Effect of Regeneration Method on RAPD-Based Genetic Variation of Cyclobalanopsis glauca (Fagaceae)

Cyclobalanopsis glauca is a dominant species of evergreen broad-leaved forests in mainland China. This study compares the genetic variation of an artificially regenerated population with its donor population and two other wild populations, by using RAPD markers. A total of 74 clear, reproducible bands were scored for 12 RAPD primers; 72 were polymorphic (P = 97.3%). AMOVA revealed that most genetic variation was within populations and only 10.35% was among populations. Various measures indicated that there is no difference in genetic diversity between the planted and the original populations. Φ_ST between the planted offspring population and the donor population was larger than those between the planted and other two natural populations, indicating that artificial regeneration might lead to biased genetic composition, given that temporal differentiation is usually lower than spatial differentiation. This divergence may be due to unequal seed production among the maternal individuals and viability differences among seeds.     

An analysis of the pattern of genetic variation in Vitellaria paradoxa using RAPD markers

Vitellaria paradoxa C.F.Gaertn. is one of the most economically and socially important tree species in the Sudano-Sahelian region. Little is known of the pattern of variation within its natural range. Eight populations covering most of the natural range from Senegal to Uganda were sampled and leaves of 118 individual trees were collected. An analysis of molecular diversity was carried out using random amplified polymorphic DNA (RAPD) markers. Fifteen random primers generated 67 polymorphic and 15 monomorphic RAPD loci ranging from size 1670 bp to 280 bp. Shannon's diversity index varied from Central Africa/Ndele (0.374) to Uganda/Amoya (0.350) but the differences between populations were smaller than the population standard errors. Correspondence analysis of unrooted neighbour-joining trees suggested that genetic distances between populations were correlated with geographic distances. This trend was confirmed by a Mantel test giving a coefficient of correlation between genetic and geographic distances of R = 0.88 (P = 0.0001). Result of AMOVA (analyses of molecular variance) showed that 14.8% (P = 0.002) of the RAPD variation was distributed among populations. Nested analysis of variance indicated that variance between the western and eastern groups of population represented 8.7% (P = 0.001) of the total variation and the variation amongst populations within group was 9.5% (P = 0.001). Eighty two percent of the variation was explained by variation amongst individuals within populations. The origin of genetic structure and level of diversity may be explained by the glacial refugia, the biological traits of Vitellaria paradoxa and by the impact of semi-domestication. Based on these results, sampling options of the natural populations are suggested for in or ex situ conservation. For the development of Vitellaria paradoxa breeding population, the sampling should consist of many individual trees selected within a few populations to capture a large proportion of variation.This revised version was published online in November 2005 with corrections to the Cover Date.     

Genetic variation of beech (Fagus sylvatica L.) in Rodopi (N.E. Greece)

The recent taxonomic classification of beech in Europe considers existence of one species (Fagus sylvatica L.) with two subspecies: F. sylvatica ssp. sylvatica and F. sylvatica ssp. orientalis. Four beech populations growing on the Greek part of the Rodopi Mountains were studied using morphological traits as well as DNA molecular markers (AFLPs and chloroplast DNA SSR). The aim of the study was to describe the variation patterns of beech in the Rodopi Mountains and to test the hypothesis of possible introgression between the beech subspecies’ sylvatica and orientalis in this area. Both morphological traits and gene markers revealed a possible influence of F. orientalis on the east side of Rodopi and at the low elevations, while characters resembling F. sylvatica were observed mainly on the western part of the mountains and in higher altitudes. There was a clinal increase of genetic diversity from the west to the east, reaching a level firstly reported for beech populations. These results can be explained either by the existence of a main refugial area for beech during the last glaciation or by the occurrence of a recent hybridization among the subspecies, which were spatially isolated during the last glaciation and came into reproductive contact during their postglacial remigration. These two scenarios are not necessarily mutually exclusive.     

Analysis of genetic relationship in 12 species of Section Strobus with ISSR markers

Genetic relationship of 12 species of Section Strobus was analyzed with ISSR markers. 117 loci were detected with 12 ISSR primers. Percentage of polymorphic bands （PPB） varied from 5.93% to 19.92%. P. pumila had the highest levels of genetic differentiation and P. flexilis had lowest. Total genetic diversity （Hr） of 12 species in Section Strobus was 26.21%, of which intraspecific genetic diversity （Hs） was 7.66%, and interspecific genetic diversity （DST） was 18.55%, and the genetic variation in interspecies accounted for 70.78% of the total genetic diversity. According to the cluster results of genetic distance, the 12 species were classified into two groups. The first group included P. griffithii, P.armandi, P. fenzeliana, P. kwangtungensis, P. strobus, P. monticola and P. wangii. The second group included P. albicaulis, P pumila, P. flexilis, P. sibirica and P koraiensis.     

Molecular characterization of a collection of the tropical multipurpose shrub legume Flemingia macrophylla

Random amplified polymorphic DNA (RAPD) markers were used for assessing genetic diversity and its structure in a collection of the drought-tolerant, tropical multipurpose shrub legume Flemingia macrophylla (Willd.) Merrill. The species is especially suited to low-input smallholder production systems and is used as dry season forage supplement, live soil cover, mulch and living barrier, among others. Genetic groups identified by RAPD analysis related closely to four morphotypes revealed by multivariate analysis of morphological, agronomic and forage quality characteristics. Overall genetic diversity in the collection was moderate (H _T = 0.241), with 79% differentiation among and high genetic similarity (GS) within groups (0.672–0.965). Results indicate a closer relationship of the semi-erect morphotypes M3 and M4 with F. stricta rather than with the erect morphotype M1. The latter was genetically the most depauperate, followed by morphotypes M2 and M4. New evidence is provided that non-Asian accessions collected in Africa and South America are derived from introduced Southeast Asian material. Furthermore, RAPD data suggest the presence of duplicates in the collection, especially in the overrepresented erect morphotype M1.     

用RAPD标记进行鹅掌楸杂种识别和亲本选配

杂种马褂木是以鹅掌楸属 (Ｌｉｒｉｏｄｅｎｄｒｏｎ)现存两个种中国马褂木 (Ｌ .ｃｈｉｎｅｎｓｅ(Ｈｅｍｓｌ.)Ｓａｒｇ .)和北美鹅掌楸 (Ｌ .ｔｕｌｉｐｉｆｅｒａＬ .)为亲本所创造的种间杂种 ,由叶培忠教授于 1 963年首次育成。 30多年的栽培试验表明 ,该杂种不仅在生长和     

Genetic diversity of Populus euphratica populations in northwestern China determined by RAPD DNA analysis

Five Populus euphratica Oliver populations in northwestern China were analyzed using RAPD DNA markers to determine genetic diversity among and within populations. One hundred-and-five polymorphic bands were observed, ranging in size from 250 bp to 1700 bp, using 10 primers. Only one population on the north side of the Tianshern Range had a unique band common to all individuals that was not found in individuals from populations in the Tarim River valley. Intra-population genetic diversity was high in two populations along the Tarim River and low in the other three populations. There was no significant correlation between genetic distances and geographic distances. The result of correspondence analysis shows that the individuals from the three populations with low genetic diversity are isolated from each other. The result of cluster analysis based on genetic distance shows that the population in the Tianshern Range is genetically distant from the other populations. These results suggest that the Tianshern Range population was genetically isolated from the other populations.     

乌桕新害虫——中华卡扁蜡蝉的形态及分子鉴定

[目的]介绍发生在贵州省龙里县乌桕上的一种新害虫——中华卡扁蜡蝉的形态及分子鉴定的方法。[方法]对中华卡扁蜡蝉卵、若虫(5龄)及成虫3个虫态的形态特征进行了详细描记;同时通过PCR扩增,获取了中华卡扁蜡蝉的线粒体COI基因序列。利用MEGA 6. 0软件对其序列组成及遗传距离进行分析,以竹鳎扁蜡蝉、红线鳎扁蜡蝉、勐仑鳎扁蜡蝉为外群,采用邻接法(NJ)构建系统发育树。[结果]系统发育树显示中华卡扁蜡蝉10个样品的COI基因序列能较好地聚为一枝;中华卡扁蜡蝉的种内遗传距离为0. 000 0. 065,4种扁蜡蝉科昆虫种间遗传距离为0. 142 0. 202,种内遗传距离与种间遗传距离不存在重叠现象。[结论] COI基因序列可作为DNA条形码片段,实现中华卡扁蜡蝉快速、准确的物种鉴定。初步调查了中华卡扁蜡蝉的发生规律及危害状况。     

大青杨及其近缘种的遗传变异和系统关系研究

对杨属青杨派主要树种大青杨、甜杨、香杨和马氏杨种间及种内遗传变异进行了ＲＡＰＤ检测，结果表明：７个随机引物对４个树种ＤＮＡ扩增产物绝大部分呈现为单型性，而有３个引物扩增产物显示出丰富的种间多型性；所有引物均在４个树种内扩增出不同程度的多态性。统计分析建立的系统树还说明了４树种可能的亲缘关系及系统发育史，同时，各树种内也均存在着遗传多样性。这对今后进行这些树种的遗传改良具有重要意义。此外还得出：分子     

Detecting interspecific and geographic differentiation patterns in two interfertile oak species (Quercus petraea (Matt.) Liebl. and Q. robur L.) using small sets of microsatellite markers

Genetic analysis was carried out in order to provide insights into differentiation among populations of two interfertile oak species, Quercus petraea and Quercus robur. Gene flow between the two species, local adaptation and speciation processes in general, may leave differential molecular signatures across the genome. Three interspecific pairs of natural populations from three ecologically different regions, one in central Europe (SW Germany) and two in the Balkan Peninsula (Greece and Bulgaria) were sampled. Grouping of highly informative SSR loci was made according to the component of variation they express—interspecific or provenance specific. ‘Species’ and ‘provenance discriminant’ loci were characterized based on F_STs. Locus specific F_STs were tested for deviation from the neutral expectation both within and between species. Data were then treated separately in a Bayesian analysis of genetic structure. By using three ‘species discriminant’ loci, high membership probability to inferred species groups was achieved. On the other hand, analysis of genetic structure based on five ‘provenance discriminant’ loci was correlated with geographic region and revealed shared genetic variation between neighbouring Q. petraea and Q. robur. Small sets of highly variable nuclear SSRs were sufficient to discriminate, either between species or between provenances. Thus, an effective tool is provided for molecular identification of both species and provenances. Furthermore, data suggest that a combination of gene flow and natural selection forms these diversity patterns. ‘Species discriminant’ loci might represent genome regions affected by directional selection, which maintains species identity. ‘Provenance specific’ loci might represent genome regions with high interspecific gene flow and common adaptive patterns to local environmental factors.     

Small-scale genetic diversity in oneseed hawthorn (<Emphasis Type="Italic">Crataegus monogyna</Emphasis> Jacq.)

We have examined the pattern of random amplified polymorphic DNA (RAPD) variation among six populations of Crataegus monogyna from northern Italy, extending over an area of about 20,000 km². The aim was to evaluate local differentiation in relation to geographical distance. Of the 73 loci analysed, 65 were polymorphic, and there were no bands at complete fixation at the population level. The mean genetic diversity was 0.291, with the values for individual populations ranging between 0.252 and 0.333. According to the analysis of molecular variance most of the genetic variation was found within populations (about 80%), with a significant proportion being attributable to genetic differences between populations. No evidence for isolation by distance was found in the set of populations sampled. The efficacy of RAPD markers in analysing genetic variation, and the contribution of the results in terms of the preservation of biodiversity and defining the most appropriate strategies for collecting forest reproductive material, are discussed.     

Interfertile oaks in an island environment. II. Limited hybridization between <Emphasis Type="Italic">Quercus alnifolia</Emphasis> Poech and <Emphasis Type="Italic">Q. coccifera</Emphasis> L. in a mixed stand

Hybridization and introgression between Quercus alnifolia Poech and Q. coccifera L. is studied by analyzing morphological traits, nuclear and chloroplast DNA markers. The study site is a mixed stand on Troodos Mountains (Cyprus), and the analyzed material includes both adult trees and progenies of specific mother trees. Multivariate analysis of morphological traits shows that the two species can be well distinguished using simple leaf morphometric parameters. A lower genetic diversity in Q. alnifolia than in Q. coccifera and a high interspecific differentiation between the two species are supported by an analysis of nuclear and chloroplast microsatellites. The intermediacy of the four designated hybrids is verified by both leaf morphometric and genetic data. Analysis of progeny arrays provides evidence that interspecific crossings are rare. This finding is further supported by limited introgression of chloroplast genomes. Reproductive barriers (e.g. asynchronous phenology, postzygotic incompatibilities) might account for this result. A directionality of interspecific gene flow is indicated by a genetic assignment analysis of effective pollen clouds with Q. alnifolia acting as pollen donor. Differences in flowering phenology and species distribution in the stand may have influenced the direction of gene flow and the genetic differentiation among effective pollen clouds of different mother trees within species.     

RAPD variation in Gremmeniella abietina attacking Pinus sylvestris and Pinus contorta in northern Sweden

Genomic DNA from 81 isolates of Gremmeniella abietina collected from eleven plantations each of Pinus sylvestris and Pinus contorta in northern Sweden was studied using RAPD markers. The DNA variation between and within populations and the race and type distribution of G. abietina populations, causing symptoms similar to those of the North American race, were studied. The degree of genetic similarity was greater among G. abietina isolates from the same geographical areas than among isolates from different geographical areas, regardless of whether they were isolated from P. sylvestris or P. contorta. RAPD variation was greatest in the central parts of northern Sweden, suggesting that sexual reproduction has been somewhat more important there than further north or south. Only the RAPD fragments characteristic of the EU race of G. abietina were found in the material tested. The RAPD pattern described as characteristic of the northern type within the EU race was identified in 62% of the isolates. Divergence from the expected profile was due to differences in occurrence of fragments OPA12-1400 and 12-1500. This indicates that this part of the RAPD profile cannot be treated as diagnostic for the northern type. A conclusion of practical importance is that there is a considerable risk of G. abietina spreading from infected P. contorta plantations to adjacent areas with indigenous P. sylvestris regeneration, and vice versa, owing to the indicated lack of host-specificity of the pathogen. It is possible, however, that host-specific strains exist, but do not differ in their RAPD profiles.     

Identification of the genus Armillaria by specific amplification of an rDNA-ITS fragment and evaluation of genetic variation within A. ostoyae by rDNA-RFLP and RAPD analysis

Genetic variation among Armillaria ostoyae isolates was studied by rDNA-restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) analysis. A total of 20 A. ostoyae isolates, mainly obtained from Picea spp. of different geographical origins, were examined. Southern hybridization of whole-cell DNAs digested with AvaII and probed with biotin-labelled cloned rDNA from Saccharomyces carlsbergensis allowed the differentiation of five RFLP groups. UPGMA cluster analysis of RAPD profiles (138 scorable bands) generated by 10 decamer primers (OPA 01-OPA 10) grouped the isolates in subclusters at similarity levels between 40% and 96%, indicating high intraspecific genetic variability. Some isolates of different geographical origins subgrouped together, suggesting that similar mutational events have occurred independently and that genetic exchange and recombination occurs among the DNAs in natural populations. The potential role of historical and current spread of spruce plants on the genetic variation of A. ostoyae isolates in Europe is discussed. Using the primer pair ARM-1 and ARM-2, an Armillaria-specific ITS-DNA fragment of about 660 bp was obtained. No intraspecific RFLP of this amplicon could be revealed, indicating low genetic variability of this region. The established informative RFLP and RAPD markers and also the Armillaria-specific ITS-DNA fragment may be powerful tools for further epidemiological, phylogenetic and host-pathogen interaction studies with A. ostoyae.     

Intrapopulation and Interpopulation Genetic Variation of Quercus in Denmark

Native Danish oak stands are fragmented and decreasing because of the extensive use of foreign seed sources. Therefore, the population structure of natural Danish oak stands was analysed by means of six polymorphic enzyme loci. A total of 17 stands of Quercus robur L. (including an ''outgroup'' sample from The Netherlands), seven Quercus petraea [Matt.] Liebl. and two putative hybrid stands were included in the study. The average genetic diversity was similar for the two species as well as for the putative hybrid stands: 0.25 for Q. robur, 0.27 for Q. petraea and 0.26 for the hybrid stands. The genotypic proportions at two (Pgm and Mnr) of the six loci showed many significant deviations from Hardy-Weinberg expectations, always with an excess of homozygotes, whereas the remaining four loci accorded to Hardy-Weinberg proportions, suggesting a low level of inbreeding. The differentiation of the Q. petraea and Q. robur populations was quantified with Wright's F-statistics. The within-species component was low, 0.022, reflecting the wind-pollinated reproductive mode of the two species. The betweenspecies component was 10-fold higher, 0.235, indicating two separate groups. A phylogenetic tree estimated from allele frequencies also supported the presence of these two groups. Despite the two well-separated groups in the tree, it was not possible to assign all individuals to the species to which they supposedly belonged. In total, 10% of the Q. robur individuals and 14% of the Q. petraea individuals were assigned to the other species, suggesting a limited amount of introgression between the two species.     

Verification of a phenotypic discrimination method for hybrid larch seedlings using DNA markers

The hybrid between Kuril larch (Larix gmelinii var. japonica) and Japanese larch (L. kaempferi) is an important afforestation tree species in Hokkaido, Japan, because of its rapid juvenile growth, straight stem, and resistance to bark gnawing by voles. To produce desirable hybrid seedlings, precise seedling discrimination is essential. However, continuous variations in morphological and phenological traits occur across L. gmelinii var. japonica × L. kaempferi and L. gmelinii var. japonica × L. gmelinii var. japonica seedlings. Therefore, we used DNA markers to verify and improve the morphological and phenological discrimination method. We collected seeds from an interspecific seed orchard and, using chloroplast DNA analysis, we showed that the hybridization rates of 1-year-old seedlings were different between years (2004, 23.2 %; 2005, 53.6 %) and between mother trees (2004, 5.8–39.4 %; 2005, 20.0–81.0 %). Discriminant analyses revealed that the root collar diameter of 2-year-old seedlings, number of sylleptic branches of 2-year-old seedlings, and day of terminal bud set in 1- and 2-year-old seedlings are traits that aid in discriminating hybrid seedlings. The proportions of correctly discriminated individuals were found to be 81.7–88.2 % when using improved phenotypic discrimination methods. These methods adopted traits with high discrimination abilities during discriminant analyses and determined the selection intensity according to the hybridization rate estimated from the DNA markers. In contrast, the proportions of correctly discriminated individuals obtained using the current method were lower, 72.7–78.5 %, because this method was based on seedling height and adopted a constant selection intensity.     

杜鹃属植物自然杂交研究进展

杜鹃花是闻名世界的观赏花卉,由于不少种类较弱的生殖隔离屏障,大量人工杂交选育品种得以问世。而在其野外重叠分布区,自然杂交种也屡见不鲜。文中着重从繁育系统、传粉特征、杂交后代与杂交区构成、人为干扰因素与分子鉴定等方面综述杜鹃属自然杂交研究现状,探讨杜鹃属植物自然杂交研究存在的问题并展望今后的研究方向及内容,提出杜鹃属植物自然杂交研究应注重特有传粉昆虫、人工干扰与杂交区构成关系、子代适应力和染色体组等方面,以期为将来揭示杜鹃属植物自然杂交历史、成因及新品种选育研究提供参考。     

Frost tolerance of various Pinus pure species and hybrids

Pinus species are widely planted by the South African forestry industry and are utilised for pulp, paper and saw timber products. Historically, Pinus patula Schiede ex Schltdl. et Cham. was the most widely planted commercial species in the summer rainfall area, but has come under severe threat due to the fungus Fusarium circinatum. Fusarium circinatum causes mortality in nurseries and in-field after establishment. Other Pinus species, such as P. tecunumanii F.Schwerdtf. ex Eguiluz et J.P.Perry and P. oocarpa Schiede ex Schltdl., have been crossed with P. patula to increase tolerance to F. circinatum and these hybrids have largely overcome the post-planting mortality problem. However, these hybrid-partner species are more prone to frost damage. This study reviewed laboratory screening techniques to assess the frost tolerance level of a range of Pinus pure species and hybrids. In vitro screening was done with the electrolyte leakage and whole-plant freezing techniques. Seedlings and rooted cuttings from a range of genotypes, supplied by Sappi, were tested in vitro at different target temperatures (?3, ?6, ?9 and ?12 °C) to determine their relative frost tolerance. These genotypes included a range of Pinus pure species, four interspecific hybrids (P. patula × P. tecunumanii low elevation [LE], P. patula × P. tecunumanii high elevation [HE], P. elliottii Engelm. × P. caribaea Morelet), and a three-way cross (P. patula × (P. patula × P. oocarpa)). Results from this study indicated that the electrolyte leakage technique was a reliable method to determine frost tolerance under laboratory conditions, with similar pure species rankings as experienced under field conditions. The interspecific hybrids of P. patula × P. tecunumanii LE and HE ranked intermediate between the parental species and the P. patula × P. tecunumanii HE hybrid was more frost tolerant than the P. patula × P. tecunumanii LE hybrid.     

Karyotype analysis of interspecific fusants of basidiomycetes by pulsed-field gel electrophoresis

The purpose of this research was to analyze the karyotype of the interspecific fusants of twoPleurotus species. Auxotrophic mutants derived from the cultivated strain ofP. ostreatus andP. cornucopiae were used. Protoplasts were fused electrically, and the fusants were selected under auxotrophic complementation. Esterase isozyme analysis showed that several fusants had isozyme bands originating from both parental strains, and others had unilateral isozyme bands. The fusant that had expressed isozyme bands of both parental strains showed chromosomal DNA bands of both of the parental strains in pulsedfield gel electrophoresis analysis. Despite the above results, the chromosomal composition of the fusants obtained by the pulsed-field gel electrophoresis did not exhibit all of the bands of both fusion parents.     

Effects of host plant hybridization on resistance to willow leaf rust caused by Melampsora sp.

Patterns of resistance to willow leaf rust caused by Melampsora sp. were measured on Salix eriocephala, Salix sericea, and their interspecific hybrids in natural field populations in 1991–94 and on potted plants in common garden experiments in 1994 and 1995. Testing was carried out to establish if the resistance of hybrids was intermediate between pure parental species (additive), equal to one of the parents (dominant), lower than both parents (susceptible), higher than both parents (resistant), or not different than either parent (null hypothesis). Support was generally found for hybrid susceptibility in the field and common garden experiments, with the null hypothesis of no difference having some support. The results from the common garden study suggest that the susceptibility of hybrids seen in the field is due to genetic differences. Hybridization between these species of willows results in increased susceptibility to this pathogen. The variation among years in the relative susceptibility of hybrid and parental willows may be due to environmental effects on the willows or to shifts in the abundance of Melampsora races.