Root peroxidases and Rhizobium, Bradyrhizobium nodulation affinities of Phaseolus vulgaris L. and P. acutifolius A. Gray congruity backcross populations

Four parents [P. acutifolius var.acutifolius (A₁₉), P. a.var. latifolius `Serowi' (A<sub>9</sub>),P. a. var. latifolius(A<sub>10</sub>), and P. vulgaris `Red Cloud' kidney (V₁)] were used to create six interspecific recurrent and congruity backcross pedigrees (V₁ × A₉, A₉ × V₁, V₁ × A₁₀, A₁₀ × V₁, V₁ × A₁₉, A₁₉ × V₁) for evaluation of Rhizobium, Bradyrhizobium nodulation affinities and root peroxidase banding patterns. Most primary hybrids nodulated with all Rhizobium, Bradyrhizobium strains, while recurrent generations nodulated with strains of the recurrent parent, suggesting a number of independent loci and random assortment for strain-specific nodulation. A proximity matrix of nodulation phenotypes produced a cluster with V₁, two recurrent and two congruity backcross hybrids with V₁ as the cytoplasmic parent; a separate cluster with all primary interspecific and balanced, congruity backcross hybrids. A₉ and A₁₀were clustered the farthest away from V₁. Root peroxidase zymograms of primary hybrids were the summation of the parents and controlled by independent loci. Advanced hybrids exhibited new root peroxidases, matching those found for otherPhaseolus spp., including ancestralP. coccineus. A proximity matrix of root peroxidase phenotypes produced a cluster with only A₉ ³V₁F₁, a cluster containing only A₁₉ ³V₁ F₂, and a large cluster with all P. acutifoliusparents and hybrids with P. acutifolius as the cytoplasmic parent in balanced hybrids or the majority parent in unbalanced hybrids. Estimation of genetic distances showed primary, interspecific hybrids to be more closely related with the cytoplasmic parent. Recurrent and congruity backcross generations varied in genetic distances between each respective parent. This is the first report of congruity backcrossing creating hybrids with biochemical traits of nonparental species. This revised version was published online in August 2006 with corrections to the Cover Date.     

不结球白菜(Brassica campestris ssp. chinensis Makino)种质资源SRAP遗传分化分析

利用SRAP分子标记分析了国内外64份不结球白菜种质资源的DNA遗传多样性和遗传分化。21对引物组合共检测出215个位点,其中112个为多态性位点,多态性比率达52.09%,平均每对引物组合产生10.24个位点和5.33个多态性位点。不结球白菜各类型中普通白菜的Nei’s基因多样性指数（0.1410）和遗传丰富度[(190) 88.37%]最高;各生态区域中江淮流域不结球白菜的Nei’s基因多样性指数（0.1451）和遗传丰富度[(185) 86.05%]最高;国内的Nei’s基因多样性指数(0.1293)和遗传丰富度[(188) 87.44%]分别高于国外。遗传变异估算表明,不结球白菜遗传分化系数58.22%,大部分变异存在于种群间;基因流为0.4031,说明群体间基因流动较少,遗传分化程度较高。以遗传相似系数0.872为截值,可把不结球球白菜分为Ⅵ个类群。     

Congruity backcrossing as a means of creating genetic variability in self pollinated crops: seed morphology of Phaseolus vulgaris L. and P. acutifolius A. Gray hybrids

Summary Seeds of early generations of three reciprocal congruity-backcross (CBC) pedigrees, developed by backcrossing Phaseolus vulgaris-P. acutifolius hybrids to each of the parent species in alternate generations, exhibited a preponderance of traits (size, shape, color, and pattern) of the cytoplasmic parent. The large size of Red Cloud (V₁), the P. vulgaris parent common to all of the pedigrees, dominated pedigrees with V₁ as the cytoplasmic parent, while the small size and rounded or square shapes of the tepary parents, wild P. acutifolius var. acutifolius PI 263590 or G400445 (A₁₉), wild P. acutifolius var. latifolius PI 406622 (A₁₀), or cultivated P. acutifolius var. latifolius Serowi PI 319443 (A₉), were the majority phenotypes when P. acutifolius was the cytoplasmic parent. Continuing through the second cycle of CBC, that is the second backcross with each of the parent species or the fourth backcross, began an amelioration of the apparent cytoplasmic effect on gene expression, as reciprocal pedigrees became more alike, usually with intermediate expression of parental traits or the appearance of new traits. The large seed size of V₁ was recovered in hybrids with P. acutifolius cytoplasm and the kidney shape of V₁ became rare in hybrids with P. vulgaris cytoplasm. Although the tepary-bean parents represented two subspecies and both cultivated and wild P. acutifolius, the three sets of reciprocal-hybrid pedigrees with P. vulgaris Red Cloud are surprisingly similar. It may be that the exotic parent used to develop a CBC pedigree should be selected more for combining ability in the interspecific cross than for specific economic traits. While the number of generations (six or more) required to produce fertile, intermediate CBC hybrids (that did not require embryo rescue) may preclude routine use of this method by practical plant breeders, the crossability of advanced hybrids with both parental species and the amount of variability apparent in advanced-hybrids progenies suggests that CBC would be valuable for maintaining exotic germplasm in immediately useful forms.     

基于ISSR对巴西网藓原变种(Syrrhopodon prolifer var.prolifer)遗传多样性的探讨

巴西网藓原变种(Syrrhopodon prolifer var.prolifer)是花叶藓科(Calymperaceae)网藓属(Syrrhopodon)植物,分布于中国的热带和亚热带地区。本研究利用简单序列重复区间(inter-simple sequence repeat,ISSR)分子标记对采集于海南省尖峰岭主峰、海南省尖峰岭雨林谷、海南省吊罗山基地、海南省吊罗山槟榔林、广东省鼎湖山西坑老鼎以及广东省鼎湖山庆云寺6个自然种群的38份标本的遗传多样性进行了评价,旨在为巴西网藓原变种的遗传多样性提供依据。结果显示:筛选出的5对引物共扩增出208条清晰的条带,其中147条为多态性条带,多态性位点百分率为70.67%,种群总的Nei's基因多样性指数为0.3007,Shannon's信息指数为0.4702,表明巴西网藓原变种的遗传多样性水平较高。6个种群的遗传分化系数为0.4185,种群间基因流为0.6948,表明58.15%的遗传变异在种群内,41.85%的遗传变异存在于种群间,说明其种群内的遗传分化相比种群间遗传分化较为明显。聚类分析显示,同一采集地点的标本有些并没有聚在一起,而地理位置较远的标本聚在一支,表明巴西网藓原变种种群间的遗传分化与地理距离关系很小。本研究为巴西网藓原变种的种群间遗传分化提供理论依据。     

Phaseolin Diversity in the Tepary Bean, Phaseolus acutifolius A. Gray

The tepary bean (Phaseolus acutifolius A. Gray) is grown mainly in and regions of Mexico and the southwestern U.S. as a subsistence crop by small farmers. It is also a store of genetic variability for traits such as disease and pest resistance and stress tolerance to improve the common bean (P. vulgaris L.). To determine geographic patterns of variation and the influence of domestication on genetic variability, the genetic diversity of phaseolin, the major seed storage protein, was characterized among 55 wild and 8 cultivated teparies using polyacrylamide gel electrophoresis. Fifteen electrophoretic phaseolin patterns were identified among wild forms, whereas only one pattern was exhibited by cultivars. This result suggests a single domestication in this species leading to a strong reduction in diversity. An additional finding is the divergence m phaseolin types between populations east and west of the Sierra Madre Occidental mountains.     

Simple Genetic Control of Hybrid Plant Development in Interspecific Crosses between Phaseolus vulgaris L. and P. acutifolius A. Gray

Crosses were performed between nine Phaseolus vulgaris lines (as females) and seven P. acutifolius lines (as- male to examine parental compatibility for the production of vigorous hybrid And backcross plants, in vitro embryo rescue techniques were required to secure hybrid and backcross proseny following interspecific crossing. Seedling development appeared to be dependent on which allele the P. vulgaris parent carried at an interspecific incompatibility locus. Seven of the nine P. vulgaris lines tested carried an allele at this locus which interacted with a nuclear factor in the P. acutifolius genome resulting in stunted, sub-lethal hybrids. The lines, ICA pijao' and ‘Sacramento Light Red Kidney’ did not carry this allele and produced vigorous hybrid progeny in combination with all P. acutifolius parents. Intensive backcrossing produced progeny which also segregated for sub-lethal and viable plant development. The observed segregation patterns suggest that a bridge crossing scheme would facilitate the introgression of P. acutifolius germplasm into incompatible P. vulgaris lines. Similarities, with an intraspecific incompatibility system are discussed.     

Genetic diversity of natural populations of Atriplex halimus L. in Morocco: An isoenzyme-based overview

Based on polyacrylamide gel electrophoresis, nine natural populations of Atriplex halimus L., a perennial shrub, collected in different regions of Morocco, were studied for their genetic variation using isoenzyme polymorphism of the highly active enzyme systems: esterases (EST), acid phosphatases (ACP) and glutamate oxaloacetate transaminase (GOT). Different allozyme frequencies from 7 different loci were obtained for all populations of this halophyte species. High levels of genetic diversity were revealed. The mean number of alleles per locus (A = 1.9–2.0), the percentage of polymorphic loci (p = 71.4–85.7) and the mean expected heterozygosity (H_e = 0.339–0.385) showed an important variability in all populations. Gene diversity was essentially explained by the within population component. The between populations differentiation accounted for 8% of the whole diversity (F_ST, averaged over all loci, is 0.08). The relationships among the 9 populations were inferred from the Nei’s genetic distances. Four major groups were formed. The northern population ‘Tanger’, forming a unique group, was highly divergent from the other groups. It appeared that the genetic distance between all groups was related to the geographic distance that separates them. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diversity in the wild potato species Solanum chacoense Bitt.

Summary The morphological and isozyme variation was studied in 22 accessions of Solanum chacoense from Paraguay and Argentina. Clear geographic groups were identified through the use of multivariate analyses. S. chacoense from mountain sites in Argentina could be readily distinguished from plains forms from Paraguay, on the basis of several correlated morphological characters. Three isozyme systems, namely phosphoglucose isomerase (PGI), glutamate-oxaloacetate transaminase (GOT) and peroxidase (PRX) were studied using starch gel electrophoresis. The banding patterns indicated that for each isozyme there were several loci, which were polymorphic. A genetic interpretation of one of the PGI loci was made, and indices of genetic diversity and genetic identity calculated. Principal components analysis, cluster analysis and genetic diversity indicated a close relationship between the geographical groups. These results are discussed in the context of in situ genetic conservation.     

Genetic Control of Abnormal Seedling Development in Phaseolus vulgaris L. and P. vulgaris×P. acutifolius A. Gray Hybrids

Abnormal hybrid seedling development hinders attempts to introgress diverse germplasm in common bean (Phaseolus vulgaris L.) breeding programs. In this study, the hypothesis that DL₁ and DL₂ loci control abnormal seedling development both in Phaseolus vulgaris L. intraspecific hybrids and in P. vulgaris×P. acutifolius A. Gray interspecific hybrids was tested. Hybrids from crosses between six P. vulgaris lines (two Andean dl₁ d₁, DL₂DL₂, two Mesoamerican DL₁DL₁ dl₂ dl₂, and two facilitators dl₁dl₁, dl₂dl₂) and P. vulgaris cultivar Ex Rico 23 developed normally, indicating that Ex Rico 23 has the facilitator genotype dl₁, dl₁, dl₂dl₂. Previous studies have shown that Ex Rico 23 ×P. acutifolius results in abnormal seedlings, but ‘ICA Pijao’, also dl₁, dl₁ dl₂dl₂, ×P. acutifolius results in normal seedlings. Neither the Andean nor the Mesoamerican lines crossed successfully with P. acutifolius, but crosses between one of the two facilitators (G3807) and P. acutifolius resulted in normal seedlings. These results support the hypothesis that different loci control intra- and interspecific hybrid seedling development.     

野生稻与亚洲栽培稻的遗传多样性

为评价野生稻与亚洲栽培稻的遗传多样性及其变异关系,56对SSR引物被用于研究广泛地理分布的55份普通野生稻(其中32份O. rufipogon和23份O. nivara)和25份亚洲栽培稻(14份indica和11份japonica)样本。298个多态性位点被检出,占总扩增等位点的98.68%。野生稻多态性位点的百分比(平均达91%)及Nei’s遗传多样性值(h)明显高于亚洲栽培稻,表明普通野生稻比亚洲栽培稻具更丰富的遗传多样性。UPGMA聚类分析显示野生稻的两个类群(O. rufipogon和O. nivara)关系密切,但在遗传上存在明显的分化,支持其作为两个独立物种的分类观点。许多普通野生稻中籼粳分化尽管不很明显,然而亚洲栽培稻的籼粳亚种分化是明显的。亚洲栽培稻与多年生普通野生稻(O. rufipogon)关系更为密切,符合异源起源的遗传分化模式。     

AFLP in Triticum aestivum L.: patterns of genetic diversity and genome distribution

The amplified fragment length polymorphism (AFLP) procedure was applied to a diverse panel of wheat (Triticum aestivum L. em. Thell.) accessions and sixty-nine of the recombinant inbred lines (RILs) from the widely used genetic mapping population derived from the cross of Opata 85 and W7984. Most (76.8%) bands were monomorphic among T. aestivum accessions. The majority of bands monomorphic in T. aestivum also were present in the synthetic wheat parent (W7984). Ten primer pairs generated 153 polymorphic AFLP bands, 140 of which could be assigned to a chromosome location and were relatively evenly distributed on the genetic linkage map. AFLP loci in T. aestivum were distributed throughout the genome; they generally have only one detectable sequence variant; and they exhibit monogenic dominant mendelian inheritance. Frequencies of polymorphic bands in the germplasm sampled are in the range that enables informative cluster analyses as well as map-based diversity and association analysis studies. AFLP bands mapped to individual loci in the Opata 85/W7984 RIL population will frequently be polymorphic in other crosses or germplasm, irrespective of whether the band arises from the T. aestivum parent or the synthetic wheat parent. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic diversity assessment in cultivated cardoon by AFLP (amplified fragment length polymorphism) and microsatellite markers

Cultivated cardoon (Cynara cardunculus L. var. altilis DC) belongs, together with globe artichoke (C. (cardunculus L. var. sylvestris L.) and wild cardoon (C. cardunculus L. var., sylvestris (Lamk) Fiori). to the family Asteraceae (Compositae). Cultivated cardoon is of regional importance in Italy. Spain and southern France, where it is used for the preparation of traditional dishes. It has been shown to have potential as a source of oil from its seeds, inulin from its roots and various biopharmaceuticals from its leaves. Levels of genetic diversity and relatedness between eleven Italian and 10 Spanish accessions were assessed by DNA profiling with eight AFLP primer combinations and at five microsatellite loci. The AFLP analysis of genetic similarities showed that the Spanish and Italian accessions represent two distinct gene pools; substantial variation was present within each accession. On the other hand a limited variation was detectable by applying SSR markers.     

The genetic structure of cocoa populations (Theobroma cacao. L.) revealed by RFLP analysis

The genetic structure of 175 genotypes of Theobroma cacao L. was investigated using 27 RFLP/cDNA loci. The number of alleles per locus was never higher than four and a high genetic diversity was found. Criollo genotypes appeared differentiated from Forastero genotypes. A deficiency of heterozygotes was found in all populations and some alleles were fixed in some populations. Within population gene diversity was high. When four morphological groups were considered, Upper Amazon Forastero was the most polymorphic and diverse population. Almost all the alleles of the whole species could be found within this group. Observed heterozygosity was the highest within Criollo and Trinitario populations but a certain proportion of homozygous genotypes was present in all groups. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic diversity and differentiation of Chinese wild soybean germplasm (G. soja Sieb. & Zucc.) in geographical scale revealed by SSR markers

Wild soybean (Glycine soja), as the progenitor of soybeans (G. max), is widely distributed in China and has been collected as a supplementary germplasm pool of soybeans. In this study, 375 wild soybean accessions from a set of genebank core collection were analysed for genetic diversity by using 42 simple sequence repeat primer pairs. The mean allele number per locus was 19.62. Ten‐percent unique alleles involving 35 or 83.33% loci differentiated among the geographical regions. The mean gene diversity (h) per locus was 0.89. A very low mean coefficient of gene differentiation (G_ST = 0.08) for geographical regions and a high mean within‐region gene diversity (H_S = 0.81) were observed, indicating that most genetic diversity existed within the regions. There was an obvious relationship between genetic distance and geographical distance. The results showed multiple centers of genetic diversity for Chinese wild soybean in North China, the Huanghe River Valley, and Central China as well as the Changjiang River Valley, implicating multiple site origins of soybeans within China.     

Genetic Variation in Commercial Varieties and Natural Populations of Sheep's Fescue, Festuca ovina s.l.

Genetic variation in two commercial varieties, ‘Liwally’ and ‘Barok’, and two Swedish natural populations of sheep's fescue, Festuca ovina s.l., was studied by means of starch gel electrophoresis. Variation in allele frequencies was found at the Dial, Gpi2, Got2, Pgdl, Pgm, Tpil and Tpi2 loci. ‘Liwally’, belonging to ssp. vallesiaca, showed clear differences compared to the other samples which belong to ssp. capillata and ssp. vulgaris. Genetic diversity, as measured by per cent polymorphic loci, number of alleles per locus and frequency of heterozygotes, was high in all samples in agreement with what has been found in other perennial, outcrossing mono-cotyledonous species with a wide distribution. The bred varieties and the wild populations did not statistically differ with respect to frequency of heterozygotes or number of alleles, though the last value was lower in the domesticated lines than in the natural populations. No significant deviation from the expected Hardy-Weinberg proportions was found in any of the samples.     

Genetic Diversity of the Date Palm (Phoenix dactylifera L.) from Algeria Revealed by Enzyme Markers

Analysis of the enzymatic polymorphism of the date palm, Phoenix dactylifera L., was undertaken to evaluate the genetic variability of Algerian cultivars. Seven enzyme systems (alcohol dehydrogenase, diaphorase, aspartate aminotransaminase, acid phosphatase, endopeptidase, leucine aminopeptidase and phosphoglucomutase) were visualized by electrophoresis. Genetic hypotheses appear to show 7 polymorphic loci and 16 alleles were counted. The study of diversity showed a high percentage of polymorphic loci, strong heterozygosity and considerable genetic diversity. The study shows that genetic variability is greater in the cultivars in the western regions (Saoura-Touat) than in the eastern regions (Rhir-Zibans). An identification key was devised and nearly 65% of the cultivars studied were identified from 5 enzyme systems.     

Genetic diversity of barley cultivars grown in Spain, estimated by RFLP, similarity and coancestry coefficients

This study was conducted with the objective of characterizing the genetic variation among a representative set of 37 barley cultivars currently grown in Spain, using restriction fragment length polymorphism (RFLP) markers. Thirty-two RFLP probes, in combination with three restriction enzymes, were used to analyse polymorphism at the molecular level. Genetic distances (GD), based on RFLP band patterns, and coancestry coefficients (f), based on pedigree records, were calculated. Of the 95 clone-enzyme combinations analysed, 71 (74.7%) were polymorphic, representing 246 RFLP patterns. A cluster analysis of GD split the sample into five distinct germplasm groups that were consistent with the history of the cultivars (winter European, spring European, CIMMYT-ICARDA materials, the single cultivar ‘Dobla’ and Spanish local materials). The Spanish group was the most distinct one and had unique alleles at markers close to major loci determining phonological adaptation. The probes which best distinguished among groups were also identified. Genetic similarity estimates were moderately consistent with f (for cultivars with complete pedigrees). The implications for integration of diversity studies into breeding programmes are discussed.     

Analysis of genetic diversity in Agave tequilana var. Azul using RAPD markers

By federal law in Mexico, A. tequilana Weber var. Azul is the only variety of agave permitted for the production of any tequila. Our objective was to assay levels of genetic variation in field populations of A. tequilana var. Azul using randomly amplified polymorphic DNA (RAPD) markers. Ten plants were collected from each of four different fields, with two fields being located in each of two principal regions of Mexico for the cultivation of A. tequilana var. Azul. The two regions are separated geographically by approximately 100km. Genetic relationships between A. tequilana var. Azul and two other varieties of A. tequilana Weber, ‘Chato’ and ‘Siguin’, were also investigated using RAPDs. Among the three varieties, 19 decamer primers produced 130 markers, of which 20 (15.4%) were polymorphic betweenA. tequilana var. Chato and A. tequilana var. Siguin. The results of RAPD analysis suggest that A. tequilana var. Siguin is more closely related to A. tequilana var. Azul than is A. tequilana var. Chato. Among the 40 field selections of A. tequilana var. Azul, only 1 of124 RAPD products (0.8%) was polymorphic and 39 of 40 plants were completely isogenic. This is one of the lowest levels of polymorphism detected to date for the analysis of a crop species, and is proposed to be the result of the promotion of a single conserved genotype over many years due to an exclusive reliance on vegetative propagation for the production of new planting materials. The significance of these results is discussed in relation to breeding programs focused on the improvement of A. tequilana var. Azul. This revised version was published online in July 2006 with corrections to the Cover Date.     

利用微卫星标记分析建鲤种质资源的研究

为了评估和合理利用建鲤种质资源。从建鲤繁育群体中随机选取185尾鱼,用20个微卫星位点进行遗传多样性分析。结果表明：20个微卫星位点在该群体中所检测到的等位基因片段长度在114~316 bp,共检测出156个等位基因和402种基因型,各位点等位基因数为5~13个,平均7.8个,基因型数10~44种,平均20.1种;各位点观察杂合度(Ho)、期望杂合度(He)分别在0.346~0.978和0.619~0.880之间,平均分别为0.6434和0.757;所检测的20个位点多态信息含量(PIC)在0.552~0.868之间,平均为0.7253,都属于高度多态位点(PIC>0.5)。实验结果表明,该建鲤繁育群体多态信息含量丰富,遗传多样性水平较高,具有较大的选育潜力。群体内平均固定系数(FIS)为0.1479,说明该建鲤群体存在杂合子缺失现象。根据个体间的遗传距离构建的聚类图可以清楚地显示每个个体之间的遗传差异,这可为建鲤保种和繁殖配组提供依据,避免近交现象。     

RAPD markers for discriminating tea germplasms at the inter-specific level in China

For the discrimination of tea germplasms at the inter‐specific level, four tea species and varieties (Camellia sinensis, C. sinensis var. assamica, C. sinensis var. pubilimba, C. sinensis var. kucha) and their 20 wild allied species (C. sp.) preserved in the China National Germplasm Tea Repositories (CNGTR) were investigated using randomly amplified polymorphic DNA (RAPD) markers. Fifteen primers were chosen from the 61 screened for RAPD amplification. The average DNA polymorphic frequency of RAPD primers at the inter‐specific level was 0.30, varying from 0.16 to 0.60, lower than that at the intra‐specific level. Using the presence, sometimes absence of unique RAPD markers, it was possible to discriminate 14 of the germplasms investigated. No single primer could discriminate all the 24 germplasms. However, OPO‐13 provided rich band patterns and it could discriminate 10 genotypes. The combination of two and three primers made it possible to discriminate 15 and 21 germplasms, respectively. Furthermore, the combination of band patterns or the DNA fingerprinting based on specific RAPD markers generated by OPO‐13, OPO‐18, OPG‐12 and OPA‐13 allowed the discrimination of all 24 germplasms investigated. Therefore, RAPD markers also provide a powerful tool to differentiate tea germplasms at the inter‐specific level.