Genetic similarity based on isoenzyme banding pattern among fifty species of Medicago representing eight sections (Fabaceae)

Genetic similarity among fifty species of genus Medicago constituting 197 accessions is described. Pooled zymogram clustering revealed Medicago monantha and Medicago medicaginoides of section Buceras distantly related to other species. At least three groups of species exhibited considerable similarity (>60%) to a major cluster of 32 species wherein five groups comprising 2–17 species with 65–71% similarity were observed. All five subspecies of Medicago sativa showed close affinity with Medicago shepardii. So far, limited success in generating inter-specific crosses in genus Medicago is supported that accessions belonging to individual species are largely grouped together, indicating incompatibility among species under study. Species of Medicago section clustered with species of sections Spirocarpos, Lunatae, Buceras, Heynianane while species of sections Hymerocarpos, Lupularia and Orbiculares clustered solely with species of Spirocarpos. Most clusters were supported with moderate bootstrap values (≥30) and Mantel’s test. Results demonstrate utility of isoenzyme based clustering in plant systematics and breeding.     

Genetic interpretation of polytene chromosomes banding pattern

This mini-review covers new data regarding the problem of the functional organization of polytene chromosomes: The localization of RNA synthesis in the polytene chromosome puffs, diffuse bands and interbands; The relative stability of banding pattern and its functional value; The informational content of bands.     

Genetic relationships among annual species of Cicer(Fabaceae) using isozyme variation

In order to determine the pattern of genetic diversity within and among the species of Cicer and to estimate interspecific genetic relationships, allelic variation was assayed for 23 isozyme loci in 63 accessions of 11 species of Cicer using starch gel electrophoresis. The total allozymic variation observed in the genus (H _t )was equal to 0.60. When partitioned (G st), 96% of this allelic diversity was found among rather than within species. The allelic diversity among species (D st)and allelic diversity within species (H s)were equal to 0.58 and 0.02, respectively. Cicer reticulatum and C. pinnatifidum had the highest proportion of polymorphic loci (17.39%) and the highest mean number of alleles per locus (1.22 and 1.17, respectively). UPGMA cluster analysis of Nei's unbiased genetic distance revealed four genetic groups. One includes C. reticulatum, C. arietinum and C. echino spermum where the first 2 species represent a putative derivative-progenitor pair. A second cluster contains C. bijugum, C. pinnatifidum and C. judaicum. Cicer yamashitae, C. chorassanicum, C. anatolicum and C. songoricum form a third group. Finally, C. cuneatum, which has a very distinct isozyme profile and peculiar morphological features, is the only member of a fourth species group. This species grouping agrees partially with those obtained from crossability and cytogenetic studies. The results suggest that the annual habit arose from perennial progenitors at least twice in the genus Cicer.     

Variation of isozyme patterns among Arachis species

The genus Arachis contains a large number of species and undescribed taxa with patterns of genetic variation that are little understood. The objectives of this investigation were to estimate genetic diversity among species of Arachis by utilizing electrophoretic techniques and to establish the potential for use of isozymes as markers for germplasm introgression. One-hundred-and-thirteen accessions representing six of the seven sections of the genus were analyzed for isozyme variation of 17 enzymes. Section Rhizomatosae species were not included because they produce very few seeds. Seeds were macerated and the crude extract was used for starch-gel electrophoretic analyses. Although the cultivated species has few polymorphic isozymes, the diploid species are highly variable and two-to-six bands were observed for each isozyme among accessions. Because of the large number of isozyme differences between A. hypogaea and A. batizocoi (the presumed donor of the B genome), this species can no longer be considered as a progenitor of the cultivated peanut. Seed-to-seed polymorphisms within many accessions were also observed which indicate that germplasm should be maintained as bulk seed lots, representative of many individuals, or as lines from individual plants from original field collections. The area of greatest interspecific genetic diversity was in Mato Grosso, Brazil; however, the probability of finding unique alleles from those observed in A. hypogaea was greatest in north, north-central, south and southeast Brazil. The large number of polymorphic loci should be useful as genetic markers for interspecific hybridization studies.     

Genetic similarity among cultivars of Phyllostachys pubescens

Phyllostachys pubescens is the most important economic bamboo species in China, which grows widely in the South of China. There are more than ten cultivars in this species but their genetic relationship still remains unknown. We used both amplified fragment length polymorphism (AFLP) and inter-simple sequence repeat (ISSR) techniques to determine genetic similarity among ten cultivars of P. pubescens and two related species. Eight hundred and twenty seven bands, in which 495 are polymorphic, were detected using 15 pairs of AFLP primers whereas total 231 bands, in which 154 bands are polymorphic, were scored using 16 ISSR primers. Statistic analysis showed that the genetic similarity matrices obtained from these two sets of molecular markers had a significant correlation (R = 0.959, P = 0.013). The dendrogram generated with AFLP and ISSR markers could clearly genetically identify ten cultivars of P. pubescens that had high similarity with genetic distances ranging from 0.023 to 0.108, and could be divided into three groups based on their genetic variation and similarity. Our results suggest that these molecular markers are useful to genetically classify cultivars or varieties of a species, particularly a bamboo species.     

Genetic variation in clonal traits of Trifolium repens and species interactions

Plants exhibit a great variety of types of clonal growth. Moderate variation in clonal traits often exists even within species. The consequences of these variations for species interaction are of great interests to ecologists. In this paper, I address the small-leaved (phalanx) to large-leaved (guerrilla) variation in white clover ( Trifolium repens ), and discuss its consequences for species and genotype coexistence. I also address the clonal and sexual resource allocation variants within the large-leaved type. Small-leaved and large-leaved genotypes differ in various aspects of clonal growth. The large-leaved genotype displays greater phenotypic plasticity but is less physiologically integrated than the small-leaved genotype. We examined the consequences in a grazed sward, where white clover and zoysia grass coexist. In this sward, white clover is patchily distributed. We first tested the hypothesis that the large-leaved genotype is more advantageous in growth than the small-leaved genotype. Results from both common garden and competition experiments supported the hypothesis. Second, we tested the hypothesis that within large-leaved plants, the clonal subtype (which invests more resources to stolons but less in flower heads than the sexual one) is more advantageous than the sexual one because it is more competitive. This hypothesis was rejected. Both subtypes coexisted in the sward. This is probably because the sexual subtype is superior for interpatch migration than the clonal one. Both subtypes differ in advantages they offer for between-patch and within-patch processes, which promotes their coexistence. Finally, field monitoring of the behavior of a large-leaved clone is described. This monitoring was conducted in a moderately grazed sward, where microenvironmental heterogeneity is extremely high in time and space.     

Genetic variability among Alexandrium tamarense and Alexandrium minutum strains studied by RAPD banding pattern analysis

We performed random amplification of polymorphic DNA (RAPD) analysis on five strains of Alexandrium tamarense and nine strains of Alexandrium minutum. Arbitrary 10-mer oligonucleotides were used as primers for the PCR. Electrophoresis on denaturing acrylamide gels improved RAPD reproducibility and increased the band number. Eight of the 20 primers assayed gave reproducible results and the band profiles generated by them were used for constructing a similarity matrix. Analyses were performed independently for the strains of each species and jointly for all the strains of both species. Results for A. tamarense showed the highest similarity for two distinct clones isolated from the same water sample in the Baltic Sea during a bloom (KAC01 and KAC02). The highest similarity among A. minutum clones was found for three strains (AL1V, AL2V and AL3V) isolated in the Ria de Vigo in NW Spain. The results show a high genetic diversity within a single species. We have shown the potential of the RAPD technique to discriminate between two conspecific strains, as well as for establishing similarities that are related to the biogeographic origin of the strains.     

Genetic relatedness among Filobasidiella species

The three accepted species of Filobasidiella, F. neoformans, F. depauperata, and F. lutea, are compared morphologically and by molecular analysis. Sequences of the internally transcribed spacer (ITS) and the small subunit (SSU) gene of the ribosomal RNA (rRNA) gene cluster were obtained, and analysed by Neighbor-joining and Maximum parsimony methods. The three species of Filobsidiella are shown to form a single monophyletic clade, rooted by Tremella mesenterica. F. lutea was recovered as a distinct, but closely related taxon with the Filobasidiella clade. This is the first report of DNA sequences from herbarium specimens of F. lutea.This revised version was published online in October 2005 with corrections to the Cover Date.     

Phylogenetic relationships among species of Prunus as inferred by isozyme markers

Summary An isozyme survey of 34 species of Prunus representing subgenera Prunus, Amygdalus, Cerasus, and Lithocerasus detected 110 presumptive alleles at 11 isozyme loci. Principal component analysis was conducted on the covariance matrix derived from allelic frequencies calculated for each species. Cluster analysis was performed on the first 30 principal components. Results generally support traditional classification of Prunus at the subgeneric level, except for members of subgenus Lithocerasus and two members of subgenus Amygdalus. Prunus glandulosa Thunb., P. japonica Thunb., and P. tomentosa Thunb. of subgenus Lithocerasus and P. triloba Lindl. of subgenus Amygdalus appear to represent primitive species. P. besseyi Bailey and P. pumila L. of subgenus Lithocerasus and P. andersonii of subgenus Amygdalus should be assigned to subgenus Prunus. Placement of its members indicates that subgenus Lithocerasus is an artificial grouping of species that are very different genetically although similar phenotypically.Paper No. 12529 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7643, USA     

基于过氧化物同工酶分析月季种质资源的亲缘关系及杂种真实性

为了提高种质资源利用率,加速月季育种进程,对27份月季种质及3个杂交组合的8个杂交后代,采用过氧化物酶(POD)同工酶方法分析其亲缘关系并进行杂种真实性鉴定。结果表明:月季种质采用POD同工酶分析具有一定的可行性。酶谱分析中,在相对迁移率为0.264~0.858的位点处共获得7条酶带,其中共有酶带3条,特征酶带4条,表明不同月季种质间遗传多样性丰富,但又存在一定同源性。基于酶带特征进行聚类分析,在相似系数为0.57处,可将27份供试材料分为3个大组。合柱组与月季组材料聚在一个大组中,两个组在形态上的相似性再次得到确认。金樱子与硕苞蔷薇分别聚在两个不同的组中,表明二者之间的亲缘关系较远。供试的古老月季品种被聚在两个不同的大组中,与野生种聚成的一组呈平行关系,表明古老月季在起源上的差异较大,可利用其作为杂交亲本进行广泛杂交以选育具有丰富遗传多样性的杂交后代。根据有无父本特征酶带对杂种后代真实性进行鉴定,初步确定2个杂交组合的6个杂交后代中5个为真实杂种,1个为自交种。该研究结果为进一步开展月季遗传育种奠定了基础。     

四种斑腿蝗科昆虫染色体带型的比较

应用染色体C带及银染核仁组成区定位分析方法对斑腿蝗科4种昆虫,即小蹦蝗属2种;峨眉小蹦蝗Pedopodisma emeiensis和秦岭小蹦蝗P.tsinlingensis;无翅蝗属2种;小无翅蝗Zubovskiaparvula和柯氏无翅蝗Z.koeppeni进行了研究,结果表明：4种蝗虫染色体数目（2n♂=21,XO)一致,小蹦蝗属M8染色体上具有端带;无翅蝗属X染色体具有特殊带纹,银染核仁组成区定位在两属各有特点,小蹦蝗属位于第8号染色体端部区域;无翅蝗属位于X染色体端部区域,除上述属内共性之外,各物种C带带纹又存在明显差异,其中峨眉小蹦蝗带型极为特殊。文中还对上述4种蝗虫带型结构特征及其进化意义作了讨论。     

Genetic analysis reveals human-mediated long-distance dispersal among war cemeteries in Trifolium micranthum

Many grassland plant species have limited capacity to disperse their seeds beyond local boundaries by natural means. Meanwhile, various forms of human transportation are observed to provide long-distance dispersal. However, the contribution of human-mediated dispersal to the spatial dynamics of established (meta)populations on the regional scale has only scarcely been addressed. Trifolium micranthum is a very small legume that is rare in western Belgium. It is found (i) inland, as a lawn weed on war cemeteries that are managed by the Commonwealth War Graves Commission, and (ii) in coastal grasslands that are managed for conservation. These stations lie over 30?km apart, though interestingly, a number of satellite war cemeteries are found within the vicinity of the coastal reserves, and these also harbor T. micranthum. We have sampled plants from these populations to study their affinities through genetic analysis (AFLP). Results indicated that the coastal cemetery populations were closely related to the inland cemeteries and not to the coastal reserves. This most likely is the result of exchange of seeds with composted lawn material among regions, whereas mowing machinery and livestock may effectuate frequent dispersal within regions. Assignment tests nonetheless indicated limited genetic admixture to have taken place at the coastal cemeteries. Thus, human management is responsible for the realization of gene flow among these remote gene pools. Human-mediated long-distance dispersal is likely to play a role in the local or regional dynamics of many other native plants, including more common and well-dispersing species.     

Genetic diversity among endangered Uruguayan populations of Butia Becc. species based on ISSR

The genus Butia Becc. (Arecaceae) comprises 18 species distributed exclusively in South America, four of them in Uruguay: Butia lallemantii, B. paraguayensis, B. yatay and B. capitata. All species show serious regeneration problems which jeopardise their continuity in the near future. Butia lallemantii and B. paraguayensis are in the most critical situation, with restricted distributions (fragmented and reduced by cattle grazing and forestation) and populations with few individuals. Taxonomy in the genus is complex, and species delimitation remains unclear. The aim of this study was to examine the genetic variability of natural populations of B. paraguayensis, B. lallemantii and B. yatay, based on inter?Csimple sequence repeat markers, in view of long term conservation plans and to assist the taxonomic resolution of these closely related species. Twenty individuals from each population were sampled including four populations of B. lallemantii, three of B. yatay and the only B. paraguayensis population reported for Uruguay. Syagrus romanzoffiana was used as outgroup. Five primers were selected based on amplification profiles. Relationships among species were evaluated by constructing dendrograms and principal coordinates analysis. Genetic distance analyses indicate the existence of low variability among Butia species. Variability within populations was high, possibly due to gene flow, past hybridisation or life history traits. This variability provides great potential for recovery. Results do not allow us to suggest changes to the present taxonomic status of these species. We propose management recommendations involving restoration of recruitment and augmentation via stocks from within populations.     

Karyological relationships among some South American species of Solanum (Solanaceae) based on fluorochrome banding and nuclear DNA amount

Fluorescent chromosome banding and measurements of nuclear DNA content by image cytometry of Feulgen-stained cells were performed in one sample each of eight diploid (2n?=?24) species of Solanum: S.?endoadenium, S.?argentinum, S.?pseudocapsicum, S.?atropurpureum, S.?elaeagnifolium, S.?sisymbriifolium, S.?chenopodioides, and S.?palustre. The species studied could be distinguished by heterochromatin amount, banding patterns, and genome size. They exhibited only GC-rich heterochromatin and showed a comparatively low heterochromatin amount (expressed as percentage of haplotype karyotype length), ranging from 2.10 in S.?argentinum to 8.37 in S.?chenopodioides. Genome size displayed significant variation between species, with 1C-values ranging from 0.75?pg (735?Mbp) in S.?palustre to 1.79?pg (1,754?Mbp) in S.?sisymbriifolium. No significant correlation between genome size and heterochromatin amount was observed, but intrachromosomal asymmetry index (A ₁) was negative and significantly correlated with heterochromatin amount. DNA content was positively and significantly correlated with karyotype length. DNA C-value distribution in the genus as well as karyotype affinities and relationships between species are discussed in relation to different infrageneric classifications of Solanum.     

Genetic similarity among Eurasian subspecies of boreal owls Aegolius funereus

Boreal owls Aegolius funereus (referred to as Tengmalm's owls in Europe) breed in boreal forests throughout the Holarctic region and in high-elevation subalpine forests further south. They are currently classified as seven subspecies; six found throughout Eurasia, and one in North America. The geographic distribution of boreal owls in North America and Eurasia is similar, as are their patterns of dispersal and irruption. Because a recent genetic study of boreal owls in North America found very little genetic differentiation among widely disparate locations, we expected that boreal owls in Eurasia similarly would have very little genetic differentiation. Using seven microsatellite markers, we analyzed genetic samples from 275 boreal owls in North America, 36 in Norway, and five in eastern Russia. We found no detectable genetic differentiation between Norwegian and Russian owls, but notable differentiation between North American and Eurasian owls. Low intra-continental genetic differentiation likely results from high rates of long-distance dispersal among subpopulations of boreal owls. In light of these results, we recommend further genetic sampling of boreal owls throughout Eurasia in order to determine whether six separate subspecies here are warranted.     

Genetic similarity between species of Akodon (Rodentia, Cricetidae)

Genetic similarity between species of rodents of the Akodon genus (A. dolores, A. molinae, and A. azarae) has been estimated by analysis of electrophoretic zymograms corresponding to 23 loci. Nei's coefficient between A. dolores and A. molinae was within the range usually found in conspecific populations. This evidence plus the successful production of "hybrids" (Merani et al., J. Exp. Zool., 206:343-346, '78) suggests that A. dolores and A. molinae may represent geographic races of the same species.