Actinomycetal complex of light sierozem on the Kopet-Dag piedmont plain

The population density of actinomycetes in the samples of light sierozem from the Kopet Dag piedmont plain (75 km from Ashkhabad, Turkmenistan) reaches hundreds of thousand CFU/g soil. The actinomycetal complex is represented by two genera: Streptomyces and Micromonospora. Representatives of the Streptomyces genus predominate and comprise 73 to 87% of the actinomycetal complex. In one sample, representatives of the Micromonospora genus predominated in the complex (75%). The Streptomyces genus in the studied soil samples is represented by the species from several sections and series: the species of section Helvolo-Flavus series Helvolus represent the dominant component of the streptomycetal complex; their portion is up to 77% of all isolated actinomycetes. The species of other sections and series are much less abundant. Thus, the percentage of the Cinereus Achromogenes section in the actinomycetal complex does not exceed 28%; representatives of the Albus section Albus series, Roseus section Lavendulae-Roseus series, and Imperfectus section belong to rare species; they have been isolated not from all the studied samples of light sierozem, and their portion does not exceed 10% of the actinomycetal complex.     

Rhizoshere microflora of some citrus as a source of antagonistic actinomycetes

Qualitative distribution of microorganisms in rhizosphere soils under citrus trees (lemon and orange) was observed by the serial dilution-spread plate method. The maximally represented actinomycete genus was Streptomyces followed by Micromonospora and Nocardia. The streptomycete strains were classified in taxonomical groups by their characteristics. Several cultures produced antibacterial or antifungal antibiotics. Some of the antibiotics have been determined as beta-lactams, polyethers, nonpolyenic macrolides and azalomycin B. Other strains synthesized exoenzymes.     

The effects of invasive North American beavers on riparian plant communities in Cape Horn, Chile: Do exotic beavers engineer differently in sub-Antarctic ecosystems?

North American beavers (Castor canadensis) were introduced into southern South America in 1946. Since that time, their populations have greatly expanded. In their native range, beavers shape riparian ecosystems by selectively feeding on particular plant species, increasing herbaceous richness and creating a distinct plant community. To test their effects as exotic engineers on sub-Antarctic vegetation, we quantified beaver impacts on tree canopy cover and seedling abundance and composition, as well as their impacts on herbaceous species richness, abundance and composition on Navarino Island, Cape Horn County, Chile (55°S). Beavers significantly reduced forest canopy up to 30 m away from streams, essentially eliminating riparian forests. The tree seedling bank was greatly reduced and seedling species composition was changed by suppressing Nothofagus betuloides and Nothofagus pumilio, but allowing Nothofagus antarctica. Herbaceous richness and abundance almost doubled in meadows. However, unlike beaver effects on North American herbaceous plant communities, much of this richness was due to invasion by exotic plants, and beaver modifications of the meadow vegetation assemblage did not result in a significantly different community, compared to forests. Overall, 42% of plant species were shared between both habitat types. Our results indicate that, as predicted from North American studies, beaver-engineering increased local herbaceous richness. Unlike in their native range, though, they did not create a unique plant community in sub-Antarctic landscapes. Plus, the elimination of Nothofagus forests and their seedling bank and the creation of invasion pathways for exotic plants together threaten one of the world’s most pristine temperate forest ecosystems.     

Extremophilic and extremotolerant actinomycetes in different soil types

Problems on the resistance of soil actinomycetes to various environmental factors (pH, salinity, temperature, and moisture) are discussed. Actinomycetes as a special group of prokaryotes were revealed to have a greater range of tolerance to these factors than was thought earlier. The regularities of the distribution of extremophilic and extremotolerant actinomycetes developing in unusual for mycelial bacteria conditions, their structural-functional characteristics, and their taxonomic composition were determined. The predominance of acidophilic representatives of the Micromonospora genus in acid soils (typical peat, soddy-podzolic, and taiga podzol) and the haloalkaliphilic Streptomyces pluricilirescens and S. prunicolor species in desert saline soils are shown. The specific features of the actinomycete complexes on thermal fields of the weakly developed stratified volcanic soils are described. In these complexes, the thermophilic forms were represented only by species of the Micromonospora genus; and the mesophilic forms, by Microbispora species. In the periodically heated desert soils, among the thermophilic actinomycetes, representatives of rare Actinomadura, Saccharopolyspora and Streptosporangium genera along with Streptomyces species were indicated. The mechanisms of the resistance of the actinomycetes to the extreme environmental conditions are discussed.     

Genetic diversity among Elaeagnus compatible Frankia strains and sympatric-related nitrogen-fixing actinobacteria revealed by nifH sequence analysis

Elaeagnus compatible Frankia isolates from Tunisian soil have been previously clustered with Frankia, colonizing Elaeagnaceae and Rhamnaceae in two different phylogenetic subgroups, while strain BMG5.6 was described as a new lineage closely related to Frankia and Micromonospora genera. In this study we further assess the diversity of captured Frankia and the relationship with BMG5.6-like actinobacteria, by using nifH gene sequences. Using PCR-RFLP screening on DNA extracted from lobe nodules, additional microsymbionts sharing BMG5.6 features have been detected proving a widespread occurrence of these actinobacteria in Elaeagnus root nodules. Neighbour-Joining trees of Frankia nifH sequences were consistent with previously published 16S rRNA and GlnII phylogenetic trees. Although four main clades could be discerned, actinobacterial strain BMG5.6 was clustered with Frankia strains isolated from Elaeagnus. The present study underscored the emanation of new diazotrophic taxon isolated from actinorhizal nodules occupying intermediate taxonomic position between Frankia and Micromonospora. Moreover, its aberrant position in nifH phylogeny should open network investigations on the natural history of nitrogen-fixing gene among actinobacteria.     

Long term effect of sewage sludge additions on populations of Nocardia asteroides,micromonospora and Thermoactinomyces in soil

Actinomycetes are considered to be members of the autochthonous component of the soil microflora. However, nocardiae and, to a lesser extent micromonosporae, can exhibit a sustained zymogenous-like response when complex recalcitrant organic substrates are added to soil in the form of dried sewage sludge. Numbers of Nocardia and Micromonospora do not increase when wet sludge, which contains less organic matter, is added to soil. In contrast, Thermoactinomyces did not follow this trend and greater numbers were isolated from the wet, rather than the dried, sludge plots. Results of herbage produced by the dried sludge plots indicate that plant nutrients were continually mineralized during the 3 yr following sludge addition.     

Psychrotolerant actinomycetes on plant substrates of tundra and taiga ecosystems

Studies of tundra flowering plants and mosses on the Тaymyr Peninsula have determined the presence of thousands and tens of thousands of colony formation units of psychrotolerant actinomycetes in 1 g of vegetation substrate, which is smaller than the amount of mesophilic forms by one to two orders of magnitude. Incubation of plants at 5°C has shown very small taxonomical variety of actinomycetes. The actinomycete complex is represented by species of the genus Streptomyces, belonging to the sections and series Albus Albus and Cinereus Achromogenes, and by the genus Micromonospora.     

Effect of montmorillonite and humate on growth and metabolic activity of some actinomycetes

In well-aerated culture solutions Ca-montmorillonite at 0.25% concentration markedly accelerated and increased growth, glucose consumption and CO₂ evolution by various Streptomyces, Micromonospora and Nocardia species. The montmorillonite was a little more active than Ca-humate and was usually still but somewhat less effective when confined to dialysis tubing. Ca-exchange resin, Na₂SiO₃ and finely powdered CaCO₃ exerted very little or no effect. In many cultures the relation of glucose consumption to biomass formation indicated a more efficient use of the glucose C for cell synthesis in the presence of clay. In other cultures the greater biomass formation was associated with a more rapid and complete utilization of the glucose present.     

Traditional uses of medicinal plants for dermatological healthcare management practices by the Tharu tribal community of Uttar Pradesh, India

The aim of present study was to explore and document medicinal plants used for the traditional dermatological healthcare management practices by the the Tharu tribal community of Uttar Pradesh. The study was conducted during 2000–2004. Information was gathered from 230 informants residing in 46 villages in Terai region of Indo-Nepal boarder using questionnaires; oral interviews and group discussions. Total 92 medicinal plant species were cited for the preparation of 113 crude drug formulations. Voucher specimens of cited plant species were collected and identified as belonging to 82 genera and 49 families. Thirty-nine medicinal plant species were reported for the first time for dermatological healthcare problems from India. The dermatological healthcare problems managed were cut and wounds, ringworm, leprosy, eczema, scabies, leucoderma, boils, carbuncles, pimples, skin blemishes, spots, eruption, and burns etc. The most commonly and popularly used medicinal plant species for management of dermatological healthcare problems in the study area were Curcuma longa L., Azadirachta indica A. Juss and Melia azedarach L. It is concluded that dermatological healthcare management practice in the study area depends largely on wildly growing medicinal plant species. There is an urgent need to properly conserve the medicinal plant species growing in this area for human welfare. There is also need for further phytopharmacological studies to provide scientific explanation for the usages of 57 medicinal plant species for which to the best of our knowledge phytopharmacological literatures are not available.     

Haloxylon stocksii (Boiss.) Benth. et Hook. f., a promising halophyte: distribution, cultivation and utilization

Neglected and underutilized species often play a vital role in securing food and livestock feed, income generation and energy needs of rural population. In spite of their great potential little attention has been given to these species. Khar, Haloxylon stocksii (Boiss.) Benth. et Hook. f. (syn. Haloxylon recurvum sensu Bunge in Boiss.) (Chenopodiaceae) is a halophyte shrub naturally growing in the arid and semi-arid saline lands. The species has been used for making Saji and a number of other beneficial applications that include the use as fodder, folk medicine and plant ash as washing agent. Moreover the species is tolerant to environmental stresses, which make it suitable for cultivation in saline land of arid and semi-arid regions. One major factor hampering its successful improvement and promotion is the limited and scattered knowledge available on this species. The purpose of this paper is to highlight the importance of H. stocksii by presenting information on species’ occurrence, ecology, uses, cultivation and ethnobotany to stimulate interest to promote its domestication and commercialization for regional and global markets.     

“Bracatinga” (Mimosa scabrella Bentham), a multipurpose tree growing in Southern Brazil: chromosome number and genetic variation

Mimosa scabrella Bentham, popularly known as “bracatinga” in Brazil, is a very important multipurpose tree especially in the southern region of the country, where it occurs naturally in plant associations called “bracatingais”. The species is presently in danger of losing genetic variability as it normally occurs in regions subjected to intense urbanization, industrialization, agriculture and cattle raising. Aiming at broadening the knowledge about the species we have investigated cytogenetic characteristics and genetic diversity among natural populations. The results show that all populations are tetraploid (2n = 4× = 52) and that there is a high genetic diversity among the populations. There is still time to avoid genetic erosion of M. scabrella if the areas where the species occurs are protected.     

Soil application of insecticides influences microorganisms and plant nutrients

An experiment was conducted under laboratory conditions to investigate the effect of four insecticides, viz. HCH, phorate, carbofuran and fenvalerate at their field application rates (7.5, 1.5, 1.0 and 0.35 kg a.i. ha⁻¹, respectively), on the growth and development of bacteria, actinomycetes and fungi as well as their role in the transformations and availability of some plant nutrients in laterite soil (Typic Orchragualf). All the insecticides in general, and HCH and phorate in particular, significantly increased the population of microorganisms in soil. The most predominant genera of microorganisms, such as Bacillus, Micrococcus and Aspergillus were not affected by most of the insecticides. However, some of the insecticides stimulated the growth and development of Bacillus, Proteus, Corynebacterium, Streptomyces, Fusarium, Trichoderma and Rhizopus. On the other hand, some insecticide exerted deleterious effect on the proportions of Pseudomonas, Staphylococcus, Nocardia, Micromonospora, Aspergillus and Rhizopus. Incorporation of insecticides also significantly stimulated the mineralization and availability of organic C, N and P in soil. Among the tested substances, the stimulations were more pronounced with HCH followed by phorate and fenvalerate.     

Heavy Metal Concentration Survey in Soils and Plants of the Les Malines Mining District (Southern France): Implications for Soil Restoration

Mining activities generate spoils and effluents with extremely high metal concentrations of heavy metals that might have adverse effects on ecosystems and human health. Therefore, information on soil and plant metal concentrations is needed to assess the severity of the pollution and develop a strategy for soil reclamation such as phytoremediation. Here, we studied soils and vegetation in three heavily contaminated sites with potential toxic metals and metalloids (Zn, Pb, Cd, As, TI) in the mining district of Les Malines in the Languedoc region (southern France). Extremely high concentrations were found at different places such as the Les Aviniéres tailing basins (up to 160,000 mg kg^?C1 Zn, 90,000 mg kg^?C1 Pb, 9,700 mg kg^?C1 of As and 245 mg kg^?C1 of Tl) near a former furnace. Metal contamination extended several kilometres away from the mine sites probably because of the transport of toxic mining residues by wind and water. Spontaneous vegetation growing on the three mine sites was highly diversified and included 116 plant species. The vegetation cover consisted of species also found in non-contaminated soils, some of which have been shown to be metal-tolerant ecotypes (Festuca arvernensis, Koeleria vallesiana and Armeria arenaria) and several Zn, Cd and Tl hyperaccumulators such as Anthyllis vulneraria, Thlaspi caerulescens, Iberis intermedia and Silene latifolia. This latter species was highlighted as a new thallium hyperaccumulator, accumulating nearly 1,500 mg kg^?C1. These species represent a patrimonial interest for their potential use for the phytoremediation of toxic metal-polluted areas.     

Arbuscular mycorrhizal fungi for salinity stress: Anti-stress role and mechanisms

Salinity stress is considered one of the most harmful environmental plant stresses, as it reduces irrigated land crop production by over 20%worldwide.Hence, it is imperative to develop salt-tolerant crops in addition to understanding various mechanisms enabling plant growth under saline stress conditions.Recently, a novel biological approach that aims to address salinity stress has gained momentum, which involves the use of arbuscular mycorrhizal (AM) fungi in plant-microbe interactions. It has ...     

Depression of tree recruitment by the Pacific rat (Rattus exulans Peale) on New Zealand's northern offshore islands

Recruitment of tree populations on islands with and without Rattus exulans Peale, and recruitment changes on islands before and after rat eradication are compared using size-class analyses. Seedling establishment in rat-proof exclosures was compared with adjacent control areas. R. exulans depress recruitment of 11 species of coastal trees among 17 species studied: Coprosma macrocarpa, Coprosma repens, Dysoxylum spectabile, Melicytus novae-zelandiae, Nestegis apetala, Pisonia brunoniana, Pittosporum crassifolium, Pouteria costata, Pseudopanax lessonii, Rhopalostylis sapida and Streblus banksii; some to the point of local extinction. Where R. exulans has reached small islands supporting dense colonies of petrels (Procellariidae, Pelecanoididae), the numbers of some plant and animal species have been greatly reduced. Successional pathways in vegetation recovering on larger islands formerly occupied by Maori, have also been altered by this rat. Similar effects by R. exulans on the plant life of Pacific islands are probable considering the length of time R. exulans has been present.     

Markers of Soil Organic Matter Transformation in Permafrost Peat Mounds of Northeastern Europe

For the paleoreconstruction of permafrost peat mounds and the identification of plant communities participating in the formation of peat, the contents of n-alkanes (C₂₀–C₃₃) have been determined, and relative changes in the stable isotope compositions of carbon and nitrogen and the C/N ratio have been analysed. Several indices (CPI_alkanes, P_aq, P_wax) have been calculated to assess the degree of decomposition of the peats studied and the contributions of different plant species to their formation. It has been found that shortand long-chain n-alkanes are concentrated in high-moor peat, while medium-chain alkanes are typical for transitional peat. Integrated analysis of the studied markers has shown that the botanical and material composition of peat, anaerobic conditions of bog formation, and permafrost play an important role in the preservation of organic carbon in permafrost peat mounds. Alternation of plant associations is the main reason for changes in n-alkane concentrations, C/N ratios, and δ13C values.     

The ecology and conservation of Kunzea sinclairii (Myrtaceae), a naturally rare plant of rhyolitic rock outcrops

Kunzea sinclairii is a local endemic on Great Barrier Island, northeastern New Zealand. While variously ranked as vulnerable and endangered in the past, we show that this species is naturally uncommon and under no threat of extinction. Previous assessments of its conservation status have been based on inadequate knowledge of its ecology. K. sinclairii is a rupestral species whose optimum habitat is low shrubland on rhyolitic rock outcrops and cliffs. Because of past logging and burning of forest adjacent to the habitat to which it is adapted, K. sinclairii expanded its range. However, in regeneration back to forest, K. sinclairii is being excluded as it is overtopped by other species. This has led to the impression that it is declining. Similarly, a suggestion that K. sinclairii could be threatened by hybridisation with the more abundant closely related K.ericoides is not supported as the hybrids are confined to the disturbed sites created by logging and fire. This case study highlights the importance of having a good understanding of the ecology of uncommon plant species before making decisions on their conservation. Natural rarity does not itself necessarily equate with increased extinction risk and these taxa should not be classified as threatened.     

Mesophilic and thermotolerant actinomycetes in strongly heated soils

Mesophilic and thermotolerant actinomycetes were identified in strongly heated desert-steppe soils of Mongolia, mountainous meadow soils of the Central Caucasus, and cyanobacterial films on volcanic ash near hot springs of Kamchatka. Thermotolerant actinomycetes in these soil objects were more abundant and had a greater taxonomic diversity in comparison with mesophilic actinomycetes. Thermotolerant Streptomyces were present in all the objects, except for sample 117 from the desert-steppe soil and the cyanobacterial film on volcanic ash. Thermotolerant actinomycetes from the Micromonospora and Actinomadura genera predominated in the desert-steppe soil; representatives of the Micromonospora genus predominated in the cyanobacterial film on volcanic ash, and representatives of the Microtetraspora genus predominated in the samples of geyserite near hot springs of Kamchatka.     

Ecogeographical distribution of wild, weedy and cultivated Sorghum bicolor (L.) Moench in Kenya: implications for conservation and crop-to-wild gene flow

The potential gene flow between a crop and its wild relatives is largely determined by the overlaps in their ecological and geographical distributions. Ecogeographical databases are therefore indispensable tools for the sustainable management of genetic resources. In order to expand our knowledge of Sorghum bicolor distribution in Kenya, we conducted in situ collections of wild, weedy and cultivated sorghum. Qualitative and quantitative morphological traits were measured for each sampled wild sorghum plant. Farmers’ knowledge relating to the management of sorghum varieties and autecology of wild sorghum was also obtained. Cluster analysis supports the existence of several wild sorghum morphotypes that might correspond to at least three of the five ecotypes recognized in Africa. Intermediate forms between wild and cultivated sorghum belonging to the S. bicolor ssp. drummondii are frequently found in predominantly sorghum growing areas. Crop-wild gene flow in sorghum is likely to occur in many agroecosystems of Kenya.     

Current knowledge and breeding perspectives for the spider plant (<Emphasis Type="Italic">Cleome gynandra</Emphasis> L.): a potential for enhanced breeding of the plant in Africa

Cleome gynandra is one of the most promising African leafy vegetables consumed in most parts of Africa. The crop is a rich source of vitamins A and C and minerals such as calcium, iron, magnesium and protein. The leaves and seeds of spider plant are used in indigenous medicine in several countries. Despite the numerous nutritive benefits and ethnopharmacological uses of the plant, C. gynandra is still underutilized due to lack of awareness and promotion of production technologies and utilization. Available information is limited and short on several relevant and rudimentary components. Hence, this review focuses on the current knowledge on C. gynandra, with regards to its botany, ecology, cultivation systems, utilization, nutraceutical properties as well as the breeding avenues that will contribute to promoting the species, aimed at ensuring food and nutritional security and efficient management of its genetic resources. Breeding programmes aimed at minimizing the bitterness of the leaves so to arouse the interest of consumers, and the mechanisms involved in the responses and adaptation of C. gynandra as a C₄ plant to salinity stress, were also explored.