Interaction of Glomus mosseae and Paecilomyces lilacinus on Meloidogyne javanica of tomato

The effects of Glomus mosseae and Paecilomyces lilacinus on Meloidogyne javanica of tomato were tested in a greenhouse experiment. Chicken layer manure was used as a carrier substrate for the inoculum of P. lilacinus. The following parameters were used: gall index, average number of galls per root system, plant height, shoot and root weights. Inoculation of tomato plants with G. mosseae did not markedly increase the growth of infected plants with M. javanica. Inoculation of plants with G. mosseae and P. lilacinus together or separately resulted in similar shoots and plant heights. The highest root development was achieved when mycorrhizal plants were inoculated with P. lilacinus to control root-knot nematode. Inoculation of tomato plants with G. mosseae suppressed gall index and the average number of galls per root system by 52% and 66%, respectively, compared with seedlings inoculated with M. javanica alone. Biological control with both G. mosseae and P. lilacinus together or separately in the presence of layer manure completely inhibited root infection with M. javanica. Mycorrhizal colonization was not affected by the layer manure treatment or by root inoculation with P. lilacinus. Addition of layer manure had a beneficial effect on plant growth and reduced M. javanica infection.     

Interaction of vesicular arbuscular mycorrhiza with root knot nematodes in tomato

Summary The interaction between the VA mycorrhizal fungus,Glomus fasciculatus and the root-knot nematodes,Meloidogyne incognita andM. javanica, and their effects on the growth and phosphorus nutrition of tomato was studied in a red sandy loam soil of pH 6.0. Inoculation of tomato roots with root-knot nematodes enhanced infection and spore production byG. fasciculatus. Inoculation of tomato plants withG. fasciculatus significantly reduced the number and size of the root-knot galls produced byM. incognita andM. javanica. Inoculation withG. fasciculatus although improved plant growth and its total phosphorus content compared to the uninoculated plants, the difference were not statistically significant.     

Role of the modification in root exudation induced by arbuscular mycorrhizal colonization on the intraradical growth of Phytophthora nicotianae in tomato

We studied the role of modification in root exudation induced by colonization with Glomus intraradices and Glomus mosseae in the growth of Phytophthora nicotianae in tomato roots. Plants were grown in a compartmentalized plant growth system and were either inoculated with the AM fungi or received exudates from mycorrhizal plants, with the corresponding controls. Three weeks after planting, the plants were inoculated or not with P. nicotianae growing from an adjacent compartment. At harvest, P. nicotianae biomass was significantly reduced in roots colonized with G. intraradices or G. mosseae in comparison to non-colonized roots. Conversely, pathogen biomass was similar in non-colonized roots supplied with exudates collected from mycorrhizal or non-mycorrhizal roots, or with water. We cannot rule out that a mycorrhiza-mediated modification in root exudation may take place, but our results did not support that a change in pathogen chemotactic responses to host root exudates may be involved in the inhibition of P. nicotianae.     

Effects of species of VA-mycorrhizal fungi on growth and mineral uptake of sorghum at different temperatures

Sorghum [Sorghum bicolor (L.) Moench] plants were grown in growth chambers at 20, 25 and 30°C in a low P Typic Argiudoll (3.65 µg P g^–1 soil, pH 8.3) inoculated with Glomus fasciculatum, Glomus intraradices, and Glomus macrocarpum to determine effects of vesicular-arbuscular mycorrhizal fungi (VAMF) species on plant growth and mineral nutrient uptake. Sorghum root colonization by VAMF and plant responses to Glomus species were temperature dependent. G. macrocarpum colonized sorghum roots best and enhanced plant growth and mineral uptake considerably more than the other VAMF species, especially at 30°C. G. fasciculatum enhanced shoot growth at 20 and 25°C, and mineral uptake only at 20°C. G. intraradices depressed shoot growth and mineral uptake at 30°C. G. macrocarpum enhanced shoot P, K, and Zn at all temperatures, and Fe at 25 and 30°C above that which could be accounted for by increased biomass. Sorghum plant growth responses to colonization by VAMF species may need to be evaluated at different temperatures to optimize beneficial effects.     

Response of strawberry to inoculation with arbuscular mycorrhizal fungi under very high soil phosphorus conditions

A field study was done to assess the potential benefit of arbuscular mycorrhizal (AM) inoculation of elite strawberry plants on plant multiplication, under typical strawberry nursery conditions and, in particular, high soil P fertility (Mehlich-3 extractible P=498 mg kg⁻¹). Commercially in vitro propagated elite plants of five cultivars (‘Chambly,’ ‘Glooscap,’ ‘Joliette,’ ‘Kent,’ and ‘Sweet Charlie’) were transplanted in noninoculated growth substrate or in substrate inoculated with Glomus intraradices or with a mixture of species (G. intraradices, Glomus mosseae, and Glomus etunicatum) at the acclimation stage and were grown for 6 weeks before transplantation in the field. We found that AM fungi can impact on plant productivity in a soil classified as excessively rich in P. Inoculated mother plants produced about 25% fewer daughter plants than the control in Chambly (P=0.03), and Glooscap produced about 50% more (P=0.008) daughter plants when inoculated with G. intraradices, while the productivity of other cultivars was not significantly decreased. Daughter plant shoot mass was not affected by treatments, but their roots had lower, higher, or similar mass, depending on the cultivar–inoculum combination. Root mass was unrelated to plant number. The average level of AM colonization of daughter plants produced by noninoculated mother plants did not exceed 2%, whereas plants produced from inoculated mothers had over 10% of their root length colonized 7 weeks after transplantation of mother plants and ∼6% after 14 weeks (harvest), suggesting that the AM fungi brought into the field by inoculated mother plants had established and spread up to the daughter plants. The host or nonhost nature of the crop species preceding strawberry plant production (barley or buckwheat) had no effect on soil mycorrhizal potential, on mother plant productivity, or on daughter plant mycorrhizal development. Thus, in soil excessively rich in P, inoculation may be the only option for management of the symbiosis.     

Influence of Glomus intraradices and Soil Phosphorus on Meloidogyne incognita Infecting Cucumis melo

The interaction among Glomus intraradices, Meloidogyne incognita, and cantaloupe was studied at three soil phosphorus (P) levels in a greenhouse. All plants grew poorly in soil not amended with P, regardless of mycorrhizal or nematode status. In soil amended with 50 μg P /g soil, M. incognita suppressed the growth of nonmycorrhizal plants by 84%. In contrast, growth of mycorrhizal plants inoculated with M. incognita was retarded by only 21%. A similar trend occurred in plants grown in soil with 100 μg P /g soil. Mycorrhizal infection had no effect on the degree of root-knot gall formation and did not affect the number of nematode eggs per egg mass. Mineral levels in plant shoots generally declined as soil P levels increased and were not significantly influenced by G. intraradices or M. incognita.     

Lunularia cruciata, a potential in vitro host for Glomus proliferum and G. intraradices

A study was conducted to define culture conditions for in vitro growth arbuscular mycorrhizal fungi (AMF) with liverworts as hosts. Lunularia cruciata (L.) Dumortier ex. Lindberg developed in vitro monoxenic mycothalli with both Glomus proliferum Dalpé & Declerck (MUCL 41827) and Glomus intraradices Schenck & Smith (MUCL 43204). AMF inoculated plants were co-cultured in plastic Petri dishes with semi-solidified medium supplemented with sucrose and grown under filtered light. Mycothalli of L. cruciata produced external hyphae and spores in quantities equivalent to those obtained with Ri T-DNA transformed root systems.     

Arbuscular mycorrhizal fungi and biological control of Verticillium-wilted cotton plants

The interaction of arbuscular mycorrhizal fungi (Glomus etunicatum, Glomus intraradices, and Glomus versiforme) with a wilt-causing soil-borne pathogen, Verticillium dahliae, was studied in cotton. It was found that establishment by arbuscular mycorrhizal fungi reduced disease index. In diseased cotton plants colonised by G. etunicatum, the disease index was less than other diseased mycorrhizal and non-mycorrhizal ones. In diseased cotton plants, chlorophyll content was lower than others. Three Glomus species significantly increased content of sugar and protein in shoot and root. Pathogen-infected plants had higher proline concentration in shoot and root than healthy plants. On the other hand, the increased content of proline as stress sensor showed that Verticillium accelerates senescence and reduces yield. These results suggest that the beneficial effects of mycorrhiza can alleviate the pathogenesis effects of V. dahliae partly, and also there is a competitive interaction between the pathogenic and symbiotic fungi.     

Differential effects of <Emphasis Type="Italic">Paenibacillus</Emphasis> spp. on cucumber mycorrhizas

The effects of 17 Paenibacillus strains on root colonization by Glomus intraradices or Glomus mosseae and plant growth parameters (shoot and root weight) of mycorrhizal cucumber plants were examined. The Paenibacillus strains were originally isolated from mycorrhizal (G. intraradices) and non-mycorrhizal cucumber rhizosphere and/or hyphosphere, except for strain EJP73, which originated from a Pinus sylvestris-Lactarius rufus ectomycorrhiza. Root colonization of cucumber plants by G. intraradices or G. mosseae was unaffected by all seven strains of Paenibacillus polymyxa, but was decreased or increased by four strains of Paenibacillus macerans and strain EJP73 of Paenibacillus sp. Overall, shoot dry weight of cucumber grown in symbioses with either G intraradices or G. mosseae was unaffected by inoculation with all of the Paenibacillus strains, except for strain MB02-429 of P. macerans, which increased the shoot dry weight in the cucumber-G. mosseae symbiosis. On the other hand, several Paenibacillus strains caused altered root growth. Three strains of P. polymyxa and four strains of P. macerans increased the root fresh weight of the cucumber–G. intraradices symbiosis, whereas three strains of P. polymyxa and one strain of P. macerans as well as Paenibacillus sp. EJP73, decreased the root fresh weight of the cucumber–G. mosseae symbiosis. In conclusion, our results show that bacteria from several species of Paenibacillus differentially affect cucumber mycorrhizas.     

AM 真菌影响三叶草根系抗氧化酶活性的系统效应

本文对三叶草接种AM 真菌根内球囊霉, 用盆栽试验和分根试验测定根系的菌根侵染率和抗氧化酶活性, 研究AM 真菌对根系抗氧化酶活性的影响以及该影响的系统性。结果表明, 盆栽试验中接种根内球囊霉显著提高了根系中SOD、POD、CAT 的活性, 表明AM 真菌可以促进根系的抗氧化酶活性; 分根试验中一半根系接种了根内球囊霉的植株, 其另一半未接种的根系SOD、POD 活性也增加, 表明AM 真菌对根系抗氧化酶系统的促进具有系统效应。由于抗氧化酶系统是植物产生抗逆性的生理生化基础, 可以推测, AM 真菌对根系抗氧化酶活性的系统性提高有助于保护根系整体, 而非仅仅保护受侵染根段。     

Increased Growth and Yield of Hydroponically Grown Greenhouse Tomato Plants Inoculated with Arbuscular Mycorrhizal Fungi and Fusarium oxysporum f. sp. radicis-lycopersici

The arbuscular mycorrhizal fungi Glomus monosporum, G. vesiculiferum, G. deserticola, G. intraradices, G. mosseae, and two unidentified species were tested to determine their effect on plant growth and fruit production of tomato (Lycopersicon esculentum Mill.) cv. Trust inoculated with Fusarium oxysporum f. sp. radicis-lycopersici (FORL) under near-commercial greenhouse conditions. Inoculation with G. monosporum and G. mosseae significantly increased fruit yield and fruit number of tomato plants grown hydroponically in sawdust. Plant height and plant dry weight increased significantly when inoculated with G. monosporum and G. mosseae. Further, plants inoculated with G. monosporum and G. mosseae showed significantly lower FORL root infection than the untreated control plants.     

Effect of Arbuscular Mycorrhizae and Induced Drought Stress on Antioxidant Enzyme and Nitrate Reductase Activities in Juniperus oxycedrus L. Grown in a Composted Sewage Sludge-amended Semi-arid Soil

We studied the influence of inoculation with a mixture of three exotic arbuscular mycorrhizal (AM) fungi, Glomus intraradices Schenck & Smith, Glomus deserticola Trappe, Bloss. & Menge and Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe, and the addition of composted sewage sludge (SS) on the activities of the antioxidant enzymes superoxide dismutase (SOD, EC 1.15.1.1) and total peroxidase (POX) and of shoot and root nitrate reductase (NR, EC 1.6.6.1) in Juniperus oxycedrus L. seedlings, an evergreen shrub, grown in a non-sterile soil under well-watered and drought-stress conditions. Both the inoculation with exotic AM fungi and the addition of composted SS stimulated significantly growth and the N and P contents in shoot tissues of J. oxycedrus with respect to the plants neither inoculated nor treated with composted SS that were either well-watered or droughted. Under drought-stress conditions, only inoculation with exotic AM fungi increased shoot and root NR activity (about 188% and 38%, respectively, with respect to the plants neither inoculated nor treated with composted SS). Drought increased the POX and SOD activities in both shoots of J. oxycedrus seedlings inoculated with exotic AM fungi and grown with composted SS, but the increase was less than in the plants neither inoculated nor treated with SS. Both the plants inoculated with exotic AM fungi and the plants grown with composted SS developed additional mechanisms to avoid oxidative damage produced under water-shortage conditions.     

Differential host plant performance as a function of soil arbuscular mycorrhizal fungal communities: experimentally manipulating co-occurring Glomus species

In order to evaluate host plant performance relative to different soil arbuscular mycorrhizal fungal (AMF) communities, Andropogon gerardii seedlings were grown with nine different AMF communities. The communities consisted of 0, 10, or 20 spores of Glomus etunicatum and 0, 10, or 20 spores of Glomus intraradices in all possible combinations. Spores were produced by fungal cultures originating on A. gerardii in a serpentine plant community; seeds of A. gerardii were collected at the same site. The experiment was performed in the greenhouse using a mixture of sterilized serpentine soil and sand to which naturally occurring non-mycorrhizal microbes were added. There was no difference in root AMF colonization rates between single species communities of either G. etunicatum or G. intraradices, but G. intraradices enhanced plant growth and G. etunicatum did not. However, plants grew larger with some combinations of G.␣intraradices plus G. etunicatum than with the same quantity of G. intraradices alone. These results suggest the potential for niche complementarity in the mycorrhizal fungi. That G. etunicatum only increased plant growth in the presence of G. intraradices could be illustrative of why AMF that appear to be parasitic or benign when examined in isolation are maintained within multi-species mycorrhizal communities in nature.     

Dual axenic culture of sheared-root inocula of vesicular-arbuscular mycorrhizal fungi associated with tomato roots

Surface-sterilized sheared-root inocula of two vesicular-arbuscular mycorrhizal (VAM) fungi (Glomus intraradices and G. versiforme) from pot cultures associated with excised tomato roots showed significant sporulation and the production of an extensive hyphal biomass. As many as 10²–10³ axenic mature spores were recovered in Petri dishes during 3 months incubation in the dark. Propagules of both species were able to complete their vegetative life cycle in vitro and efficiently colonize Acacia albida roots after 1 month under greenhouse conditions. The effectiveness of 0.5 cm pieces of VAM roots as starter inocula indicates the high inoculum potential of intravesicle propagules.     

Comprehensive report on the prevalence of root-knot nematodes in the Poonch division of Azad Jammu and Kashmir,Pakistan

The present study documents the root-knot nematodes (RKN) fauna of the Poonch division in Azad Jammu and Kashmir infecting vegetables. An overall prevalence of 40% of RKN was recorded. Of the four districts investigated, maximum prevalence was recorded in district Poonch with 59%, followed by Sudhnuti with 58%. The lowest prevalence of RKN was found in districts Bagh (29%) and Haveli (33%). Out of 15 vegetables investigated, RKN was found on five crops. The highest prevalence of 37.8% was recorded on okra, followed by 31.3% on cucumber and 17.5% on tomato. RKN was less prevalent on eggplant (8.3%) and beans (7.7%). Three RKN species, that is Meloidogyne incognita, Meloidogyne javanica and Meloidogyne arenaria, were found infecting the hosts. M. javanica was found to be the most prevalent followed by M. incognita and M. arenaria. This trend was found in all the districts. Overall prevalence of M. javanica as sole population was 9% and that of M. incognita was 2%. Meloidogyne arenaria was not found in any of the fields as sole population. The prevalence of M. incognita with M. javanica or M. arenaria as mixed populations was 8% and 5%, respectively, and that of M. javanica with M. arenaria was 4%. Similarly, all the three species prevailed as mixed populations in 12% of the fields in the division. The severity of RKN infections, measured as galling index, was found to be variable within each infected field (GI 2–9). Identification of RKN species was based on the morphology of perineal patterns and confirmed by molecular SCAR and CO1 makers based identification. In conclusion, RKN were distributed in the Poonch division and M. javanica was predominant. Cucumber, okra, tomato and eggplant were severely attacked by these nematodes warranting the adoption of stringent control strategies for their management.     

黄顶菊与3种本地植物竞争对丛枝菌根真菌种类和多样性的影响

【目的】外来植物黄顶菊对生态环境和农业经济造成了严重危害,了解黄顶菊与3种不同本地植物种植生长对丛生菌根(AM)真菌群落结构和多样性造成的影响,可以从土壤微生物角度进一步解释黄顶菊的入侵机制。【方法】通过同质园小区试验模拟黄顶菊入侵的生态进程,以黄顶菊和3种本地植物狗尾草、藜、黄香草木樨为研究对象,采用AM真菌的形态学鉴定方法,研究黄顶菊与3种本地植物不同种植方式对AM真菌群落结构和多样性的影响。【结果】(1)黄顶菊根际土壤聚集的AM真菌种类与其伴生本地植物种类有关:黄顶菊与狗尾草混种处理中优势种为网状球囊霉和根内球囊霉,而黄顶菊分别与藜、草木樨混种处理中优势种均为网状球囊霉、根内球囊霉和缩球囊霉;(2)黄顶菊分别与狗尾草和黄香草木樨混种处理中AM真菌种类既高于本地单种处理,也高于黄顶菊单种处理,说明随着黄顶菊的入侵和地上植物多样性的改变,AM真菌种类也发生改变;(3)与3种本地植物单种相比,黄顶菊各混种处理和黄顶菊单种处理中黄顶菊根际土壤根内球囊霉的重要值均增加,表明黄顶菊入侵有利于根内球囊霉的生长和发育。【结论】黄顶菊入侵改变了根际土壤AM真菌的群落结构和多样性,AM真菌的改变既与本地植物种类有关,也与入侵程度有关。     

Interaction between the root-lesion nematode Pratylenchus vulnus and the mycorrhizal association of Glomus intraradices and Santa Lucia 64 cherry rootstock

The effects of the interaction between Pratylenchus vulnus and the endomycorrhizal fungus Glomus intraradices on growth and nutrition of Santa Lucia 64 cherry rootstock was studied under microplot conditions during one growing season. Fresh top weight, and stem diameter of mycorrhizal plants and high P treatments with and without P. vulnus were significantly higher than those of non-mycorrhizal plants. The lowest shoot length and fresh root weights were recorded in nematode inoculated plants in low P soil. Mycorrhizal infection did not affect the number of nematodes per gram of root in plants infected with P. vulnus. In the presence of the nematode, internal spore production by G. intraradices was significantly reduced. No nutrient deficiencies were detected through foliar analysis, although low levels of Ca, Mn and Fe were detected in nematode treatments. Mycorrhizal plants achieved the highest values for N, P, S, Fe, and Zn, whereas high P treatments increased absorption of Ca and Mn. Early mycorrhizal infection of Santa Lucia 64 cherry rootstock by G. intraradices confers increased growth capacity in the presence of P. vulnus.     

Community of arbuscular mycorrhizal fungi in drought-resistant plants, <Emphasis Type="Italic">Moringa</Emphasis> spp., in semiarid regions in Madagascar and Uganda

The community structure of arbuscular mycorrhizal (AM) fungi in the roots of drought-resistant trees, Moringa spp., was examined in semiarid regions in Madagascar and Uganda. Root samples were collected from 8 individuals of M. hildebrandtii and 2 individuals of M. drouhardii in Madagascar and from 21 individuals of M. oleifera in Uganda. Total DNA was extracted from the root samples, and partial nSSU rDNA of AM fungi was amplified using a universal eukaryotic primer NS31 and an AM fungalspecific primer AM1. The PCR products were cloned and divided by restriction fragment length polymorphism (RFLP) analysis with HinfI and RsaI. Some representatives in each RFLP types were sequenced, and a neighbor-joining phylogenetic analysis was conducted for the obtained sequences with analogous sequences of AM fungi. The RFLP and phylogenetic analyses showed that AM fungi closely related to Glomus intraradices or G. sinuosum were detected in many samples. The AM fungal groups frequently detected in the Moringa spp. might be widely distributed species in semiarid environments.     

The Development and Influence of Meloidogyne incognita and M. javanica on Wheat

The effects of soil temperature and initial inoculum density (Pi) of Meloidogyne incognito and M. javanica on growth of wheat (Triticum aestivum cv. Anza) and nematode reproduction were studied in controlled temperature baths in the glasshouse. Nematode reproduction was directly proportional to temperature between 14 and 30 C for M. incognita and between 18 and 26 C for M. javanica. Reproduction rates (Pf/Pi, where Pf = final number of eggs) for Pi''s of 3,000, 9,000, and 30,000 eggs/plant were greatest at each temperature when Pi = 3,000. Maximum M. incognita reproduction rate (Pf/Pi = 51.12) was at 30 C. At 26 C, M. javanica reproduction (Pf/Pi = 14.82, 9.02, and 4.23 for Pi = 3,000, 9,000, and 30,000, respectively) was about half that of M. incognita when Pi = 3,000 or 9,000 but similar when Pi = 30,000. Reproduction of both species was depressed between 14 and 18 C. Shoot and root growth and head numbers were inversely related to soil temperature between 14 and 30 C but were not affected by the Pi of M. incognita when 7 d old seedlings were inoculated. When newly germinated seedlings were inoculated with M. incognita or M. javanica, the Pi did not affect shoot and root fresh weights, shoot/root ratio, and tillering, but it did reduce root dry weight (M. javanica at 26 C) and increase shoot dry weight (M. incognita at 18-22 C). The optimum temperature range is lower for wheat growth than for nematode reproduction. Wheat cv. Anza is a good host for M. incognita and M. javanica, but it is tolerant to both species.     

Studies on the diversity of arbuscular mycorrhizal fungi and the efficacy of two native isolates in a highly alkaline anthropogenic sediment

A field survey of the arbuscular mycorrhizal status of herbaceous plant species was conducted in a highly alkaline anthropogenic sediment resulting from the disposal of waste from an acetylene and polyvinyl chloride factory. Most plant species found at the site were mycorrhizal and the dominant mycotrophic plant species was Conyza bilbaoana. Fungal species richness was assessed by identification of spores extracted from the sediment and from continuously propagated trap pot cultures. All of the six species of arbuscular mycorrhizal fungi (AMF) found were from the genus Glomus. Glomus intraradices and G. mosseae were found in field-collected sediment samples and also occurred most frequently in trap cultures. To test the symbiotic effectiveness of these two fungi, seedlings of C. bilbaoana were inoculated with either native G. intraradices BEG163 or G. mosseae BEG198 and non-native G. intraradices BEG75 or G. mosseae BEG25 isolates in sterile and non-sterile sediment collected from the study site. All four isolates were able to colonise C. bilbaoana. However, AMF native to the target sediments were generally more effective than the non-native fungi in promoting plant establishment and growth under highly alkaline conditions. The non-native G. intraradices was, however, more effective than the non-native G. mosseae. The results of this study suggest the use of adapted AMF as inoculants for phytorestoration of alkaline anthropogenic-stressed sediments.