Root and microbial biomass dynamics under the canopy of the desert shrub Zygophyllum dumosum

Summary A study was done to evaluate the influence of soil moisture and rainfall on root and microbial biomass production under the canopy of the desert shrub Zygophyllum dumosum. During the study period the root biomass production increased following the early rains but subsequently declined, remaining fairly constant thoroughout the season. In contrast microbial biomass and soil organic matter increased during the rainy season and declined with the onset of the dry summer period. Based on our results we suggest that the moisture event and not the amount and the organic matter content regulate root and microbial biomass production at the 0 to 10 cm soil layer.Contribution of the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. paper no. 2617-E, 1989 series     

Bioguided Fractionation and Isolation of an Antiplasmodial Saponin from the Roots of Nauclea xanthoxylon (A.Chev.) Aubrév. (Rubiaceae)

The root extract of Nauclea xanthoxylon (A.Chev.) Aubrév. displayed significant 50 % inhibition concentration (IC₅₀s) of 0.57 and 1.26 μg/mL against chloroquine resistant and sensitive Plasmodium falciparum (Pf) Dd2 and 3D7 strains, respectively. Bio-guided fractionation led to an ethyl acetate fraction with IC₅₀s of 2.68 and 1.85 μg/mL and subsequently, to the new quinovic acid saponin named xanthoxyloside ( 1 ) with IC₅₀s of 0.33 and 1.30 μM, respectively against the tested strains. Further compounds obtained from ethyl acetate and hexane fractions were the known clethric acid ( 2 ), ursolic acid ( 3 ), quafrinoic acid ( 4 ), quinovic acid ( 5 ), quinovic acid 3-O-β-D-fucopyranoside ( 6 ), oleanolic acid ( 7 ), oleanolic acid 3-acetate ( 8 ), friedelin ( 9 ), β-sitosterol ( 10a ), stigmasterol ( 10b ) and stigmasterol 3-O-β-D-glucopyranoside ( 11 ). Their structures were characterised with the aid of comprehensive spectroscopic methods (1 and 2D NMR, Mass). Bio-assays were performed using nucleic acid gel stain (SYBR green I)-based fluorescence assay with chloroquine as reference. Extracts and compounds exhibited good selectivity indices (SIs) of >10. Significant antiplasmodial activities measured for the crude extract, the ethyl acetate fraction and xanthoxyloside ( 1 ) from that fraction can justify the use of the root of N. xanthoxylon in ethnomedicine to treat malaria.     

Contribution of microwave accelerated distillation in the extraction of the essential oil of Zygophyllum album L.

Introduction – The aerial parts of Zygophyllum album L. are used in folk medicine as an antidiabetic agent and as a drug active against several pathologies. In this work we present the chemical composition of Algerian essential oils obtained by microwave accelerated distillation (MAD) extraction, a solventless method assisted by microwave. Objective – Under the same analytical conditions and using GC‐FID and GC‐MS, the chemical composition of the essential oil of Zygophyllum album L. extracted by MAD was compared with that achieved using hydrodistillation (HD). Methodology – The extracted compounds were hydrosoluble, and they were removed from the aqueous solution by a liquid extraction with an organic solvent. Results – Employing MAD (100°C, 30 min), the essential oil contained mainly oxygenated monoterpenes with major constituents: carvone and α‐terpineol. However, most of the compounds present in the hydrodistilled volatile fraction were not terpene species, with β‐damascenone as a major constituent. Conclusion – The MAD method appears to be more efficient than HD: after 30 min extraction time, the obtained yields (i.e. 0.002%) were comparable to those provided by HD after 3 h extraction. MAD seems to be more convenient since the volatile fraction is richer in oxygenated monoterpenes, species that are recognised for their olfactory value and their contribution to the fragrance of the essential oil. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of thermoperiod on recovery of seed germination of halophytes from saline conditions

Recovery of seed germination from NaCl salinity of desert shrubs (Haloxylon recurvum and Suaeda fruticosa, and the herbs Zygophyllum simplex and Triglochin maritima was studied under various thermoperiods. The percentage of ungerminated seeds that recovered when they were transferred to distilled water varied significantly with variation in species and thermoperiods. Zygophyllum simplex had little recovery from all NaCl concentrations in all thermoperiods. Haloxylon recurvum, S. fruticosa, and T. maritima showed substantial recovery. Percentage recovery was highest in S. fruticosa, followed by T. maritima, and H. recurvum. Thermoperiodic effects varied with the species investigated. There was little thermoperodic effect on the percentage recovery of S. fruticosa, except in the higher salinity treatment at higher thermoperiods. Variation in thermoperiod appears to play an important role in recovery of germination of halophytes from salt stress when seeds are transferred to distilled water.     

ZxAKT1 is essential for K+ uptake and K+/Na+ homeostasis in the succulent xerophyte Zygophyllum xanthoxylum

The inward‐rectifying K⁺ channel AKT1 constitutes an important pathway for K⁺ acquisition in plant roots. In glycophytes, excessive accumulation of Na⁺ is accompanied by K⁺ deficiency under salt stress. However, in the succulent xerophyte Zygophyllum xanthoxylum, which exhibits excellent adaptability to adverse environments, K⁺ concentration remains at a relatively constant level despite increased levels of Na⁺ under salinity and drought conditions. In this study, the contribution of ZxAKT1 to maintaining K⁺ and Na⁺ homeostasis in Z. xanthoxylum was investigated. Expression of ZxAKT1 rescued the K⁺‐uptake‐defective phenotype of yeast strain CY162, suppressed the salt‐sensitive phenotype of yeast strain G19, and complemented the low‐K⁺‐sensitive phenotype of Arabidopsis akt1 mutant, indicating that ZxAKT1 functions as an inward‐rectifying K⁺ channel. ZxAKT1 was predominantly expressed in roots, and was induced under high concentrations of either KCl or NaCl. By using RNA interference technique, we found that ZxAKT1‐silenced plants exhibited stunted growth compared to wild‐type Z. xanthoxylum. Further experiments showed that ZxAKT1‐silenced plants exhibited a significant decline in net uptake of K⁺ and Na⁺, resulting in decreased concentrations of K⁺ and Na⁺, as compared to wild‐type Z. xanthoxylum grown under 50 mm NaCl. Compared with wild‐type, the expression levels of genes encoding several transporters/channels related to K⁺/Na⁺ homeostasis, including ZxSKOR, ZxNHX, ZxSOS1 and ZxHKT1;1, were reduced in various tissues of a ZxAKT1‐silenced line. These findings suggest that ZxAKT1 not only plays a crucial role in K⁺ uptake but also functions in modulating Na⁺ uptake and transport systems in Z. xanthoxylum, thereby affecting its normal growth.     

准噶尔荒漠大翅霸王的生殖物候及结实格局

大翅霸王是多年生早春开花草本植物,是准噶尔荒漠地区的建群种之一。对野生大翅霸王的生殖物候、果实形态、结实格局和种子萌发特性进行了研究。结果表明:(1)大翅霸王的营养期生长期为20—30d,占整个生活周期的1/4,生殖生长期长约90—100d,其中花期约占1/2,果熟期短;(2)大翅霸王种群能产生3种形态的果实,可将植株分为5翅型、4/5翅型和3/4/5翅型植株,它们分别占种群植株数的3.45%、83.15%和13.40%。(3)依据个体大小的变化,3种类型果实在植株上的比例发生了显著变化。随植株个体的增大,三翅果所占比例逐渐增多,由0增加到2.65%;四翅果所占比例也增多,但在二级个体上有最大比例17.01%;五翅果实所占比例最高(80%)且没有显著变化。(4)三翅果、四翅果和五翅果内种子形态无差异,萌发率均小于30%;划破种皮能不同程度的加速和促进种子的萌发。大翅霸王特有的生殖物候和果实的表型多样性是其对荒漠干旱地区恶劣多变环境长期适应的结果。     

模拟长期大风胁迫对霸王叶解剖结构特征的影响

以乌鲁木齐市达坂城长期大风区的优势种灌木霸王为研究对象,采用盆栽实验的方法,设置小风3m/s、中风7m/s、大风12m/s以及对照(自然风速),选择持续吹风90d的霸王叶采用石蜡切片法对其叶解剖结构特征进行比较观察。研究表明:与对照组(平均风速0.3m/s)相比,在12m/s风速下,霸王叶厚度增加了48%;在模拟大风、中风、小风(12、7和3m/s)下,叶表皮厚度分别较对照增加了213%、117%和45%,栅栏组织排列紧密,其厚度分别增加了110%、70%和47%;在大风和中风(12和7m/s)风速下,叶脉厚度分别增加了109%和76%。研究认为,模拟长期大风胁迫下,霸王叶通过增加叶片厚度即叶表皮层、栅栏组织及叶脉厚度来减少风对它的机械损害和水分散失。     

Isolation of four new pterocarpans from Zygophyllum eurypterum (Syn. Z. atriplicoides) with enzyme-inhibition properties

Four new pterocarpans, atricarpan A (=(-)-1,2-dihydroxy-4-(hydroxymethyl)-3,9-dimethoxypterocarpan; 1), atricarpan B (=(-)-2,3-ethylenedioxy)-1,4-dihydroxy-9-methoxypterocarpan; 2), atricarpan C (=(-)-1,9-dimethoxypterocarpan-3-carboxylic acid; 3), and atricarpan D (=(-)-2,9-dimethoxy-4-(5-oxohexyl)pterocarpan; 4) were isolated from the BuOH extract of the whole plant of Zygophyllum eurypterum. The structure elucidations of those compounds were based primarily on 1D- and 2D-NMR analysis, including COSY, HMBC, and HMQC correlations. Compounds 1-4 also inhibited butyrylcholinesterase (BChE; EC 3.1.1.8) enzyme in a concentration-dependent manner with IC(50) values between 12.5-65.0 microM. Similarly, compounds 1 and 4 inhibited lipoxygenase (LOX; EC 1.13.11.12) and acetylcholinesterase (AChE; EC 3.1.1.7) enzymes with IC50 values of 13.5 and 20.5 muM, respectively.     

盐处理下ZxSOS1调控旱生植物霸王Na~＋、K~＋转运蛋白基因的表达

本研究以多浆旱生植物霸王（Zygophyllum xanthoxylum）野生型（WT）及质膜Na＋/H＋逆向转运蛋白基因ZxSOS1-RNAi（RNA干扰）株系（L9）为材料,采用实时荧光定量PCR的方法分析了ZxSOS1被干扰后,霸王各组织中参与Na＋、K＋转运的重要通道或转运蛋白编码基因表达丰度的变化。结果显示,50 mmol·L-1 NaCl处理下,随处理时间延长,WT和L9根和茎中ZxSOS1和ZxSKOR、叶中ZxSOS1、ZxNHX和ZxVP1的表达丰度逐渐增加;ZxHKT1;1和ZxAKT1在WT根中的表达丰度呈增加趋势,而在L9根中则呈降低趋势;盐处理48 h后,L9株系中上述各基因的表达丰度均显著低于WT。由此从基因表达水平解析了ZxSOS1-RNAi株系叶和茎中Na＋的分配比例显著下降、根中显著增加,而K＋在其叶和根中的分配比例下降、茎中显著增加的调控机制。可见,ZxSOS1可通过调节各组织中参与Na＋、K＋转运的重要通道或转运蛋白编码基因的表达以调控霸王体内Na＋、K＋转运、空间分配和稳态平衡,进而调节植株的生长。