Assessing the genetic diversity of Portuguese maize germplasm using microsatellite markers

A collection of Portuguese maize accessions representing a valuable source of genes for introduction into modern cultivars is stored at the Portuguese Plant Germplasm Bank (Banco Português de Germoplasma Vegetal—BPGV). To assess genetic diversity among inbreds, microsatellite analysis was carried out for 54 inbred lines representing the diversity of Portuguese dent and flint maize germplasm. Fifty American and other European elite inbreds were also analysed for comparison. Fifteen microsatellite loci distributed throughout the maize genome were chosen based on their repeat unit and base composition. A total of 80 alleles were detected with an average allele number of 5.33 per locus. Polymorphism information content (PIC) values and observed genetic distances showed the existence of large variability among inbreds. Cluster analysis indicated that almost all of the inbreds could be distinguished from each other and Portuguese inbreds were present in all clusters formed. These associations were consistent with the known pedigree records of the inbreds, confirming a mixed origin of Portuguese materials. Comparative analysis of microsatellite diversity among groups was established according to important traits for both breeding and line identification. This revealed that, although most of the genetic diversity (>95%) was attributable to differences among inbreds of different groups, the existence of phenotypic differentiation in endosperm colour, kernel type and cob colour could be suggested for grouping. These findings support the joint use of molecular and morphological traits in management of the germplasm collection. In this study, SSR markers proved to be effective to characterise and identify maize inbred lines, and demonstrate associations among them. This revised version was published online in July 2006 with corrections to the Cover Date.     

玉米新合成群体8种等位酶17个位点的遗传多样性及与数量性状相关性研究

采用淀粉凝胶平板电泳方法,研究了华中农业大学4个玉米新合成群体(WBM, LBM, WLS,LLS), 2个美国群体(BSSSR和BS16)和6个自交系的ADH, CAT, EST, GLU, GOT, MDH, PGD,PHI 8种等位酶的17个位点的47个等位基因的遗传多样性及其与数量性状的相关。采用NC II遗传交配设计,6个群体与6个自交系组配成36个组合,田间试验在武昌、安     

Allozyme variation in cultivars of Cucurbita pepo L.

Summary Cultivars of Cucurbita pepo were analyzed for their isozyme phenotypes by horizontal starch gel electrophoresis. Considerable allozymic variation was observed between cultivars, especially in the aspartate aminotransferase and malate dehydrogenase isozyme systems. Each of the five fruit types represented in the 21 cultivars tested (zucchini, pumpkin, spaghetti, acorn, scallop and yellow straightneck) could be distinguished by specific allozymes or combination of allozymes. Cultivars within a fruit type gave very similar allozyme phenotypes and often could not be distinguished on the basis of the 6 assays used. Despite the outcrossing nature of the species, allozyme polymorphism within most cultivars was low and did not seriously interfere with the analysis. Approximately half of the hybrid lines tested gave heterozygous phenotypes at one or more loci, indicating that such loci could be used to screen for the percentage of hybrid seed obtained from crosses.     

过氧化物酶及种子蛋白分析鉴定甜椒杂交种纯度

用聚丙烯酰胺均匀胶和等电聚焦电泳技术，分析了甜椒种子及种苗的过氧化物同功酶谱和种子水溶蛋白图谱。在过氧化物酶谱带的两个位点ＰＲＸ－１和ＰＲＸ－２上，自交系亲本与Ｆ１杂交种有明显的差异。水溶蛋白的一个位点ＰＲＯＴ亲本与Ｆ１有明显差异。供试甜椒组合的过氧化物酶和蛋白的图谱，分别具有这些位点。     

Inheritance of isozymes in peach x Prunus kansuensis and peach x Prunus davidiana hybrids

Summary Isozyme variation and inheritance were investigated with starch gel electrophoresis in peach (Prunus persica L. Batsch) x P. kansuensis Rehd. and peach x P. davidiana (Carr.) Franch. interspecific hybrids. Of five enzyme systems surveyed for polymorphism, four systems were identified as polymorphic [isocitrate dehydrogenase (IDH, EC 1.1.1.41), phosphoglucomutase (PGM, EC 2.7.5.1), aspartate aminotransferase (AAT, EC 2.6.1.1), and 6 phosphogluconate dehydrogenase (PGD, EC 1.1.1.44)] and may be useful as genetic markers in future cultivar and rootstock development. Analysis of progenies segregating for pairs of loci suggests a possible linkage between the loci coding for Aat-1 and Pgd-2. Independent assortment was observed for isozyme loci Idh/Pgm-2, Idh/Aat-1, Idh/Pgd-2, Pgm-2/Aat-1, Pgm-2/Pgd-2, and Aat-2/Aat-1. The red leaf locus, Gr, assorted independently of the isozyme loci: Idh, Pgm-2, Aat-1, and Pgd-2.     

Utilization of isozyme polymorphism for cultivar identification of 45 commercial peas (Pisum sativum L.)

Forty five Pisum sativum cultivars were analysed by isozyme electrophoresis with the objective to find protein markers for exact and reproducible discrimination of individual genotypes. The combination of six enzyme systems (acid phosphatase, amylase, esterase, leucine aminopeptidase, shikimate dehydrogenase and phosphoglucomutase) with two electrophoretic techniques (NATIVE-PAGE, isoelectric focusing) and use of seed and leaf tissue enabled to identify all 45 studied cultivars. Critical factors which may affect utilization of isozyme electrophoresis for commercial applications in pea breeding and seed production and testing are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study of genetic diversity in Indian and exotic sesame (Sesamum indicum L.) germplasm using random amplified polymorphic DNA (RAPD) markers

Fifty-eight accessions of sesame (Sesamum indicum L.), an important oil seed crop of the tropics and subtropics were analysed using random amplified polymorphic DNA (RAPD) technique. The material analysed comprised 36 collections from 18 different states of India and four adjoining countries of the Indian subcontinent, and 22 exotic accessions from 21 sesame growing countries around the world. The results from PCR amplifications with the selected 24 random 10-mer primers were statistically analysed. The value of Jaccard’s similarity coefficients ranged from 0.19 to 0.89. The results indicated the presence of high level of genetic diversity. However, the extent of genetic diversity was greater in the collections from Indian subcontinent as compared to the exotics. Among the Indian accessions, the collections from Rajasthan and North-eastern states were highly diverse. The phenetic analysis grouped 48 out of 58 accessions in six clusters and the remaining highly diverse accessions were placed outside these close-knit clusters. The Bootstrap estimates obtained by Wagner parsimony analysis were significant for seven out of 49 nodes in the majority-rule consensus tree (<95% occurrence). The results of both the analyses were, however, broadly comparable when the constitution of the individual clusters were considered. The principal components analysis indicated that the first two components accounted for only 21% of the total variations and in order to explain <75% of variations 18 components were required. The high level of genetic diversity prevalent among the Indian collections is probably indicative of the nativity of this crop species. Similarly, the relatively lower level of polymorphism in exotic germplasm could be ascribed to the comparatively recent introductions of limited germplasm of this crop into some of the non-traditional sesame growing countries. This revised version was published online in August 2006 with corrections to the Cover Date.     

Use of isozyme analysis in the breeding of synthetic rapeseed cultivars

Eleven winter rapeseed inbred lines (I₄) were characterized according to isozyme banding patterns from seven polymorphic enzyme systems. All lines could be qualitatively and quantitatively distinguished using two enzyme systems, shikimate dehydrogenase (SDH) and diaphorase (DIA). Genetic distances were calculated among lines and 15 selected two-line hybrids were planted as experimental synthetics in field-trials. Syn-0 populations produced seed yields between 0.4% lower and 12.9% higher than the mean yields of the respective parental lines. Syn-1 seed yields were 11–24.1% higher than the respective parental lines and the yield improvement was positively correlated with the genetic distance between the parental lines. This tendency suggests that genetic distances between cross components, calculated from isozyme polymorphism, can be used in prognosis of yield performance of synthetic rapeseed cultivars. Isozyme analysis was also applied to study fertilization behaviour in line mixtures, and differences among parental lines were observed with regard to the tendency for self-pollination or out-crossing. The partially very high outcrossing rate suggests the possible existence of a self-incompatibility system.     

苹果酸脱氢酶在番茄F1杂种纯度检测中的应用

本文应用垂直板不连续系统的聚丙烯酰胺凝胶电泳（ＰＡＧＥ）法,分析了５个杂交一代种（佳粉一号、佳粉二号、佳粉十号、佳粉十五号、双抗二号）发芽肿种苗的五种同工酶（苹果酸脱氢酶（ＭＤＨ）、乙醇脱氢酶（ＡＤＨ）、磷酸葡萄糖变位酶（ＰＧＭ）、酯酶（ＥＳＴ）、异柠檬酸脱氢酶（ＩＤＨ）。发现５个杂交一代种中,３个要交一代种与其双亲的苹果酸脱氢酶（ＭＤＨ）谱带有有明显稳定的区别。两个杂交一代种与其双亲酯（ＥＳＴ）     

A Multivariate Analysis of Soybean Genotypes Grown Under Different Cropping Systems

Nature and magnitude of genetic diversity was assessed using Mahalanobis's D² statistics and canonical analysis in 50 genotypes of soybean grown in monoculture and in association with maize. All the genotypes were grouped in 10 clusters in case of monoculture, while 8 clusters were formed for intercropping. Monoculture was more suitable environment for expressing the genetic diversity than intercrop. Some genotypes had consistently the similar clustering pattern in both the cropping systems, while others were affected by the cropping system in expressing the genetic diversity. This was confirmed by the canonical analysis. Days to flowering and maturity, seed yield/plant, plant height and 100-seed weight were mainly responsible for genetic diversity in monoculture. Besides phenological traits, pod length and width, and seed yield/plant exerted marked influence on the genetic diversity of soybean genotypes grown in association with maize. Geographical distribution was not necessarily reflected by the genetic divergence, though some degree of relationship between geographic diversity and genetic diversity was evident under both the cropping systems. The performance of some genotypes varied from cropping system to another, while that of others remained unaffected. Breeding programmes to develop varieties suitable for sole crop, intercrop and both the cropping systems have been suggested.     

Genetic analysis and nomenclature for seven isozyme systems in Brassica nigra, B. oleracea and B. campestris

General criteria for the assignment of names to enzyme systems, regions of activity, isozyme loci and allozymes have been lacking in crucifer species. This paper proposes a standard nomenclature for seven isozyme systems in the three diploid species of U's triangle: Brassica nigra, B. oleracea and B. campestris. Gel/electrode buffers, which provided the best resolution for seven isozyme systems, acid phosphatase (APS), aconitase (ACO), leucine aminopeptidase (LAP), 6-phosphogluconate dehydrogenase (6 PGD), phosphoglucoisomerase (PGI), phosphoglucomutase (PGM), and triosephosphate isomerase (TPI), were proposed as standards. Isozyme genetic analysis was determined for B. oleracea and B. campestris from previous studies and by segregation of selfed progenies of heterozygous B. nigra plants. Several populations were studied and 148 allozymes at the 18 loci observed were described for the three species. Their relative mobility was studied using a pure line of oilseed rape as reference. The comparison of the different alleles within and between the species is discussed.     

Isozyme and quantitative traits polymorphisms in European provenances of perennial ryegrass (Lolium perenne L)

Twenty populations of Lolium perenne originating from a range of habitats in Europe were compared for isoenzyme polymorphisms and agronomically important quantitative traits in order to establish relationships of the levels of diversity with the origin of each population and to assess their suitability to be included in the European core collection of Lolium germplasm. Forty genotypes from each of the twenty populations and each genotype represented by three clonal propagules, were field planted in a fully randomized spaced plant design and fifteen quantitative characters including yield, persistency, reproductive and disease resistence characters were evaluated over a period of two years. Seven putative isozyme loci were assayed to compare the allozyme divergence of populations. The results of the isozyme survey indicate that 71–100% of the loci were polymorphic, 2.3–3.0 alleles/locus and the gene diversity was varying from 0.234–0.410. Of the total allelic diversity 94% remained within populations (H_s) whilst only 6% was distributed among populations (D_st). The differences between populations were determined on the basis of allele frequencies and multivariate analyses of quantitative characters. Populations significantly differed in their allele frequencies at all loci analysed. Random mating was predominant in all populations at most of the loci. The study revealed that the German accession BA 10998 was clearly distinct from the rest both in quantitative characters and allele frequencies. German accession BA 11015 with the lowest gene diversity showed the highest genetic variation for quantitative characters. However, no strict relationship was found between the genetic distance and the geograpical distribution of the populations. Among the quantitative characters, flowering time showed a strong relationship with the type of management practised at the collection site than their place of origin. This revised version was published online in July 2006 with corrections to the Cover Date.     

Electrophoretic variation as a tool for determining seed purity and for breeding hybrid varieties of Brassica oleracea

Summary Isozyme phenotypes at four known genetic loci were determined in parental inbreds and corresponding F₁ hybrid seed lots of four commercial broccoli, two cauliflower, and two cabbage varieties to determine seed purity. Most inbred lines were completely homozygous at all four loci but differed with respect to alleles at one to three loci. Several parental inbreds of the cabbage hybrids were segregating at two to three of the loci. Models were developed to estimate seed purity in cases where parents were either fixed or segregating at diagnostic loci. Estimates of contamination ranged from 1.5 to 40.1%. These estimates were comparable with those from commercial grow-outs with a tendency for the former estimates to be higher. It was concluded that more stable SI alleles or genetic male sterility should be used to reduce contamination. Electrophoretic variation was further discussed as a tool for selecting homozygous plants and for strong self-incompatibility.     

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.     

梨属植物等位酶遗传多样性研究

利用超薄平板微型聚丙烯酰胺凝胶的等电聚焦电泳技术,对286份梨材料进行了等位酶遗传变异分析。在8个酶系中共检测到19个清晰位点和82个等位基因,19个位点均为多态位点,位点最大等位基因数为6,体现出梨丰富的遗传种质多样性;不同的居群具有特有等位基因;通过82个等位基因可以将286份材料完全区分开,表明等位酶基因型指纹可用作梨品种区分与鉴定的依据。     

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.     

同工酶差异位点分析在蔬菜杂交种纯度检测中的应用

用10种同工酶和蛋白质分析体系，分析了7种重要蔬菜的71个杂交种与其亲本之间的差异位点，以及这些差异位点用于杂交种纯度检测的可能性和存在的问题。试验表明，作物的不同种类，杂交种与亲本之间的亲缘关系以及作物各类的遗传多态性，都会影响同工酶差异位点产生的多寡，从而影响到这一技术是否能用于此种作物的纯度检测。分析了不同同工酶在不同蔬菜中的多态性以及在蔬菜种子纯度检测中的表现。     

玉米杂交种及其亲本自交系的生化指纹鉴定

本试验以浙单9号等五个玉米杂交组合及其亲本自交系为材料,进行种子盐溶蛋白聚丙烯酰胺凝胶电泳等多种电泳鉴定方法的研究,以揭示玉米杂交种及其亲本自交系的“生化指纹”(biochenucal fingerprint),以及筛选出适合于玉米杂交种及其亲本自交系真实性和纯度鉴定的方法。结果表明,各供试玉米杂交种及其亲本自交系都具有相应的、唯一的种子盐溶蛋白聚丙烯酰胺凝胶电泳所显现的生化指纹。对于有些组合。玉米芽鞘和叶片绿色组织过氧化物酶同工酶电泳图谱存在阴极第4、第5酶带差异,因这两条酶带的差异稳定,并且重现性好,故能用过氧化物酶同工酶技术对其进行有效地鉴定。上述两种方法,尤其是前者,因技术要求不高,费用低,快速及重现性好等特点,能满足我国目前种子检验室日常玉米品种纯度快速测定工作的要求,具育良好的应用前景。     

Simple sequence repeat polymorphism in Quality Protein Maize (QPM) lines

A set of 23 Quality Protein Maize (QPM) lines, including 13 lines developed in India and 10 lines at CIMMYT (International Maize and Wheat Improvement Center), Mexico, was analyzed using microsatellite or simple sequence repeat (SSR) markers. Polymorphic profiles for 36 SSR loci have aided in differentiating the QPM inbred lines. The study resulted in identification of SSR markers, such as bnlg439, phi037, bnlg125, dupssr34 andbnlg105, with high polymorphism information content in the selected QPM genotypes. Detection of 30 unique/rare SSR alleles could contribute to effective differentiation of 14 of the 23 QPM inbreds. An opaque2-specific microsatellite marker, phi057, also facilitated differentiation of opaque2-carrying QPM inbreds from the non-opaque genotypes. Analysis using SSR markers indicated high levels of heterozygosity in majority of the Indian QPM lines and in one CIMMYT QPM inbred, CML188. Cluster analysis using SSR data, followed by canonical discriminant analysis, clearly distinguished the Indian QPM inbreds from those developed at CIMMYT. The cluster patterns were largely in congruence with the available pedigree information of the QPM inbreds studied. The study demonstrates the effectiveness of SSR markers in QPM genotype discrimination and analysis of genetic relationships, and could potentially contribute towards effective utilization of the elite QPM germplasm in Indian maize breeding programmes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of isozymes in Salvia columbariae

Summary Salvia columbariae is a herbaceous annual species which has potential for domestication as a new source of industrial oil. Isozyme markers provide a mean by which this process may be facilitated. Isozyme survey of field grown Salvia columbariae plants showed variation for malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), and phosphogllucomutase (PGM). Selfed seed was obtained from the field and was grown in the greenhouse for segregation analyses. Electrophoretic results indicated that MDH was variable at zone 1, showing presence or absence of a band. The observed segregation ratio was not significantly different from expected ratio for Pgi-4 and Pgm-3 isozymes, indicating monogenic control of the two loci. Pgi-4 locus was heterozygous for a null allele. Cross dimerization between the allozyme Pgi-3 and Pgi-4 loci resulted in an intergenic band for this isozyme system.Abbreviations ACO aconitase - ADH alcohol dehydrogenase - DTT-DL dithiothreitol - FDH formate dehydrogenase - GOT glutamate-oxalacetate transaminase - IDH isocitric dehydrogenase - MDH malate dehydrogenase - MNR menadione reductase - 6PGD 6-phosphogluconate dehydrogenase - PGI phosphoglucose isomerase - PGM phosphoglucomutase - PVP-40 polyvinylpyrrolidone - SKDH shikimate dehydrogenase - TPI triosephosphate isomerase