Morphological Identification of the Main Fungi Associated with Sesame in Burkina Faso

Several fungal species are responsible for diseases that damage sesame crop and cause production losses. These seed-borne fungi cause serious damage by reducing seed germination. To identify the fungi associated with sesame seeds in Burkina Faso, 72 sesame seed samples were collected from 24 localities in the main production areas (Sudanian zone, Sudano-Sahelian zone, Sahelian zone). These samples were submitted for seed health analysis using the blotting paper incubation method. The results obtained revealed that the seed samples were contaminated by various fungi, the main ones being: Fusarium spp. Link: Fr. infecting 97.22% of the samples, Macrophomina phaseolina (Tassi) Goid. (90.28%), Alternaria sesamicola E. Kawamura (83.33%), Curvularia lunata (Wakker) Boedijn (76.39%), Cercospora sesami A. Zimmerm. (73.61%), Phoma sorghina Boerema, Dorenbosch, & Van Kesteren (73.61%), Aspergillus flavus Link: Fr. (69.44%), Cladosporium sphaerospermum Penz. (56.94%), Rhizopus sp. Ehrenb. (40.28%) and A. niger Tiegh. (36.11%). In each seed sample, 0.25% to 94% of the seeds host one or more fungal species. Regarding the climatic zones, the results revealed that A. sesamicola and A. flavus were more represented in the Sudanian zone than in the Sudano-Sahelian and Sahelian zones;while P. sorghina, and C. sphaerospermum were more encountered in the Sahelian zone than in the other two zones. This study showed that the majority of sesame seeds produced and used by farmers in Burkina Faso host one or more species of fungi at high levels.

Isolation and molecular characterization of bioactive secondary metabolites from Callyspongia spp.associated fungi

Objective:To isolate and characterize the bioactive secondary metabolite from Callyspongia spp.associated fungi.Methods:In vitro antibacterial screening of fungi associated with Callyspongia species,collected from south east coast of India,against selected clinical isolates of bacteria were conducted in this study.The extracts showing good antimicrobial activity were subjected to further analysis to identify the active constituents sponge associated fungi(both biomass and filtrate) with five different solvents.The compound responsible for bioactivity was characterized using Fouvier-transform infrared(FT-IR) and gas chromatography-mass spectrometry(GC-MS) instrumental analysis to identify the functional group and compound.The molecular characterization of the elite fungal strains were done by isolating their genomic DNA and amplify the internal transcribed spacer(ITS) region of 5.8srRNA using specific ITS primer. The novelty of the strain was proved by BlastN analysis against non-redundant(NR) database and hence was submitted to GenBank.Results:Active compound was Desmethylnomifensine confirmed by GC-MS and the potent fungi was Aspergillus flavus GU815344.Conclusions: The isolate exhibits a marked antagonistic activity against potential bacterial pathogens thus illuminating the advanced researches in this decade to focus on clinical pharmacology to identify novel therapeutic targets.The present study depicts a promising scenario to focus on Aspergillus flavus derived compounds which can be easily scaled up for large biomass production and stable formulation as a drug.

General and specialized metabolites in peanut roots regulate arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizae(AM)fungi form symbiotic associations with plant roots,providing nutritional benefits and promoting plant growth and defenses against various stresses.Metabolic changes in the roots during AM fungal colonization are key to understanding the development and maintenance of these symbioses.Here,we investigated metabolic changes in the roots of peanut(Arachis hypogaea L.)plants during the colonization and development of AM symbiosis,and compared them to uncolonized roots.The primary changes during the initial stage of AM colonization were in the contents and compositions of phenylpropanoid and flavonoid compounds.These compounds function in signaling pathways that regulate recognition,interactions,and pre-colonization between roots and AM fungi.Flavonoid compounds decreased by 25%when the symbiosis was fully established compared to the initial colonization stage.After AM symbiosis was established,general metabolism strongly shifted toward the formation of lipids,amino acids,carboxylic acids,and carbohydrates.Lipid compounds increased by 8.5%from the pre-symbiotic stage to well-established symbiosis.Lyso-phosphatidylcholines,which are signaling compounds,were only present in AM roots,and decreased in content after the symbiosis was established.In the initial stage of AM establishment,the content of salicylic acid increased two-fold,whereas jasmonic acid and abscisic acid decreased compared to uncolonized roots.The jasmonic acid content decreased in roots after the symbiosis was well established.AM symbiosis was associated with high levels of calcium,magnesium,and D-(+)-mannose,which stimulated seedling growth.Overall,specific metabolites that favor the establishment of AM symbiosis were common in the roots,primarily during early colonization,whereas general metabolism was strongly altered when AM symbiosis was well-established.In conclusion,specialized metabolites function as signaling compounds to establish AM symbiosis.These compounds are no longer produced after the symbiosis between the roots and AM becomes fully established.

Genome-wide and candidate gene association studies identify BnPAP17 as conferring the utilization of organic phosphorus in oilseed rape

Phosphorus(P)is essential for living plants,and P deficiency is one of the key factors limiting the yield in rapeseed production worldwide.As the most important organ for plants,root morphology traits(RMTs)play a key role in P absorption.To investigate the genetic variability of RMT under low P availability,we dissected the genetic structure of RMTs by genome-wide association studies(GWAS),linkage mapping and candidate gene association studies(CGAS).A total of 52 suggestive loci were associated with RMTs under P stress conditions in 405 oilseed rape accessions.The purple acid phosphatase gene BnPAP17 was found to control the lateral root number(LRN)and root dry weight(RDW)under low P stress.The expression of BnPAP17 was increased in shoot tissue in P-efficient cultivars compared to root tissue and P-inefficient cultivars in response to low P stress.Moreover,the haplotype of BnPAP17^(Hap3)was detected for the selective breeding of P efficiency in oilseed rape.Over-expression of the BnPAP17^(Hap3)could promote the shoot and root growth with enhanced tolerance to low P stress and organic phosphorus(Po)utilization in oilseed rape.Collectively,these findings increase our understanding of the mechanisms underlying BnPAP17-mediated low P stress tolerance in oilseed rape.

Effects of cyclooxygenase 2 inhibitor on growth-associated protein 43 and nerve growth factor expression in dorsal root ganglion during neuropathic pain development

BACKGROUND： Inflammatory responses in injured nerves have been recognized as important factors for initially sensitizing nociceptive neurons. Cyclooxygenase （COX） is the rate-limiting enzyme in prostaglandin synthesis, and COX-2 inhibitor is involved in mechanisms of analgesia and anti-inflammation. OBJECTIVE： To investigate the effects of COX-2 inhibitor on thermal and mechanical hyperalgesia, as well as expression of growth associated protein 43 （GAP-43） and nerve growth factor （NGF） in dorsal root ganglion, in a rat model of neuropathic pain due to chronic constriction injury. DESIGN, TIME AND SETTING： A randomized, controlled, comparison study that was performed at the Surgical Department and Pathological Laboratory, Second Affiliated Hospital of Shantou University Medical College from September 2006 to September 2007. MATERIALS： COX-2 inhibitor, Iornoxicam, was purchased from Nycomed Pharmaceutical （Austria）; rabbit anti-GAP-43, and rabbit anti-NGF polyclonal antibodies were purchased from Boster, Wuhan, China. METHODS： A total of 50 adult, Wistar rats were randomly assigned to four groups： normal control （n = 5）, model （n = 15）, normal saline control （n = 15）, and Iornoxicam treatment （n =15）. With exception of the control group, the sciatic nerve of all rats was loosely ligated to establish a model of chronic constriction injury. The model rats were divided into three subgroups according to varying post-operative survival periods： 3, 7 and 14 days （n = 5）, respectively. Rats in the Iornoxicam treatment group were intraperitoneally injected with 1.3 mg/kg lornoxicam every 12 hours throughout the entire experimental procedure. Rats in the normal saline control group were intraperitoneally injected with 1.3 mL/kg saline. MAIN OUTCOME MEASURES： Immunohistochemistry revealed expression of GAP-43 and NGF in the L5 dorsal root ganglions. Mechanical withdrawal threshold and thermal withdrawal latency were used to observe neurological behavioral changes in rats. RESULTS： The relative gray values of GAP-43- and NGF-positive neurons in the model group were remarkably increased compared with the normal control rats （P 〈 0.01）, while the relative gray values in the Iomoxicam treatment group were significantly less than the model and normal saline control groups （P 〈 0.01）. Mechanical withdrawal threshold and thermal withdrawal latency gradually decreased with increasing injury time in the model, normal saline control, and Iornoxicam treatment groups, and were significantly less than the normal control group （P 〈 0.05）. In addition, mechanical withdrawal threshold and thermal withdrawal latency were significantly greater in the Iornoxicam treatment group compared with the model and normal saline control groups （P 〈 0.05）. CONCLUSION： Intraperitoneal injection of the COX-2 inhibitor Iornoxicam attenuated mechanical and thermal hyperalgesia induced by sciatic nerve chronic constriction injury and inhibited the increased expression of GAP-43 and NGF.

Preemptive analgesic effects of low-dose ketamine on growth-associated protein expression in dorsal root ganglion of chronic constriction injury model rats

BACKGROUND： Ketamine is a noncompetitive N-methyl-D-aspartate （NMDA） receptor antagonists and plays an important role in the treatment of pain. OBJECTIVE： To analyze the preemptive analgesic effects of different doses of ketamine on growth-associated protein-43 （GAP43） expression in dorsal root ganglion in a rat model of chronic sciatic nerve constricted injury, and to study the differences between high-dose and low-dose ketamine DESIGN： Randomized controlled animal study. SETTING： Medical College of Shantou University. MATERIALS： Thirty-five adult male Sprague Dawley rats were provided by the Experimental Animal Center of Guangzhou University of Traditional Chinese Medicine. Ketamine hydrochloride injection was provided by Hengrui Pharmaceutical Co., Ltd., Jiangsu. METHODS： This study was performed at the Immunological Laboratory, Medical College of Shantou University from September to December 2006. Model of chronic sciatic nerve constricted injury： after anesthesia, the right sciatic nerve was exposed and ligated l-cm distal to the ischiadic tuberosity with a No. 3-0 cat gut suture. Grouping and intervention： 35 rats were randomly divided into 4 groups： normal control group （n = 5）, chronic constriction injury （CCI） group （n = 10）, low-dose ketamine group （n = 10）, and high-dose ketamine group （n = 10）. Rats in the normal control group did not undergo any surgery or drug intervention. Rats in the CCI group received intraperitoneal injection of saline （1 mL）, and their sciatic nerves were ligated after 10 minutes. Rats in the low-dose ketamine group underwent intraperitoneal injection of ketamine （25 mg/kg） 10 minutes prior to ligation of sciatic nerve; while, rats in the high-dose ketamine group were given intraperitoneal injection of ketamine （50 mg/kg） 10 minutes prior to ligation of sciatic nerve. On the third and the seventh days after surgery, dorsal root ganglion were resected from the sciatic nerve and cut into sections. MAIN OUTCOME MEASURES： GAP-43 expression in dorsal root ganglion was detected by immunohistochemistry and image analysis system, as well as semi-quantitative analysis. RESULTS： Thirty-five Sprague Dawley rats were included in the final analysis. Qualitative analysis： GAP-43 expression in the CCI group was higher than in the normal control group. Quantitative analysis： after three post-operative days, GAP-43 expression in the CCI group was significantly higher than in the normal control group （t = 22.919, 7.319, P 〈 0.05）. GAP-43 expression in the low-dose and high-dose ketamine group was significantly lower than in the CCI group （t = 11.166, 26.474, P 〈 0.05）. After seven postoperative days, GAP-43 expression in the low-dose and high-dose ketamine groups was significantly lower than in the CCI group （t = 2.382, 5.016, P 〈 0.05）. CONCLUSION： Preoperative administration of ketamine inhibited the increased GAP-43 expression in dorsal root ganglion during neuropathic pain.

Research Progress on the Process and Mechanism of Arbuscular Mycorrhizal Fungi Colonizing Roots

The arbuscular mycorrhiza （AM） is a kind of fungi-plant associated sym- biont formed by the arbuscular mycorrhizal fungi and plants in soil. Present study was limited to the population and community level, mainly in horticulture, land recla- mation, forest and environmental restoration. Research progress was also made at the cellular level and molecular level. Process and related mechanism of mycorrhizal fungi infecting root were reviewed, and future study on the mechanism of arbuscular mycorrhizal fungi infecting root should be continued.

Plant growth and their root development after inoculation of arbuscular mycorrhizal fungi in coal mine subsided areas

Coal mining often cause serious land degradation, soil erosion, and desertification affecting growth of the local vegetation, especially the roots. Arbuscular mycorrhizal fungi （AMF） inoculation is considered a potential biotechnological tool for mined soil remediation because mycorrhizal fungi could improve plant growth environment, especially under adverse conditions due to their good symbiosis. A field experiment was conducted to study the ecological effects of AMF （Funneliformis mosseae, Rhizophagus intraradices） on the growth of Amygdalus pedunculata Pall. and their root development in the regenerated mining subsidence sandy land. The reclamation experiment included four treatments： inoculation of Funneliformis mosseae （F.m）, inoculation of Rhizophagus intraradices （R.i）, combined inoculation of F.m and R.i and non-inoculated treatment. Root mycorrhizal colonization, plant height, crown width, soil moisture, root morphology and certain soil properties were assessed. The results showed that AMF improved the shoot and root growth of Amygdalus pedunculata Pall., and significantly increased root colonization after 1 year of inoculation. Available phosphorus content, activities of phosphatase as well as electrical conductivity in soil rhizosphere of all the three inoculation treatments were higher than that of the non-inoculated treatment. AMF increased the quantity of bacteria and fungi in soil rhizosphere compared with the non-inoculated treatment. Our study indicates that revegetation with AMF inoculum could influence plant growth and root development as well as soil properties, suggesting that AMF inoculation can be effective method for further ecological restoration in coal mine subsided areas.

Evaluation of maize root growth and genome-wide association studies of root traits in response to low nitrogen supply at seedling emergence

Nitrogen(N) deficiency is one of the main factors limiting maize(Zea mays L.) productivity. Genetic improvement of root traits could improve nitrogen use efficiency. An association panel of 461 maize inbred lines was assayed for root growth at seedling emergence under high-nitrate(HN, 5 mmol L^(-1))and low-nitrate(LN, 0.05 mmol L^(-1)) conditions. Twenty-one root traits and three shoot traits were measured. Under LN conditions, the root-to-shoot ratio, root dry weight, total root length, axial root length,and lateral root length on the primary root were all increased. Under LN conditions, the heritability of the plant traits ranged from 0.43 to 0.82, a range much wider than that of 0.27 to 0.55 observed under HN conditions. The panel was genotyped with 542,796 high-density single-nucleotide polymorphism(SNP) markers. Totally 328 significant SNP markers were identified using either mixed linear model(MLM) or general linear model analysis, with 34 detected by both methods. In the 100-kb intervals flanking these SNP markers, four candidate genes were identified. Under LN conditions, the protoporphyrinogen IX oxidase 2 gene was associated with total root surface area and the DELLA protein-encoding gene was associated with the length of the visible lateral root zone of the primary root. Under HN conditions, a histone deacetylase gene was associated with plant height. Under both LN and HN conditions, the gene encoding MA3 domain-containing protein was associated with the first whorl crown root number. The phenotypic and genetic information from this study may be exploited for genetic improvement of root traits aimed at increasing NUE in maize.

Growth traits and nitrogen assimilation-associated physiological parameters of wheat(Triticum aestivum L.) under low and high N conditions

In this study, 14 wheat cultivars with contrasting yield and N use efficiency （NUE） were used to investigate the agronomic and NUE-related traits, and the N assimilation-associated enzyme activities under low and high N conditions. Under deficient-N, the cultivars with high N uptake efficiency （UpE） and high N utilization efficiency （UtE） exhibited higher plant biomass, yields, and N contents than those with medium and low NUEs. The high UpE cultivars accumulated more N than other NUE type cultivars. Under sufficient-N, the tested cultivars showed similar patterns in biomass, yield, and N content to those under deficient-N, but the varietal variations in above traits were smaller. In addition, the high UpE cultivars displayed much more of root biomass and larger of root length, surface area, and volume than other NUE type cultivars, indicating that the root morphological traits under N deprivation are closely associated with the plant biomass through its improvement of the N acquisition. The high UtE cultivars showed higher activities of nitrate reductase （NR）, nitrite reductase （NIR）, and gluta- mine synthetase （GS） at stages of seediling, heading and filling than other NUE type cultivars under both low and high N conditions. Moreover, the high UpE and UtE cultivars also displayed higher photosynthetic rate under deficient-N than the medium and low NUE cultivars. Together, our results indicated that the tested wheat cultivars possess dramatically genetic variations in biomass, yield, and NUE. The root morphological traits and the N assimilation enzymatic acitivities play critical roles in regulating N accumulation and internal N translocation under the N-starvation stress, respectively. They can be used as morphological and biochemical references for evaluation of UpE and UtE in wheat.

Distribution and Association of Arbuscular Mycorrhizal Fungi in Different Cultivars of Wheat from Lalganj Pratapgarh District of Utter Pradesh, India

Arbuscular mycorrhizal fungi are key components of soil micro-flora and obviously interact with other microorganisms in the rhizosphere which is the zone of influence of plant roots on microbial populations and other soil constituents. Keeping in view the importance of AM fungi, the present study was undertaken for assessing the AM fungal spore population dynamics in the rhizosphere soil and its colonization in rhizosphere soils in relation to soil physico-chemical factors. Present study represents an attempt to establish the qualitative and quantitative distribution of AM fungal species in rhizosphere soils of wheat. Thirteen different wheat cultivars collected from four different sites of Lalganj Pratapgarh (U.P.), India were examined for the AM infection. All the wheat cultivars were found to be infected with arbuscular mycorrhizae. However, their population in rhizosphere and root infection varied to a considerable extent from species to species. The maximum spore population and highest percentage of root colonization were found with the rhizosphere soil of cultivars Ankur Kedar.

基于健康社会决定因素的宁夏中老年人慢性病共病的影响因素研究

背景人口老龄化进程日益加快,中老年人健康问题突出。慢性病共病严重威胁中老年人的健康和生活质量,阻碍健康中国行动的进展,探讨其与健康社会决定因素的关系具有积极意义。目的了解宁夏中老年人慢性病共病情况及健康社会决定因素情况,分析中老年人健康社会决定因素与慢性病共病的关联,为中老年慢性病共病患者的健康管理和干预策略制定提供参考。方法采用多阶段分层随机抽样方法于2022-06-27—08-27调查宁夏石嘴山市、银川市、固原市的10个区/县1997名中老年人的健康相关数据,应用Apriori算法分析宁夏地区中老年人的共病模式,采用非条件Logistic回归分析探讨宁夏中老年人慢性病共病与健康社会决定因素的关联性。结果宁夏地区中老年人慢性病共病人数418例,慢性病共病率20.9%;关联规则结果显示有14条共病模式,其中11条与冠心病有关,9条与高血压有关,9条与糖尿病有关;非条件Logistic回归分析结果显示,年龄≥60岁、子女数量为2~3个、已建立健康档案、工作状况为离退休和无业、养老保险为城乡居民基本养老保险的中老年人慢性病共病率较高(P<0.05),夜间睡眠时长为7~8 h和>8 h、大专及以上文化水平的中老年人慢性病共病率较低(P<0.05)。结论中老年慢性病共病的影响因素涉及个体、社区、社会各个方面,建议从多维度对慢性病共病患者进行干预,以期提高其健康水平。

接种AMF对‘阿坝’垂穗披碱草根系耐低温生理的影响

为明确丛枝菌根真菌(AMF)对禾本科牧草耐低温能力的影响,本研究以根内球囊霉(Glomus intraradices,GI)和‘阿坝’垂穗披碱草(Elymus nutans‘Aba’)为试验材料,通过盆栽法,探究了低温条件下[15℃/10℃,16 h/8 h(光照/黑暗)]接种根内球囊霉对‘阿坝’垂穗披碱草根系生理特性的影响。结果表明:1)低温对‘阿坝’垂穗披碱草的菌根侵染率无显著影响(P>0.05)。2)低温增加了‘阿坝’垂穗披碱草根系中过氧化氢(H_(2)O_(2))和丙二醛(MDA)含量,降低了超氧阴离子产生速率(O_(2)^(·-)),而接种GI抑制了由低温引起的H2O2和MDA含量的积累,对O_(2)^(·-)的影响不显著。3)低温增加了超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性,降低了过氧化氢酶(CAT)活性,其中SOD、POD和APX活性均是接种组(LT-AMF)显著低于不接种组(LT)(P<0.05)。4)低温显著增加了可溶性蛋白(SP)含量,降低了甜菜碱(Gb)含量,对游离脯氨酸(Pro)含量无显著影响,接种GI显著降低了SP含量,对Pro和Gb含量无显著影响。综上所述,接种GI能通过增加抗氧化酶活性和降低渗透胁迫强度增强‘阿坝’垂穗披碱草根系对低温的耐受能力。

丛枝菌根真菌对元宝枫生长及其根系形态的影响

【目的】阐明丛枝菌根(arbuscular mycorrhizal,AM)真菌对元宝枫生长状况及根系形态特性的影响,探讨元宝枫根系形态与其生长发育的关系。【方法】在元宝枫幼苗生长基质中接种摩西斗管囊霉(Funneliformis mosseae)和根内根孢囊霉(Rhizophagus intraradices)2种AM真菌,以不接种AM真菌为对照,通过盆栽试验,培养90 d后,测定元宝枫的生长状况、根系活力及根系形态指标,利用单因素方差分析和多重比较方法,分析接菌与不接菌处理之间的差异,采用envfit()函数、冗余度分析和变差分解分析元宝枫生长状况与其他指标间的关系。【结果】①接种2种AM真菌后,元宝枫株高、地径、茎干质量和根系活力较对照显著提高,根冠比下降。根内根孢囊霉对元宝枫的促生作用比摩西斗管囊霉显著。②与对照相比,接种2种AM真菌后,元宝枫根表面积和根体积显著增大,粗根根长占总根长的比例增加,细根根长占总根长的比例显著降低。根内根孢囊霉对元宝枫根系形态的影响比摩西斗管囊霉显著。③元宝枫生长状况与其根系活力和根系形态密切相关。【结论】接种AM真菌有助于增强元宝枫的根系活力,改善其根系形态,促使其汲取更多养分,进而提高其生物量。

草莓连作根腐病原菌及根际真菌群落变化多样性研究

草莓是一种兼具营养和经济价值的水果,草莓连年栽培导致连作障碍发生严重,发病率逐渐增加,严重影响了草莓的产量。从连作3年且患有根腐病的草莓根际土壤中分离出病原菌,经鉴定分别为Fusarium pseudocircinatum、Fusarium solani、Fusarium luffae、Aspergillus westerdijkiae、Cladosporium oxysporum、Ectophoma multirostrata、Neopestalotiopsis rosae和Neocosmospora rubicola。进一步对连作前后草莓根际土壤真菌变化进行分析,结果表明,连作后真菌总数量下降,在属水平上,Pulvinula、Aspergillus、Acremonium、Funneliformis、unclassified_Cercozoa和unclassified_Pezizaceae等真菌的相对丰度均显著或极显著增加,unclassified_Hypocreales、Mortierella和Rhizophlyctis等真菌的相对丰度均显著或极显著降低。对连作后土壤的理化性质进行检测,结果表明,有机质含量极显著降低,全磷、硝态氮含量极显著增加,pH值显著增加。这说明土壤理化性质的改变和优势菌种的更替都是导致草莓连作障碍发生的原因,可为防治草莓根腐病和连作障碍提供科学依据。

Dynamic of Soil Microorganisms from Root Region of Ginseng with Different Growing Years

Objective To see the dynamic of fungi, bacilli and actinomyces communities from root region of ginseng with different growing years.Method With ginseng root region soils from several sampling sites of Jilin Province as materials, concentrations of fungi, bacilli and antinomyces were evaluated by spread-plate method. Result Though there are differences on statistic data among soil samples, commonly with the increasing of growing years, concentration of fungi in ginseng root region increased, which were on the contrary for bacilli and antinomyces, and bacilli changed even more significant than antinomyces. Conclusion Concentrations of soil microorganisms can be influenced by soil type, planting mode and growing years simultaneously, but growing years influenced even more significantly.

樟子松根内真菌分子生态网络复杂性与稳定性

根内真菌通过复杂的相互作用发挥其生态功能影响宿主植物生长发育,但其互作网络复杂性和稳定性特征及其影响因素尚不明确。为揭示樟子松(Pinus sylvestris var.mongolica)天然林和人工林根内真菌网络复杂性与稳定性特征及其对环境因素的响应,以呼伦贝尔沙地樟子松天然林和不同引种地(呼伦贝尔沙地、科尔沁沙地和毛乌素沙地)不同林龄(中龄林、近熟林和成熟林)人工林为研究对象,采用分子生态网络分析法对根内真菌群落网络复杂性和稳定性进行比较分析,为樟子松人工林科学管理提供理论依据。主要结果有:1)樟子松根内真菌网络均以正相关关系为主,而天然林网络负相关关系比例更高;人工林根内真菌网络复杂性高于天然林,且毛乌素沙地网络最为复杂,不同引种地人工林网络复杂性在近熟林达到最大值。2)子囊菌门(Ascomycota)为天然林和人工林主要关键真菌类群;在属水平上,主要为丝盖伞属(Inocybe)、美口菌属(Calostoma)、Cladophialophora等。腐生菌与其他真菌联系密切,病原菌作为关键菌群存在于人工林。3)天然林网络稳定性更强,科尔沁沙地人工林网络稳定性高于其他人工林;不同引种地人工林网络稳定性均在中龄林达到最大值。4)根内真菌网络复杂性主要受年平均温度和年平均降水量以及土壤养分含量影响,而网络稳定性与环境因子无显著相关关系。结论:环境因素和林龄塑造了根内真菌网络复杂性和稳定性的时空动态,天然林根内真菌网络更稳定可能有利于林木生长,人工林通过更复杂的网络满足养分需求;腐生营养型真菌与其他真菌联系密切,病原菌作为关键菌群可能对人工林生长和健康有消极影响。

广西金花茶根系丛枝菌根真菌染色方法探讨

金花茶(Camellia nitidissima)为山茶科山茶属植物,属于国家一级保护植物,具有很高的观赏价值及药用价值。但目前金花茶野生资源少,因此寻找高效的人工种植方法快速繁殖金花茶优良种苗,进而大幅度提高规模化种植金花茶的产量十分必要。丛枝菌根(arbuscular mycorrhiza,AM)真菌能显著促进植物生长发育、提高作物产量、增强植物抗逆性和抗病性,金花茶接种AM真菌,对金花茶有积极的影响。由于几乎所有的AM真菌接种试验均涉及菌根发育状况观察与侵染率测定,而目前AM侵染状况的观察测定方法种类繁多,良莠不齐,因此本研究探究一种金花茶根系AM真菌检测的最佳染色方法,以便更好地观察AM真菌对金花茶根系的侵染情况。本研究以金花茶健康植株根系为试验材料,探讨5种染色剂(苏丹红Ⅳ、酸性品红、苯胺蓝、台酚蓝、醋酸墨水)对金花茶根系AM真菌的染色效果。研究表明:5%醋酸墨水染色液的染色效果最佳,根皮层细胞内AM真菌的菌丝、泡囊、孢子等结构清晰可见,且能够明确分辨AM真菌与其他未知真菌,根的染色效果可以长久保存;利用苏丹红Ⅳ和酸性品红染色的AM真菌菌丝、泡囊与背景反差不明显,而且酸性品红的染色效果保存时间短,不利于观察;苯胺蓝和台酚蓝的染色效果略次于醋酸墨水,且价格昂贵,成本高。除醋酸墨水外,其他4种染色剂均是疑似致癌物,长期使用对操作人员的健康产生非常大的安全隐患。醋酸墨水染色操作简便、毒性低、成本低廉、染色效果极佳,适用于金花茶根系AM真菌的染色和制片观察。本研究结果可为今后金花茶菌根种苗的应用提供新的思路。

健康与罹病三七内生真菌的分离鉴定及其群落特征差异分析

[目的]本文旨在探究健康与罹患根腐病三七内生真菌群落特征差异及在不同植株部位的分布特征与随生长年限的变化规律。[方法]选取1年、2年生健康与罹患根腐病的三七植株,采用组织分离法对其根、茎部位的内生真菌进行分离,基于形态特征和ITS序列分析对分离得到的菌株进行分类鉴定,并对内生真菌群落组成及多样性特征进行分析。[结果]共分离获得966株内生真菌,经鉴定隶属于3门、5纲、14目、25科、31属。从菌株分离数及分离率看:罹病植株>健康植株,2年生>1年生,根部>茎部。健康和罹病三七的可培养内生真菌组成存在明显差异,其中曲霉属、耙齿菌属、毛壳属和青霉属在健康三七内生真菌群落中占主导,而镰刀菌属、曲霉属、篮状菌属、毛壳属和木霉属是罹病三七内生真菌的优势属。植株部位对三七内生真菌群落组成具有明显影响,其中罹病三七根部镰刀菌属的分离频率高达52%,显著高于其茎部的11.2%,且在罹病三七根部大量分离到木霉属和篮状菌属等有益真菌,其分离频率分别为11.0%和14.5%,而三七茎部内生真菌群落多样性、丰富度和均匀度均高于根部。此外,随着生长年限的增加,三七内生真菌群落的发育更加完善,健康和罹病三七内生真菌群落组成及多样性特征也随之变化,其中尖孢镰刀菌和腐皮镰刀菌在罹病三七植株中的分离频率大幅增加,达到14.5%和32.9%。健康三七内生真菌多样性、丰富度和均匀度随生长年限增加逐渐上升,而罹病三七内生真菌多样性和均匀度逐渐降低。[结论]三七植株内生真菌多样性丰富,健康和罹病三七可培养内生真菌定殖数量及群落组成具有显著差异,且植株部位与生长年限均对三七可培养内生真菌群落特征具有显著影响。

施氮下接种丛枝菌根真菌对太行山南麓典型灌木荆条生长性状的影响

为明确施氮与接种丛枝菌根真菌(AMF)对植物生长的联合效应,选取太行山区典型灌木物种荆条为研究对象,探究施氮、接种丛枝菌根真菌及二者交互作用对荆条各项生长指标的影响。结果显示,施氮处理对荆条株高无显著影响,接种菌根真菌以及与施氮联合处理使株高显著增加25%和28%,不同处理对基径均无显著影响;施氮和接种菌根真菌显著促进地上与地下生物量积累,其中二者联合处理效果更好,且植株根冠比显著低于其他处理;三种处理均显著增加荆条叶片净光合速率、荧光参数、植株总根长、根表面积和根体积,联合处理对荆条叶面积和叶绿素含量影响最为显著;接种AMF处理和联合处理导致根直径显著降低。研究表明,施氮和接种丛枝菌根真菌对荆条地上部分生长及根系形态和生物量均有一定促进作用,菌根共生能够明显改善施氮条件下荆条生长状况,影响根系构型,提高光合作用,有助于荆条有效应对太行山区逆境条件,推动区域植被恢复与重建。