Control of Seed Growth in Soya Beans [Glycine max (L.) Merrill]

The seed is the primary sink for photosynthate during reproductivegrowth and an understanding of the mechanisms controlling therate of seed growth is necessary to understand completely theyield production process. The growth rate of individual seedsof seven soya bean [Glycine max (L.) Merrill] cultivars withgenetic differences in seed size varied from 10.8 to 3.9 mgseed^–1 day^–1. The growth rates were highly correlatedwith final seed size. The growth rate of cotyledons culturedin a complete nutrient medium was highly correlated with thegrowth rate of seeds developing on the plant and with finalseed size. The number of cells per seed in the cotyledons variedfrom 10.2 to 5.7 x 10⁶ across the seven cultivars. The numberof cells per seed in the cotyledons was significantly correlatedwith final seed size and the seed growth rate both on the plantand in the culture medium. The data suggest that genetic differencesin seed growth rates are controlled by the cotyledons and thenumber of cells in the cotyledons may be the mechanism of control. Glycine max L., soya bean, seed size, growth rate, cell number, sink activity     

Pod and Seed Mycoflora on Transgenic and Conventional Soybean [Glycine max (L.) Merrill] cultivars in Mississippi

A 2-year (1999-2000) study was conducted at Starkville and Stoneville, MS to determine if the occurrence of the mycoflora varied on Roundup Ready (transgenic) compared to conventional soybean (Glycine max) cultivars. A total of 7,658 fungal isolates were identified from the pod and seed tissues of four cultivars compared at growth stages R6 and R8. Ninety-nine percent of all fungi isolated were mitosporic fungi and ascomycetes. In both years, total fungal isolates from the two locations were greater from the pod (65%) than from seed (33%) tissues. Isolation frequency from conventional cultivars was 54% compared to 46% for the transgenic cultivars. The most common fungi identified that are reported pathogens of soybean included Alternaria, Cercospora, Cladosporium, Diaporthe, Fusarium and Verticillium spp. When main effects and interactions were compared among the frequency data for the fungal genera, significant differences occurred, but consistent trends were not noted. Isolation frequencies of Diaporthe spp. during the R6 growth stage, were significantly greater on the conventional than on the transgenic cultivars in both years of the study, but only at Starkville. Isolation frequencies from samples taken during the R8 growth stage were similar at both locations in 1999 and 2000. Fusarium spp. isolated at R6 and R8 growth stages from pod and seed tissues were significantly greater on conventional than on transgenic cultivars in 2000. Even though frequencies were often significantly different between the transgenic and conventional cultivars, the data was not consistent between locations, pod and seed tissues, or growth stages. The pod and seed mycoflora of transgenic and conventional soybean cultivars was, therefore, similar in Mississippi.     

Rhizobium inoculant for soybean [Glycine max (L.) Merrill] in Mekong Delta

Summary Rhizobial inoculation trials were conducted in an acid heavy clay soil in Mekong Delta, Viet Nam, using peat based inoculants produced locally and the commercial granular product of Nitragin CCo., Wisconsin, USA. The pH of these soils ranged from 4.5 to 5.1. Two soybean cultivars, MTD₆ and MTD₁₀, were tested as host plants. There were no significant differences between locally made inoculant treated plants and the uninoculated controls in both cultivars. But, the Nitragin inoculation improved all plant characteristics examined in both cultivars. Grain yields of Nitragin inoculated plants of cultivar MTD₆ and cultivar MTD₁₀ were 6.5 and 5.5 times as much as those of the controls; protein content of grain increased 11 and 16 percent, respectively. Well nodulated plants had shorter life cycles, flowering durations, and days to flowering. The Rhizobium symbiosis resulted in an additional 153 kg grain-N/ha. These studies show that a surface coated commercial multistrain inoculant can be used to successfully grow soybeans in the acid, heavy clay soils of the Mekong Delta.     

Apical proliferation of embryogenic tissue of soybean [Glycine max (L.) Merrill]

Somatic embryos and embryogenic tissues were initiated from immature zygotic embryos of soybean [Glycine max (L.) Merrill cv. Fayette]. Zygotic embryos were placed on a medium containing 40 mg/l of 2,4-dichlorophenoxyacetic acid and 6% sucrose. Somatic embryos were first seen 4 weeks after cultures were initiated. Following transfer, secondary somatic embryos proliferated directly from the apical or terminal portions of the older primary somatic embryos. Single somatic embryos or clusters of embryos were seen growing directly from the top of older somatic embryos. Light microscopy revealed that these embryos were of surface or subsurface origin. The apical soybean somatic embryo tissue may represent cotyledonary tissue (which has been shown to be most responsive) at a very young and manipulatable state.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid Salaries and research support were provided by state and federal funds appropriated to OARDC-OSU. Journal Article No. 131-87     

Diallel analysis for aluminium tolerance in tropical soybeans [Glycine max (L.) Merrill]

The soybean is a major crop in the agricultural systems of the Brazilian Cerrados (Savannahs), whose soils are acidic, devoid of nutrients and need to be amended before they are cultivated. However, below the ploughed layer there is a scarcity of nutrients and toxic aluminium (Al). These limit root growth, subsequently causing nutritional imbalance and drought stress. Our aim in the investigation described here was to identify genetic differences in the aluminium tolerance of soybeans by a 9 × 9 diallel cross among contrasting varieties grown in high-Al areas and in hydroponics. Combining ability analysis indicated predominantly additive gene effects, and the additive-dominance model explained most of the genetic differences in this germ plasm for mineral element absorption and root growth under aluminium stress. The relationship between the two factors suggest that conjugation hydroponics and field evaluations in breeding programmes would further improve soybeans with respect to yield stability under tropical cultivation conditions.     

Factors Affecting Shedding of Flowers in Soybean (Glycine max (L.) Merrill)

Flower shedding in soybean, Glycine max (L.) Merrill, was studiedusing cultivar ‘Clark’, isoline E₁t, which has relativelylong racemes for convenient identification and observation ofindividual flowers. On each raceme studied, pod set was greatestat the proximal (basal) positions, whereas shedding was greatestat the most distal positions. When proximal flowers were removedas they reached anthesis, pod set increased at the more distalpositions. Pod set was increased in some instances by applicationof water directly to the ovaries as a drop in the calyx cup.Peroxidase activity changed in parallel with ovary development,increasing rapidly in growing pods but not in shedding flowers.Increases in flower peroxidase was mainly in ovary walls. Flowerstaken at or near anthesis from positions with high percent podset could be grown in vitro with especially good ovary enlargement,whereas ovaries in flowers taken from positions of low pod setdid not enlarge in culture. Unidentified substances were extracted from young pods which,when incorporated into lanolin and tested in an in situ bioassay,could mimic the effect of proximal flowers in inducing sheddingof distal flowers. Indole-3-acetic acid resembled the extractedmaterials in inducing shedding, but differed by eliciting side-effectsthat extracts did not. The growth substances abscisic acid,gibberellic acid, and benzyladenine did not promote sheddingin the in situ test. The evidence was taken to indicate that soybean flower sheddingis induced in distal flowers by substances from the more proximal,fertilized ovaries, and that this is possibly due to interferencewith some of the intense metabolic changes that follow pollinationand fertilization.     

Detoxification of Formaldehyde by the Spider Plant (Chlorophytum comosum L.) and by Soybean (Glycine max L.) Cell-Suspension Cultures

The phytotoxicity of formaldehyde for spider plants (Chlorophytum comosum L.), tobacco plants (Nicotiana tabacum L. cv Bel B and Bel W3), and soybean (Glycine max L.) cell-suspension cultures was found to be low enough to allow metabolic studies. Spider plant shoots were exposed to 7.1 [mu]L L-1 (8.5 mg m-3) gaseous [14C]-formaldehyde over 24 h. Approximately 88% of the recovered radioactivity was plant associated and was found to be incorporated into organic acids, amino acids, free sugars, and lipids as well as cell-wall components. Similar results were obtained upon feeding [14C]formaldehyde from aqueous solution to aseptic soybean cell-suspension cultures. Serine and phosphatidylcholine were identified as major metabolic products. Spider plant enzyme extracts contained two NAS+-dependent formaldehyde dehydrogenase activities with molecular mass values of about 129 and 79 kD. Only the latter enzyme activity required glutathione as an obligatory second cofactor. It had an apparent Km value of 30 [mu]M for formaldehyde and an isoelectric point at pH 5.4. Total cell-free dehydrogenase activity corresponded to 13 [mu]g formaldehyde oxidized h-1 g-1 leaf fresh weight. Glutathione-dependent formaldehyde dehydrogenases were also isolated from shoots and leaves of Equisetum telmateia and from cell-suspension cultures of wheat (Triticum aestivum L.) and maize (Zea mays L.). The results obtained are consistent with the concept of indoor air decontamination with common room plants such as the spider plant. Formaldehyde appears to be efficiently detoxified by oxidation and subsequent C1 metabolism.     

Sonication-assisted Agrobacterium-mediated transformation of soybean [Glycine max (L.) Merrill] embryogenic suspension culture tissue

Successful transformation of plant tissue using Agrobacterium relies on several factors including bacterial infection, host recognition, and transformation competency of the target tissue. Although soybean [Glycine max (L.) Merrill] embryogenic suspension cultures have been transformed via particle bombardment, Agrobacterium-mediated transformation of this tissue has not been demonstrated. We report here transformation of embryogenic suspension cultures of soybean using “Sonication-Assisted Agrobacterium-mediated Transformation” (SAAT). For SAAT of suspension culture tissue, 10–20 embryogenic clumps (2–4 mm in diameter) were inoculated with 1 ml of diluted (OD_600nm 0.1–0.5) log phase Agrobacterium and sonicated for 0–300 s. After 2 days of co-culture in a maintenance medium containing 100 μM acetosyringone, the medium was removed and replaced with fresh maintenance medium containing 400 mg/l Timentin^?. Two weeks after SAAT, the tissue was placed in maintenance medium containing 20 mg/l hygromycin and 400 mg/l Timentin^?, and the medium was replenished every week thereafter. Transgenic clones were observed and isolated 6–8 weeks following SAAT. When SAAT was not used, hygromycin-resistant clones were not obtained. Southern hybridization analyses of transformed embryogenic tissue confirmed T-DNA integration. Received: 22 August 1997 / Revision received: 22 October 1997 / Accepted: 11 November 1997     

Nitric oxide donor regulates Agrobacterium-mediated genetic transformation efficiency in soybean [Glycine max (L.) Merrill]

The present study investigates the potentiality of Sodium nitroprusside (SNP) to enhance the efficiency of genetic transformation in soybean. Half-seeds cultured on co-cultivation [4.44 μM N⁶-benzyl adenine (BA) and 30 μM SNP]; shoot induction (4.44 μM BA and 30 μM SNP) and rooting medium [4.93 μM indole 3-butyric acid (IBA) and 30 μM SNP] exhibited improved transformation efficiency (34.6%) in contrast to the regeneration system devoid of SNP (23%). The putatively transformed plants were evaluated by GUS assay and molecular analysis like PCR and Southern hybridization. Furthermore, the transformation system developed herein entails a shorter period (75-days) for developing plantlets from half-seeds of soybean. The outcome of this study revealed that the addition of SNP increased regeneration efficiency of plants, which translated to improved transformation efficiency in soybean.

     

Diallel analysis for mineral element absorption in tropical adapted soybeans [Glycine max (L.) Merrill]

The Brazilian tropical adapted soybeans contains, in addition to superior morphological characters, genetic factors for tolerance to cultivation in acidic, mineral-stressed soils. However, the selection process for these hindrances has been empirical, and information on the genetics of mineral element uptake by the plant is necessary. The objective of this investigation was to identify the mode of inheritance for the absorption of phosphorus, potassium, calcium, magnesium, iron, aluminium, manganese, zinc and copper in a 9 × 9 diallel cross. General combining ability (GCA) was higher than specific combining ability (SCA), with the exception of copper, manganese and zinc, indicating predominantly additive effects. The ratios of GCA/SCA varied between 3.4 (calcium) and 8.5 (magnesium). The regression of covariance (W_r) on variance (V_r) showed that the additive-dominance model explained the genetic differences in this germ plasm. However, the detection of overdominance could be related to possible heterozygosity in the parental varieties for mineral absorption. Broad-sense heritability values were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively. This is an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.     

Plant Regeneration from Protoplasts of Soybean (Glycine max L.)

Protoplasts were isolated enzymatically from immature cotyledons of soybean. The protoplasts divided to form calli in the K8P liquid medium. The calli further grew to 2–3 mm on the solid K8 medium and were transferred onto the MSB medium (MS minerals+B5 organic components+0.5–1.0 mg/l 2,4-D+0.2–0.5 mg/l BA) to obtain compact and nodular calli. Shoot formation was initiated on M1 medium (MSB medium with 0.15 mg/1 NAA, and BA, KT and ZT, 0.5 mg/l of each, 500 mg/1 CH). Differentiation frequency was 13.6–24.2%. Plants have been regenerated from protoplasts of immature cotyledons in 2 cultivars, and normal pods were obtained from them.     

Somatic embryogenesis from cultured epicotyls and primary leaves of soybean [Glycine max (L.) Merrill]

Summary Regeneration of several varieties of soybean [Glycine max (L.) Merrill] by somatic embryogenesis from cultured epicotyls and primary leaves has been demonstrated. Somatic embryogenesis was induced from epicotyls and primary leaves when cotyledon halves with the intact zygotic embryo axes were cultured on Murashige and Skoog (MS) medium supplemented with 10 mg 1⁻¹ (45.2 μM) 2,4-D. Stable, continuously proliferating globular embryo cultures (GEC) were established from small groups of somatic embryos on MS medium supplemented with 20 mg 1⁻¹ (90.5 μM) 2,4-dichlorophenoxyacetic acid (2,4-D). Rapid multiplication of shoot tips from germinating somatic embryos was achieved on Cheng’s basal medium (CBO) containing 2.5 mg 1⁻¹ (11.3 μM) 6-benzyladenine. Fertile plants were obtained from individual somatic embryos and in vitro propagated adventitious shoot bud cultures.     

大豆遗传转化研究进展

综述了大豆遗传转化体系及其优缺点,转基因大豆的研究成果、生产状况和生物安全性评价,分析了大豆遗传转化中存在的一些问题及其解决办法,展望了未来大豆遗传转化的发展前景。     

Transformation of soybean [Glycine max (L.) Merrill] using proliferative embryogenic tissue maintained on semi-solid medium

Summary Transgenic soybean can be efficiently produced by particle bombardment of embryogenic suspension culture material. Unfortunately, the time required to obtain a transformation-competent soybean suspension culture line is often lengthy and can result in reduced fertility of regenerated plants. In addition, establishment and maintenance of embryogenic suspension cultures can be very difficult. The objective of this work was to minimize the time required to obtain transformation-competent embryogenic tissue and optimize DNA delivery into that tissue. Somatic embryos were induced from immature cotyledons of soybean [Glycine max (L.) Merrill cv ‘Jack’] by placement of cotyledons, adaxial side up, on a MS-based induction medium containing 40 mg (181 μM) 2,4-dichlorophenoxyacetic acid (2,4-D) per 1 and 6% sucrose. Embryogenic tissues, which formed from the surface of the cotyledons within 2–4 wk, were transferred to an embryo proliferation medium containing 20 mg (90 μM) 2,4-D per 1 and 3% sucrose. After 4 wk, proliferative embryogenic tissue could be used for transformation via particle bombardment. Desiccation of target tissue, period of subculture prior to bombardment, and the number of bombardments per target tissue were evaluated for enhancement of transient β-glucuronidase (GUS) expression. The highest number of blue foci was observed when the target tissue was desiccated for 10 min in an uncovered Petri plate containing proliferation medium, subcultured on the same day of bombardment, and bombarded three times on a single day. For stable transformation, selection was started 20 d after bombardment using 9 mg hygromycin per 1 for 4 wk, and 18 mg per 1 thereafter. Stably transformed clones were obtained from tissue bombarded once and twice on a single day. GUS assays and Southern hybridization analysis of DNA from putative clones confirmed stable integration of the introduced genes. Fertile transgenic plants were obtained in 11–12 mo following culture initiation.     

Quantitative detection of transgenes in soybean [Glycine max (L.) Merrill] and peanut (Arachis hypogaea L.) by real-time polymerase chain reaction

Quantitative real-time polymerase chain reaction (PCR) assays were designed that enabled the zygosity of transgenes in soybean [Glycine max (L.) Merrill] and peanut (Arachis hypogaea L.) to be determined. The two zygosity assays, based on TaqMan technology that uses a fluorogenic probe which hybridizes to a PCR target sequence flanked by primers, were both accurate and reproducible in the determination of the number of transgenes present in a cell line. In the first assay, in which TaqMan assays were performed on increasing amounts of a plasmid containing the transgene of interest, a linear relationship between the level of fluorescence and the template amount was produced. Using the resultant linear relationships as standard curves, we were able to determine the zygosity of both soybeans segregating for the cry1Ac transgene and that of a T₁ peanut segregating for the hph transgene. In the second assay, a relative determination of copy number (referred to as comparative Ct) was performed on transgenic soybeans by comparing the amplification efficiency of the transgene of interest to that of an endogenous gene in a multiplexed PCR reaction. Both methods proved to be sufficiently sensitive to differentiate between homozygotes and hemizygotes. These assays have numerous potential applications in plant genetic engineering and tissue culture, including the hastening of the identification of transgenic tissue, selecting transformation events with a low number of transgenes and the monitoring of the transmission of transgenes in subsequent crosses.     

Composition and Distribution of Adenylates in Soybean (Glycine max L.) Nodule Tissue

Adenylates (ATP, ADP, and AMP) may play a central role in the regulation of the O2-limited C and N metabolism of soybean nodules. To be able to interpret measurements of adenylate levels in whole nodules and to appreciate the significance of observed changes in adenylates associated with changes in O2-limited metabolism, methods were developed for measuring in vivo levels of adenylate pools in the cortex, plant central zone, and bacteroid fractions of soybean (Glycine max L. Merr cv Maple Arrow x Bradyrhizobium japonicum strain USDA 16) nodules. Intact nodulated roots were either frozen in situ by flushing with prechilled Freon-113(-156[deg]C) or by rapidly (<1 s) uprooting plants and plunging them into liquid N2. The adenylate energy charge (AEC = [ATP + 0.5 x ADP]/[ATP + ADP + AMP]) of whole-nodule tissue (0.65 [plus or minus] 0.01, n = 4) was low compared to that of subtending roots (0.80 [plus or minus] 0.03, n = 4), a finding indicative of hypoxic metabolism in nodules. The cortex and central zone tissues were dissected apart in lyophilized nodules, and AEC values were 0.84 [plus or minus] 0.04 and 0.61 [plus or minus] 0.03, respectively. Although the total adenylate pool in the lyophilized nodules was only 41% of that measured in hydrated tissues, the AEC values were similar, and the lyophilized nodules were assumed to provide useful material for assessing adenylate distribution. The nodule cortex contained 4.4% of whole-nodule adenylates, with 95.6% being located in the central zone. Aqueous fractionation of bacteroids from the plant fraction of whole nodules and the use of marker enzymes or compounds to correct for recovery of bacteroids and cross-contamination of the bacteroid and plant fractions resulted in estimates that 36.2% of the total adenylate pool was in bacteroids, and 59.4% was in the plant fraction of the central zone. These are the first quantitative assessments of adenylate distribution in the plant and bacteroid fractions of legume nodules. These estimates were combined with theoretical calculations of rates of ATP consumption in the cortex (9.5 nmol g-1 fresh weight of nodule s-1), plant central zone (38 nmol g-1 fresh weight of nodule s-1), and bacteroids (62 nmol g-1 fresh weight of nodule s-1) of soybean nodules to estimate the time constants for turnover of the total adenylate pool and the ATP pool within each nodule fraction. The low values for time constant (1.6-5.8 s for total adenylate, 0.9-2.5 s for ATP only) in each fraction reflect the high metabolic activity of soybean nodules and provide a background for further studies of the role of adenylates in O2-limited nodule metabolism.     

Effects of Temperature and Photoperiod on Flowering in Soya bean [Glycine max (L.) Merrill]: a Quantitative Model

Factorial combinations of five photoperiods (8 h 20 min, 10h, 11 h 40 min, 13 h 20 min and 15 h) and three night temperatures(14, 19 and 24 C) combined with a single day temperature (30C) were imposed on nodulated plants of nine soya bean genotypes[Glycine max (L.) Merrill] grown in pots in growth cabinets.The times to first appearance of open flowers were recorded.For a photoperiod-insensitive cultivar, and for the remainingeight photoperiod-sensitive genotypes in photoperiods shorterthan the critical daylength, the rates of progress towards flowering(the reciprocals of the times taken to flower) were linear functionsof mean diurnal temperature. For all photoperiod-sensitive genotypes,times to flowering in photoperiods longer than the criticaldaylength increased as inverse functions of both increasingphotoperiod and decreasing temperature. A consequence of thesetwo relations is that the critical daylength becomes longerwith higher mean temperatures. In the five photoperiod-sensitivegenotypes which flowered in all environments before the experimentwas terminated (after 150 d) the delays in flowering due tolow temperatures or long photoperiods were limited by a maximumperiod to flowering specific for each genotype. These resultsare discussed in relation to the development of a simple techniquefor the large-scale screening of soya bean germplasm to determinephoto-thermal response surfaces for flowering. Glycine max (L.) Merrill, soya bean, flowering, photoperiod, temperature, screening, germplasm     

Characterization of Photothermal Flowering Responses in Maturity Isolines of Soyabean [Glycine max (L.) Merrill] cv. Clark

All eight isolines of three maturity genes (E₁/e₁, E₂ /e₂, andE₃ /e₃) of soyabean [Glycine max (L.) Merrill] cv. Clark weregrown in widely different combinations of photoperiod and temperature.Under the more inductive conditions, i.e. in a warm mean temperature(30°C) when daylengths were less than the critical value(i.e. less than about 13 h), the isolines flowered at similartimes (23-24 d). The responses of all isolines to temperaturewere also similar, if not identical. Increase in daylength abovethe critical photoperiod progressively delayed flowering untilthe time taken to flower (f) reached a maximum at the ceilingphotoperiod. The relations between the rate of progress towardsflowering (1/f) and photoperiod (between the critical and ceilingvalues) were linear. The coefficient characterizing the slopeof the response (photoperiod sensitivity) varied amongst theisolines. These responses could be grouped into three categoriesof increasing sensitivity: (1) least sensitive, e₁e₂e₃ , e₁E₂e₃, e₁e₂E₃ ; (2) intermediate, E₁e₂e₃ , e₁E₂E₃ ; and (3) mostsensitive, E₁E₂e₃, E₁e₂E₃ , E₁E₂E₃ . Thus, in the Clark cultivargenetic background, E₁ induces greater photoperiod sensitivitybut neither E₂ nor E₃ on their own have any effect. However,both E₂ and E₃ together induce photoperiod sensitivity comparableto that induced by E₁ alone. Furthermore, in addition to thisepistasis, either E₂ or E₃ has considerable epistatic effecton E₁, further increasing photoperiod sensitivity. The effectsof these genes and their epistasis were also reflected in theextent of the maximum delays to flowering which occur when theceiling photoperiod is exceeded, and also possibly in earlinessin circumstances when photoperiods were below the critical value.Copyright1994, 1999 Academic Press Glycine max (L.) Merrill, soyabean, maturity genes, flowering, photoperiod, temperature     

Surviving and Thriving in Terms of Symbiotic Performance of Antibiotic and Phage-Resistant Mutants of Bradyrhizobium of Soybean [Glycine max (L.) Merrill

Rhizobial inoculation plays an important role in yielding enhancement of soybean, but it is frequently disturbed by competition with bacterial population present in the soil. Identification of potential indigenous rhizobia as competitive inoculants for efficient nodulation and N(2)-fixation of soybean was assessed under laboratory and field conditions. Two indigenous bradyrhizobial isolates (MPSR033 and MPSR220) and its derived different antibiotic (streptomycin and gentamicin) and phage (RT5 and RT6)-resistant mutant strains were used for competition study. Nodulation occupancy between parent and mutant strains was compared on soybean cultivar JS335 under exotic condition. Strain MPSR033 Sm(r)?V(r) was found highly competitive for nodule occupancy in all treatment combinations. On the basis of laboratory experiments four indigenous strains (MPSR033, MPSR033 Sm(r), MPSR033 Sm(r)?V(r), MPSR220) were selected for their symbiotic performance along with two exotic strains (USDA123 and USDA94) on two soybean cultivars under field conditions. A significant symbiotic interaction between Bradyrhizobium strains and soybean cultivar was observed. Strain MPSR033 Sm(r)?V(r) was found superior among the rhizobial treatments in seed yield production with both cultivars. The 16S rRNA region sequence analysis of the indigenous strains showed close relationship with Bradyrhizobium yuanmingense strain. These findings widen out the usefulness of antibiotic-resistance marked phage-resistant bradyrhizobial strains in interactive mode for studying their symbiotic effectiveness with host plant, and open the way to study the mechanism of contact-dependent growth inhibition in rhizobia.     

Molecular Genetic Identification and Certification of Soybean (Glycine max L.) Cultivars

An approach to certification of soybean genotypes has been developed. The procedure employs three methods of DNA analysis based on polymerase chain reaction (PCR): PCR with arbitrary primers (AP PCR), simple sequence repeat polymorphism (SSRP) analysis, and inter-simple sequence repeat (ISSR) analysis. The approach to certification proposed may be used in both genetic and breeding research and seed production. A certificate form that reflects the unique characteristics of each cultivar studied is proposed. The results of molecular genetic analysis of allele distribution in genotypes of soybean from different ecological geographic zones permit estimation of the adaptive significance of individual alleles.