Effects of nonindigenous tadpoles on native tadpoles in Florida: evidence of competition

The impacts of nonindigenous species on native ecosystems can be severe, sometimes leading to the extinction of native taxa. Interspecific competition is a potential mechanism of negative impact of invasive species, but few studies have conclusively demonstrated competition between native and nonindigenous taxa. In this study I used experimental manipulations to examine the competitive effects of the larvae of two widely introduced anurans, the cane toad, Bufo marinus, and the Cuban treefrog, Osteopilus septentrionalis, on the growth and development of the larvae of two native anurans (the southern toad, Bufo terrestris, and the green treefrog, Hyla cinerea). The presence of O. septentrionalis larvae consistently impacted growth and development of native larvae, resulting in reduced growth rates and delayed metamorphosis of both native species and smaller mass at metamorphosis of B. terrestris. Hyla cinerea larvae transformed at greater body masses when reared with the rapidly transforming nonindigenous species as a result of competitive release. The negative effects of O. septentrionalis on native larvae were generally significant whether native tadpoles were exposed to O. septentrionalis alone or in combination with B. marinus. In contrast, B. marinus tadpoles did not significantly impact the growth or development of either native species. Neither nonindigenous species significantly decreased the survivorship of native larvae, although a trend toward decreased survivorship was evident for H. cinerea. These results suggest that nonindigenous larval anurans may adversely impact native tadpole communities as a result of interspecific competition.     

Nuclear intron-targeting markers in genetic diversity analysis of black nightshade (Solanum sect. Solanum,Solanaceae) accessions

Different molecular markers are routinely used in studies of potato (Solanum tuberosum) and the genus Solanum in general. Genome sequence databases provide potential to design new markers for various applications. Here we present the application of a recently developed core set of nuclear intron-targeting (indel) markers. These markers are based on the fact that in the plant genome introns are more variable than exons; therefore primers flanking exons can reveal polymorphisms related to introns. We detected such variation among accessions of the eight different species of black nightshades (Solanum sect. Solanum). Members of this group are important sources of food, mostly in Africa, while others are poisonous weeds with near global distribution. The tested 29 primers were designed previously for potato based on Solanaceae EST and other genomic databases and targeted 16 different genes. Our results showed that Solanum intron-targeting markers are not very polymorphic but identified considerable structure among accessions indicating fairly high interspecies differentiation. Further analyses showed that inbreeding is unlikely to be the major driving force in determining the genetic structure of the analyzed species. All phylogenetic analyses resolved the species included in our study as distinct clades with high support values, but provided weak information about their internal relationships. In summary, indel markers would be useful for the assignment of new Solanum germplasm to taxonomic groups or to identify certain taxa. They could also be used to address important question about genetic diversity and should yield results comparable to other markers covering the whole genome.     

Landraces in Inland areas of the Basilicata region, Italy: monitoring and perspectives for on farm conservation

A collecting expedition has been carried out in the inland areas of the Basilicata Region, South Italy. Each of the 14 selected municipalities was subdivided in three strata based on the geographical distribution of population and orography: 1. city boundaries, 2. group of country houses, 3. isolated farm houses. Five sites were selected within each stratum/town for a total of 185 sites. In 101 sites crop species germplasm was collected and the farmer-maintainers were interviewed. Altogether 350 accessions were collected, the most common species were Capsicum annuum, Lycopersicon esculentum and Phaseolus vulgaris. A significant number of landraces are still preserved on farm, mostly in isolated farm houses (average age of farmers: 60?years) adopting traditional farming systems but a number of young farmers were also present. Perspectives for on farm conservation and management are discussed and public economic support for “farmer-maintainers” proposed.     

Taxonomy and genetic diversity of domesticated Capsicum species in the Andean region

The Capsicum genus is native to tropical America and consists of 27 species, five of which are used as fresh vegetables and spices: Capsicum annuum L., Capsicum chinense Jacq., Capsicum frutescens L., Capsicum baccatum L. and Capsicum pubescens R. et P. The study of the relationships among species of cultivate Capsicum species will be useful for breeding new cultivars or hybrids. This study is focused on the genetic diversity and relationships of these species that were collected in the Andean region. Ten microsatellites and four AFLP combinations were used to characterize 260 Capsicum accessions. The AFLP tree turned out to be informative regarding relationships among species. The data clearly showed the close relationships between C. chinense and C. frutescens. Moreover, C. cardenasii and C. eximium were indistinguishable as a single, morphologically variable species. Our data showed C. baccatum and C. praetermissum to be distinct species that form a compact group. In the present work, AFLP fingerprinting indicated that C. chacoense was placed in the C. baccatum complex and showed C. tovarii as a separate species. In addition, SSR data indicated that there is intraspecific differentiation in the species C. chinense, C. baccatum and C. pubescens, as the PCoA-based clustering showed a clear geographic division related to country. Even though Bolivia is considered to be the nuclear area for these species, we have found similar variability in Ecuador and Peru for several Capsicum species.     

Rhizobia nodulating African Acacia spp. and Sesbania sesban trees in southern Ethiopian soils are metabolically and genomically diverse

The diversity of 110 rhizobial strains isolated from Acacia abyssinica, A. seyal, A. tortilis, Faidherbia albida, Sesbania sesban, Phaseolus vulgaris, and Vigna unguiculata grown in soils across diverse agro-ecological zones in southern Ethiopia was assessed using the Biolog™ system and amplified fragment length polymorphism (AFLP) fingerprinting technique. By cluster analysis of the metabolic and genomic fingerprints, the test strains were grouped into 13 Biolog and 11 AFLP clusters. Twenty-two strains in the Biolog method and 15 strains in the AFLP analysis were linked to eight and four reference species, respectively, out of the 28 included in the study. Most of the test strains (more than 80% of 110) were not related to any of the reference species by both methods. Forty-six test strains (42% of 110) were grouped into seven corresponding Biolog and AFLP clusters, suggesting that these groups represented the same strains, or in some cases clonal descendants of the same organisms. In contrast to the strains from S. sesban, isolates from Acacia spp. were represented in several Biolog and AFLP clusters indicating the promiscuous nature of the latter and widespread occurrence of compatible rhizobia in most of the soil sampling locations. The results showed that indigenous rhizobia nodulating native woody species in Ethiopian soils constituted metabolically and genomically diverse groups that are not linked to reference species.     

Soil nematode genera that predict specific types of disturbance

Nematode community indices would be more cost-effective and interpretable if ambiguous genera were removed and indices reduced to only genera with known sensitivity or response to specific types of disturbance. The objective of the present study was to perform a methodical multivariate analysis of existing datasets of high quality and enumerate the genera that respond universally consistent to a specific type of disturbance, treatment, or management worldwide. We collected 20 sources of original data from land used for agricultural purposes, whether cropland, livestock grazing or fruit orchard with manipulated treatments in cultivation, inorganic or organic fertilization or contaminated by heavy metals. Canonical correspondence analysis was performed to determine the effect of disturbance type on the composition of soil nematode communities. Genera that performed consistently in a single direction and across at least two seasons were identified. Briefly, cultivation reduced abundances of Diphtherophora, Prismatolaimus and Tylenchorhynchus. Application of synthetic chemical fertilizers reduced numbers of Plectus. Application of organic fertilizers resulted in increased numbers of Cruznema, Mesorhabditus, Mesodorylaimus and Nygolaimus. No genera met the criteria for responding positively to either cultivation or inorganic fertilization or negatively to organic fertilization. The source of nutrients apparently affected nematode communities differently. Selected nematode genera were correlated positively with the heavy metals Cd, Cu and Zn, while nematode genera correlated negatively with Cr and Se. These genera need to be verified by independent data to confirm that they respond predictably and consistently to these specific types of disturbance. Once verified, this subset of genera will improve interpretation of index values and can be the initial targets for developing molecular probes that can be made accessible to non-specialists.     

Flora and plant genetic resources of ancient olive groves of Apulia (Southern Italy)

A floristic study of vascular flora of ancient olive groves of Apulia (Italy) was carried out from 2009 to 2011. Research was made in the fields and in the ecological infrastructures of four olive groves, located in protected areas: National Park of Gargano, Park of Dune Costiere, State and Marine Natural Reserve of Torre Guaceto and of Le Cesine. Floristic analysis was carried out by Raunkiaer and Braun-Blanquet. Biological forms and chorological types were named according to Raunkiear. Overall, 408 taxa were identified, of which 332 species, 73 subspecies and 3 varieties, belonging to 275 genera and 74 families. A small segment of 18 taxa, out of 408, was considered of conservation interest. For these taxa the topography of the collecting site, plant community, population density, degree of vulnerability and habitats were recorded, according to the Directive 92/43/EEC. Another segment of 111 taxa, out of a total of 408, was considered important for usage, which for the sake of presentation has been divided in five arbitrary categories: food crops, fodder crops, medicinal, aromatic and officinalis, crop wild relatives and edible wild species. For each of these taxa, an attempt to provide relevant information was made. Only two taxa, i.e., Muscari parviflorum and Aegilops uniaristata are common to both segments. The work was carried out within the competence of the LIFE+ CENT.OLI.MED. (LIFE07 NAT/IT/000450) project, with the aim to gather information for improving conservation and management of olive groves of Apulia, as well as of their related wild life.     

The Criollo cacao tree (<Emphasis Type="Italic">Theobroma cacao</Emphasis> L.): a review

In commercial terms, Criollo cacao trees (Theobroma cacao L.) are reputed to be the source of the commercial product (fermented and dried cocoa beans), which sells for the best price on the market. Nevertheless, the term “Criollo” has numerous meanings and interpretations depending on if it is used by commercial users or botanists, growers or breeders. Our review aims to specify which cocoas can justifiably carry the Criollo name. “Criollo” is a botanical subspecies of Theobroma cacao, i.e. Theobroma cacao subsp. cacao; however, the true Criollos form just one of the ten currently accepted genetic groups in the species. We thus provide an overview of genetic studies on the subject (published or not), along with what is currently known about “True Criollo” or “Ancient Criollo” cacao trees. In fact, there are few representatives in collections that are duly acknowledged to be true Criollos, particularly in the two International Cocoa Genebanks, where only seven clones are available. It is nonetheless certain that some true Criollos do exist in other collections but have not been formally identified (by genetic studies) as members of the Criollo genetic group. Likewise, some true Criollos, be they cultivated or subspontaneous, exist in Mexico and Central and South America (Venezuela and Colombia). However, certain clones called “modern Criollos”, which are closely related to the true Criollos but arise from hybridization with other genetic groups, are more common.     

Effects of Sodium on Potassium Nutrition in Three Tropical Root Crop Species

The potassium (K) nutrition and high K requirement of tropical root crops may be affected by their sodium (Na) status, as has been observed in a number of plant species. Solution culture was used to study the effects of K and Na supplies in tannia [Xanthosoma sagittifolium (L.) Schott.], sweet potato [Ipomoea batatas (L.) Lam.] and taro [Colocasia esculenta (L.) Schott]. At low K supply, Na ameliorated symptoms of K deficiency and increased growth in tannia, and to a lesser extent in sweet potato, but not in taro. None of the species responded to Na at adequate K supply. Differences in response to Na were attributed to differences in Na translocation to plant tops. At maximum Na supply, the Na concentration in index leaves averaged 1.82% in tannia, 0.205% in sweet potato, and 0.0067% in taro. An increase in the supply of Na resulted in a shift in the critical K concentration for deficiency (i.e., 90% of maximum yield) in index leaves from 2.9% to 1.2% in tannia, and from 4.8% to 2.5% in sweet potato. The critical K concentration in taro was 3.3%, irrespective of Na supply. To overcome the problem in tannia and sweet potato of determining the critical concentration relevant to a leaf sample of unknown K status, a relationship was established for each species relating the critical K concentration to the concentration of Na in the index leaves.     

Polyphasic characterization of mung bean (Vigna radiata L.) rhizobia from different geographical regions of China

Polyphasic characterization of 54 indigenous mung bean (Vigna radiata L.) rhizobia from different geographic regions of China was determined by analyzing the variability of 16S rRNA gene RFLP, 16S–23S rRNA gene Intergenetic Spacer (IGS) RFLP, G-C rich RAPD and phenotype assays. Based on these characteristics, mung bean rhizobia were clustered into four groups. Group I comprised 16 slow-growing isolates from a variety of geographic regions. This group was genetically distinct from Bradyrhizobium japonicum and Bradyrhizobium liaoningense, and may represent a new species. Group II was composed of 18 isolates, which could be sub-divided into two sub-groups that were respectively related to B. japonicum and B. liaoningense. Group III comprised 12 isolates from South China and clustered together with Bradyrhizobium elkanii. Group IV formed a miscellany of 8 fast-growing isolates variously related to the genera Sinorhizobium, Rhizobium and Mesorhizobium.     

Effect of fertilizer treatments and planting time on the yield of some grain legumes of the benue river basins of Nigeria

A selection process for an ideal cover crop for yarn, maize, and cassava was initiated in 1993 cropping season in Makurdi, Nigeria. Four types of food legume crops grown locally were selected for the trials. The yield potentials of akidi (Phaseolus vulgaris), ground akidi (Sphenostylis stenocarpa), odudu (Phaseolus lunatus), and kafanji (Vigna unguiculata) were evaluated in two cropping seasons and under conditions where either no fertilizers, 50 kg nitrogen‐potassium‐phosphorus (NKP)/ha or 21 kg P/ha from single superphosphate (SSP) source were applied. The crops were planted in April and repeated in August of the same year in a 4 x 3 factorial in a split‐plot design. Fertilizer NKP generally increased the grain yield of all the crops significantly. The yield differences due to P fertilizers for odudu and akidi were not statistically significant (P=0.05). The P fertilizer resulted in significant increases in the grain yield of kafanji (from 1.113 to 1.7 mt/ha) and ground akidi (0.97 to 1.27). The biomass, root systems, and nodule yields were also increased proportionally by P application for all the legumes. No significant yield differences was observed between early and late crops in grain yield when no fertilizer was used. However, the crops produced about 30–40% less nodules, biomass, and root yield due to late planting (August).     

Tempo-spatial dynamics of arbuscular mycorrhizal fungi under clonal plant Psammochloa villosa Trin. Bor in Mu Us sandland

Tempo-spatial dynamics of AM fungi within the rhizome system of Psammochloa villosa (Poaceae) were investigated in Mu Us sandland, northwest China. Soil samples in the annual and perennial ramet rhizospheres of P. villosa were collected in 2007. AM fungal percent colonization reached maximal values in the rainy season and spore number in the dry season. Spore number exhibited positive correlation with soil pH and available phosphorous (P) (P < 0.01), and negative correlation with available nitrogen (N) (P < 0.05). Vesicular, arbuscular, hyphal and total colonization were positively correlated with soil organic matter and available P (P < 0.01), and negatively correlated with available N (P < 0.01). Fourteen species of AM fungi in four genera were isolated. The same AM fungal taxa were found in the annual and perennial ramet rhizospheres, although the last ones had higher fungal colonization and spore number. A high Shannon-Weiner diversity index of AM fungi was observed. Spore number and species richness indicated that Glomus was the predominant AM fungi, especially the small-spored taxa. AM fungal dynamics under P. villosa are highly seasonal: different aged ramets and nutrient availability have effects on AM fungal development and abundance in Mu Us sandland.     

Towards the conservation of crop wild relative diversity in North Africa: checklist,prioritisation and inventory

Crop wild relatives (CWR) are wild species that are more or less genetically related to crops that can be used to introgress useful genes for improvement of productivity, resistance to biotic and abiotic stresses and quality of cultivated crops. They are important in crop improvement to achieve food security for an increasing population and to overcome the challenges caused by climate change and the new virulence of major diseases and pests. These genetic resources are increasingly threatened in their natural habitats through over-exploitation and land reclamation and degradation. Therefore, their efficient and effective conservation would be taxonomically and genetically valuable and will contribute to maintaining and promoting the sustainability of crop diversity, facilitating agricultural production and supporting the increasing demand for food, feed and natural resources. A checklist of 5780 Crop Wild Relatives (CWR) taxa from North Africa was obtained using the CWR Catalogue for Europe and the Mediterranean (PGR Forum). Of which consists 76% of the flora of North Africa. The checklist contains 5588 (~97%) native taxa and 192 introduced. Families with higher taxa richness are Fabaceae, Asteraceae, and Poaceae. These three families constitute more than 33% of the total taxa included in the checklist. About 9% (502) CWR taxa identified as a priority for conservation in North Africa using four criteria, the economic value of the crop, the relatedness degree of wild relatives to their crop, threat status using IUCN red list assessment, and finally the centre of origin and/or diversity of the crop. Of these, 112 taxa were assigned high, 268 medium and 122 low priorities for effective conservation. Those assessed as threatened using IUCN Red list and national assessment represent approximately 2% (119 taxa) of the CWR in the region. However, 21 taxa are assessed as critically endangered (CR), 53 as endangered (EN), and 45 as vulnerable (VU). Wild relatives of some globally important crops are present, with those related to wheat (Triticum aestivum L. and T. durum L.) and barley (Hordeum vulgare L.) among the highest priority crops for the North Africa region. Amongst CWR assessed as threatened, only 8 (6.7%) CWR are related to food crops, Avena agadiriana B.R. Baum. et G. Fedak (VU), A. atlantica B.R. Baum et G. Fedak (VU), A. murphyi Ladiz. (EN), Beta macrocarpa Guss. (EN), Olea europaea subsp. maroccana Guss. (VU), Rorippa hayanica Maire (VU) and Aegilops bicornis (Forssk.) Jaub. et Spach (VU). The wild relative of Safflower Carthamus glaucus M. Bieb is restricted to Egypt and Libya and assessed as rare in Egypt. The information available about the conservation and threat status of CWR in North Africa still lags behind, and more investigations are required.     

Isolation and characterization of plant growth promoting endophytic bacterial isolates from root nodule of Lespedeza sp.

Thirty-nine endophytic bacterial strains were isolated from the nodule of Lespedeza sp. grown in two different locations of South Korea. All strains were checked for their plant growth promoting (PGP) abilities under in vitro conditions. Most of the isolates showed multiple PGP activity, i.e., indole acetic acid production, ACC deaminase activity, siderophore production, and phosphate solubilization. The strains were identified by using 16S rRNA gene sequence analysis as belonging to Alphaproteobacteria, Betaproteobacteria, Actinobacteria, and Firmicutes phylum with nine different genera Arthrobacter, Bacillus, Bradyrhizobium, Burkholderia, Dyella, Methylobacterium, Microbacterium, Rhizobium, and Staphylococcus. Gene nodA amplification showed positive results only for strains from Bradyrhizobium and Rhizobium genera. The strains from Bradyrhizobium and Rhizobium genera enhanced plant growth, nodulation, and acetylene reduction activity when inoculated on Vigna unguiculata L. (cowpea), whereas other strains did not induce nodule formation but enhanced plant growth. Herbaceous legume Lespedeza sp. formed root nodules with diverse bacterial group, and probably, these bacteria can be used for stimulating plant growth.     

A new taxonomic treatment for some wild relatives of mungbean (<Emphasis Type="Italic">Vigna radiata</Emphasis> (L.) Wilcz.) based on their molecular phylogenetic relationships and morphological variations

Mungbean (Vigna radiata (L.) Wilcz.) is an important leguminous crop cultivated mainly in Asia. Its wild relatives are considered useful genetic resources for mungbean breeding. However, the taxonomic history of mungbean and its wild relatives is complicated and some confusion is still present in recent publications. In this study, we examined the rDNA-ITS sequences and morphological characteristics of 83 gene bank accessions closely related to mungbean. As a result, we classified the 83 accessions into five species and one unclassified accession. The proper taxon name for each species was determined (Vigna grandiflora (Prain) Tateishi et Maxted, Vigna mungo (L.) Hepper, V. radiata, Vigna subramaniana (Babu ex Raizada) Raizada, and Vigna trinervia (Heyne ex Wight et Arn.) Tateishi et Maxted) based on a review of their taxonomic history and morphological comparisons between gene bank accessions and type specimens. A new taxonomic treatment is proposed and a morphological key has been prepared. In this treatment, Vigna radiata (L.) Wilcz. var. setulosa (Dalz.) Ohwi et Ohashi is treated as a synonym of Vigna radiata (L.) Wilcz. var. sublobata (Roxb.) Verdc., and Vigna hainiana Babu, Gopinathan et Sharma is a synonym of V. subramaniana. Accession ‘NI1135’ was revealed to be most closely related to, but is considerably differentiated from, mungbean (V. radiata) based on its rDNA-ITS sequences. It also has distinguishing morphological characters. Plants with similar morphologies and DNA profiles might be distributed in the Indian Himalaya. However, since only one accession is available at present, the taxonomic classification of ‘NI1135’ needs to be reconsidered in the future.     

Use of native and exotic garden plants by suburban nectarivorous birds

A lack of food resources is often used as a reason for the decline in native birds in cities. This study investigated the use of exotic and native nectar resources by the nectarivore guild of birds, which often forms a major component of suburban bird communities in Australia. We investigated the food resource (nectar volume, concentration and sugar reward) of two common native and two exotic garden plant genera. We also determined the relative preference of the nectarivorous bird community for native and exotic plants and examined the relationship between nectarivore foraging preferences and particular garden characteristics. Banksias and grevilleas (native genera) produced significantly higher volumes of nectar than camellias and hibiscus (exotic genera) per floral unit, per plant and per cubic metre of foliage. Banksias also produced significantly more concentrated nectar and consequently a higher sugar reward per floral unit than the other three genera. Fourteen bird species were recorded using the study plants, although only three species were commonly observed feeding: the Red Wattlebird (Anthochaera carunculata), Little Wattlebird (Anthochaera chrysoptera) and Noisy Miner (Manorina melanocephala). Banksia and grevillea plants were preferred by all bird species, which spent significantly more time in banksia than in any other genus. Other variables influencing the time birds spent in a plant were the number of floral units per plant and the number of banksia and callistemon plants present in the garden. Overall, the native genera, banksia and grevillea were not only a more valuable source of food than the exotic genera, camellia and hibiscus, but they were also the preferred foraging sites for suburban nectarivorous birds. Whether the surplus of nectar from native shrubs is associated with territories of larger and aggressive honeyeaters competitively excluding small birds from gardens, is an important research agenda for understanding these urban bird communities.     

Fungal diversity in soils and historic wood from the Ross Sea Region of Antarctica

Microorganisms play a dominant role in Antarctic ecosystems, yet little is known about how fungal diversity differs at sites with considerable human activity as compared to those that are remote and relatively pristine. Ross Island, Antarctica is the site of three historic expedition huts left by early explorers to the South Pole, Robert F. Scott and Ernest Shackleton. The fungal diversity of these wooden structures and surrounding soils was investigated with traditional culturing methods as well as with molecular methodology including denaturing gradient gel electrophoresis (DGGE) using the internal transcribed spacer (ITS) regions of ribosomal DNA for identification. From historic wood and artifact samples and soils adjacent to the huts as well as soil samples obtained from the Lake Fryxell Basin, a remote Dry Valley location, and remote sites at Mt. Fleming and the Allan Hills, 71 fungal taxa were identified. The historic huts and associated artifacts have been colonized and degraded by fungi to various extents. The most frequently isolated fungal genera from the historic woods sampled include Cadophora, Cladosporium and Geomyces. Similar genera were found in soil samples collected near the huts. Sampling of soils from locations in the Transantarctic Mountains and Lake Fryxell Basin at considerable distances from the huts and with different soil conditions revealed Cryptococcus spp., Epicoccum nigrum and Cladosporium cladosporioides as the most common fungi present and Cadophora species less commonly isolated. DGGE revealed 28 taxa not detected by culturing including four taxa which possibly have not been previously described since they have less than 50% ITS sequence identity to any GenBank accessions. Fungi capable of causing degradation in the wood and artifacts associated with the expedition huts appear to be similar to those present in Antarctic soils, both near and at more remote locations. These species of fungi are likely indigenous to Antarctica and were apparently greatly influenced by the introduction of organic matter brought by early explorers. Considerable degradation has occurred in the wood and other materials by these fungi.     

Symbiotic effectiveness and host ranges of indigenous rhizobia nodulating promiscuous soyabean varieties in Zimbabwean soils

Presence of indigenous rhizobia nodulating promiscuous soyabean was determined in 92, mainly sandy soils, from wetter agro-ecological zones of Zimbabwe suited to soyabean production. A total of 129 isolates were obtained from nodules of promiscuous soyabean varieties, Magoye and Hernon 147, and a specific variety, Roan grown in potted soils. Magoye nodulated in 80%, Hernon 147 in 50% and Roan in only 25% of the 92 soils tested. Rhizobia populations ranged from undetectable to 2.4×10⁴ cells g⁻¹ of soil. Twenty-one of these isolates were tested for symbiotic effectiveness on two varieties, promiscuous Magoye and specific Roan. Differences in parameters such as nodule numbers, nodule weights and total N fixed reflected diversity among the indigenous isolates. Three isolates had significantly higher N₂-fixing potential in comparison with the commercial strain MAR 1491 on promiscuous Magoye. Host ranges of 34 isolates were evaluated on nine legume species: Arachis hypogaea, Cajanus cajan, Crotalaria juncea, Glycine max, Macroptilium atropurpureum, Phaseolus vulgaris, Sesbania sesbania, Vigna subterranea, Vigna unguiculata. Of these 34 isolates, 33 formed nodules with M. atropurpureum of which 61% were moderately effective to very effective while all nodulated V. unguiculata with 58% being moderately effective to very effective. Twenty-eight isolates nodulated V. subterranea and C. cajan (short season variety) with 76 and 36% of these being moderately to very effective, respectively. None of the isolates formed nodules on Phaseolus vulgaris, Arachis hypogaea or Sesbania sesban. Our results indicate that the ability of even specific varieties of soyabean to nodulate with indigenous isolates in African soils is greater than generally assumed.     

Earthworm (Lumbricidae) diversity in the Central Balkans: An evaluation of their conservation status

In this paper we summarize the current knowledge on earthworm diversity in the central part of the Balkans, in the State of Serbia. Up to now, 71 species and 8 subspecies, belonging to 18 genera, are known from investigated territory. Our aim was to produce a single priority list for earthworm conservation, particularly as the Balkan countries did not have their own Red Lists for earthworms and none of the species had a legally protected status. The list underlines the diversity of earthworms, zoogeographical position as well as category of threat. The analysis based on the IUCN (2001) Red List Categories shows that 17 of 79 taxa are Critically Endangered (5 species are serious Critically Endangered, but 12 species are only suspect for the Critically Endangered category), 9 species are Endangered and 14 species are Vulnerable. Serious candidates for their inclusion in CR category within the IUCN (2001) Red List are: Cernosvitovia biserialis, Dendrobaena kozuvensis, Lumbricus improvisus, Serbiona kosowensis montenegrina and Serbiona serbica. Of all registered earthworms, 34 taxa (43.1%) were identified only as endemic species. Unfortunately, most of the high-priority species are endemic (23 taxa). The position of the Central Balkans contributes to the great biodiversity of earthworms on its territory, but the fact that nearly 36% of its lumbricids are threatened is a strong signal that action is required.     

Genetic diversity analysis of yams (Dioscorea spp.) cultivated in China using ISSR and SRAP markers

Yam (Dioscorea spp.) is widely cultivated in China and many landraces are maintained by local farmers. However, there is little information available about their diversity and species identity. In this study, inter simple sequence repeat (ISSR) and sequence related amplified polymorphism (SRAP) techniques were used to assess genetic diversity within 21 yam landraces from seven cultivated populations. We observed high level of polymorphism among these landraces, specifically, 95.3 % for ISSR and 93.5 % for SRAP. Analysis of molecular variance revealed a significantly greater variation among the four yam species (40.39 %) and their populations (35.78 %) than within the populations (23.83 %). The unweighted pair group method arithmetic averages clusters and principal component analysis for 21 landraces formed four well-separated groups containing landraces of each of the four species, namely, Dioscorea opposita Thunb., Dioscorea alata L., Dioscorea persimilis Prain et Burkill, and Dioscorea fordii Prain et Burkill. The ISSR and SRAP primers were highly discriminatory among the 21 landraces; all 21 landraces could be easily differentiated using these primers. The average mean of gene flow (Nm = 0.1081) estimated from high genetic differentiation (Gst = 0.8222) suggested that gene flow among the populations was relatively restricted. The lack of genetic diversity within individual yam species suggests that it is critical to develop long-term strategies for enhancing genetic diversity within various yam species.