4种草坪草菌根发育状况及其主要土壤影响因子

为明确影响草坪草菌根发育的土壤主控因子,以高羊茅、麦冬、吉祥草、结缕等4种草坪草为材料,研究了4种草坪草根系的丛枝菌根侵染率及其与根系可溶性糖,根际土壤有效磷、有机碳、有机质,根系和土壤球囊霉素含量等的关系。结果表明:4种草坪草菌根侵染率在12.14%~35.25%,且高羊茅>结缕草>麦冬>吉祥草。根系可溶性糖含量以吉祥草最高,为53.58 mg/g,结缕草最低,为21.05 mg/g;土壤有效磷含量以结缕草最高,为10.34 mg/kg,土壤有机碳和有机质含量均以麦冬最高。相关分析表明,草坪草根系菌根侵染率、侵入点与土壤有机碳、有机质、易提取球囊霉素相关土壤蛋白含量呈极显著负相关,与根系难提取球囊霉素含量呈极显著正相关。综上,田间栽培的4种草坪草菌根发育较好,其菌根发育状况主控因子为土壤养分、根系可溶性糖、球囊霉素。

崂山百合伴生植物根围AM真菌分布与菌根发育特点研究

2014年10月,从山东崂山采集了崂山百合(Lilium tsingtauense)伴生植物辽东水蜡(Ligustrum obtusifolium)、小米空木(Stephanandra incisa)和山樱花(Cerasus serrulata)根系和根围土样,分离AM真菌孢子、进行AM真菌形态鉴定、测定菌根发育状况等。本次调查共分离到AM真菌4属24种,其中自辽东水蜡根围分离获得4属13种、小米空木根围分离4属12种山樱花根围分离4属13种。辽东水蜡根围的优势种是摩西球囊霉(Glomus mosseae)和地球囊霉(Glomus geosporum);小米空木根围的优势种是摩西球囊霉、蜜色无梗囊霉(Acaulospora mellea)和极大巨孢囊霉(Gigaspora gigantean);山樱花根围的优势种是摩西球囊霉、疣突球囊霉(Glomus verruculosum)和聚丛球囊霉(Glomus aggregatum)。崂山百合伴生植物总侵染率、丛枝定殖率、泡囊定殖率、菌丝定殖率和孢子密度随土壤深度增加而下降;同一种植物不同土层间AM真菌侵染定殖数量差异显著。三种伴生植物根围孢子密度分别与酸性磷酸酶、脲酶和pH值呈正相关;丛枝定殖率、总侵染率分别与碱性磷酸酶和脲酶呈正相关;菌丝定殖率与速效P呈正相关关系。

Phylogenetic Analysis of the Sequences of rDNA Internal Transcribed Spacer (ITS) of Phytophthora sojae

The internal transcribed spacer （ITS） region （ITS1, ITS2 and 5.8S rDNA） of the nuclear ribosomal DNA （nrDNA） was amplified via the PCR method in seventeen different isolates of Phytophthora sojae using the common primers of the ITS of fungi. Around 800 bp- 1,000 bp fragments were obtained based on the DL2000 marker and the sequences of the PCR products were tested. Taking isolate USA as outgroup, the phylogenetic tree was constructed by means of maximum parsimony analysis, and the genetic evolution among isolates was analyzed. The results showed that there is a great difference between the base constitution of ITS 1 and ITS2 among various isolates. The seventeen isolates are classified into three groups, and the isolates from the same region belong to the same group, which shows the variation in geography.

EFFECT OF HOST PLANTS AND INOCULUM FORMS ON THE INOCULUM POTENTIAL OF ARBUSCULAR MYCORRHIZAL FUNGI

The effects of inoculum forms (single-spore, multi-spores, or colonized root pieces) and host plants (Nicotiana tabacum L., Sorghum sudanense (Piper) Stapf, and Trifolium repens L.) on the development and inoculum potential (IP) of the arbuscular mycorrhizal fungi (AMF) :Glo-mus macrocarpum Tul & Tul, donuis mosseae (Nicol & Gerd.) Gerdemann & Trappe, Glomus ver-siforme (Karsten) Berch, and Sclerocystis sinu/osa Gerdemann & Bakhi cultured in pots were investigated. The lag phase of treatment with 50 spores or 0.5 g (fresh weight) of colonized root pieces was 4 weeks, much shorter than that of the treatment with 1 spore (8 weeks); the value of IP (VIP) and percentage of root colonization (PRC) of the former were greater than those of the latter. Only on the early stages of colonization was there difference between the 50 spores and the 0.5 g (fresh weight) of colonized root piece inoculation treatments. The EP per plant inoculated with 0.5 g (fresh weight) of colonized root pieces of AMF was greater than that of the other two treatments except G. versiforme on Nicotiana tabacum, while the PRC of the plants inoculated with 50 spores and 0.5 g (fresh weight) of colonized root pieces of AMF was higher than that of the 1 spore inoculation after 10 weeks. Trie VIP of AMF on Trifolium repens was significantly higher than that on the other two hosts. The VIP of G. mosseae, G. versiforme, and S. sinuosa was respectively greater than that of G. macrocarpum. This suggested that different species of AMF produced different VIP of the inoculum . Nicotiana tabacum was much better than the other host plants which used to be inoculated with single spore, and to produce inocula of AMF.

丛枝菌根观察与侵染率测定方法的比较

菌根生长状况观察与侵染率测定是菌根学研究中一项重要的基础性工作。综述了丛枝菌根(AM)染色观察与侵染率测定方法研究概况,并对其进行比较和评价。认为采用醋酸墨水染色观察AM生长状况与采用根段侵染率加权法和放大交叉法测定AM真菌侵染率是目前较为科学、准确、易行的方法。根据不同需要也可选择其他适宜的方法,如要了解丛枝发育状况,可采用放大交叉法;如要了解泡囊和侵入点数量,可采用直接计数法,从而使其研究结果具有可比性。有必要建立基于分子生物学技术和脂肪酸定量分析技术测定一种或数种AM真菌侵染状况,这将有力推动AM真菌生理、生态功能研究的发展。

Phylogenetic constrains on mycorrhizal specificity in eight Dendrobium(Orchidaceae) species

Plant phylogeny constrains orchid mycorrhizal(OrM) fungal community composition in some orchids. Here, we investigated the structures of the OrM fungal communities of eight Dendrobium species in one niche to determine whether similarities in the OrM fungal communities correlated with the phylogeny of the host plants and whether the Dendrobium-OrM fungal interactions are phylogenetically conserved. A phylogeny based on DNA data was constructed for the eight coexisting Dendrobium species,and the OrM fungal communities were characterized by their roots. There were 31 different fungal lineages associated with the eight Dendrobium species. In total, 82.98% of the identified associations belonging to Tulasnellaceae, and a smaller proportion involved members of the unknown Basidiomycota(9.67%). Community analyses revealed that phylogenetically related Dendrobium tended to interact with a similar set of Tulasnellaceae fungi. The interactions between Dendrobium and Tulasnellaceae fungi were significantly influenced by the phylogenetic relationships among the Dendrobium species. Our results provide evidence that the mycorrhizal specificity in the eight coexisting Dendrobium species was phylogenetically conserved.

Indigenous Microbial Community Structure in Rhizosphere of Chinese Kale as Afected by Plant Growth-Promoting Rhizobacteria Inoculation

Plant growth-promoting rhizobacteria （PGPR） have been widely recognized as an important agent, especially as a biofertilizer, in agricultural systems. The objectives of this study were to select effective PGPR for Chinese kale （Brassica oleracea var. alboglabra） cultivation and to investigate the effect of their inoculation on indigenous microbial community structure. The Bacillus sp. SUT1 and Pseudomonas sp. SUT19 were selected for determining the efficiency in promoting Chinese kale growth in both pot and field experiments. In the field experiment, PGPR amended with compost gave the highest yields among all treatments. The Chinese kale growth promotion may be directly affected by PGPR inoculation. The changes of microbial community structure in the rhizosphere of Chinese kale following PGPR inoculation were examined by denaturing gradient gel electrophoresis （DGGE） and principal coordinate analysis. The DGGE fingerprints of 16S rDNA amplified from total community DNA in the rhizosphere confirmed that our isolates were established in the rhizosphere throughout this study. The microbial community structures were slightly different among all the treatments, and the major changes depended on stages of plant growth. DNA sequencing of excised DGGE bands showed that the dominant species in microbial community structure in the rhizosphere were not mainly interfered by PGPR, but strongly influenced by plant development. The microbial diversity as revealed by diversity indices was not different between the PGPR-inoculated and uninoculated treatments. In addition, the rhizosphere soil had more influence on eubacterial diversity, whereas it did not affect archaebacterial and fungal diversities.