三种泌盐红树植物对盐胁迫的耐受性比较

在盐度 0、5、15、2 5和 35 (% )下种植泌盐红树植物老鼠 (Acanthus ilicifolius)、桐花树 (Aegiceras corniculatum)和白骨壤(Avicennia marina)的繁殖体 ,以繁殖体萌发、幼苗生长、叶片泌盐量、叶片组织液盐含量和蒸腾蒸发量为指标 ,比较其对盐胁迫的耐受性。盐度提高对胎生种类桐花树和白骨壤的萌根速率无显著影响 ,但高盐度明显抑制非胎生种类老鼠的萌根。白骨壤的萌苗率不受盐度影响 ,但 2 5以上的盐度导致桐花树和老鼠的萌苗率下降。在盐度范围 5～ 35内 ,白骨壤幼苗的茎高生长随盐度的增加而减少 ,但减少量比桐花树小 ,而老鼠的减少量最大。老鼠因盐度提高而导致的叶片长度的减少量最大。在盐度提高的情况下 3种植物均具有泌盐量增加的效应 ,在任一盐度下泌盐能力的顺序均为白骨壤 >桐花树 >老鼠。淡水培养时 ,3种红树植物的叶片组织液盐含量 (约 2 % )均高于环境盐度 0。在盐度范围 5～ 35内 ,白骨壤的叶片组织液盐含量维持在较稳定的水平 (4 .3%～ 5 .0 % ) ,桐花树的变化范围为 2 .4 %～ 4 .5 % ,老鼠 2 .3%～ 5 .3%。淡水培养时 ,3种植物的蒸腾蒸发量类似 ,但盐性条件下白骨壤的蒸腾蒸发量显著高于桐花树和老鼠。随着盐度的增加 ,老鼠的蒸腾蒸发量下降最多。这些结果均表     

桐花树内生和根际细菌多样性及抗血栓活性研究

红树植物内生菌在红树共生体的物质循环、能量传递和健康维护等方面起着重要作用。为探究红树植物内生菌的多样性,进一步揭示内生菌在红树共生体的功能多样性提供菌种资源,该研究选择6种分离培养基和采用传统稀释涂布法对从广西北海滩涂上采集的桐花树组织和根际土壤样品进行分离,对获得的可培养细菌进行多样性分析,并通过体外溶栓实验筛选出具有抗血栓活性的菌株。结果表明:(1)基于16S rRNA基因序列系统进化分析,从桐花树组织和根际土壤中共获得125株细菌;分布于变形菌门(Proteobacteria)、放线菌门(Actinobacteria)和厚壁菌门(Firmicutes) 3个门27个科39个属74个种中,芽孢杆菌属为优势菌属,菌株数量占13.5%。(2)抗血栓活性实验表明,初筛获得18株具有抗血栓活性细菌,总阳性率为24.32%;将初筛有活性的菌株进行复筛和重复验证实验,进一步验证其活性,结果复筛出3株细菌B1850、B1989和B2632具有很强抗血栓活性。综上所述,广西北海滩涂上红树植物桐花树中存在丰富的可培养细菌资源,具有从中挖掘新的纤溶酶和开发溶血栓药物的潜力。     

Response of Aegiceras corniculatum to synthetic sewage under simulated tidal conditions

Young plants of Aegiceras corniculatum, a dominant mangrove species, were collected from Futian Mangrove Swamp in Shenzhen, The People's Republic of China, and grown in simulated tide tanks containing mangrove sediments. After acclimatisation in the greenhouse for 6 months, the plants were irrigated with either synthetic sewage of various strengths (NW,FW and TW) or artificial seawater (as control). NW had the characteristics and strength equivalent to municipal wastewater, while FW and TW contained 5 and10 times the nutrient and heavy metal concentrations of the NW, respectively. Results showed that the young plants of A. corniculatum were able to tolerate the wastewater (TW) with highest concentration of nutrients and heavy metals after one year treatment. The growth of TW treated plants,measured in terms of stem height, basal diameter and biomass, was comparable to that found in the control. The plants treated with NW and FW had significantly greater growth than the control, indicating that the nutrients contained in sewage are beneficial to mangrove plants. Physiological parameters such as chlorophyll content, the ratio of chlorophyll a and b, proline concentration and root activity did not show any significant changes among plants treated with wastewater of various strengths and the control, suggesting that sewage addition did not cause any apparent physiological impact on growth of A. corniculatum. Nevertheless, the plants which received sewage with highest levels of heavy metals (TW treatment) appeared to have lower content of free water but higher amount of bound water than FW, NW and the control. Higher electric conductance was also found in plants treated with TW. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reproductive biology and genetic diversity of a cryptoviviparous mangrove aegiceras corniculatum (Myrsinaceae) using allozyme and intersimple sequence repeat (ISSR) analysis

Mangroves consist of a group of taxonomically diverse species representing about 20 families of angiosperms. However, little is known about their reproductive biology, genetic structure, and the ecological and genetic factors affecting this structure. Comparative studies of various mangrove species are needed to fill such gaps in our knowledge. The pollination biology, outcrossing rate, and genetic diversity of Aegiceras corniculatum were investigated in this study. Pollination experiments suggested that the species is predominantly pollinator-dependent in fruit setting. A quantitative analysis of the mating system was performed using progeny arrays assayed for intersimple sequence repeat (ISSR) markers. The multilocus outcrossing rate (tm) was estimated to be 0.653 in a wild population. Both allozyme and ISSR were used to investigate genetic variation within and among populations. The combined effects of founder events and enhanced local gene flow through seedling dispersal by ocean currents apparently played an important role in shaping the population genetic structure in this mangrove species. Both allozyme variation (P = 4.76%, A = 1.05, HE = 0.024) and ISSR diversity (P = 16.18%, A = 1.061, HE = 0.039) were very low at the species level, in comparison with other woody plants with mixed-mating or outcrossing systems. Gene differentiation among populations was also low: allozyme GST = 0.106 and ISSR GST = 0.178. The unusually high genetic identities (0.997 for allozyme and 0.992 for ISSR loci), however, suggest that these populations are probably all descended from a common ancestral population with low polymorphism.     

Characterization of seven genomic and one dbEST-derived microsatellite loci in the river mangrove<Emphasis Type="Italic"> Aegiceras corniculatum</Emphasis> (Myrsinaceae)

We developed seven microsatellite markers from the genome of Aegiceras corniculatum using the FIASCO protocol and one dbEST-derived microsatellite marker. Polymorphism of each locus was assessed in 45 individuals from China, Thailand and Australia. The average allele number of these microsatellites was 4.4 per locus, ranging from 2 to 8. The observed (H _O ) and expected (H _E ) heterozygosity were from 0.178 to 1.000 and from 0.164 to 0.828, respectively. These microsatellite markers would provide a useful tool for genetic and conservation studies of A. corniculatum.     

The suitability of non-target native mangroves for the survival and development of the lantana bug <Emphasis Type="Italic">Aconophora compressa</Emphasis>, an introduced weed biological control agent

Aconophora compressa (Hemiptera: Membracidae), a biological control agent introduced against the weed Lantana camara (Verbenaceae) in Australia, has since been observed on several non-target plant species, including native mangrove Avicennia marina (Acanthaceae). In this study we evaluated the suitability of two native mangroves, A. marina and Aegiceras corniculatum (Myrsinaceae), for the survival and development of A. compressa through no-choice field cage studies. The longevity of females was significantly higher on L. camara (57.7 ± 3.8 days) than on A. marina (43.3 ± 3.3 days) and A. corniculatum (45.7 ± 3.8 days). The proportion of females laying eggs was highest on L. camara (72%) followed by A. marina (36%) and A. corniculatum (17%). More egg batches per female were laid on L. camara than on A. marina and A. corniculatum. Though more nymphs per shoot emerged on L. camara (29.9 ± 2.8) than on A. marina (13 ± 4.8) and A. corniculatum (10 ± 5.3), the number of nymphs that developed through to adults was not significantly different. The duration of nymphal development was longer on A. marina (67 ± 5.8 days) than on L. camara (48 ± 4 days) and A. corniculatum (43 ± 4.6 days). The results, which are in contrast to those from previous glasshouse and quarantine trials, provide evidence that A. compressa adults can survive, lay eggs and complete nymphal development on the two non-target native mangroves in the field under no-choice condition.     

Development of microsatellite markers in a mangrove tree species Aegiceras corniculatum (Myrsinaceae)

Aegiceras corniculatum is an ecologically important mangrove tree species. We isolated 18 polymorphic microsatellite loci from this species. These loci provided microsatellite markers with polymorphism of two to eight alleles per locus. The observed and expected heterozygosities ranged from 0.050 to 0.550, and from 0.097 to 0.736, respectively. These markers will contribute to research on the conservation, genetic diversity and mating patterns of A. corniculatum.     

人工湿地污水处理系统3种红树植物生理生态特性

研究了淡水条件下潜流型人工湿地污水处理系统中红树植物海桑、桐花树和木榄的生理生态特性。一年后,海桑、桐花树和木榄株高增长量分别为134、32cm和21cm,基径增长量分别为18.2、14.3mm和12.9mm,生物量增长量分别为747、113g/株和55g/株,表明海桑生长最快,桐花树次之,木榄最慢。从2004年1月至12月,海桑、桐花树和木榄各项生理指标的平均值分别为:叶片总叶绿素含量1.91、1.26、0.91mg/gFW,叶绿素a含量1.44、0.93、0.64mg/gFW,叶绿素b含量0.5、0.34、0.17mg/gFW,净光合速率9.67、6.39、3.57μmolCO2/(m2·s),蒸腾速率54、38、24mmolH2O/(m2·s),气孔导度285、222、110mmolH2O/(m2·s),电解质渗出率10.2、12.9、13.5%和SOD活性447、396、386U/gFW。结果表明光合作用和水分代谢海桑>桐花树>木榄,植物受伤害程度海桑<桐花树≈木榄。另外,3种红树植物全年的生理生态特征的变化规律基本相似,4～10月份生长较快,大部分生理指标维持高水平,1～3月份和11～12月份由于温度较低,生长比较慢,大部分生理指标处于较低水平。综合比较一年来人工湿地中3种红树植物的各项生理生态特征,结果显示海桑好于桐花树,桐花树好于木榄。     

茅尾海桐花树根际放线菌的分离鉴定和抗菌活性研究

利用滤纸片扩散法,以大肠杆菌、蜡状芽胞杆菌和绿脓杆菌等为指示菌,对茅尾海桐花树根际土壤中分离的30株放线菌进行抑菌活性分析,发现其中有22株发酵液具有抗菌活性.经复筛有4株放线菌具有较强且广谱的抗菌活性,对大肠杆菌、蜡状芽胞杆菌和绿脓杆菌显示了较强的抑制活性,特别抑制临床多耐药菌肺炎克雷伯氏菌和鲍曼不动杆菌.通过形态特征、16S rRNA基因序列和生理生化分析,这4株放线菌属于链霉菌,其中S3、S4、S14分别与Streptomyces coelicolor (KF742497)、Streptomyces lateritius (AY999855)及Streptom yces variabilis (FJ486480)具有98.8％、98.6％、98.7％的相似性,S4在进化上与Streptomyces intermedius、Streptomyces silaceus和Streptomyces flavorectus在同一个分支,而S3和S14与其他菌株的进化关系较远,在生理生化及形态特征与相关的模式菌株有较明显差异,有可能是新的种.     

Genome-Guided Investigation Provides New Insights into Secondary Metabolites of Streptomyces Parvulus SX6 from Aegiceras Corniculatum

Whole-genome sequencing and genome mining are recently considered an efficient approach to shine more light on the underlying secondary metabolites of Streptomyces. The present study unearths the biosynthetic potential of endophytic SX6 as a promising source of biologically active substances and plant-derived compounds for the first time. Out of 38 isolates associated with Aegiceras corniculatum (L.) Blanco, Streptomyces parvulus SX6 was highly active against Pseudomonas aeruginosa ATCC® 9027™ and methicillin-resistant Staphylococcus epidermidis (MRSE) ATCC® 35984™. Additionally, S. parvulus SX6 culture extract showed strong cytotoxicity against Hep3B, MCF-7, and A549 cell lines at a concentration of 30 μg/ml, but not in non-cancerous HEK-293 cells. The genome contained 7.69 Mb in size with an average G + C content of 72.8% and consisted of 6,779 protein-coding genes. AntiSMASH analysis resulted in the identification of 29 biosynthetic gene clusters (BGCs) for secondary metabolites. Among them, 4 BGCs showed low similarity (28–67% of genes show similarity) to actinomycin, streptovaricin, and polyoxypeptin gene clusters, possibly attributed to antibacterial and anticancer activities observed. In addition, the complete biosynthetic pathways of plant-derived compounds, including daidzein and genistein were identified using genome mining and HPLC-DAD-MS analysis. These findings portray an exciting avenue for future characterization of promising secondary metabolites from mangrove endophytic S. parvulus.