RFLPs of chloroplast and mitochondrial DNA in wild soybean, Glycine soja, growing in China

RFLPs of chloroplast (cp) and mitochondrial (mt) DNA have been used to characterize the cytoplasmic genome of wild soybean, Glycine soja, growing in China. We have found from the RFLPs of that the cytoplasmic genomes of most Chinese wild soybeans have a combination of cpIII with mt-a or a combination of cpII with mt-b accompanied by mtIV or mtV according to our classification. CpII was not observed in combination with mt-a and cpIII was not observed in combination with mt-b. The regional distribution of these two types showed clines with opposite directions. The Yangtze River Valley had the greatest diversity in each of cp and two mt profiles detected in this study and the cytoplasmic genome combining these three profiles showed the highest degree of polymorphism in this region. The Yangtze River Valley may be a center of cytoplasmic diversity of wild soybean and may contain various genetic resources of soybean.     

Genetic diversity and gene flow dynamics revealed in the rare mixed populations of wild soybean (Glycine soja) and semi-wild type (Glycine gracilis) in China

Thus far, there is little knowledge of the genetic diversity, structure and gene flow dynamics in rare wild and semi-wild soybean mixed populations, and such information is vital for understanding of the origin of semi-wild soybean (Glycine gracilis) and the biosafety protection of wild soybean from transgenic soybeans. Population eco-genetic data are necessary to provide a more coherent and comprehensive understanding of the genetic events that occurred in the natural habitats of wild soybean (Glycine soja). We tested genetic diversity and structure of 11 wild mixed populations of wild soybean (Glycine soja) and semi-wild soybean (G. gracilis), 1 wild soybean population, and 1 cultivated soybean variety population were studied using 20 nuclear microsatellite markers (SSRs). We found based on microsatellite polymorphisms that the mixed populations were characterized by higher mean heterozygosity (H _o = 0.029) and outcrossing rate (t _m = 6.35 %), and lower fixation index (F _is = 0.891), and the semi-wild plants had distinctly higher heterozygosity (H _o = 0.081) than that of the wild plants (H _o = 0.007). The occurrence of semi-wild plants influenced population genetic structure but not geographical population differentiation. These mixed populations exhibited strong ecogeographical differentiation, which suggests that their original populations were colonized over a long phytogeographical history. The introgression occurred through pollen gene flow from the soybean fields into wild populations and created the semi-wild plants, with significant genetic differentiation from the typical wild ones. Introgressive genes could become established by two possible modes in wild soybean populations by both self-segregation and/or intrapopulation secondary hybridization. The latter deserves attention because of the possibility of rapid transgene escape.     

Genetic diversity and geographical peculiarity of Tibetan wild soybean (Glycine soja)

Tibet is the highest Plateau in China and the world, however wild soybean has been found in its southeastern fringe region adjacent to the northwest of Yunnan Province. Tibetan wild soybean was distributed only in the Gongrigabuqu-River Gorge in southeast Tibet. This regional plant species belong to the flora of Himalayan-Hengduan Mountains, which comprises composite elements of ancient arcto-tertiary flora, tropical and semitropical flora. To date, few studies have been carried out on Tibetan wild soybean. Studying Tibetan wild soybean together with other regional ones helps to understand the history of the origin and dissemination of wild soybean species in China. Here we reported the status of genetic diversity in Tibetan wild soybean and the genetic relationship between Tibetan and other regional wild soybeans revealed by nuclear SSR markers. The results showed that the Tibetan wild soybean sample was significantly differentiated from other regional ones, as characterized by the lowest mean allelic richness ( [^(\textr)] {\hat{\text{r}}}  = 1.40) and gene diversity (H _e = 0.130) and the highest ratios of regionally unique alleles (63.26%) and fixed alleles (46.94%). These genetic attributes suggested that Tibetan wild soybean may have undergone severe adaptation selection for the plateau climate and ecogeographical conditions, and had less genetic exchange with inland populations. The regional population south of the Changjiang River (Central and South China) showed higher genetic richness. UPGMA cluster analysis revealed two large geographical groups, Tibetan and inland, and revealed closer relationship among the eastern populations, which suggested that the dissemination of this species in the eastern part of China might be rapider.     

Molecular analysis and physicochemical properties of electrophoretic variants of wild soybean Glycine soja storage proteins

Cultivated soybeans (Glycine max) are derived from wild soybeans (Glycine soja) and can be crossed with them to produce fertile offspring. The latter exhibit greater genetic variation than the former, suggesting a possibility that wild soybeans contain storage proteins with properties different from and better than those of cultivated soybeans. To identify a wild soybean suitable for breeding a new soybean cultivar, we analyzed seed proteins from 390 lines of wild soybeans by electrophoresis. We found some lines containing electrophoretic variants of glycinin and beta-conglycinin subunits: one line containing a small alpha' subunit of beta-conglycinin and two and five lines containing small A3 and large A4 polypeptides of glycinin, respectively. Beta-Conglycinin and glycinin containing such variant subunits exhibited solubility and emulsifying ability similar to those of the predominant types of wild and cultivated soybeans. Glycinins containing small A3 and large A4 gave a shoulder derived from the start of denaturation at a temperature 4 degrees C lower than that of glycinin from the predominant types of wild and cultivated soybeans, although their thermal denaturation midpoint temperatures were very similar to each other. Cloning and sequencing of the predominant and variant subunit cDNAs revealed that the small alpha' and the small A3 lacked 24 amino acid residues in the extension region and four amino acid residues in the hypervariable region, respectively, and that the large A4 did not have an insert corresponding to the difference in the electrophoretic mobility but Arg279 and Gln305 were replaced by glutamine and histidine, respectively, in the hypervariable region. These suggest that small differences even in the hypervariable region can affect the thermal stability, as well as the electrophoretic mobilities, of the proteins.     

Phenotypic diversity of the big seed type subcollection of wild soybean (Glycine soja Sieb. et Zucc.) in China

Wild soybean (Glycine soja), the progenitor of soybeans, has become an important germplasm source for soybean breeding. The Chinese G. soja germplasm collection includes two subcollections, one typical wild soybean (G. soja) and the other ‘big seed type’ (semi-wild soybean, G. gracilis). In order to understand the nature of this big seed type subcollection, a considerable number of 1,185 accessions were investigated focusing on phenotypes, compositional structure and genetic diversity of this subcollection. The results showed that there were 617 combined morphotypes formed by six major morphological traits. The morphotype number and diversity gradually decreased among four sections from small to large 100-seed weight sizes. The big seed subcollection accumulated distinctly high frequencies for white flower, grey pubescence, seed non-bloom and four seed coat colours (green, yellow, brown and black), differing from the typical G. soja. Between the two subcollections, only the compositional structures of leaf shapes were almost in agreement. A rare strip-shaped leaf only appeared in typical G. soja and small-seeded grade (100-seed wt) of the big seed type. Seed non-bloom trait showed that the increased frequencies were concomitant with the augmenting of 100-seed weight. The data suggested that white flower accumulated rapidly in the big seed type, followed by seed non-bloom, while the slowest rate of accumulation was grey pubecence, and that the ‘large-seeded type (2.51–3 g 100-seed wt)’ of typical G. soja and the ‘smallest-seeded type (3.01–3.5 g 100-seed wt)’ of the big seed type could have a closer genetic relationship. The morphotype number and genetic diversity showed reduced values with increased 100-seed weights. The geographical distribution of genetic diversity indicated two tendencies: decreased from north to south and also from east to west. Our results suggested that Northeast China was the first centre of morphological diversity for the big seed type, and the North was the secondary centre in China.     

Evaluation of genetic structure of Korean wild soybean (Glycine soja) based on saponin allele polymorphism

Korean wild soybeans (Glycine soja) hypocotyl exhibit seven common saponin allele combinations: Sg-1 ^a /sg-4/sg-6 (phenotype: Aa), Sg-1 ^b /sg-4/sg-6 (Ab), Sg-1 ^a /Sg-4/sg-6 (AaBc), Sg-1 ^b /Sg-4/sg-6 (AbBc), Sg-1 ^a /sg-4/Sg-6 (Aa + α), Sg-1 ^a /Sg-4/Sg-6 (AaBc + α) and Sg-1 ^b /Sg-4/Sg-6 (AbBc + α). Diversity of saponin allele frequency (H_af) and saponin allele combination frequency (H_acf) was evaluated by Shannon–Weaver Index that was ranged from 0.75 to 1.04 and 0.28 to 1.25, respectively. High values of H_af and H_acf were found in Jeollanam-do and its adjoining regions Jeollabuk-do and Gyeongsangnam-do. The genetic index of Korean wild soybean increased towards south from north and west from east regions. The frequency of Sg-1 ^b and Sg-6 allele combinations increased towards south region (Jeollanam-do). These results suggest that Jeollanam-do region is the primary center of diversity, Jeollabuk-do and Gyeongsangnam-do regions are the secondary center of diversity and the remaining regions (Gyeonggi-do, Gangwon-do, Chungcheongbuk-do, Chungcheongnam-do, Jeollabuk-do, Gyeongsangbuk-do and Jeju-do) are the tertiary center of diversity for soyasaponin polymorphism in Korea. Furthermore, saponin allele frequency distribution suggested that alleles Sg-1 ^b and Sg-6 dispersed from Jeollanam-do to other regions of Korea. Our findings have laid the foundation for uncovering genetic diversity in Korean wild soybeans that could be exploited in soybean breeding programs.     

Synchronous evidence from both phenotypic and molecular signatures for the natural occurrence of sympatric hybridization between cultivated soybean (Glycine max) and its wild progenitor (G. soja)

The genus Glycine subgenus Soja includes two species, the important crop, soybean (G. max), and its wild progenitor (G. soja), and an intermediate semi-wild type (G. gracilis). However, the origin of the semi-wild type is in dispute, from independent evolutionary processes or from sympatric hybridization, although many studies support the hypothesis of a hybridization origin. Here, we reveal conclusive evidence for the natural occurrence of sympatric hybridization between wild and cultivated soybeans leading to G. gracilis by capturing natural F₁ seeds based on phenotypic and molecular signatures. The F₁ hybrids occurred through pollen flow between wild and cultivated soybeans, with many heterozygous loci and similar genetic parameters compared to the maternal wild populations; while paternal soybeans showed the lowest genetic diversity. The F-statistics showed genetic differentiation of the hybrids from the paternal soybeans and maternal wild populations; the differentiation of hybrids from wild soybeans was less than that of hybrids from cultivated soybeans. Natural F₁ hybrids generated various seed sizes in the offspring, suggesting that cultivar-genes introgressed into wild soybeans, and the degree of outcrossing in wild soybeans seems to be very important for gene spread, exchange and recombination in the evolution of populations.     

Taxonomic relationships and interspecific hybridization in the genus Lolium (grasses)

Phylogenetic trees of the 8 species of the genus Lolium and of Festuca pratensis have been derived from frequency data at 13 isozyme loci using different distance algorithms. The best tree was obtained by the distance-Wagner method with the Cavalli-Sforza and Edwards chord distance. This tree appears robust when tested by bootstrap resampling of loci. This confirmed previous knowledge on species relationships in the genus Lolium, with supplementary data on the taxonomic position of the less studied L. persicum and L. canariense. Attempts were made to hybridize 4 Lolium species and F. pratensis. True interspecific hybrids, as confirmed by isozyme markers, were obtained for L. perenne x L. temulentum, L. temulentum x L. rigidum, L. temulentum x L. canariense and L. canariense x F. pratensis. This is the first report of this new form of Festulolium, which was obtained at a fairly high frequency, giving argument to a possible genetic proximity between L. canariense, an endemic species restricted to Atlantic islands, and F. pratensis, which has a more widespread, northern distribution. However, chromosome pairing analysis at meiosis did not support this conclusion, as the F1 L. canariense x F. pratensis definitely showed a higher level of asynapsis compared to that reported for L. perenne x F. pratensis. The apparently close relation between L. canariense and F. pratensis seen on the tree is therefore postulated to be an artefact, due to the low number of loci studied.     

Phylogenetic relationships of Actinidia and related genera based on micromorphological characters of foliar trichomes

The phylogenetic relationships within the genus Actinidia and among 3 allied genera Clematoclethra, Saurauia, and Sladenia have been very controversial. In order to understand the systematic implication of foliar trichomes in those genera, the micromorphological characteristics of foliar trichomes from 34 taxa were examined by means of light microscopy and scanning electron microscopy (SEM). The observed micromorphological characteristics were classified into eight main types. A phylogenetic analysis of Actinidia and related genera based on 15 micromorphological characters of foliar trichomes was conducted using Wagner parsimony method and Sladenia celastrifolia, Rhododendron hybridum and R. simsii as a complex outgroup. In the resulting phylogenetic tree, Actinidia is shown to be a monophyletic group, and Clematoclethra and Saurauia form another monophyletic group. This study also presents the phylogenetic relationships among 4 sections within the genus Actinidia: the monophyly of sect. Leiocarpae and of sect. Strigosae, and polyphyly of sect. Maculatae and of sect. Stellatae.     

Natural introgression from cultivated soybean (<Emphasis Type="Italic">Glycine max</Emphasis>) into wild soybean (<Emphasis Type="Italic">Glycine soja</Emphasis>) with the implications for origin of populations of semi-wild type and for biosafety of wild species in China

Introgression from soybean cultivars to its wild progenitor species is an interesting antidromic recombination in natural ecosystem with many consequences, including the alteration of genetic diversity, the origin of semi-wild soybean, and implication for biosafety of the wild progenitor species with future release of the genetically modified varieties. Although such interspecific introgression is not suspected to be ubiquitous in the sympatric regions of wild and cultivated soybeans, the documentations published based on some molecular experimental analyses on the introgression have been little substantiated by the occurring process morphologically and remain deficient for unquestionable evidence, owing to the lack of actual insight into the population dynamics. Here, we found the phenomenon of gene escape and presented the evidence for occurrence of introgression from soybeans into the wild species and for how originates about the semi-wild type soybean based on morphological investigation of population dynamics. Our results suggest that more attention should be paid to the escape of genetically modified genotypes to safeguard the biosafety of wild soybean gene pool, if GM soybeans are released in China, the place of origin of cultivated soybeans.     

The extent of embryo and endosperm growth following interspecific hybridization between Cicer arietinum L. and related annual wild species

In vivo interspecific pollinations were performed and immature seed development investigated by histological methods in order to study crossability barrier(s) in Cicer L. species wide hybridization. Seven of the eight wild annual Cicer species, belonging to the secondary and tertiary gene pools, were used in reciprocal crosses with the cultivated chickpea. It was confirmed that the zygote was formed in all interspecific crosses. The embryos showed continued and retarded growth at different rate in various crosses, but eventually aborted at an early pro-embryo stage in all crosses except C. arietinum L. ×C. echinospermum Dav. Reciprocal cross differences were observed in early embryo growth rate and could have implications in obtaining hybrids. This study further emphasizes the necessity for developing appropriate and efficient in vitro procedures for rescuing immature globular hybrid pro-embryos, which will make the wild Cicer gene resources amenable to chickpea improvement.     

Copper,nitrogen, and Rhizobium japonicum relationships in determinate soybean

A relationship among Cu, N, and Rhizobium japonicum was hypothesized because previous research had shown that (a) 35% or more legumes in the Atlantic Coastal Plain have Cu concentrations of 6 mg kg^‐1 or less, (b) Cu influences N fixation in some legumes, and (c) irrigated soybean (Glycine max L. Merr.) can accumulate most of its N through fixation. Soybean were grown on a Cu‐deficient Norfolk (fine‐loamy, siliceous, thermic Typic Paleudult) loamy sand with 3 fertilizer sources of Cu, 2 strains of R. japonicum, and with or without 336 kg ha^‐1 of N fertilizer. Application of Cu significantly increased the number of pods plant^‐1 suggesting pod abortion in determinate soybean may be caused by low Cu, but seed yield was not increased. Fertilization with N increased vegetative growth, but not total biomass or seed yield. Inoculation with R. japonicum strain 110 significantly increased seed yield by 0.3 Mg ha^‐1 compared to strain 587. The yield increase was similar with or without fertilizer N application indicating strain response was not totally caused by improved N efficiency. There was no relationship between seed yield and nodule occupancy as measured by the ELISA technique.     

Genetic differentiation and diversity of phenotypic characters in Chinese wild soybean (<Emphasis Type="Italic">Glycine soja</Emphasis> Sieb. et Zucc.) revealed by nuclear SSR markers and the implication for intraspecies phylogenic relationship of characters

Genetic diversity is reduced from wild soybean to cultivars and from landraces to modern varieties. However, intraspecies genetic diversity loss between characters or phenotypes also existed in wild soybean. We revealed the phylogenic relationship of character types in Chinese wild soybean using 42 SSR markers. We conjectured that white flower, no-seed bloom, grey pubescence, and four seed coat colours were evolutionarily acquired phenotypes. There were a small decrease (∆H = 0.1–6.46%) of gene diversity and a moderate reduction (∆Na = 10.81–53.54%) of number of alleles but a violent loss (80.74–98.59%) of unique alleles in the acquired phenotypes. Our results seemed to suggest that ovoid and elliptic leaves were differentiated at the earliest and subsequently lanceolate leaf appeared before the domestication of soybeans within wild soybean, and that G. gracilis type was another earliest type, maybe emerged since the appearance of soybeans or it was concomitant with the domestication of soybean.     

Seed longevity studies in wild type,cultivated and inter-specific recombinant inbred lines (RILs) of soybean [Glycine max (L.) Merr.]

Genetic Resources and Crop Evolution - Loss of seed viability is a serious hurdle in production and ambient seed storage of soybean. Understanding the factors affecting seed viability,&nbsp;and...     

Changes in characters of soybean glycinin groups I, IIa, and IIb caused by heating

Soybean glycinin groups I, IIa, and IIb were purified from soybeans composed of only glycinin groups I, IIa, and IIb, respectively. When these protein solutions were heated, the amount of the particulate protein formed in these solutions was greatest in the order of groups IIa, IIb, and I. The protein solubilities decreased upon the addition of magnesium chloride in the order of groups IIa, IIb, and I. It was determined by differential scanning calorimetry analysis that the denaturation temperatures of groups I, IIa, and IIb were 92.8, 96.0, and 97.9 degrees C, and that the enthalpies of their transitions were 24.2, 27.4, and 28.1 J g(-)(1), respectively. The alpha-helix rates of groups I, IIa, and IIb in aqueous solution were analyzed by circular dichroism and were 19, 16, and 15%, respectively. The beta-sheet rates of groups I, IIa, and IIb were 44, 38, and 39%, respectively. In all group proteins, the alpha-helix rates were decreased by heating and the beta-sheet rates were increased. The surface hydrophobicity of these group proteins increased as a result of heating, and those of groups IIa and IIb were larger than that of group I. The surface hydrophobicity of these protein groups increased by heating, and those of groups IIa and IIb were larger than that of group I and beta-conglycinin. Breaking stress of curds prepared from these group proteins containing more than 1 of beta-conglycinin ration showed similar values, but the order of those containing less than 1 in strength was groups I, IIb and IIa. These results suggest that the increase of particulate contents and the curd formation are related to the increase of surface hydrophobicity by heating.     

Accumulation of carbohydrates and proline in water-stressed soybean (Glycine max L.)

Abstract

A wide range of metabolites accumulates under water stress depending on certain metabolic alterations. For example, free amino acids, especially free proline, accumulate in response to water stress ((l)). Proline accumulation is closely connected with carbohydrate metabolism. Thus, a carbohydrate requirement for proline accumulation in water-stressed leaves has been reported (2, 3).     

Phylogenetic relationships of Cajanus cajan (L.) Millsp. (pigeonpea) and its wild relatives based on seed protein profiles

Total seed storage protein of 9 accessions of cultivated C. cajan and 10 wild Cajanus species was reported and compared by sodium dodecyl sulphate polyacrylamide gel electrophoresis. A considerable variation was detected among the protein profiles of different accessions of C. cajan while those of wild species were very specific and distinctly different from each other. Relative similarities between various taxa were estimated by Jaccard's similarity index and cluster analysis was performed to produce a UPGMA dendrogram. The clustering of 10 wild species and C. cajan more or less agrees with their sectional classification and available data based on morphological characteristics, crossability, genome pairing in hybrids and nuclear RFLPs. The species closest to C. cajan is C. cajanifolia although the accessions of C. cajan also share some bands present in the profiles of C. scarabaeoides, C. goensis, C. lineatus, C. acutifolius and C. volubilis. This points towards polyphyletic origin of the cultigen which has been discussed in this paper.     

Morphology,spatial arrangement and origin of macropores in some hapludalfs,West Germany

Twenty oriented blocks, roughly 10 cm along each edge, were collected from the Bv and C horizons of four Hapludalfs near Hannover (West Germany). At least two blocks were obtained from each horizon of each profile. The macropores (0.1–1 mm) in these blocks were then examined by micromorphological methods. The 3-dimensional arrangements of pores were observed by two approaches, viz., (1) preparing photographic sequences of successive polished sections obtained from the sample blocks and then stacking photographs to simulate pore geometry; (2) preparing resin casts of tubular pores.Examination of stacked photographs and the resin casts by scanning electron microscopy (SEM) followed by electron-optical image analyses indicate interconnected systems of pores with the most frequently occurring diameters between 150 and 250 μm. Interconnections among pores are very similar in numbers throughout the Bv horizons.Comparisons of the diameters, branching, and tapering of macropores with similar features of plant roots suggest that most pores between 0.1 and 1 mm have been produced by roots. Some may be due to fauna, but all seem to have been of biological origin and are therefore considered biopores.     

Characterizing the cytoplasmic diversity and phyletic relationship of Chinese landraces of soybean, Glycine max, based on RFLPs of chloroplast and mitochondrial DNA

Restriction fragment-length polymorphism (RFLP) of chloroplast and mitochondrial DNA of many soybean landraces were analyzed to characterize their cytoplasmic genome and to consider the diversity and phylogeny of soybean in China. Three chloroplast and five mitochondrial types were distinguished, and seven cytoplasmic genome types were observed in different combinations in specimens collected from China. The cytoplasmic genome diversity was higher at the Yangtze River Valley. The main group of cytoplasmic genomes was composed of five types related phylogenetically and occurred in the southern region of China. Two unique types were very different in cytoplasmic genome constitution from each other and from the main group. They were considered to be derived from wild plants with the same cytoplasmic genome and to occur in two remote regions, the northern region and the Yangtze River Valley of China, respectively. Therefore, when considered with regard to the cytoplasmic genome of soybean landraces detected in China, seven genome types are distinguished, some types may be assumed to have arisen in wild soybean before domestication; and the Yangtze River Valley is the center of cytoplasmic diversity of the soybean.     

Karyological diversity of wild Rosa in Yunnan, southwestern China

Wild Rosa resources in Yunnan are very abundant and hold many important and useful traits for improving modern rose. However, many of them have no cytological data and few were karyologically analysed. In this article, karyological study of 24 wild Rosa taxa belonging to different sections was carried out by means of traditional squashing and pressing. The chromosome number of 8 taxa and karyotypes of most studied ones were reported for the first time. 22 resources were diploids with 14 chromosomes (2n = 2x = 14), while Rosa moyesii Hemsl. et Wils. and Rosa macrophylla Lindl. from Sect. Cinnamomeae DC. were hexaploids with 42 chromosomes (2n = 6x = 42). Only type 1A and type 2A been found, karyotypes of genus Rosa in Yunnan were symmetric. Also, the studied taxa differed much from each other in chromosome length, position of centromere, satellite position and satellite number, etc. The results implied that wild Rosa germplasm in Yunnan were rich in karyologcal diversity, and polyploidization might have played and were still playing very important roles in the evolution and speciation in genus Rosa, mainly in Sect. Cinnamomeae in alpine areas of northwestern Yunnan. The cytological data would supply chromosomal proofs not only for the taxonomy, phylogeny and evolution of genus Rosa in this special geological area, but also for the exploitation of useful traits of wild Rosa into the breeding of new cultivars.