高通量测序解析多环芳烃污染盐碱土壤翅碱蓬根际微生物群落多样性

【目的】以多环芳烃(PAHs)污染盐碱土壤为对象,分析比较翅碱蓬根际与非根际土壤细菌群落多样性,为植物-微生物联合修复PAHs污染盐碱土壤提供依据。【方法】在胜利油田油井附近采集翅碱蓬根际土壤和无翅碱蓬生长区域的裸地表层土壤,基于高通量测序技术分析样品中微生物群落结构,并进一步运用Real-time PCR解析土壤中PAHs双加氧酶基因丰度。【结果】翅碱蓬根际土壤盐含量为22.51 g/kg,明显低于裸地土壤的40.03 g/kg,土壤pH值差别不大,分别为8.20和8.22;根际土壤有机质和总氮含量分别为24.41 g/kg和1.59 g/kg,C/N值为15,裸地土壤有机质和总氮含量分别为18.80 g/kg和0.71 g/kg,C/N值为26;高通量测序得到根际和裸地土壤样品优质序列分别为53 854条和30 312条,在97%相似水平下,根际土壤样品所得OTU数、Chao 1指数和ACE指数分别为5 934、11 461和15 555,分别高于裸地土壤对应指数的值(4 262、8 262、11 186),序列分析结果显示,根际土壤包含细菌32门758属,多于裸地土样28门676属,翅碱蓬根际土壤群落结构多样性均高于裸地土壤;PAHs污染盐碱土壤中存在丰富的微生物资源,有Thioalkalispira、Halothiobacillus、Thiohalophilus等多种嗜盐碱或耐盐碱微生物,并在根际土壤中检测到了PAHs双加氧酶基因(PAH-RHDα)。【结论】Thioalkalispira、Halothiobacillus、Thiohalophilus等嗜盐碱或耐盐碱微生物是胜利油田PAHs污染盐碱土壤中的优势菌属;翅碱蓬能有效降低根际土壤盐含量并改善C/N值,增加微生物群落结构多样性,提高PAHs关键功能基因的丰度,有助于促进嗜盐碱PAHs降解微生物在PAHs污染盐碱土壤的生物修复中发挥作用。     

Structural and Functional State of Thylakoids in a Halophyte Suaeda altissima before and after Disturbance of Salt–Water Balance by Extremely High Concentrations of NaCl

Halophyte plants Suaeda altissima L. were grown in water culture at different concentrations of NaCl in the medium, and their leaves were sampled to examine the ultrastructure of chloroplasts. In parallel tests, the functional state of chloroplasts was assessed from parameters of chlorophyll fluorescence. In addition the effects of NaCl on plant growth and on the contents of Na⁺, K⁺, and water in organs of S. altissima were investigated. At a wide range of external salt concentrations (0–750 mM NaCl), S. altissima plants retained the chloroplast ultrastructure and photosynthetic function in an intact condition. The impairment of thylakoid ultrastructure and the accompanying increase in nonphotochemical quenching of excited states of chlorophyll was only observed at an extremely high concentration of NaCl in the medium (1 M) that led to disruption of ionic homeostasis and lowered water content in tissues.     

Highly efficient Agrobacterium-based transformation system for callus cells of the C3 halophyte Suaeda salsa

Genetic manipulation technologies have been limited in the halophyte Suaeda salsa L. due to the lack of an efficient transformation system. Here, we examined factors affecting transformation and developed an efficient transformation system at the cell level using S. salsa hypocotyl as starting material. S. salsa hypocotyl explants from 10-day-old seedlings were precultured for 2 days on a hygromycin (hyg)-free callus induction medium (CIM) and then inoculated with Agrobacterium tumefaciens suspension at a concentration of 0.5 at OD₆₀₀ for 5–10 min. After cocultivation with A. tumefaciens for 4 days in the dark, followed by selection on carbenicillin (carb) for 3 days, explants were placed on CIM containing 10 mg l⁻¹ hyg and 500 mg l⁻¹ carb with three to four consecutive subcultures for up to 45 days. β-Glucuronidase assays showed an average transformation frequency of 62.89%. Gene integration was confirmed by polymerase chain reaction analysis and Northern blot analysis. To our knowledge, this is the first study to show Agrobacterium-mediated transformation in the C₃ halophyte S. salsa.     

Switching from negative to positive density-dependence among populations of a cobble beach plant

Understanding the co-occurrence of ecologically similar species remains a puzzling issue in community ecology. The species-rich mouse lemurs (Microcebus spec.) are distributed over nearly all remaining forest areas of Madagascar with a high variability in species distribution patterns. Locally, many congeneric species pairs seem to co-occur, but only little detailed information on spatial patterns is available. Here, we present the results of an intensive capture-mark-recapture study of sympatric Microcebus berthae and M. murinus populations that revealed small-scale mutual spatial exclusion. Nearest neighbour analysis indicated a spatial aggregation in Microcebus murinus but not in M. berthae. Although the diet of both species differed in proportions of food categories, they used the same food sources and had high feeding niche overlap. Also, forest structure related to the spatial distribution of main food sources did not explain spatial segregation because parts used by each species exclusively did not differ in density of trees, dead wood and lianas. We propose that life history trade-offs that result in species aggregation and a relative increase in the strength of intra-specific over inter-specific competition best explain the observed pattern of co-occurrence of ecologically similar congeneric Microcebus species.     

Some studies on field distribution and seed germination ofSuaeda fruticosa andSporobolus arabicus with reference to salinity and sodicity of the medium

Summary Vegetation of two wasteland sites near Dera Chahl, 30 km from Lahore, was studied quantitatively. Soil samples obtained from the two sites were analysed.Suaeda fruticosa (L.) Forssk. was a dominant species on saline and sodic soil whereas soil underSporobolus arabicus Boiss. was saline and non-sodic. Seed germination studies show thatSporobolus arabicus is relatively more affected by Nasalinity than by Ca-salinity. This species tolerates salinity to some extent but is sensitive to sodicity.Suaeda fruticosa is relatively more tolerant to salinity and sodicity thanSporobolus arabicus and is capable of growing on saline and sodic soils.     

两种外生菌根真菌在辽东栎幼苗上的混合接种效应

 辽东栎（Quercus liaotungensis）是中国暖温带落叶阔叶林的主要优势树种之一。铆钉菇（Gomphidius viscidus）和臭红菇（Russula foetens）是在自然环境中与其共生形成外生菌根的真菌。在前期工作证明铆钉菇和臭红菇接种对辽东栎幼苗生长有明显促进作用并以两菌种混合接种效果较好的基础上,探讨了不同的接种量和两个菌种不同比例的混合接种对辽东栎幼苗生长和氮、磷养分的影响。对应于试验的12、18、24 g·pot-1 3个接种量处理,随着接种量的增加,辽东栎幼苗的菌根侵染率增加,铆钉菇菌根的比例增加,而臭红菇菌根的比例减少。辽东栎幼苗的生物量、株高、净光合速率和全株的全氮、全磷含量,均以18 g·pot-1接种量的最高。当接种物中铆钉菇∶臭红菇的比例分别为2∶1、1∶1、1∶2时,辽东栎幼苗的菌根侵染率分别为96.54%、91.02%、92.13%,但彼此间差异不显著。随着接种物中铆钉菇比例的减少,铆钉菇菌根所占比例由42.49%降为23.33%,而臭红菇菌根的比例由57.51%增加为76.67%。辽东栎幼苗的生物量和净光合速率均是以接种比例为1∶1的最高。接种比例为1∶1的辽东栎幼苗的全氮含量也是最高的,并且与另两种接种比例处理的差异显著,而对于全株的全磷含量,则是随着接种物中臭红菇的比例增加而增加。     

辽宁盘锦三角洲翅碱蓬根系及内生细菌群落多样性

【目的】翅碱蓬(Suaeda heteroptera)是一种典型的盐碱指示物,对重金属和石油污染的盐碱土壤有一定的修复作用,但是关于翅碱蓬根系与根系内生微生物之间的关系、微生物的多样性以及根系微生物在生物修复中所起作用的研究较少。本文以盘锦"红海滩"的翅碱蓬为例,研究翅碱蓬根系及根系内生细菌菌群种类和结构。【方法】通过传统的培养方法和非培养的高通量测序方法对翅碱蓬根系土壤样品、根系附着物样品以及根系匀浆样品中微生物群落多样性进行分析。【结果】传统方法共分离得到67株细菌,选择代表菌28株,根据其形态特征和生理生化特征,结合16S r RNA基因序列比对进行鉴定,它们分别属于盐单胞菌属(Halomonas)、海细菌属(Marinobacterium)、芽孢杆菌属(Bacillus)、副球菌属(Paracoccus)、假单胞菌属(Pseudomonas)、游动球菌属(Planococlus)、沙雷氏菌属(Serratia)、刘志恒菌属(Zhihengliuella)等。利用高通量测序技术对样品进行多样性分析,其中根系附着物样品的菌群丰度和多样性最高,依次分别为根系土壤样品和根系匀浆样品。3个样品中有效序列群落结构可分为12个门,包括酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)、绿菌门(Chlorobi)、绿弯菌门(Chloroflexi)、蓝菌门(Cyanobacteria)、厚壁菌门(Firmicutes)、芽单胞菌门(Gemmatimonadetes)、浮霉菌门(Planctomycetes)、变形菌门(Proteobacteria)、螺旋体门(Spirochaetes)和疣微菌门(Verrucomicrobia)。根系匀浆样品中蓝菌门为优势门类,占整个菌群的42%,变形菌门为次优势类群,占33%。变形菌门在根系附着物样品中为优势门类,占46%,拟杆菌门为次优势门类,占16%。根系土壤样品中拟杆菌门为优势门类,占整个菌群的37%,次优势类群为变形菌门,占20%。【结论】翅碱蓬根系和内生菌具有丰富的多样性,其根系微生物可能会在重金属和石油污染土壤的生物修复中起一定的修复作用。     

盐地碱蓬延伸因子(SsEF-1α)的克隆与表达分析

从盐胁迫下的盐地碱蓬(Suaeda salsa)的cDNA文库中获得了一个延伸因子(SsEF-1α)的cDNA片段。以此片段为探针,对其在不同胁迫处理下的盐地碱蓬中表达利用Northern杂交进行分析,结果表明,不同盐浓度处理、同一盐浓度不同时间处理下及双氧水刺激条件下延伸因子在碱蓬叶中的表达量先呈现减少然后增加的趋势;聚乙二醇(PEG)及低温诱导下均呈现上升趋势。由此可见该基因在盐、氧化、高渗和低温胁迫条件下产生一定的反应。     

不同生境中辽东栎的构型差异

辽东栎具有很强的萌生能力,在东灵山区,存在于多种林分中,对生活在落叶阔叶混交林和次生落叶阔叶灌丛中辽东栎植株的构型进行了比较统计分析,结果表明不同生境中的辽东栎构型具有较大差异。具体表现在：（１）混交林中的辽东栎个体多生活在林隙中,同灌丛中的个体相比,树冠窄小,枝倾角较大,第一枝级枝条（上层）较长,但分枝率较小,叶面积指数较低;（２）枝,叶的方位角,叶倾角（上层）在不同生境中发生显著变化。因此,叶     

不同盐处理对盐地碱蓬幼苗肉质化的影响

用不同的钠盐和含Cl-的盐处理盐地碱蓬(Suaeda salsa)幼苗后,测定不同器官的肉质化及相关生理指标,结果表明:NaF处理明显抑制盐地碱蓬幼苗的生长;NaCl处理下生长最好,其中叶片的肉质化程度显著高于对照,正在伸展茎次之,而根则不明显;其次是NaHCO3,肉质化程度也明显高于对照;CaCl2和KCl处理下肉质化程度都与对照相似;MgCl2处理下叶片的肉质化程度明显低于对照.这些结果表明,NaCl处理明显促进盐地碱蓬肉质化是Na 和Cl-两种离子作用的结果,而Na 起主导作用;在这个过程中,HCO3-有一定的作用,Mg2 抑制肉质化.