Chloroplast gene sequence data suggest a single origin of the predisposition for symbiotic nitrogen fixation in angiosperms.

Of the approximately 380 families of angiosperms, representatives of only 10 are known to form symbiotic associations with nitrogen-fixing bacteria in root nodules. The morphologically based classification schemes proposed by taxonomists suggest that many of these 10 families of plants are only distantly related, engendering the hypothesis that the capacity to fix nitrogen evolved independently several, if not many, times. This has in turn influenced attitudes toward the likelihood of transferring genes responsible for symbiotic nitrogen fixation to crop species lacking this ability. Phylogenetic analysis of DNA sequences for the chloroplast gene rbcL indicates, however, that representatives of all 10 families with nitrogen-fixing symbioses occur together, with several families lacking this association, in a single clade. This study therefore indicates that only one lineage of closely related taxa achieved the underlying genetic architecture necessary for symbiotic nitrogen fixation in root nodules.

Sequencing and functional analysis of the genome of a nematode egg-parasitic fungus, Pochonia chlamydosporia

Pochonia chlamydosporia is a worldwide-distributed soil fungus with a great capacity to infect and destroy the eggs and kill females of plant-parasitic nematodes. Additionally, it has the ability to colonize endophytically roots of economically-important crop plants, thereby promoting their growth and eliciting plant defenses. This multitrophic behavior makes P. chlamydosporia a potentially useful tool for sustainable agriculture approaches. We sequenced and assembled ∼41 Mb of P. chlamydosporia genomic DNA and predicted 12,122 gene models, of which many were homologous to genes of fungal pathogens of invertebrates and fungal plant pathogens. Predicted genes (65%) were functionally annotated according to Gene Ontology, and 16% of them found to share homology with genes in the Pathogen Host Interactions (PHI) database. The genome of this fungus is highly enriched in genes encoding hydrolytic enzymes, such as proteases, glycoside hydrolases and carbohydrate esterases. We used RNA-Seq technology in order to identify the genes expressed during endophytic behavior of P. chlamydosporia when colonizing barley roots. Functional annotation of these genes showed that hydrolytic enzymes and transporters are expressed during endophytism. This structural and functional analysis of the P. chlamydosporia genome provides a starting point for understanding the molecular mechanisms involved in the multitrophic lifestyle of this fungus. The genomic information provided here should also prove useful for enhancing the capabilities of this fungus as a biocontrol agent of plant-parasitic nematodes and as a plant growth-promoting organism.

Endophytic colonization of barley (Hordeum vulgare) roots by the nematophagous fungus Pochonia chlamydosporia reveals plant growth promotion and a general defense and stress transcriptomic response

Plant crop yields are negatively conditioned by a large set of biotic and abiotic factors. An alternative to mitigate these adverse effects is the use of fungal biological control agents and endophytes. The egg-parasitic fungus Pochonia chlamydosporia has been traditionally studied because of its potential as a biological control agent of plant-parasitic nematodes. This fungus can also act as an endophyte in monocot and dicot plants, and has been shown to promote plant growth in different agronomic crops. An Affymetrix 22K Barley GeneChip was used in this work to analyze the barley root transcriptomic response to P. chlamydosporia root colonization. Functional gene ontology (GO) and gene set enrichment analyses showed that genes involved in stress response were enriched in the barley transcriptome under endophytism. An 87.5 % of the probesets identified within the abiotic stress response group encoded heat shock proteins. Additionally, we found in our transcriptomic analysis an up-regulation of genes implicated in the biosynthesis of plant hormones, such as auxin, ethylene and jasmonic acid. Along with these, we detected induction of brassinosteroid insensitive 1-associated receptor kinase 1 (BR1) and other genes related to effector-triggered immunity (ETI) and pattern-triggered immunity (PTI). Our study supports at the molecular level the growth-promoting effect observed in plants endophytically colonized by P. chlamydosporia, which opens the door to further studies addressing the capacity of this fungus to mitigate the negative effects of biotic and abiotic factors on plant crops.

Some isolates of the nematophagous fungus Pochonia chlamydosporia promote root growth and reduce flowering time of tomato

The fungal parasite of nematode eggs Pochonia chlamydosporia is also a root endophyte known to promote growth of some plants. In this study, we analysed the effect of nine P. chlamydosporia isolates from worldwide origin on tomato growth. Experiments were performed at different scales (Petri dish, growth chamber and greenhouse conditions) and developmental stages (seedlings, plantlets and plants). Seven P. chlamydosporia isolates significantly (P < 0.05) increased the number of secondary roots and six of those increased total weight of tomato seedlings. Six P. chlamydosporia isolates also increased root weight of tomato plantlets. Root colonisation varied between different isolates of this fungus. Again P. chlamydosporia significantly increased root growth of tomato plants under greenhouse conditions and reduced flowering and fruiting times (up to 5 and 12 days, respectively) versus uninoculated tomato plants. P. chlamydosporia increased mature fruit weight in tomato plants. The basis of the mechanisms for growth, flowering and yield promotion in tomato by the fungus are unknown. However, we found that P. chlamydosporia can produce Indole-3-acetic acid and solubilise mineral phosphate. These results suggest that plant hormones or nutrient ability could play an important role. Our results put forward the agronomic importance of P. chlamydosporia as biocontrol agent of plant parasitic nematodes with tomato growth promoting capabilities.

Chitosan enhances parasitism of Meloidogyne javanica eggs by the nematophagous fungus Pochonia chlamydosporia

Pochonia chlamydosporia (Pc), a nematophagous fungus and root endophyte, uses appressoria and extracellular enzymes, principally proteases, to infect the eggs of plant parasitic nematodes (PPN). Unlike other fungi, Pc is resistant to chitosan, a deacetylated form of chitin, used in agriculture as a biopesticide to control plant pathogens. In the present work, we show that chitosan increases Meloidogyne javanica egg parasitism by P. chlamydosporia. Using antibodies specific to the Pc enzymes VCP1 (a subtilisin), and SCP1 (a serine carboxypeptidase), we demonstrate chitosan elicitation of the fungal proteases during the parasitic process. Chitosan increases VCP1 immuno-labelling in the cell wall of Pc conidia, hyphal tips of germinating spores, and in appressoria on infected M. javanica eggs. These results support the role of proteases in egg parasitism by the fungus and their activation by chitosan. Phylogenetic analysis of the Pc genome reveals a large diversity of subtilisins (S8) and serine carboxypeptidases (S10). The VCP1 group in the S8 tree shows evidence of gene duplication indicating recent adaptations to nutrient sources. Our results demonstrate that chitosan enhances Pc infectivity of nematode eggs through increased proteolytic activities and appressoria formation and might be used to improve the efficacy of M. javanica biocontrol.

Indian paint fungus : a method for recognizing and reducing hazard in advanced grand and white fir regeneration in eastern Oregon and Washington /

Bibliography: p. 9.

Researches on the life-history of Hemileia vastatrix, the fungus of the "coffee-leaf disease".

Linn.soc. Jour.(Bot.) v.19, p.299-335, 1882.

Report on insect and fungus pests no. 1,

Mode of access: Internet.

Immortal holding a numinous fungus

H: 1 ft. 7 1/64 in.; gilt bronze

Dissertatio botanico-medica in qua Fungus melitensis ... /

Also published in Linne's Amoenitates academicae, v. 4, ed. 1, 1759 (and 1760); ed. 2, 1788, p. 351-367; Sel. ex. Amoenitat. v. 2, 1766, p. 153-171. cf. Hulth, Bibl. Linn. (1907) p. 101.

Sea anemone host selection by the symbiotic saddled cleaner shrimp Periclimenes holthuisi

A preliminary field survey was conducted to determine the distribution of ectosymbiotic shrimp Periclimenes holthuisi on the sea anemone Stichodactyla haddoni in Moreton Bay (Queensland, Australia). Laboratory experiments were also carried out to verify whether the shrimp show a preference for one anemone host. In the field, 45 individuals of P. holthuisi were found to be associated with 70% of the specimens of S. haddoni (n=20). We inferred this shrimp population was not space-limited because not all anemones were colonized. After having been isolated from their natural host for 2 weeks, when placed between individuals of S. haddoni and Macrodactyla doreensis (an anemone that is sympatric with S. haddoni), shrimp overwhelmingly selected S. haddoni (92%). To establish whether M. doreensis may serve as an alternative host for P. holthuisi, unacclimated shrimp were forced to associate with this anemone. Macrodactyla doreensis showed little tentacle reaction during this association; shrimp were found on the anemone's tentacles and the column. The finding that M. doreensis can serve as an alternative host for P. holthuisi demonstrates that this anemoneshrimp is adaptable to another anemone host and thus may not be highly host specific.

The effects of Produced Formation Water (PFW) on coral and isolated symbiotic dinoflagellates of coral

There is concern of the effects of Produced Formation Water (PFW, an effluent of the offshore oil and gas industry) on temperate/tropical marine organisms of the North West Shelf (NWS) of Australia. Little is known of the effects of PFW on tropical marine organisms, especially keystone species. Exposing the coral Plesiastrea versipora to a range (3-50% v/v) of PFW from Harriet A oil platform resulted in a reduction in photochemical efficiency of the symbiotic dinoflagellate algae in hospite ( in the coral tissues), assessed as a decrease in the ratio of variable fluorescence (F-v) to maximal fluorescence (F-m) measured using chlorophyll fluorescence techniques. Significant differences were noted at PFW concentrations >12.5% ( v/v). In corals where F-v/F-m was significantly lowered by PFW exposure, significant discolouration of the tissues occurred in a subsequent 4-day observation period. The discolouration ( coral bleaching) was caused by a loss of the symbiotic dinoflagellates from the tissues, a known sublethal stress response of corals. PFW caused a significant decrease in F-v/F-m in symbiotic dinoflagellates freshly isolated from the coral Heliofungia actiniformis at 6.25% PFW, slightly lower than the studies in hospite. Corals exposed to lower PFW concentrations (range 0.1%-10% PFW v/v) for longer periods (8 days) showed no decrease in F-v/F-m, discolouration, loss of symbiotic dinoflagellates or changes in gross photosynthesis or respiration ( measured using O-2 exchange techniques). The study demonstrates minor toxicity of PFW from Harriet A oil platform to corals and their symbiotic algae.

Nitrogen transfer within and between plants through common mycorrhizal networks (CMNs)

Mycorthizae play a critical role in nutrient capture from soils. Arbuscular mycorrhizae (AM) and ectomycorrhizae (EM) are the most important mycorrhizae in agricultural and natural ecosystems. AM and EM fungi use inorganic NH4+ and NO3-, and most EM fungi are capable of using organic nitrogen. The heavier stable isotope N-15 is discriminated against during biogeochemical and biochemical processes. Differences in N-15 (atom%) or delta(15)N (parts per thousand) provide nitrogen movement information in an experimental system. A range of 20 to 50% of one-way N-transfer has been observed from legumes to nonlegumes. Mycorrhizal fungal mycelia can extend from one plant's roots to another plant's roots to form common mycorrhizal networks (CMNs). Individual species, genera, even families of plants can be interconnected by CMNs. They are capable of facilitating nutrient uptake and flux. Nutrients such as carbon, nitrogen and phosphorus and other elements may then move via either AM or EM networks from plant to plant. Both N-15 labeling and N-15 natural abundance techniques have been employed to trace N movement between plants interconnected by AM or EM networks. Fine mesh (25similar to45 mum) has been used to separate root systems and allow only hyphal penetration and linkages but no root contact between plants. In many studies, nitrogen from N-2-fixing mycorrhizal plants transferred to non-N-2-fixing mycorrhizal plants (one-way N-transfer). In a few studies, N is also transferred from non-N-2-fixing mycorrhizal plants to N-2-fixing mycorrhizal plants (two-way N-transfer). There is controversy about whether N-transfer is direct through CMNs, or indirect through the soil. The lack of convincing data underlines the need for creative, careful experimental manipulations. Nitrogen is crucial to productivity in most terrestrial ecosystems, and there are potential benefits of management in soil-plant systems to enhance N-transfer. Thus, two-way N-transfer warrants further investigation with many species and under field conditions.

Spatial distribution of symbiotic shrimps (Periclimenes holthuisi, P-brevicarpalis, Thor amboinensis) on the sea anemone Stichodactyla haddoni

This study investigated the spatial distribution patterns of three shrimp species, Periclimenes holthuisi, P. brevicarpalis, and Thor amboinensis on the sea anemone Stichodactyla haddoni in the laboratory. Anemones were partitioned into five zones (mouth, inner tentacle, outer tentacle, upper column, and lower column), and shrimp distribution on these zones was determined. Regardless of species, significantly higher numbers of shrimps chose outer tentacles (>40%) over other zones during daytime. Such distribution might be attributed to their feeding practices as these crustaceans clipped and ate parts of the outer tentacles. Periclimenes holthuisi also showed varying temporal distribution patterns on their hosts. At night when anemones contracted their tentacles, shrimp moved in significant numbers from the outer tentacle region either to the column or off the anemones. Shrimps returned to the tentacles during daytime when anemones expanded their tentacles. Thus, spatial and temporal distribution of shrimps depend upon their feeding activities and degree of anemone expansion.

Endemic infection of the amphibian chytrid fungus in a frog community post-decline

The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.