence, seasonal changes in seed dormancy of the buried weed seeds were assessed by testing the germination of seed lots that were buried in envelopes. From a comparison between field observations and simulated data, it appeared that the model overestimated the rate of dormancy release in spring, whereas germination and pre-emergence growth were simulated well. In general, therefore, both the numbers of emerging seedlings and the timing of emergence could be predicted accurately, when dormancy was not simulated but introduced from experimental data. Improvement of predictions of field emergence of weeds should mainly focus on increasing the precision of the simulation of dormancy release. Close correlations were found between seedbed temperature and both the extent and rate of seedling emergence, but analysis with the simulation model revealed that they were only partly based on causal relationships, so that they have limited predictive value.     

蓼属-未知花粉类型外壁超微结构的研究

花粉壁的构造提供了若干在系统发育上有用的特征,其中外壁的层次、结构以及纹饰是基本的。为此,本文以花粉壁的外部纹饰和内部结构为重点,用扫描电镜（ＳＥＭ）和透射电镜（ＴＥＭ）的薄切片技术,对蓼属一新的花粉类型－－长花蓼型的花粉外壁构造的特点进行了观察和研究。结果表明：外壁结构分化成两个明显的层次,即外面的外壁外层以及内面的外壁内层,其外壁外层无覆盖层,仅由柱状层和底层组成的。     

The New Flavonoids from Polygonum sphaerostachyum (Polygonaceae)

Two novel flavone glycosides, 3′-hydroxy-5,4′-dimethoxy-6,7-methylenedioxyflavone-3-O-［β-D-xylopyranosyl(1→6)］-β-D-glucopyranoside(1)and5,4′-dimethoxy-3′-isopropenylacetyl-6,7-methylenedioxyflavone-3-O-［β-D-xylopyranoxyl(1→6)］-β-D-glucopyranoside (2), were isolated from Polygonum sphaerostachyum Meisn., and their structures were deduced by spectral and chemical methods. This is the first report on the isolation of flavone glycosides from P. sphaerostachyum.     

盐碱胁迫下西伯利亚蓼体内无机离子的变化

研究了碳酸氢钠溶液处理后西伯利亚蓼营养器官内部无机离子含量的变化。实验结果表明碳酸氢钠溶液处理前西伯利亚蓼茎部认为是“K+库”;碳酸氢钠溶液处理过程中“K+库”转变成为“Na+库”,以维持叶部的正常生理功能,并且“Na+库”具有一定的限度;碳酸氢钠溶液处理后,西伯利亚蓼不同部位对外界盐碱胁迫的反应存在多样性。植株在“Na+库”达到限度之前进行旺盛的光合作用,在有限的时间内向地下组织输送更多的有机养分,用以繁殖后代。     

Occurrence of polygodial in plant organs and tissue culture of Polygonum hydropiper

Shoots of Polygonum hydropiper L. (waterpepper), especially in the leaves and flower-heads, contain significant amounts of the sesquiterpenoid polygodial, a compound with a potential use as a natural pesticide. The polygodial content of the tepals is particularly high: up to 8.5% of the dry weight. Roots and seeds do not contain detectable amounts of polygodial. Polygodial containing organs e.g. leaves and tepals, were found to contain cavities. Fourier transform infra-red (FTIR) microspectroscopy demonstrated that polygodial or its congeners are found in these cavities but not in other tissues or cells. Comparable cavities containing polygodial-like compounds were absent in the closely related species Polygonum persicaria L.
Callus cultures and cell suspensions as well as root- and shoot cultures were initiated from mature P. hydropiper plants. Polygodial could be detected only in shoot cultures. Our results indicate that functioning plastids may be essential for polygodial production and cavities for its accumulation.     

Modelling the relative growth rate as a function of plant nitrogen concentration

The relationship between the relative growth rate (RGR) and the nitrogen concentration of the whole plant (PNC) was analyzed by using experimentally determined relations (1) between the PNC and the fraction of dry matter (LWR) and nitrogen in leaves, (2) between the specific leaf area (SLA) and the leaf nitrogen concentration (LNC) and (3) between the net assimilation rate (NAR) and the LNC on an area basis. A strong dependence of RGR on nitrogen concentration resulted from the increase in NAR, LWR and SLA with increasing PNC. A curvilinear relationship between RGR and PNC gave an optimum curve for nitrogen productivity against PNC.     

Identification of Polygonum orientale constituents using high-performance liquid chromatography high-resolution tandem mass spectrometry

Our primary focus in this research was to identify and characterize its bioactive compounds for potential therapeutic use. Twenty-seven metabolites of Polygonum orientale were identified using LC-QTOF tandem mass spectrometry. Interestingly, P. orientale extracts included several highly oxygenated flavonoids were isolated from P. orientale by column chromatography. ¹³C NMR data of highly oxygenated flavonoids (1–7) are reported here for the first time. In addition, nitric oxide, 1,1-diphenyl-2-picrylhydrazyl, and water-soluble tetrazolium salt assays were carried out on the isolated compounds to investigate their anti-inflammatory, anti-oxidant, and neuroprotective activities, respectively. Compounds 1, 2, 3, 5, 7, and 8 significantly attenuated lipopolysaccharide-stimulated NO production in BV2 cells without affecting cell viability. Compounds 9–12 exhibited significant antioxidant activity, while compounds 8, 9, and 12 exhibited protective effects against glutamate-induced neurotoxicity in HT22 cells. Our results indicate that P. orientale is a promising source of natural agents for the potential treatment of inflammation and neurodegenerative diseases.