丛枝菌根真菌对紫花苜蓿吸收土壤中镉和锌的影响

采用温室盆栽试验方法,研究了镉(Cd)、锌(Zn)污染土壤中,8种不同丛枝菌根真菌( AMF)Glomus lamellosum(G.la)、Acaulospora mellea( A.m)、Glomus mosseae( G.m)、Glomus intraradices( G.i)、Glomus etunicatum( G.e)、Glomus constrictum( G.c)、Diversispora spurcum( D.s)、Glomus aggregatum( G.a)对紫花苜蓿(Medicagosativa L.)吸收Cd、Zn的影响.结果表明,Cd、Zn污染下AMF仍然明显侵染紫花苜蓿,并促进紫花苜蓿对Cd、Zn的吸收积累,但不同AMF影响的效应和植株不同部位对重金属的吸收积累规律存在差异.AMF处理下紫花苜蓿根部Cd、Zn含量和积累量明显增加,但地上部Cd、Zn的含量则降低,地上部Zn的积累量也减小,这表明AMF处理减弱了Cd、Zn由根部向地上部的运移,减轻了植物地上部毒害.接种AMF条件下,植株尤其是根部生物量增加是Cd、Zn在其体内含量和积累量增加的重要因素,不同种类AMF促进植株生物量增加的幅度不同,导致植株对Cd、Zn的积累和抗性存在差异.     

丛枝菌根真菌群落对白三叶草植株生物量磷吸收和土壤磷酸单酯酶活性的影响

丛枝菌根真菌(AMF)在土壤与植物的磷素循环中发挥着关键的作用。采用盆栽实验研究了丛枝菌根真菌群落对白三叶草植株生物量、磷吸收和土壤磷酸单酯酶活性的影响。结果表明,接种不同AMF群落均能显著地促进白三叶草植株的生长及其对磷素的吸收,提高根际土壤磷酸单酯酶的活性。Mnp处理中,白三叶草生物量最大,白三叶草总生物量、茎叶生物量和根系生物量分别比对照处理(-M)提高64.48%、61.48%和84.91%。不同菌根处理中,Mck处理显著地提高白三叶草磷吸收和土壤磷酸单酯酶活性,白三叶草磷吸收总量和茎叶磷吸收量分别比对照(-M)提高107.18%和91.91%,土壤碱性磷酸单酯酶和酸性磷酸单酯酶活性相对对照(-M)分别提高54.33%和138.43%。碱性磷酸单酯酶活性与AMF群落中的Acaullospora属孢子数呈显著的正相关关系,而酸性磷酸单酯酶活性则主要受Paraglomus属孢子数的影响。说明接种AMF群落可显著地影响土壤的磷酸单酯酶活性,从而影响白三叶草的生长及其对磷素的吸收。     

丛枝菌根真菌对旱稻根际Pb形态分布的影响(英文)

[目的]为了研究丛枝菌根真菌对旱稻根际土壤中重金属铅(Pb)化学赋存形态的影响。[方法]采用盆栽实验的方法,研究了不同Pb处理水平(0、300、600mg/kg)下,接种丛枝菌根真菌(AMF)Glomus mosseae对旱稻(OryzalsativaL.)根际Pb形态分布的影响。[结果]接种处理下,旱稻根系侵染率以及根外菌丝量随着土壤Pb含量增加而显著降低(P<0.05)。与未接种处理相比,接种处理显著提高Pb处理下根际pH;300mg/kgPb处理下,接种显著增加土壤球囊霉素含量,600mg/kgPb处理下,接种处理显著降低土壤球囊霉素含量(P<0.05);在Pb处理下,与未接种处理相比,接种处理显著提高可交换态Pb含量,显著降低了碳酸盐结合态以及铁锰氧化物结合态Pb含量,却显著增加了土壤中有机质结合态Pb含量(P<0.05)。[结论]这说明接种丛枝菌根真菌可以改变旱稻根际土壤中Pb的形态分布。     

内蒙古孑遗植物丛枝菌根真菌共生特性调查

对内蒙古荒漠珍稀、孑遗植物四合木、绵刺、白刺、霸王和强旱生植物半日花与丛枝菌根真菌的共生特性进行了调查。通过显微镜观察根系样本,采用十字交叉法统计常见科、属丛枝菌根真菌的菌丝、丛枝、泡囊的侵染率,观察侵染面积,阐明丛枝菌根真菌的侵染率。结果表明:这些孑遗植物均被丛枝菌根真菌(AMF)侵染,多数种类侵染率较高;不同种孑遗植物侵染率有一定的差异。在不同地理环境和土壤条件下,同种孑遗植物菌根侵染状况也有明显的差异。四合木、半日花等的丛枝菌根真菌的侵染率很高,菌根类型主要为疆南星型菌根。     

地面覆盖对越橘菌根侵染率及根系活力和过氧化物酶活性的影响

对越橘栽培土壤进行粉碎的玉米秸秆、粉碎的稻草秸、苔藓、锯末、草炭等5种不同有机物覆盖处理。结果表明,有机物覆盖处理可以提高越橘的根系活力和菌根侵染率,降低过氧化物酶活性,促进了越橘的生长。     

苗期接种不同丛枝菌根真菌对烟草青枯病防治效果的影响

【目的】研究漂浮育苗条件下,探讨接种不同丛枝菌根真菌及其结合生防制剂对烟株不同生育时期农艺性状、青枯病抗病效果及烤后烟叶品质的影响。【方法】采用漂浮育苗技术培育烟苗,于播种期分别接种摩西球囊霉、聚丛球囊霉和生防制剂进行烟苗农艺性状、烟叶化学成分及抗病性等比较试验。【结果】与对照相比,各处理均可不同程度改良烟株农艺性状,优化总糖与烟碱、总氮与烟碱的比例,改善烟叶品质;接种摩西球囊霉的菌根苗＋生防制剂20mL对于改良烟株农艺性状和改善烟叶品质具有更好的效果,而接种聚丛球囊霉的菌根苗＋生防制剂20mL对青枯病的防治效果最好,接种摩西球囊霉的菌根苗＋生防制剂20mL次之。【结论】漂浮育苗时接种摩西球囊霉＋生防制剂（20mL）处理可更好的改善烟株综合素质。     

AM真菌在植物病虫害生物防治中的作用机制

丛枝菌根(Arbuscular Mycorrhizae,AM)真菌是一类广泛分布于土壤生态系统中的有益微生物,能与大约80%的陆生高等植物形成共生体。由土传病原物侵染引起的土传病害被植物病理学界认定为最难防治的病害之一。研究表明,AM真菌能够拮抗由真菌、线虫、细菌等病原体引起的土传性植物病害,诱导宿主植物增强对病虫害的耐/抗病性。当前,利用AM真菌开展病虫害的生物防治已经引起生态学家和植物病理学家的广泛关注。基于此,围绕AM真菌在植物病虫害生物防治中的最新研究进展,从AM真菌改变植物根系形态结构、调节次生代谢产物的合成、改善植物根际微环境、与病原微生物直接竞争入侵位点和营养分配、诱导植株体内抗病防御体系的形成等角度,探究AM真菌在植物病虫害防治中的作用机理,以期为利用AM真菌开展植物病虫害的生物防治提供理论依据,并对本领域未来的发展方向和应用前景进行展望。     

Effects of nitrogen feeding for extraradical mycelium of Rhizophagus irregularis maize symbiosis incorporated with phosphorus availability

In terrestrial ecosystems, plants are frequently in symbiosis with arbuscular mycorrhizal fungi (AMF) with mineral nutrients and photosynthesis carbon exchanges in between. This research sought to identify the effects of phosphorus (P) levels on the nitrogen (N) uptake via extraradical mycelium (ERM) and the mycorrhizal growth response (MGR) of maize plants within the AMF symbiosis. Pots were separated into root compartments and hyphae compartments (HCs) with two layers of a 30‐μm mesh membrane and an air gap in between, where only hyphae could pass through, to avoid both N diffusion and root growth effects. Maize plants were inoculated with Rhizophagus irregularis with different N fertilization in HCs under two different P fertilization levels. Our results indicated that a strong increase in MGR with low‐P fertilization. The same tendency was not observed with high‐P fertilization, although both had a large increase in P concentration as a potential source of growth in shoot tissue of mycorrhizal plants. Substantial effects (10.5% more N) were observed in the case of high‐P availability for the host plants from ERM fed with N, whereas under low‐P conditions ERM may prioritize P uptake rather than N uptake. The AM fungi increase the uptake of N and P, which are most limiting in the soil with fewer forces from soil resources. In addition, there was still more P accumulated than N due to the high N for ERM with high‐P supply. Low N in HCs corresponded with a lower colonization rate in roots but with high hyphae density in HCs; this result suggest that N and P availability might change the ratio of extraradical to intraradical hyphae length.     

High colonization by native arbuscular mycorrhizal fungi (AMF) of rubber trees in small-holder plantations on low fertility soils in North East Thailand

Rubber tree is a very important crop in Thailand, representing an essential source of income for farmers. In the past two decades, rubber tree plantations have been greatly expanding in unfavorable areas, where climate conditions are difficult and soil fertility is very poor. To optimize latex yields, mineral fertilizers have been widely used. A better understanding of the roles of the biological compartment in soil fertility is essential to determine alternative management practices to sustain soil fertility and optimize latex yields. Arbuscular mycorrhizal fungi (AMF) are widely recognized as beneficial for plants, mainly through their role in improving plant nutrient uptake. The objective of this study was to assess the AMF populations in rubber tree plantations and the impact of both soil characteristics and plantation age on these communities. Our results showed that all rubber trees were highly colonized, regardless of the soil structure and nutrient contents. AMF colonization was not affected by the age of the trees, suggesting that maintaining the symbiosis is likely to be beneficial at all stages. A better understanding and management of the microbial communities would contribute to maintaining or restoring soil fertility, leading to a better tree growth and optimized latex yield.     

Suppression of the fungal pathogen Magnaporthe grisea by Stenotrophomonas maltophilia,a seed-borne rice (Oryza sativa L.) endophytic bacterium

The present work was carried out to study the potential of bacteria isolated from the seeds of rice plant for the biocontrol of five rice pathogenic fungi. Eleven endophytic bacteria isolated from rice seeds were evaluated for their antagonistic potential. Of five pathogens studied, only the growth of Magnaporthe grisea was inhibited by one bacterial isolate in an in vitro dual culture assay. Based on 16S rDNA sequence analysis, and biochemical and morphological characteristics, this strain was closely related to Stenotrophomonas maltophilia. We named this new isolate to be S. maltophilia SEN₁ (seed endophyte). This isolate was further tested for the production of volatile and diffusible antibiotics against M. grisea, for plant growth-promoting (PGP) traits and colonization of some rice cultivars. In addition, S. maltophilia SEN₁ was tested for its ability to promote plant growth and reduce the incidence of rice blast disease under greenhouse conditions. When applied to the soil, this isolate increased seedling growth and suppressed blast disease in plants of three studied cultivars. This study also showed this isolate could colonize the root interior of other rice cultivars. This study indicates that the S. maltophilia isolate studied has an excellent potential to be used as biocontrol agents of M. grisea or biofertilizer under in vitro and in vivo conditions.