Molecular marker-mediated validation of morphologically defined landraces of Pejibaye (<Emphasis Type="Italic">Bactris gasipaes</Emphasis>) and their phylogenetic relationships

RAPD markers were used to evaluate the genetic variability and structure of seven morphologically defined landraces of pejibaye (Bactris gasipaes Kunth, Palmae) to determine their validity and phylogenetic relationships. Two hundred and twenty plants of four Amazonian and three Central American landraces of var.gasipaes (the domesticate) and 30 plants of var.chichagui (H. Karsten) Henderson (the crop ancestor) maintained at the National Research Institute for Amazonia, Manaus, Amazonas, Brazil, were utilized. Eight RAPD primers yielded 113 markers, with good reproducibility, of which 97 were polymorphic. The four Amazonian landraces had an average heterozygosity of 0.30, with 86% polymorphism, greater than the Central American landraces (0.25; 74.3%) and var.chichagui (0.27; 80%). Among landrace genetic diversity (G_ST) was 15%, while within (Hs) was 85%, essentially equivalent to the AMOVA within (82.2%) and among (17.8%) variances. The Jaccard similarities, PCA, gene flow coefficients and Exact tests suggested that only one landrace exists in Central America, called Utilis after the first taxon described there, and that the Solimões landrace is part of the Putumayo landrace, rather than a separate entity. The Pará and Pampa Hermosa landraces were validated in accordance with their morphometric interpretations. The dendrogram of Neis genetic distances among valid landraces and var.chichagui supported the hypothesis of a single origin for pejibaye in southwestern Amazonia, with two migration routes: one to the northeast, becoming the Pará landrace, and another to the northwest along the Andes, spreading into western Amazonia (Pampa Hermosa and Putumayo landraces) and across the Andes, reaching Central America (Utilis landrace).     

<Emphasis Type="Italic">Rhizobium</Emphasis>,<Emphasis Type="Italic"> Bradyrhizobium</Emphasis> and<Emphasis Type="Italic"> Agrobacterium</Emphasis> strains isolated from cultivated legumes

The present study was conducted to isolate and characterize rhizobial strains from root nodules of cultivated legumes, i.e. chickpea, mungbean, pea and siratro. Preliminary characterization of these isolates was done on the basis of plant infectivity test, acetylene reduction assay, C-source utilization, phosphate solubilization, phytohormones and polysaccharide production. The plant infectivity test and acetylene reduction assay showed effective root nodule formation by all the isolates on their respective hosts, except for chickpea isolate Ca-18 that failed to infect its original host. All strains showed homology to a typical Rhizobium strain on the basis of growth pattern, C-source utilization and polysaccharide production. The strain Ca-18 was characterized by its phosphate solubilization and indole acetic acid (IAA) production. The genetic relationship of the six rhizobial strains was carried out by random amplified polymorphic DNA (RAPD) including a reference strain of Bradyrhizobium japonicum TAL-102. Analysis conducted with 60 primers discriminated between the strains of Rhizobium and Bradyrhizobium in two different clusters. One of the primers, OPB-5, yielded a unique RAPD pattern for the six strains and well discriminated the non-nodulating chickpea isolate Ca-18 from all the other nodulating rhizobial strains. Isolate Ca-18 showed the least homology of 15% and 18% with Rhizobium and Bradyrhizobium, respectively, and was probably not a (Brady)rhizobium strain. Partial 16S rRNA gene sequence analysis for MN-S, TAL-102 and Ca-18 strains showed 97% homology between MN-S and TAL-102 strains, supporting the view that they were strains of B. japonicum species. The non-infective isolate Ca-18 was 67% different from the other two strains and probably was an Agrobacterium strain.     

Cytological and RAPD data revealed genetic relationships among nine selected populations of the wild bramble species, <Emphasis Type="Italic">Rubus</Emphasis><Emphasis Type="Italic">parvifolius</Emphasis> and <Emphasis Type="Italic">R. coreanus</Emphasis> (Rosaceae)

Rubus parvifolius L. and R. coreanus Miq. are the two morphologically distinct, endemic wild brambles in East Asia that may be useful in raspberry breeding and cultivar development. In this study, genetic relationships among a total of nine populations of these two species, collected from Sichuan Province in southwestern China, were investigated by cytological and RAPD analyzing. With the exception of ploidy levels, R. parvifolius and R. coreanus had similar cytological features. Six R. parvifolius populations included diploids, triploid, tetraploid, and mixed diploid-tetraploid cytotype plants; among them, the population that produced the fewest seeds was the triploid, while the three R. coreanus populations were all diploid. But obvious genetic differentiation between R. parvifolius and R. coreanus was revealed by RAPD markers, the Euclidean’s GS coefficient generated by UPGMA cluster analysis between R. parvifolius and R. coreanus was only 0.442, about half of that observed within species. Both genetic relationships among these populations and the origin of polyploidy in R. parvifolius populations are also discussed.     

Genetic Characterization of Brazilian Annual <Emphasis Type="Italic">Arachis</Emphasis> Species from Sections <Emphasis Type="Italic">Arachis</Emphasis> and <Emphasis Type="Italic">Heteranthae</Emphasis> using RAPD Markers

The genus Arachis is divided into nine taxonomic sections. Section Arachis is composed of annual and perennial species, while section Heteranthae has only annual species. The objective of this study was to investigate the genetic relationships among 15 Brazilian annual accessions from Arachis and Heteranthae using RAPD markers. Twenty-seven primers were tested, of which nine produced unique fingerprintings for all the accessions studied. A total of 88 polymorphic fragments were scored and the number of fragments per primer varied from 6 to 17 with a mean of 9.8. Two specific markers were identified for species with 2n = 18 chromosomes. The phenogram derived from the RAPD data corroborated the morphological classification. The bootstrap analysis divided the genotypes into two significant clusters. The first cluster contained all the section Arachis species, and the accessions within it were grouped based upon the presence or absence of the ‘A’ pair and the number of chromosomes. The second cluster grouped all accessions belonging to section Heteranthae.     

Phylogenetic relationships between <Emphasis Type="Italic">Ensete</Emphasis> and <Emphasis Type="Italic">Musa</Emphasis> species as revealed by the <Emphasis Type="Italic">trnT trnF</Emphasis> region of cpDNA

Complete sequences of transcribed spacers and introns from the trnT trnF region of chloroplast DNA (cp DNA) were generated from Musaceae species to establish the phylogenetic relationships among 3 species of Ensete including the economically important Ensete ventricosum (Welw.) Cheesman and 13 species of Musa. Parsimony analysis and pair wise distance data produced a single tree, with Ensete and Musa as clearly distinguished clades. Six Musa and three Ensete clades were generated. The topology of these clades did not change when the data were split into spacers and introns, although the split resulted in poor bootstrap support. Removing a hotspot from the entire data set improved clade support. The clades produced are discussed with reference to existing taxonomic and phylogenetic treatments. In contrast to previous suggestions, most of the Rhodochlamys species that we investigated clustered together with strong support establishing their distinctiveness from the Musa species studied. Ensete glaucum (Roxb.) Cheesman and Musa beccartii Simmonds appear to represent ancestral forms of Ensete and Musa, respectively for the presently studied species, and both genera have a common ancestor that is yet to be established. Our data also show that E. ventricosum cannot be reduced to E. glaucum, nor can E. gilleti (De Wild.) Cheesman be reduced to E. ventricosum, as some authorities have suggested. Ensete gilleti or a species very close to it appears to be the ancestral species of E. ventricosum.     

Production and cytogenetics of trigeneric hybrid involving <Emphasis Type="Italic">Triticum</Emphasis>, <Emphasis Type="Italic">Psathyrostachys</Emphasis> and <Emphasis Type="Italic">Secale</Emphasis>

Trigeneric hybrids may help establish evolutionary relationships among different genomes present in the same cellular-genetic background, and also offers the possibility to transfer different alien characters into cultivated wheat. In this study, a new trigeneric hybrid involving species from the Triticum, Psathyrostachys and Secale was synthesized by crossing wheat-P. huashanica amphiploid (PHW-SA) with wheat-S. cereale amphiploid (Zhongsi 828). The crossability of F₁ hybrid was high with 35.13%, and the fertility was 41.95%. The morphological characteristics of F₁ plants resembled the parent Zhongsi 828. The trigeneric hybrids pollen mother cells (PMCs) regularly revealed averagely 19.88 univalents, 9.63 ring bivalents, 3.97 rod bivalents, 0.60 trivalents and 0.03 tetravalents per cell. Multivalents consisted of trivalents and tetravalents can be observed in 52.7% of cells. A variation of abnormal lagging chromosome, micronuclei and chromosome bridge were formed at anaphase I and telophase II. The mean chromosomes number of F₂ progenies was 2n = 46.13, and the distribution range was 42–53. GISH results revealed that most F₂ plants had 6–12 S. cereale chromosomes, and only 0–2 P. huashanica chromosomes were detected. The results indicated that S. cereale chromosomes can be preferentially transmitted in the F₂ progenies of trigeneric hybrid than P. huashanica chromosomes. A survey of disease resistances revealed that the stripe rust resistance from the PHW-SA were completely expressed in the F₁ and some F₂ plants. The trigeneric hybrid could be a useful bridge for the transference of P. huashanica and S. cereale chromatins to common wheat.     

Putative Role of <Emphasis Type="Italic">Flavobacterium</Emphasis>, <Emphasis Type="Italic">Dokdonella</Emphasis> and <Emphasis Type="Italic">Methylophilus</Emphasis> Strains in Paracetamol Biodegradation

Paracetamol, the most widely and globally used analgesic and antipyretic, is easily accumulated in aquatic environments. In the present study, the biodegradation of paracetamol in different media (one for general growth, one specific for sulfate reducing bacteria, a mineral salts medium and municipal wastewater) inoculated with two types of sludge (from anaerobic lagoon and from oxidation ditch) under different oxygenic conditions (anoxic; moderate oxygenation in open flasks and high oxygenation by aeration) was investigated. In addition, bacteria with relative abundances increasing simultaneously with paracetamol degradation, when this drug was the only carbon source, thus with a putative role in its degradation, were identified using 16S rRNA gene sequences. The results show that aerobic microorganisms had a major role in the degradation of paracetamol, with 50 mg/L totally removed from municipal wastewater after 2 days incubation with aeration, and that the metabolites 4-aminophenol and hydroquinone plus one compound not identified in this work were produced in the process. The identification of bacteria with a role in the degradation of paracetamol revealed a strain from genus Pseudomonas with the highest final relative abundance of 21.2%, confirming previous works reporting strains of this genus as paracetamol decomposers. Besides, genera Flavobacterium, Dokdonella and Methylophilus were also in evidence, with initial relative abundances of 1.66%, 1.48 and 0.00% (not detected) in the inoculum and 6.91%, 3.80 and 3.83% after incubation, respectively. Therefore, a putative role of these genera in paracetamol biodegradation is suggested for the first time.

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Analysis of the geographic distribution and relationships among Peruvian wild species of <Emphasis Type="Italic">Arracacia</Emphasis>

Relationships between Arracacia species were studied according to 28 morphological discriminant characters, in 90 accessions: 83 Arracacia (Arracacia elata, A. incisa and A. xanthorrhiza), and seven accessions of Neonelsonia acuminata, which has been confused with A. elata. The geographic distribution of the Arracacia species was determined from the passport data of the 90 accessions. A. elata was clearly differentiated from N. acuminata according to morphological characteristics. The species A. incisa was more closely related to A. xanthorrhiza. Within A. xanthorrhiza two forms, monocarpic, and polycarpic, were identified. The distribution of wild Arracacia species in Peru is characterized by two main ecological zones: (1) a dry zone, like the western Yunga and western and inter-Andean valleys of the Quechua region (with seasonal rain from November to March), where the species A. incisa and A. xanthorrhiza are present, and (2) a humid zone, like the Eastern Quechua where A. elata is adapted. These informations could be useful to establish strategies for in situ and ex situ conservation and management of germplasm.     

Divergent evolution of wild and cultivated subspecies of <Emphasis Type="Italic">Triticum timopheevii</Emphasis> as revealed by the study of <Emphasis Type="Italic">PolA1</Emphasis> gene

Triticum timopheevii (genome symbol AAGG) comprises two subspecies, cultivated ssp. timopheevii, and wild ssp. armeniacum. These two subspecies are considered as allotetraploids of AA genome from Triticum diploid species and SS genome from Aegilops species. The difference in genome symbol (G vs. S) is due to wide genetic variations among four SS genome species, Ae. bicornis, Ae. longissima, Ae. searsii, and Ae. speltoides. In order to study the origin of T. timopheevii, we compared 19th intron (PI19) sequence of the PolA1 gene, encoding the largest subunit of RNA polymerase I. Two different sized DNA fragments containing PI19 sequences (PI19A and PI19G) were amplified both in ssp. timopheevii and ssp. armeniacum. Shorter PI19A (112 bp) sequences of both subspecies were identical to PI19 sequences of two AA species, T. monococcum and T. urartu. Interestingly, the longer PI19G (241–243 bp) sequences of ssp. armeniacum showed more similarity to PI19 sequences of Ae. speltoides whereas ssp. timopheevii showed more similarity to PI19 sequences of other three SS genome species. The results indicated that two subspecies of T. timopheevii, ssp. armeniacum or ssp. timopheevii, might have arisen independently by allotetraploidization of AA genome with Ae. speltoides or one of the remaining three Aegilops species, respectively.     

Geographic distribution and domestication of wild emmer wheat (<Emphasis Type="Italic">Triticum dicoccoides</Emphasis>)

The transition from hunting and gathering to agriculture had revolutionary consequences for the development of human societies. Crops such as wheat, barley, lentil, pea and chickpea played a crucial role in the establishment of complex civilizations in south west Asia. Wild emmer wheat (Triticum dicoccoides) was one of the first cereals to be domesticated in the Fertile Crescent between c. 12,000 and c. 10,000 years ago. This step provided the key for subsequent bread wheat evolution. Wild emmer is found today in the western Fertile Crescent in Jordan, Syria and Israel, the central part of southeastern Turkey and mountain areas in eastern Iraq and western Iran. In this review, we summarize issues concerning geography and domestication of wild emmer wheat based on published molecular and archaeobotanical data and on our recent findings. We suggest that modern domestic tetraploid wheats derived from wild emmer lines from southeast Turkey. However, our understanding of emmer domestication is not complete. The “dispersed-specific” domestication model proposed for einkorn might well be appropriate also for emmer.     

Genomic relationships between wild and cultivated <Emphasis Type="Italic">Brassica oleracea</Emphasis> L. with emphasis on the origination of cultivated crops

Wild taxa in Brassica oleracea L. play an important role to improve cultivated crops, but the genomic relationships between wild and cultivated forms have not been well clarified. An overall survey of genomic relationships among 39 accessions covering 10 wild and 7 cultivared types in B. oleracea was performed using amplified fragment length polymorphism and simple sequence repeat. The cultivated types were clustered together with B. oleracea ssp. oleracea, B. incana, B. bourgeaui, B. montana, B. cretica and B. hilarionis, while 4 wild taxa from Sicily, B. rupestris, B. insularis, B. macrocarpa and B. villosa formed the other group. It implies the low possibility that current B. oleracea crops originated in Sicily.     

Genetic diversity and relationships of wild and cultivated <Emphasis Type="Italic">Zanthoxylum</Emphasis> germplasms based on sequence-related amplified polymorphism (SRAP) markers

The genus Zanthoxylum, belonging to Rutaceae, has a long history of cultivation both for economic and chemical values in China. To effectively conserve and sustainably utilize this genus resource, a study on genetic diversity and relationships of Zanthoxylum germplasms was carried out by employing SRAP markers. We used 16 primer combinations to assess genetic variations and relationships among 175 accessions from eight cultivated provenances, including Shandong, Henan, Shanxi, Shaanxi, Gansu, Sichuan, Guizhou and Yunnan. A total of 145 clear repetitive and intense bands were yielded, and the percentage of polymorphic bands was 100 % for per primer combination, indicating a relatively high diversity among Zanthoxylum germplasms. From a geographic perspective, the highest genetic diversity level was observed within Guizhou provenance (N _a  = 1.97, Ne = 1.52, H = 0.31, I = 0.46) while Henan provenance had the lowest genetic diversity (N _a  = 1.68, Ne = 1.45, H = 0.25, I = 0.37). Based on AMOVA results, the abundant genetic variation was mainly caused by variation of intra-provenances (84.96 %), rather than among provenances (15.038 %). The results indicated low genetic differentiation (G _st  = 0.133) and high gene flow (N _m  = 3.2605) among provenances. The neighbor-joining tree revealed that the 175 accessions could be divided into four groups, and groupings indicated a divergence between the cultivated accessions of Zanthoxylum bungeanum Maxim. and Z. armatum DC. Moreover, three accessions of Z. piperitum DC. var. inerme without prickles introduced from Japan gathered one cluster. Cluster IV is composed of accessions of different geographical origin, including 11 wild species and 10 cultivated accessions of Z. bungeanum. The cluster analysis also reflected a relatively close relationship between the geographical origins and the classification of accessions in cluster I. Structure analysis indicated that collected Zanthoxylum accessions could be divided into two major groups. The information obtained from our research would benefit to make use of Zanthoxylum germplasms and assist the management of a Zanthoxylum germplasms collection.     

<Emphasis Type="Italic">Achromobacter insolitus</Emphasis> and <Emphasis Type="Italic">Zoogloea ramigera</Emphasis> associated with wheat plants (<Emphasis Type="Italic">Triticum aestivum</Emphasis>)

This study reports for the first time the presence of diazotrophic bacteria belonging to the genera Achromobacter and Zoogloea associated with wheat plants. These bacterial strains were identified by the analysis of 16S rDNA sequences. The bacterium IAC-AT-8 was identified as Azospirillum brasiliense, whereas isolates IAC-HT-11 and IAC-HT-12 were identified as Achromobacter insolitus and Zoogloea ramigera, respectively. A greenhouse experiment involving a non-sterilized soil was carried out with the aim to study the endophytic feature of these strains. After 40 days from inoculation, all the strains were in the inner of roots, but they were not detected in soil. In order to assess the location inside wheat plants, an experiment was conducted under axenic conditions. Fifteen days after inoculation, preparations of inoculated plants were observed by the scanning electron microscope, using the cryofracture technique, and by the transmission electron microscope. It was observed that all isolates were present on the external part of the roots and in the inner part at the elongation region, in cortex cells, but not in the endodermis or in the vascular bundle region. No colonizing bacterial cells were observed in wheat leaves.     

<Emphasis Type="Italic">Trichoderma</Emphasis> improves the growth of <Emphasis Type="Italic">Leymus chinensis</Emphasis>

Bio-fertilizer application has been proposed as a strategy for enhancing soil fertility, regulating soil microflora composition, and improving crop yields, and it has been widely applied in the agricultural yields. However, the application of bio-fertilizer in grassland has been poorly studied. We conducted in situ and pot experiments to investigate the practical effects of different fertilization regimes on Leymus chinensis growth, with a focus on the potential microecological mechanisms underlying the responses of soil microbial composition. L. chinensis biomass was significantly (P?<?0.05) increased by treatment with 6000 kg ha^?1 of Trichoderma bio-fertilizer compared with other treatments. We found a positive (R² =?0.6274, P <?0.001) correlation between bacterial alpha diversity and L. chinensis biomass. Hierarchical cluster analysis and nonmetric multidimensional scaling (NMDS) revealed that soil bacterial and fungal community compositions were all separated according to the fertilization regime used. The relative abundance of the most beneficial genera in bio-fertilizer (BOF) (6000 kg ha^?1Trichoderma bio-fertilizer) was significantly higher than in organic fertilizer (OF) (6000 kg ha^?1 organic fertilizer) or in CK (non-amend fertilizer), there the potential pathogenic genera were reduced. There were significant negative (P?<?0.05) correlations between L. chinensis biomass and the relative abundance of several potential pathogenic genera. However, the relative abundance of most beneficial genera were significantly (P?<?0.05) positively correlated with L. chinensis biomass. Soil properties had different effects on these beneficial and on these pathogenic genera, further influencing L. chinensis biomass.     

Identification of <Emphasis Type="Italic">SUB1A</Emphasis> alleles from wild rice <Emphasis Type="Italic">Oryza rufipogon</Emphasis> Griff.

Submergence stress is a major constraint to rice production in South and Southeast Asia. Most rice (Oryza sativa L.) cultivars die within a week of complete submergence, while a small number of accessions are submergence-tolerant for up to 2 weeks or more. These cultivars have the tolerant allele of the SUB1A gene, one of three ERF genes at this locus on rice chromosome 9. In all O. sativa varieties studied, the SUB1A gene is limited to a subset of indica accessions of O. sativa. Thus far, there has been no published report of the SUB1A gene in wild rice species. Here we report evidence of the SUB1A gene found in wild species of O. rufipogon Griff. accessions by the use of degenerate primers corresponding to the most highly conserved regions of the SUB1 locus. The results indicated that two SUB1A-like alleles, e.g. OrSub1A-1 and OrSub1A-2, were identified from two O. rufipogon accessions. Submergence treatment shows that both of the accessions with SUB1A-like genes were submergence-intolerant. This preliminary study provides insight into the origin and allelic variation of SUB1A, an agronomically important gene that is rapidly being introduced into widely-grown rice cultivars.     

Genetic evidence for speciation in <Emphasis Type="Italic">Cannabis</Emphasis> (Cannabaceae)

Sample populations of 157 Cannabis accessions of diverse geographic origin were surveyed for allozyme variation at 17 gene loci. The frequencies of 52 alleles were subjected to principal components analysis. A scatter plot revealed two major groups of accessions. The sativa gene pool includes fiber/seed landraces from Europe, Asia Minor, and Central Asia, and ruderal populations from Eastern Europe. The indica gene pool includes fiber/seed landraces from eastern Asia, narrow-leafleted drug strains from southern Asia, Africa, and Latin America, wide-leafleted drug strains from Afghanistan and Pakistan, and feral populations from India and Nepal. A third putative gene pool includes ruderal populations from Central Asia. None of the previous taxonomic concepts that were tested adequately circumscribe the sativa and indica gene pools. A polytypic concept of Cannabis is proposed, which recognizes three species, C. sativa, C. indica and C. ruderalis, and seven putative taxa.     

Genetic characterization and species relationships among selected Asiatic <Emphasis Type="Italic">Vigna</Emphasis> Savi

Twenty-four ISSR primers were employed for diversity analysis, genotyping and assessment of species relationships in Asiatic Vigna from the Indian subcontinent. A total of 396 fragments were scored with an average of 16.5 products per primer. Primer no 827 was the most informative primer with highest resolving power (Rp), marker index (MI) as well as genotypic index (GI). Linear correlation was observed between Rp, MI and GI. The wild forms, V. mungo var. silvestris, V. radiata var. sublobata and V. radiata var. setulosa grouped closer to their respective cultigens. V. hainiana emerged as a distinct taxon and seems to be more primitive in comparison to the other close wild relatives of greengram and blackgram. Moderate gene flow and genetic differentiation was detected between the species analyzed. Analysis of molecular variance performed for the group (mungo–radiata–hainiana) in three different combinations revealed that nearly half of the variation exists within the populations while the remaining half is equally distributed among species and among populations within species.     

Salt tolerance in <Emphasis Type="Italic">Zea mays</Emphasis> (L). following inoculation with <Emphasis Type="Italic">Rhizobium</Emphasis> and <Emphasis Type="Italic">Pseudomonas</Emphasis>

This study aimed to investigate the effect of inoculation with plant growth-promoting Rhizobium and Pseudomonas species on NaCl-affected maize. Two cultivars of maize (cv. Agaiti 2002 and cv. Av 4001) selected on the basis of their yield potential were grown in pots outdoors under natural conditions during July. Microorganisms were applied at seedling stage and salt stress was induced 21 days after sowing and maintained up to 50% flowering after 120 days of stress. The salt treatment caused a detrimental effect on growth and development of plants. Co-inoculation resulted in some positive adaptative responses of maize plants under salinity. The salt tolerance from inoculation was generally mediated by decreases in electrolyte leakage and in osmotic potential, an increase in osmoregulant (proline) production, maintenance of relative water content of leaves, and selective uptake of K ions. Generally, the microbial strain acted synergistically. However, under unstressed conditions, Rhizobium was more effective than Pseudomonas but under salt stress the favorable effect was observed even if some exceptions were also observed. The maize cv. Agaiti 2002 appeared to be more responsive to inoculation and was relatively less tolerant to salt compared to that of cv. Av 4001.     

Genetic polymorphism of <Emphasis Type="Italic">Malus sieversii</Emphasis> populations in Xinjiang,China

Malus sieversii (Ledeb.) Roem. is a wild apple species which is distributed in the western mountains in Xinjiang, P.R. China, as well as in Central Asia, including Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan and Turkmenistan. M. sieversii germplasm is valuable for plant breeders for drought, cold and disease resistance. Genetic polymorphisms of 20 populations of M. sieversii and 2 populations of M. niedzwetzkyana in Xinjiang, China were analyzed using RAPD markers. We present geographical distribution data as well as the discovery of a rare king old tree. Different types of pollen grain morphology were analyzed.     

Maintaining Genetic Resources of Peach Palm (<Emphasis Type="Italic">Bactris gasipaes</Emphasis> Kunth): The Role of Seed Migration and Swidden-fallow Management in Northeastern Peru

Knowledge of the effects of farmer practices on population genetic parameters of peach palm (Bactris gasipaes Kunth) is relevant to the improvement and conservation of the palm’s genetic resources. Microsatellite markers were used to assess genetic diversity and population structure of peach palm in swidden-fallow agroforestry systems in northeastern Peru. The study covered eight communities, comprising two study areas 160 km apart – one occupied by indigenous Amerindians and the other by mixed race campesinos. Simultaneous analysis of an ex situ peach palm germplasm collection provided a means to compare population genetic parameters. Farmers who were surveyed on seed selection practices for peach palm reported that an average of only four palms (4.3 for campesino and 1.5 for indigenous populations) were used to provide seed for the establishment of the forest gardens sampled. As expected, inbreeding coefficients observed within communities were relatively high (f = 0.105 − 0.210), however, observed heterozygosities within communities were also high (0.625–0.741). A metapopulation approach was used to describe migration within and among regions, implying a hierarchical structure of gene flow which maintains relatively high levels of genetic diversity. Seed migration was found to occur over longer distances (≤600 km) and at a higher frequency (46% of palms sampled) in the indigenous study area, and a proportionally greater number of alleles was found (49 vs. 43 over three loci) with twice as many private alleles occurring only in the indigenous populations. The farmers’ practice of preserving remnant palms through successive swidden generations may have contributed to the maintenance of alleles by reducing the severity of founder effects. Although the campesino study area exhibited a significant (20% of the variation; p < 0.01) isolation-by-distance relationship across 35 km distance, in general, both study populations had relatively limited genetic structure (θ = 0.012–0.03), which is believed to have resulted from the exchange of seeds over long distances and periods of time.