Inheritance of polymorphic markers generated by DNA amplification fingerprinting and their use as genetic markers in soybean

DNA amplification fingerprinting (DAF) using a high primer-to-template ratio and single, very short arbitrary primers, was used to generate amplified fragment length polymorphic markers (AFLP) in soybean (Glycine max (L.) Merr.). The inheritance of AFLPs was studied using a cross between the ancestral Glycine soja PI468.397 and Glycine max (L.) Merr. line nts382, F1 and F2 progeny. The amplification reaction was carried out with soybean genomic DNA and 8 base long oligounucleotide primers. Silver-stained 5% polyacrylamide gels containing 7 M urea detected from 11 to 28 DAF products with primers of varying GC content (ranging from 50 to 100% GC). Depending on their intensity, AFLPs were classified into three classes. DAF profiles were reproducible for different DNA extractions and gels. Forty AFLPs were detected by 26 primers when comparing G. soja and G. max. Most AFLPs were inherited as dominant Mendelian markers in F1 and F2 populations. However, abnormal inheritance occured with about 25% of polymorphisms. One marker was inherited as a maternal marker, presumably originating from organelle DNA while another showed apparent paternal inheritance. To confirm the nuclear origin and utility of dominant Mendelian markers, three DAF polymorphisms were mapped using a F11 mapping population of recombinant inbred lines from soybean cultivars Minsoy × Noir 1. The study showed that DAF-generated polymorphic markers occur frequently and reliably, that they are inherited as Mendelian dominant loci and that they can be used in genome mapping.     

The Influence of Genotype, Temperature and Moisture on Seed Longevity in Chickpea, Cowpea and Soya bean

Seed of three chickpea (Cicer arietinum L.), three cowpea [Vignaunguiculata (L.) Walp.] and four soya bean [Glycine max (L.)Merr.] cultivars were hermetically stored for up to 2 yearsin various constant environments which included temperaturesfrom —20 to 70 °C and moisture contents (fresh weightbasis) from 5 to 25 per cent. In all cases the survival curvescould be described by negative cumulative normal distributions.The longevity of the various seed lots differed but the valueof the standard deviation (the reciprocal of which gives theslope of the survival curve when percentage germination is transformedto probit) was the same for all cultivars within a species whenstored under similar conditions. Within each species the relativeeffects of moisture and temperature on longevity did not differsignificantly between cultivars. In all three species therewas a negative logarithmic relationship between seed moisturecontent and longevity, but the relative effect of moisture contentdiffered between the species: differences in the longevity ofsoya bean seed as a function of moisture content were less thanfor either cowpea or chickpea. The relative effect of temperatureon seed longevity did not differ between the three species,and the seed of all three species showed increasing temperaturecoefficients for the change in rate of loss of viability withincrease in temperature. The complete pattern of loss in viabilityin all three species can be described by a single equation whichwas developed for barley and has also been shown to apply toonion seed. The constants applicable to the three grain legumeshave been calculated so that it is now possible to predict percentageviability of any seed lot of these species after any storageperiod under a very wide range of storage conditions. Cicer arietinum L., chickpea, Glycine max (L.) Merr., soya bean, Vigna unguiculata (L.) Walp., cowpea, seed longevity, seed storage, moisture content, temperature     

Legume Nodule Morphology with Regard to Oxygen Diffusion and Nitrogen Fixation

Soybean (Gtycine max (L.) Merr. cv. Fiskeby V), white clover(Trifolium repens L. cv Blanca) and lucerne (Medicago sativaL.cv. Europe) nodules grown in fluid culture of Perlite wereexamined by cryo-scanning electron microscopy. The surfacesof all three species consisted of loosely packed cortical cells,collapsed areas covering intact cells and in soybean, troughswhich lacked the layers of loosely packed cells and were coveredby an amorphous matrix. The superficial cortical cells werehydrophobic and their surfaces were covered by a solvent-extractablestippling. This stippling was absent from the surfaces of underlyingcells. Air-filled intercellular spaces in fractured noduleswere seen throughout the cross-section. Nitrogen fixation, intercellular pathways, hydrophobicity, oxygen diffusion, cryo-SEM, soybean, Glycine max (L.) Merr. cv. Fiskeby V, clover, Trifolium repens L. cv. Blanca, lucerne, Medicago saliva L. cv. Europe.     

Differential sensitivity of suspension cultures of maize,several soybean genotypes and glycine canescens to the herbicide DPX-F6025, 2-(([(4-chloro-6-methoxypyrimidine-2-yl)amino carbonyl]amino sulfonyl)) benzoic acid,ethyl ester

Previous field observations and greenhouse studies described here involving DPX-F6025, a soybean herbicide, show that soybean cultivars and maize have different sensitivities to the herbicide. The sensitivity of suspension cultures of the soybean (Glycine max (L.) Merr.) cultivars A3127, Earlyana and Old Dominion, and G. canescens F.J. Herm and maize (Zea mays L.) were tested against varying concentrations of DPX-F6025. The response of the cells in vitro correlates well with the whole plant response since maize and Old Dominion are much more sensitive than G. canescens and A3127, and Earlyana is more tolerant yet. The respective I₅₀ values were about 1, 5, 60, 75 and 800 nM. The inhibitory effect of 1 μM DPX-F6025 was at least partially reversed by exogenous valine and/or isoleucine. Levels of free isoleucine, leucine and valine in the cultured cells did not correlate with herbicide sensitivity.     

Changes in Soybean Raceme and Petiole Anatomy Induced by 6-Benzylaminopurine

An enlargement of the peduncle and rachis of the terminal racemeand the petiole of the uppermost mainstem leaf was observedin soybean plants [Glycine max (L.) Merr.] treated with thecytokinin, 6-benzylaminopurine (BAP). Histological studies wereperformed to determine the timing and extent of anatomical changesaccompanying BAP treatment. Swelling of treated ‘Tracy-M’peduncles, rachises, and petioles was observed within 4–6d after treatment initiation. A significant increase in totalcross-sectional tissue area was observed at lower and intermediateinternodes of treated rachises after 11 d. Rachis enlargementwas due to increases in both cell size and cell number, particularlyof the vascular tissue. In treated petioles of IX93-100, procambialcells of vascular bundles were the first to respond to the BAPtreatment. These cells differentiated into a vascular cambiumwhich formed secondary xylem and phloem. Soybean, Glycine max (L.) Merr., anatomy, rachis, BAP.     

A rapid, simple method for nuclei isolation from plant protoplasts

A rapid, simple method for nuclei isolation and purification from soybean (Glycine max L. Merr.) protoplasts is described. The isolated nuclei exhibited active amino acid incorporation and RNA synthesis, but DNA synthesis was not detectable. Analysis by CsCl density gradient centrifugation showed that DNA isolated from nuclei had a single band, while DNA isolated from protoplasts consisted of three bands comprised of nuclear DNA, mitochondrial DNA, and chloroplast DNA.     

Role of N2 fixation in the soybean N credit in maize production

Many studies have shown that maize (Zea mays L.) requires less fertilizer N for optimum yield when grown in rotation with soybean [Glycine max (L.) Merr] than when grown in monoculture, which is referred to as the `soybean N credit' in the maize growing areas of the United States. Because the specific source of this soybean N credit is unclear, our objective was to determine the role of nodules and N₂ fixation as a contributing source of the soybean N credit. Our research approach was designed to separate the effect of symbiotic N₂ fixation from other rotational effects, as the treatments included: maize grown after nodulated (N₂ fixing) soybean and maize grown after non-nodulated (non N₂ fixing) soybean. A separate experiment examined maize grown after maize. For each previous crop, maize was grown the following year with varying rates of fertilizer applied N. In both years, the yield differences between nodulated and non-nodulated soybean as the previous crop were much smaller than the apparent yield decrease associated with continuous maize. Although small in magnitude, maize following non-nodulated soybean accumulated less total N, was paler in leaf color, and yielded less than maize following nodulated soybean in the more favorable year of 1999, while most of these differences were not observed in 2000. These findings indicate that soybean nodules and N₂ fixation, while having a certain role, are not the major determinants of the soybean N credit.     

Growth Analysis of Soybean Seedlings During the Lifespan of the Cotyledons

Patterns of seedling growth of Glycine max in light and darknesswere compared during the period from germination to cotyledonabscission. Fitted growth curves and the derived functions,relative growth rate, unit leaf rate, leaf area ratio and specificleaf area, were used to assess the relative importance in seedlinggrowth of cotyledon storage reserves, cotyledon photosynthesisand leaf photosynthesis. The cotyledons are of an intermediatetype with a predominant storage and a minimal photosyntheticfunction. Cotyledon reserves support seedling growth until theprimary leaves expand, after which growth depends on leaf photosynthesis. Glycine max (L.) Merr., soybean, cotyledons, growth analysis, seedling development     

Genetic mapping of three quantitative trait loci for soybean aphid resistance in PI 567324

Host-plant resistance is an effective method for controlling soybean aphid (Aphis glycines Matsumura), the most damaging insect pest of soybean (Glycine max (L.) Merr.) in North America. Recently, resistant soybean lines have been discovered and at least four aphid resistance genes (Rag1, Rag2, Rag3 and rag4) have been mapped on different soybean chromosomes. However, the evolution of new soybean aphid biotypes capable of defeating host-plant resistance conferred by most single genes demonstrates the need for finding germplasm with multigenic resistance to the aphid. This study was conducted to map quantitative trait loci (QTL) for aphid resistance in PI 567324. We identified two major QTL (QTL_13_1 and QTL_13_2) for aphid resistance on soybean chromosome 13 using 184 recombinant inbred lines from a ‘Wyandot'' × PI 567324 cross. QTL_13_1 was located close to the previously reported Rag2 gene locus, and QTL_13_2 was close to the rag4 locus. A minor QTL (QTL_6_1) was also detected on chromosome 6, where no gene for soybean aphid resistance has been reported so far. These results indicate that PI 567324 possesses oligogenic resistance to the soybean aphid. The molecular markers closely linked to the QTL reported here will be useful for development of cultivars with oligogenic resistance that are expected to provide broader and more durable resistance against soybean aphids compared with cultivars with monogenic resistance.     

Protein Synthesis During Rehydration, Germination and Seedling Growth of Naturally and Precociously Matured Soybean Seeds (Glycine max)

Soybean seeds [Glycine max (L.) Merr.] synthesize de novo andaccumulate several non-storage, soluble polypeptides duringnatural and precocious seed maturation. These polypeptides havepreviously been coined ‘maturation polypeptides’.The objective of this study was to determine the fate of maturationpolypeptides in naturally and precociously matured soybean seedsduring rehydration, germination, and seedling growth. Developingsoybean seeds harvested 35 d after flowering (mid-development)were precociously matured through controlled dehydration, whereasnaturally matured soybean seeds were harvested directly fromthe plant. Seeds were rehydrated with water for various timesbetween 5 and 120 h. Total soluble proteins and proteins radio-labelledin vivo were extracted from the cotyledons and embryonic axesof precociously and naturally matured and rehydrated seed tissuesand analyzed by one-dimensional PAGE and fluorography. The resultsindicated that three of the maturation polypeptides (21, 31and 128 kDa) that had accumulated in the maturing seeds (maturationpolypeptides) continued to be synthesized during early stagesof seed rehydration and germination (5–30 h after imbibition).However, the progression from seed germination into seedlinggrowth (between 30 and 72 h after imbibition) was marked bythe cessation of synthesis of the maturation polypeptides followedby the hydrolysis of storage polypeptides that had been synthesizedand accumulated during seed development. This implied a drasticredirection in seed metabolism for the precociously maturedseeds as these seeds, if not matured early, would have continuedto synthesize storage protein reserves. Glycine max (L.) Merr, soybean, cotyledons, maturation, germination/seedling growth     

Citrate metabolism in. soybean cotyledons

Citrate metabolism and the citrate cleavage enzyme were investigatedin soybean (Glycine max (L.), Merr.) cotyledons throughout developmentand during the first 5 days of germination. It was noted thatboth the lipid synthesizing and the acetyl CoA generating systemsare present when the soybean seed matures, and that the activityof these systems declines throughout development as citrateincreases. Citrate represents 1% of the cotyledon dry weightat seed maturity. During the first 24 hr of germination, therewas an activation of the citrate cleavage enzyme and a concomitantdrop of some 60% in citrate content. Accompanying the drop incitrate content is the de novo synthesis of fatty acids foruse in the production of phospholipids. All of the data areconsistent with the hypothesis that acetyl CoA for lipid synthesisis supplied by the citrate molecule via the citrate cleavageenzyme and that activity of this system is necessary both duringseed development and during germination. ¹ Research was supported by cooperative investigations of theAgricultural Research Service, United States Department of Agriculture,and Illinois Agricultural Experiment Station. ² This research represents partial fulfillment of Ph.D. degree. (Received September 20, 1976; )     

Flower and Pod Development in Water-Deficient Soybeans (Glycine max L. Merr.)

Water deficits during flowering decrease the number of seed-bearingpods in soybean (Glycine max L. Merr.). Failure to set podsmay indicate an inherent sensitivity to low tissue water potential(     

Germination and Early Growth of Plants Studied Using Neutron Radiography

Seed swelling, germination, root extension, lateral root initiationand shoot growth were studied in soils of different water contents,using non-destructive, serial neutron radiography. Seeds fromthree varieties of soya beans (Glycine max L.) and one varietyeach of maize (Zea mays L.) and vetch (Vicia sativa L.) wereused. The seeds germinated when they had increased in size bya certain amount, if germination is taken as the time when theradicle first appears. The rate at which roots and shoots extendalso depend on soil water content. Glycine max L., Vicia sativa L., Zea mays L., Soya bean vetch, maize, seed germination, root extension, lateral root initiation, neutron radiography     

Using competitive and facilitative interactions in intercropping systems enhances crop productivity and nutrient-use efficiency

This paper reviews recent research on the processes involved in the yield advantage in wheat (Triticum aestivum L.)/maize (Zea mays L.), wheat/soybean [Glycine max (L.) Merr.], faba bean (Vicia faba L.)/maize, peanut (Arachis hypogaea L.)/maize and water convolvulus (Ipomoea aquatica Forsk.)/maize intercropping. In wheat/maize and wheat/soybean intercropping systems, a significant yield increase of intercropped wheat over sole wheat was observed, which resulted from positive effects of the border row and inner rows of intercropped wheat. The border row effect was due to interspecific competition for nutrients as wheat had a higher competitive ability than either maize or soybean had. There was also compensatory growth, or a recovery process, of subordinate species such as maize and soybean, offsetting the impairment of early growth of the subordinate species. Finally, both dominant and subordinate species in intercropping obtain higher yields than that in corresponding sole wheat, maize or soybean. We summarized these processes as the `competition-recovery production principle'. We observed interspecific facilitation, where maize improves iron nutrition in intercropped peanut, faba bean enhances nitrogen and phosphorus uptake by intercropped maize, and chickpea facilitates P uptake by associated wheat from phytate-P. Furthermore, intercropping reduced the nitrate content in the soil profile as intercropping uses soil nutrients more efficiently than sole cropping.     

Metabolic changes in soybean nodules after inhibition of nitrogen fixation by treatment with oxygen

Metabolites that accumulated in soybean [Glycine max (L.) Merr.]nodules after inhibition of nitrogen fixation were analysedto determine what carbon compounds the bacteroids might obtainfrom their host. Exposure of roots of intact soybean plantsto 100% O₂ for 5 min caused a decrease in acetylene reductionactivity within 10 min and then the activity recovered onlyslowly. Analysis of carbohydrates, organic acids, volatile compoundsand amino acids in extracts of nodules revealed that succinate,malate and alanine all accumulated within 10 min after treatmentwith O₂. The concentrations of sucrose, acetone, tyrosine, valine,isoleucine, leucine, and ornithine in the nodules increasedslowly after such treatment. The results are discussed in termsof carbon sources for supporting nitrogen fixation of soybeanbacteroids. Key words: Glycine max, carbon metabolism, nitrogen fixation, nodules     

Acetylcholine and Red-light Influence on Ethylene Evolution from Soyabean Leaf Tissues

Acetylcholine (Ach) and red light inhibited ethylene evolutionfrom excised green soyabean (Glycine max (L.) Merr.) leaf discs.Neostigmine, an Ach-esterase inhibitor, mimicked this effectwhile atropine, an Ach antagonist, increased ethylene evolution.Acetylcholine and red light partially overcame the atropine-inducedresponse. The results were interpreted as an influence of acetylcholineupon the ethylene formation process. Glycine max, ethylene inhibition, leaf discs     

Identification of Rotylenchulus reniformis Resistant Glycine Lines

Identification of resistance to reniform nematode (Rotylenchulus reniformis) is the first step in developing resistant soybean (Glycine max) cultivars that will benefit growers in the mid-South region of the United States. This study was conducted to identify soybean (G. max and G. soja) lines with resistance to this pathogen. Sixty-one wild and domestic soybean lines were evaluated in replicated growth chamber tests. Six previously untested soybean lines with useful levels of resistance to reniform nematode were identified in both initial screening and subsequent confirmation tests: released germplasm lines DS4-SCN05 (PI 656647) and DS-880 (PI 659348); accession PI 567516 C; and breeding lines DS97-84-1, 02011-126-1-1-2-1 and 02011-126-1-1-5-1. Eleven previously untested moderately susceptible or susceptible lines were also identified: released germplasm lines D68-0099 (PI 573285) and LG01-5087-5; accessions PI 200538, PI 416937, PI 423941, PI 437697, PI 467312, PI 468916, PI 594692, and PI 603751 A; and cultivar Stafford (PI 508269). Results of previously tested lines evaluated in the current study agreed with published reports 69.6% of the time for resistant lines and 87.5% of the time for susceptible lines. Soybean breeders may benefit from incorporating the newly identified resistant lines into their breeding programs.     

Role of sucrose-phosphate synthase in partitioning of carbon in leaves

Variations in leaf starch accumulation were observed among four species (wheat [Triticum aestivum L.], soybean [Glycine max L. Merr.], tobacco [Nicotiana tabacum L.], and red beet [Beta vulgaris L.]), nine peanut (Arachis hypogea L.) cultivars, and two specific peanut genotypes grown under different nutritional regimes. Among the genotypes tested, the activity of sucrose phosphate synthase was correlated negatively with leaf sucrose content in seven of the nine peanut cultivars as well as the two peanut cultivars grown with different mineral nutrition. The peanut cultivars differed in the effect of 10 millimolar sucrose on sucrose phosphate synthase activity in leaf extracts. Enzyme activity in crude leaf extracts was inhibited by sucrose (10-42%) in four of the cultivars tested whereas five cultivars were not. Overall, the results suggest that a correlation exists between the activity of sucrose phosphate synthase and starch/sucrose levels in leaves.     

Changes in Seed Constituents During Germination and Seedling Growth of Precociously Matured Soybean Seeds(Glycine max)

During 7 d of precocious maturation of soybean seed (Glycinemax), the starch content declined and soluble sugar levels increasedin patterns similar to natural seed dehydration and maturation.Total seed protein content and total seed dry weight increasedwhereas oil content remained relatively unchanged. Overall,the proportions of the constituents in precociously maturedseeds were comparable to naturally mature seeds. Precociouslymatured soybean seeds showed much the same germination and seedlinggrowth frequency patterns as naturally matured seeds. Duringgermination and seedling growth of precociously matured seeds,starch, soluble sugar, protein and oil levels followed patternssimilar to naturally mature, germinating seeds and seedlings.Therefore, precocious maturation may be used as a model systemto investigate the control of the physiological and biochemicalevents occurring during seed maturation which lead to germinationand subsequently, seedling growth. Glycine max (L.) Merr., soybean, cotyledons, maturation, germination/seedling growth     

Relative Virulence of Meloidogyne incognita Host Races on Soybean

Sensitivity and host efficiency of susceptible (''Lee 68'', ''Coker 156'') and resistant (''Bragg'', ''Centennial'', ''Forrest'', ''Lee 74'') soybean (Glycine max (L.) Merr.) cultivars for races of Meloidogyne incognita (Mi) were determined in greenhouse experiments. Eight Mi populations collected from the southeastern United States were utilized. All Mi races reproduced readily on Lee 68 and Lee 74 and moderately on Forrest and Bragg. Coker 156 exhibited resistance to races 1 and 2, and some race 3 populations, but was very susceptible to certain race 3 and 4 populations. Reproduction of all races was lowest on Centennial. Forrest and Centennial shoot growth was not significantly suppressed by any race. There were no distinct differences in virulence between races except for a race 3 population which reproduced readily on all cultivars, stunting their growth. Considerable variation in reproduction existed within races 1 and 3.