Max Cultivars Research Articles

Genetic regulation of linolenic acid concentration in wild soybean Glycine soja accessions

AbstractSoybean [Glycine max (L.) Merr.] oil from current commercial cultivars typically contains ca. 8% linolenic acid. Inheritance studies have shown that linolenic acid concentration in soybean seed is determined by at least two genes which govern activity of the predominant ω‐6 and ω‐3 desaturases. Selection of germplasm exhibiting homozygous recessive alleles that encode these desaturases has enabled development of soybeans having less than 3.0% linolenic acid. However, accessions of the wild ancestor of modern soybean cultivars, Glycine soja (Sieb. and Zucc.), have oils containing twice the highest linolenic acid concentration found in normal G. max cultivars. Although little is known about inheritance of linolenic acid in wild soybean, it would appear that additional or alternative forms of genes may govern its synthesis. To test this hypothesis, cultivated soybean germplasm was hybridized with wild soybean genotypes having significant differences in linolenic acid concentration. Seed of F3 progeny from these G. max x G. soja populations exhibited distinct segregation patterns for relative estimates of ω‐6 and ω‐3 desaturase activity. Frequency class distribution analyses of the segregation patterns, and linear relations between median ω‐6 or ω‐3 desaturation estimates and corresponding linolenic acid concentration among allelic classes from these populations suggested the high‐linolenic acid trait in wild soybean genotypes was determined by a set of desaturase alleles that were different from corresponding alleles in G. max. Introgression of these alternative alleles in G. max germplasm opens a new avenue of research on the genitic regulation of linolenic acid, and may lead to the production of highly polyunsaturated soybean oils for various industrial applications.

Chloride tolerance in soybean and perennial Glycine accessions

Diversity for chloride tolerance exists among accessions of perennial Glycine. Accessions whose tolerance thresholds exceed those of Glycine max cultivars may be useful germplasm resources. Soybean cultivars including ‘Jackson’ (sensitive) and ‘Lee’ (tolerant) and 12 accessions of perennial Glycine were evaluated for sodium chloride tolerance after 14 days in hydroponic culture at 0, 5, 10, and 15 g L-1 NaCl. Sodium chloride had adverse effects on the growth of G. max cultivars and perennial Glycine accessions; however differential responses to salinity were observed among accessions. Considerably greater variation in sodium chloride tolerance existed among the perennial Glycine accessions than among the G. max cultivars. Sodium chloride tolerance thresholds ranged from 3.0 to 17.5 g L-1 NaCl for the perennial accessions but only ranged from 5.2 to 8.0 g L-1 for the cultivars, based on a Weibull model of leaf chlorosis. All G. max cultivars were severely injured or killed by NaCl at 10 g L-1 and above. Five tolerant perennial Glycine accessions, G. argyrea 1626, G. clandestina 1388 and 1389, and G. microphylla 1143 and 1195, were significantly lower in leaf chlorosis score than any of the G. max cultivars at the 10 g L-1 NaCl treatment. Two accessions, G. argyrea 1626 and G. clandestina 1389 were able to tolerate 15 g L-1 NaCl with only moderate visual injury while all other accessions were severely injured or killed at this salt level. Variability for chloride tolerance observed among the perennial Glycine accessions has potential utility for developing enhanced salt tolerance in soybean.

Bradyrhizobium strains and the nodulation, nodule efficiency and growth of soybean (Glycine max L.) in Egyptian soils

Six strains and a commercial inoculant ofBradyrhizobium japonicum were evaluated in association withGlycine max (L.) cultivar Clark. Inoculated and uninoculated plants were grown in pot and field experiments. Nodules were counted and weighed and roots and shoots were separated and analysed for total nitrogen. In pot experiments, two of six bacterial strains were superior to the other four, and to the commercial inoculant (Nitragin) in promoting greater root and top growth and plant nitrogen accumulation. In the field experiment, there were indications that environmental conditions may have affected nodulation by the bacteria. The strains could be divided into three groups according to nodule efficiencies, accumulation of plant dry matter, and total nitrogen content. The greater variations in nodule efficiencies of the tested strains could be attributed to the quantities of bacteroid, cytosol protein and leghaemoglobin in the nodules.

Ancestral U.S. Soybean Cultivars Characterized for Tolerance to Ultraviolet‐B Radiation

In an effort to characterize the U.S. soybean [Glycine max (L) Merr.] germplasm pool for variation in tolerance to ultraviolet‐B (UV‐B) radiation, 10 U.S. ancestral soybean cultivars were exposed in a greenhouse to a level of UV‐B radiation simulating a 25% O3 depletion. Two modern cultivars previously characterized for UV‐B sensitivity, Williams (tolerant) and Essex (sensitive), 10 wild annual soybean (G. soja Sieb. & Zucc.) accessions of diverse geographic origin were also included in the study. Significant variation was observed among the G. max cultivars in UV‐B radiation effects on leaf expansion, leaf area, height, aerial dry biomass, and seed yield. The cultivars CNS and Lincoln were consistently the most sensitive to UV‐B radiation, while the cultivars Williams, Arksoy, Richland, Mandarin, Manchu, and Mukden were most tolerant. The wild G. soja accessions as a group were about as sensitive to UV‐B radiation as the G. max cultivars, except that seed yield of G. soja accessions was not significantly reduced by UV‐B radiation. There was, however, UV‐B radiation treatment × genotype interaction for fewer growth traits among the wild G. soja accessions than among the G. max cultivars. Production of UV‐B–absorbing compounds and specific leaf weight were both implicated as important contributing factors to UV‐B radiation tolerance in G. max cultivars.

DNA Synthesis and Mitosis of Shoot Apical Meristem Cells during Early Germination of Soybean Seed.

Germinating seeds of Glycine max (L.) cultivar. L-65 (Dr. W.G, variety) were treated with 3H-thymidine at various times after seed soaking began at 25°C and the shoot apical meristem was squashed on slides. Then, microf luorography was carried out. The tritiumlabeled nuclei and mitoses were examined through the microscope. Consequently, it was suggested that most shoot apical meristem cells begin the DNA synthesis at 22-24 h after soaking of seed and lasts for 5 h, while mitosis starts at 26-28 h and the period is about 2.5 h. It was further supposed that shoot apical meristem cells stays at G0 or G1 period in the dormant seed.

Inter-specific variation in the karyotypes of the genus Glycine Willd.

Karyotype analysis of six species of genus Glycine indicated chromosome number to be 2n=40 in G. canescens, G. clandestina, G. latifolia, G. max cultivars Monetta and MACS-13 and 2n=80 in G. tabacina and G. tomentella. Tetraploid species (2n=80) had nearly double the length of haploid chromosome complement of diploid species. Chromosomes were median to submedian. Diploid species (2n=40) had one pair of SAT-chromosomes whereas tetraploid species (2n=80) had two pairs of SAT-chromosomes. Karyotypes of all these species were more or less similar, inspite of broad inter-specific variations in the morphological characters, suggesting the species differentiation might have been due to micromutations.

An attempt to elucidate the origin of cultivated soybean via comparison of nucleotide sequences encoding glycinin B4 polypeptide of cultivated soybean, Glycine max, and its presumed wild progenitor, Glycine soja

Nucleotide sequences of cDNAs encoding soybean glycinin B4 polypeptide were compared for three soybean cultivars and two introductions of wild soybean, G. soja. For three G. max cultivars, only two nucleotide substitutions were found, while G. max and G. soja nucleotide sequences had four substitutions. These data give added proof that G. max originated from G. soja. On the other hand, the time required for the accumulation of four nucleotide substitutions (calculated from the parameters of 11S globulin molecular evolution) appeared to be longer than the duration of the soybean domestication period.

PS 90 SOYBEAN

PS 90 is an early-maturity group II soybean (Glycine max) cultivar which is 1 d earlier and similar in yield to the cultivar Corsoy 79. Its main advantage is its good phytophthora tolerance and good lodging rating.Key words: Glycine max, PS 90 cultivar, soybean

KG 60 SOYBEAN

KG 60 is a moderately early maturing soybean (Glycine max) cultivar which is 1 d later and 14% higher yielding than the cultivar Pioneer 0877. Its main advantage is its very high yield potential.Key words: Glycine max, soybean cultivar

KG 40 SOYBEAN

KG 40 is an early-maturing soybean (Glycine max) cultivar which has similar maturity and 4% higher yield than the cultivar Maple Arrow. Its main advantage is its yield performance and a high degree of phytophthora tolerance.Key words: Glycine max, soybean cultivar

PS 80 SOYBEAN

PS 80 is a Maturity Group I soybean (Glycine max) cultivar which is 2 d later in maturity and slightly higher yielding than the cultivar Pioneer 1677. Its main advantage is superior export seed quality.Key words: Glycine max, Soybean cultivar

Characterization ofR. fredii QB1130, a strain effective on commercial soybean cultivars

Two rhizobial strains (QB1130 and C3A) from northeast China were identified asRhizobium fredii on the basis of growth rate, media acidification and growth on a wide range of carbon substrates. The strains were shown to be distinct from USDA 191 on the basis of plasmid number and size. Bothnif and commonnod genes were located on the 295 kb plasmid of strains QB1130 and USDA 191, while onlynif genes were identified on this plasmid in C3A. When used to inoculate four commercial soybean (Glycine max) cultivars, one of the strains (C3A) was found to be ineffective, while the other (QB1130) was at least as effective as USDA 191, a strain ofR. fredii reported to be widely effective on North American cultivars of soybean. Further, QB1130 was capable of more effective nodulation of cowpea or the uncultivated soybean line, Peking, than either USDA 191 or the slow-growingBradyrhizobium japonicum USDA 16. Strain QB1130 should be useful for studies directed at improving symbiotic performance in soybean, or for studies of the comparative physiology and genetics of FG and SG strains on a single host.

Root Hair Specific Proteins in Glycine max

Abstract In root hairs from seedlings of Glycine max cultivars, isolated from the root system and com­ pared with the complete organ, specific soluble proteins have been found. By FPLC chromatography and SDS gel electrophoresis root hair specific proteins with molecular weights of 13, 21, 34, 38 and 42 kDa were separated. Additionally, proteins with molecular weights of 12, 20, 69 and 74 kDa were significantly enriched in root hairs compared to roots without root hairs. By using CNBr activated Sepharose with antibodies against the root system without root hairs, the pres­ ence of root hair specific proteins was confirmed in extracts from isolated root hair cells. Enrichment of Fe and Ca in some of the proteins from the root hairs is demonstrated. The present knowledge of the biochemical specificity of legume root hairs, the target cells of Rhizobium and Bradyrhizobium infection, is discussed.

Genetic study of glutamate oxaloacetic transaminase in soybean

A four-band electrophoretic zymogram for glutamate oxaloacetic transaminase (GOT, EC 2.6.1.1) is observed in mature soybean (Glycine max (L.) Merr.) seed. The zymogram pattern has a cluster of three bands (Rf's of 0.26, 0.29, and 0.32) and a single band. No variation was observed in the cluster of three bands. The fourth band has three variants that are controlled by a single locus, Got, with three alleles. They are designated as Got-a (Rf = 0.52), Got-b (Rf = 0.54), and Got-c (Rf = 0.57), respectively. In the wild soybean, G. soja (Sieb. & Zucc), the Got-a allele was found in four accessions from South Korea (PI 407.194, PI 407.269, PI 407.270, and PI 504.286; frequency 4/187). The Got-c allele also was found in four G. soja accessions from South Korea (PI 407.184, PI 407.207, PI 407.222, and PI 407.225; frequency 4/187). All other G. soja accessions examined carry the Got-b allele (frequency 179/187). All the G. max cultivars and accessions examined are homozygous for the Got-b allele (frequency 320/321) except for cv. Hardee, in which two seeds were homozygous for the Got-c allele. Linkage tests show that the Got locus segregates independently of the Ap, Dia1, Dia2, Idh1, Pgd2, and W1 loci. No linkage was detected when isozyme loci other than Got were tested (Am3–W1, Ap–W1, Dia1–W1, Pgd–W1, Dia1–Idh1, Pgd2–Idh1, and Ap–Idh2). Key words: soybean, glutamate oxaloacetic transaminase, GOT, electrophoresis, isozymes.

Genetic Variability for Desirable Agronomic Traits in Populations Containing Glycine soja Germplasm1

The wild soybean (Glycine soja Sieb. et Zucc.) may be a source of useful characters for improvement of the cultivated soybean [Glycine max (L.) Merr.] species. Successful introgression of genes from G. soja into G. max will require the development of populations with an adequate frequency of segregates that do not possess the undesirable agronomic characters of the wild species. The objective of this study was to determine the genetic variability for desirable agronomic traits of G. max in backcross populations containing different percentages of G. soja germplasm. No selection was conducted during backcrossing to allow the evaluation of segregation patterns that would not be influenced by genetic linkages or physiological associations between desirable and undesirable characteristics in G. soja. The populations were formed by crossing each of two G. soja accessions to a different G. max cultivar, ‘Amsoy 71’ or ‘Century’, and backcrossing to the G. max parent to obtain BC0 to BC5 populations. The F2 plants and their F3 progeny from each population were evaluated for agronomic score, vining, lodging, plant height, days to stage R7, seed weight, shattering, leaf abscission, and seed coat color. The percentage of segregates with an agronomic rating equal to the G. max parent averaged across the Amsoy 71 and Century populations was zero in BC0, and BC1, 2% in BC2, 22% in BC3, 51% in BC4, and 65% in BC5. The results indicated that, in the introgression of G. soja germplasm, at least two backcrosses are required to recover any segregates that are agronomically acceptable when at least 50 plants are backcrossed each generation. Three backcrosses may be preferred to obtain a relatively high frequency of segregates that may be useful in a cultivar development program.

Agronomic Performance of Soybean Genotypes from Glycine max ✕ Glycine soja Crosses1

Genetic improvement of the cultivated soybean [Glycine max (L.) Merr.] may be possible through hybridization with its wild progenitor, G. soja Sieb. & Zucc. When useful genetic traits are found in the wild species, backcrossing is a method that may be useful for transferring the desired genes from G. soja to G. max. One objective of our study was to determine the number of generations of backcrossing necessary to recover the yield and agronomic performance of the cultivated parent following interspecific hybridization of the two species. A second objective was to determine if the yield potential of the recurrent parent in a backcrossing program could be enhanced by the introgression of G. soja germplasm. Two G. soja accessions were crossed to one of two high‐yielding G. max cultivars, followed by five backcrosses to the respective G. max parent. The F2 plants from the backcross populations were visually examined and selected for absence of vining, lack of hardseededness, shattering resistance, maturity, and seed coat color similar to the G. max parent. Progeny of selected plants from the backcross populations were evaluated for seed yield, maturity, lodging, and height in four environments during 2 years. Significant variation was observed among lines in each backcross generation for the four traits. The mean yield and lodging resistance of the populations improved from the BC1 to the BC4 generation. No line from the BC1 generation performed as well as the recurrent parent for all traits. Three backcrosses to the cultivated parent were necessary to obtain a reasonable number of lines similar to the recurrent parent. The introgression of G. soja germplasm into the two soybean cultivars was not an effective method for increasing their yield potential.

Genotypic Variability of Soybean Response to Agrobacterium Strains Harboring the Ti or Ri Plasmids

Twenty four diverse cultivars of soybean (Glycine max [L.] Merrill) and three lines of its annual wild progenitor Glycine soja Sieb and Zucc. were tested for their response to Agrobacterium strains harboring either the Ti (tumor-inducing) plasmid (pTi) from Agrobacterium tumefaciens or the Ri (root-inducing) plasmid (pRi) from Agrobacterium rhizogenes following uniform wounding and inoculation. Based upon gall weight at 8 weeks postinfection, three G. max cultivars (Biloxi, Jupiter, and Peking) and one G. soja line, Plant Introduction (PI) 398.693B, were judged highly susceptible to A. tumefaciens strain A348 (pTiA6), ten genotypes moderately susceptible, 11 weakly susceptible, and two nonsusceptible. Of 26 genotypes inoculated with strain R1000 (pRiA4b), only seven responded in a clearly susceptible fashion by forming small, fleshy roots at internodal infection sites. Cotyledons excised from 1- or 3-day old seedlings of Peking and Biloxi cultivars also formed galls when infected in vitro with agrobacteria carrying either the Ti or Ri plasmid. Tumor lines established from cotyledon and stem galls induced by A. tumefaciens A348 (pTiA6) exhibited the T-DNA borne traits of phytohormone-independent growth and octopine synthesis. Additionally, DNA isolated from cultured tumors hybridized with labeled T-DNA probe.

Seedling emergence and establishment of germinated seeds in soybean.

The present experiments were conducted with an aim to obtain higher percentages of seedling emergence and establishment by sowing the germinated seeds than by direct sowing in the field. By this new method it is possible to lessen the labor needed for transplanting. A series of experiments with soybean (Glycine max cultivar. Enrei) were carried out on the field nursery beds. The results obtained are summarized as follows : (1)When seeds were put on so as to direct the hilum to the valley parts of the filter paper folded up in V-shape, seed germination became considerably promoted. The highest germinability was obtained when water depth was maintained at about one-fourth of the seed height (seed width in practice) (Fig. 1). (2)Assuming the percentage of seedling establishment being 100% by transplanting the seedlings raised in paper pots, those of germinated seeds and of direct sowing were 92% and 73%, respectively (Fig. 3). (3)The percentages of seedling establishment by sowing germinated seeds dried out on the filter paper in the laboratory did not decrease conspicuously within about one week, but thereafter it decreased so rapidly. Those of the germinated seeds stored under refrigeration were higher than those of air-dried ones in the laboratory within the same period (Fig. 5). (4)The percentages of seedling establishment by sowing the germinated seeds submerged in water during 1, 2 and 3 days were 83%, 44% and 10%, respectively (Fig. 6). (5)More uniform seedlings can be obtained when shallow planted at the depth of 1-3 cm than 5-6 cm under field conditions (Fig. 7).

The isolation and characterization of a root lectin from soybean (Glycine max (L), cultivar Chippewa).

A lectin has been isolated from the roots of 5-day soybean (Glycine max (L) cultivar Chippewa) seedlings, and its properties have been compared to those of the soybean seed lectin. The sugar-binding activities of the two lectins, both in terms of specific hemagglutinating activity and sugar specificity, are indistinguishable. Molecular properties of the two lectins, measured as relative molecular weights, isoelectric and electrophoretic patterns, amino acid compositions, immunochemical cross-reactivity, and chromatographic behavior on Sepharose-concanavalin A adsorbents suggest that the seed and the root lectin are very similar but not identical. On the basis of these comparisons, we conclude that models regarding biological functions of soybean lectin derived from studies using the seed lectin can be extended to include the root lectin in this cultivar. Studies on the distribution of the lectin in the root tissue suggest that it is associated with the outer surface of the root and is concentrated in the segments of the root at which hair and early secondary roots are observed. Since this is the region at which Rhizobium binding occurs and at which nodulation probably is initiated, all the reported observations on the root lectin are consistent with its proposed role in the specific interaction of the developing soybean with its symbiont.

The amino acid sequence of soybean leghaemoglobin c2

1. Introduction The leghaemoglobin found in the root nodules of the soybean plant (G&&e max cultivar Lincoln) after rhizobial infection was originally fractionated into two major and two minor components [ 1,2]. Recently, the second of the major components, leghaemoglobin c, has been found to consist of two distinct molecular species, leghaemoglobin cl and c2, separable by elution from a DEAE cellulose column using a continuous acetate gradient at pH 5.2 [3]. Since the amino acid sequence of the first major component, leghaemoglobin a, is known [4] and it has been well characterized both structurally, and functionally [S-8] we felt it would be of value to elucidate the primary structure of a second major component, leghaemoglobin c2, as a step towards establishing a function (if any) for the multiplicity of leghaemoglobin species found in the root nodules of most legumes. 2. Materials and methods Soybean plants were grown as previously described [9] and isolated by gradient elution (10 to 50 mM acetate) at pH 5.2 from a DEAE cellulose column [3]. The leghaemoglobin c2 fraction was pooled and rechro- matographed on a shallow gradient (25-35 mM acetate) to ensure removal of the cl component. The protein (65 mg) was dehaemed by the HCl-acetone method [lo] and succinylated in an auto-pH titrator at pH 9.2 by the addition of eight lots of