An intersubgeneric hybrid between Glycine tomentella Hayata and the soybean,G. max (L.) Merr.

Summary The objective of the present paper is to provide information on the morphology and cytology of an intersub-generic hybrid (2n=59) between Glycine tomentella Hayata (2n=78) and G. max (L.) Merr. (2n=40) obtained through in vitro immature seed culture. The hybrid plant was slow in vegetative growth and twinning like the female parent but morphologically was intermediate between both parents for several traits. At metaphase I, the average chromosome associations and ranges for 25 cells were 44.0 I (37–51)+7.5 II (3–11). The plant was completely pollen and seed sterile. The present investigation suggests that wild perennial Glycine species can be exploited as either the male or female parent in wide hybridization programs with the soybean, G. max.     

Nutrient culture medium components affecting plant recovery from immature embryos of three Glycine genotypes and an interspecific hybrid grown in vitro

Summary Immature embryos of Glycine max (L.) Merr. cv. Bay, G. tabacina (Labill.) Benth. and G. tomentella Hayata were cultured on 72 media combinations to identify a nutrient medium which would allow a greater percentage of interspecific plants to be recovered from cultured embryos of G. max × various perennial Glycine species. The highest mean plant recovery rate of 79% was from a medium containing B5 nutrient salts as reported by Gamborg et al. (1968), vitamin components according to Williams (1978) and 30 g/l sucrose. This is as compared with 25% from a medium used previously. In an additional test, 67% of hybrid embryos of G. max × G. tomentella were recovered from the same medium, from which G. tomentella was most effectively recovered in all testing.Contribution No. 89-276-J of the Kansas Agric. Exp. Stn., Manhattan.     

Interspecific hybridisation of soybeans and perennial Glycine species indigenous to Australia via embryo culture

Summary Five sterile hybrids (2n=59) between a synthetic amphiploid of Glycine tomentella (2n=38) and G. caneseens (2n=40) as female and soybean cultivars Lincoln and Hark as males have been produced by embryo or ovule culture using transplanted endosperm. The hybrid plants are twining perennials like the female parent but possess a number of morphological characters which reflect the presence of the soybean genome. Indophenol oxidase isozymes from leaf extracts also provide good evidence of the hybrid nature of the cultured plants. These hybrids open the way for the exploitation of the diverse germplasm resources of the perennial Glycine species in soybean breeding.     

Production of interspecific hybrids between Alstroemeria pelegrina L. var. rosea and A. magenta Bayer by ovule culture

Interspecific hybrids were efficiently produced in the cross-incompatible combination between Alstroemeria pelegrina L. var. rosea and A. magenta Bayer by culturing immature ovules with placenta 7–14 days after pollination on 2 g/l Gelrite-solidified MS medium containing 3% (w/v)sucrose. The plants showed intermediate characteristics between the parents and their hybridity was confirmed by karyotype and DNA analyses. The mean number of chromosome association per PMC at metaphase I was 2.60I+6.70II, pollen stainability was20.8%, and they produced viable seeds after self-pollination. Furthermore, mature plants were obtained when the hybrids were backcrossed as male parents with both the parents. The backcross-progeny from A. pelegrina var. rosea × hybrids exhibited 3.8 to 79.7% pollen stainability and that from A. magenta × hybrids 78.8 to 98.3%. Almost all of these plants produced viable seeds after self-pollination, which implies that they can beutilized for breeding of novel cultivars of Alstroemeria. This revised version was published online in July 2006 with corrections to the Cover Date.     

Interspecific hybridization in the genus Arachis through embryo culture

Summary The embryos of a cultivated tetraploid peanut (Arachis hypogaea), a wild diploid species (A. villosa), and their hybrid embryos, which generally abort in nature, were cultured in vitro and the plants have been successfully transferred to the soil. The hybrids showed triploid chromosome number (3x=30). The significance of wide hybridization in peanut-improvement programs is discussed.     

Establishment of Chinese soybean Glycine max core collections with agronomic traits and SSR markers

It is very important to efficiently study and use genetic diversity resources in crop breeding and sustainable agriculture. In this study, different sampling methods and sample sizes were compared in order to optimize the strategies for building a rationally sized core collection of Chinese soybean (Glycine max). The diversity in the core collection captured more than 70% of that in the pre-core collection, no matter what sampling methods were used, at a sampling proportion of 1%. Core collections established with both simple sequence repeat (SSR) marker data and agronomic traits were more representative than those chosen on an independent basis. An optimal sampling method for a soybean core collection was determined, in which strategy ‘S’ (allocating accessions to clusters according to the proportion of square root of the original sample size within each ecotype) was used based on SSR and agronomic data. Curve estimation was used to estimate the allelic richness of the entire Chinese soybean germplasm and a minimum sample size for a core collection, on which a sampling proportion of about 2% was determined to be optimal for a core collection. Further analysis on the core collection with fourteen agronomic traits and allelic constitution at 60 SSR loci suggested that it highly represented the entire collections both on genetic structure and diversity distribution. This core collection would provide an effective platform in proper exploitation of soybean germplasm resources for the study of complex traits and discovering important novel traits for crop genetic development.     

A partially male-sterile mutant line of soybeans,Glycine max (L.) Merr.: inheritance

Summary A partial male sterility system in the soybean (Glycine max (L.) Merr.) germplasm population AP6(SI)CI was found to be controlled monogenically by a recessive allele, msp. Observations of msp msp plants in different environments suggested that environmental conditions significantly affect expressivity of the msp allele with respect to male sterility. We obtained no experimental evidence of cytoplasmic effects on msp expression. Background genotypes, however, seem to affect msp expressivity through their determination of flowering dates and resultant interactions with varying environmental conditions.Homogeneous populations of partially male-sterile plants can be generated by increasing families of msp msp plants in fertility-inducing environments, if measures are implemented to prevent the introduction and/or build-up of fertile genotypes that arise from natural cross-pollinations.Joint contribution: North Central Region, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, and Journal Paper No. J-9596 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011; Project 2107.     

Heterosis of interspecific soybean hybrids for traits related to N2 fixation

Summary Three greenhouse experiments were conducted to compare the performance of soybean (Glycine max (L.) Merr.), wild soybean (G. soja Sieb. et Zucc.), and soybean x wild soybean hybrids for traits relating to N₂ fixation including nodulation, acetylene reduction, nodule leghemoglobin concentration, and nitrogen (N) accumulation and dry matter (DM) accumulation. In all three experiments G. max generally exceeded G. soja in nodulation, acetylene reduction, and N and DM accumulation while the soybean possessed higher nodule leghemoglobin concentration. In Experiment I, the mean of the hybrids did not differ significantly from the G. max parent in nodule mass, acetylene reduction activity, nodule leghemoglobin concentration, or DM accumulation. The hybrids did exceed the soybean parent in N accumulation, thus demonstrating high parent heterosis. In Experiments IIA and IIB with a more carefully chosen set of G. soja parents, high parent heterosis of individual crosses was common. Across the three experiments average high parent heterosis was 34, 28, and 28%, respectively, for nodule mass, N accumulation, and DM accumulation. If one accepts the assumption that hybrid vigor results from the accumulation of dominant alleles, then these alleles could theoretically be accumulated via selection in a homozygous genotype. If this is true than the results of the experiments reported here suggest that interspecific soybean x wild soybean crosses could serve as sources of homozygous lines which would exceed currently available soybean cultivars in nodule mass, and N and DM accumulation.This work was supported in part by the USDA Competitive Grants Program, Grant 82-CRCR-1-1039 and Cooperative Agreement 58-32U4-2-370 between the U.S. Department of Agriculture and the Agronomy Department, University of Maryland, Scientific Article No. A-4648, Contribution No. 7644 of the Maryland Agricultural Experiment Station.     

Production of interspecific hybrids between <Emphasis Type="Italic">Lilium longiflorum</Emphasis> and <Emphasis Type="Italic">L. lophophorum</Emphasis> var. <Emphasis Type="Italic">linearifolium</Emphasis> via ovule culture at early stage

Interspecific hybridization was carried out between Lilium longiflorum and L. lophophorum var. linearifolium by using the cut style method of pollination, as a contrast, intraspecific hybridization between L. longiflorum ‘Gelria’ and L. longiflorum was also made, but no mature seeds and offspring were obtained from the two combinations under in vivo condition. Ovules excised from each carpel 5–35 days after pollination (DAP) were cultured on B5 or half-strength B5 medium containing sucrose at different concentrations in vitro. In L. longiflorum × L. lophophorum var. linearifolium, only 1.17% of ovules excised at 10 DAP developed into seedlings, and in L. longiflorum ‘Gelria’ × L. longiflorum, only 0.99% of ovules excised at 25 DAP developed into seedlings; none of the ovules excised at other different DAP in the two cross combinations produced any seedlings. The results showed that interspecific hybridization had a more serious post-fertilization barrier than the intraspecific hybridization, and that a lower concentration (3%) of sucrose led to better embryo development and higher percentage of seedlings in ovule cultures. All hybrid seedlings obtained were successfully transplanted to soil and grew normally. The progenies investigated were identified as true hybrids based on inter-simple sequence repeat (ISSR) analysis.     

Clonal propagation of F1 hybrids as a tool in genetic studies of the soya bean [Glycine max (L.) Merrill]

Summary A simple technique for the vegetative propagation of F1 hybrid soya bean plants is described. By growing 1- and 2-wk old cuttings, all treated with 1-naphtylacetic acid and the fungicide metalaxyl, average success rates of 18 and 34% respectively were obtained. Cuttings grown under a long-day regime for two months produced large numbers of F2 seeds to be used in genetic studies. This method reduced the time and effort necessary to obtain hybrid progeny.     

Interspecific hybrids of Cyclamen persicum Mill. and C. purpurascens Mill. produced by ovule culture

Summary Interspecific crosses were made to introduce the scent of flowers of C. purpurascens into C. persicum cultivars and ovule culture was used to rescue the abortive hybrid embryos. Cultivars of C. persicum diploid (CPD, 2n=2×=48) and C. persicum tetraploid (CPT, 2n=4×=96) were the pistillate parents and wild species of C. purpurascens (CP, 2n=34) were staminate parents. After pollination, crossed ovaries were collected periodically and examined using paraffin sections. Histological observations suggested that both hybrid ovules of CPD x CP and CPT x CP should be transferred to culture medium 35 days after pollination. Based up on this observation, crossed ovaries were collected 28 days after pollination and ovules with placenta were transferred to MS (1962) medium containing 3% sucrose. These ovules were cultured in the dark at 25° C. The hybrids (2n=41) derived from CPD x CP had the scent of C. purpurascens, whereas the hybrids (2n=65) derived from CPT x CP had the scent of C. persicum. Although both hybrids had complete genomes from the parents and produced a few viable pollen grains, they failed to yield viable seeds by self- and cross-pollination with fertile pollen grains of C. persicum cultivars.Abbreviations CPD C. persicum diploid - CPT C. persicum tetraploid - CP C. purpurascens     

Production of hybrids between Cajanus acutifolius and C. cajan

There are many wild species of pigeonpea which are endemic to Australia. These wild species are cross incompatible with cultivated species of Indian origin. Cajanus acutifolius is one such species which does not easily cross with cultivated pigeonpea. Interspecific pollinations lead to hybrid seeds which were semi-shrivelled. Very few seeds germinated to give rise to F1 plants. Backcrossing the hybrid plants to C. cajan, the male parent, gave rise to aborting seeds which did not germinate in vivo hence BC1 plants are obtained after saving the aborting embryos in vitro. BC₁ plants showed normal meiotic pairing, but had low pollen fertility. The reasons for embryo abortion and low pollen fertility in spite of normal meiosis could be due to the effect of wild species cytoplasm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic differentiation between summer and autumn maturing cultivars of soybean (Glycine max (L.) Merrill) in Kyushy district of Japan

Summary 135 soybean landraces and pure line selections from Kyushu district fo Japan were assayed for isozyme and seed protein loci in order to determine the genetic structure groups of summer and autumn maturing cultivars. Out of the 16 tested loci, Dial, Enp, Estl, and Ti exhibited a marked difference in allelic frequency between both groups. The summer cultuvar groups had a high frequency for Dial-b, Enp-b, Estl-a and Ti-b, whereas Dial-a, Enp-a, Estl-b, and Ti-a were predominant in the autumn groups. The analysis of multi-locus genotypes revealed that both groups mostly consisted of different multi-locus genotypes. The allelic combination Dial-b Enp-b Estl-a Ti-b was most frequently observed in the summer cultivars, whereas four genootypes, Dial-a Enp-a Estl-a Ti-a, Dial-a Enp-a Estl-b Ti-a, Dial-a Enp-b Estl-b and Dial-a Enp-a Estl-b Ti-b, occupied most of the autumn cultivars. These results indicated that both groups were appreciably differentiated from each other. The summer cultivar groups also included a few accessions having the multi-locus genotypes observed predominantly in the autumn groups or Acol-b charcteristic of the landraces native to northern Japan. It seems likely that the summer cultivar groups was not phyletically derived from a single common ancestor, but partly involves the landraces with early maturity derived from northern Japan. Dial, Enp, Estl and Ti are useful genetic markers ot trace the origin and dissemination paths of Japanse soybean landraces.     

Genetic variation in soybean (Glycine max (L.) Merril) for cookability and water absorption during cooking

Summary Improvement of cookability is an important objective in breeding of food legumes. The present study was undertaken to investigate variation in cookability in soybean. Genetic variation was observed among lines from two crosses. Absence of associations between cookability and protein content, oil content and grain yield indicate that selection for cookability can be achieved without adversely affecting the expression of these characters.     

Recurrent selection for yield in Glycine max using genetic male-sterility

Summary Recurrent selection, using genetic male sterility to facilitate intermating in Glycine max, was evaluated when selecting among individual space-planted S₀ soybean plants for three yield-related traits: 1) seed yield per se (YLD), 2) apparent harvest index (AHI), and 3) a selection index in which seed yield was regressed on maturity (REG). The original intermating population was a combination of the cultivar Century and two F₂ populations segregating for male sterility. The selection intensity through three cycles of selection was 20%. The YLD population increased in mean yield by 2.8±2.2 g plant^-1 cycle^-1 buf shifted significantly toward late maturity by 3.9±0.6 days cycle^-1. The AHI population decreased in yield by 4.4±2.6 g cycle^-1 while maturity shifted slightly earlier; there was very little change in AHI. The REG population increased in yield by 5.7±2.4 g plant^-1 cycle^-1 while shifting toward later maturity by only 0.8±0.5 day cycle^-1. We concluded that selection among S₀ plants in these populations, using the selection index of yield regressed on maturity, was affective in increasing single plant yields without causing a significant shift in maturity. Selecting for yield per se caused an unacceptable shift toward late maturity and selection for AHI was ineffective for increasing yield or AHI.     

Tagging the juvenile locus in soybean [Glycine max (L.) Merr.] with molecular markers

Soybean cultivars carrying the `long juvenile trait' show a delayed flowering response under short day conditions. The incorporation of this character into genotypes of agronomic interest may allow a broader range of sowing dates and latitudes for a single cultivar adaptation. The objective of this work was to identify molecular markers linked to the juvenile locus in soybean. Experiments were carried out using two pairs of near isogenic lines(NILs) differing in the presence of the long juvenile trait, and RAPD markers. Four hundred primers were first screened to find polymorphism associated with the trait. Additional differences between NILs were sought by digesting the genomic DNA with five restriction enzymes. Polymorphic fragments detected between NILs were tested for linkage to the juvenile locus in the corresponding F₂ segregating populations. Marker bc357-HaeIII was linked (χ²L = 46.316) to the juvenile locus with an estimated recombination frequency of 0.13 ± 0.03in one of the genetic backgrounds studied. The fragment was cloned, sequenced and converted into a SCAR marker. Moreover,bc357-HaeIII was used as RFLP probe. Both, SCAR and RFLP generated markers linked to the juvenile locus in the two genetic backgrounds analysed. Results presented in this work can be utilised for both, the localisation of the gene associated with the character and for tagging the juvenile trait in soybean breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ovule and embryo culture to obtain hybrids from interspecific incompatible pollinations in chickpea

Many of the wild species of chickpea were not accessible to the improvement of chickpea due to cross incompatibility. In these interspecific incompatible crosses, fertilization takes place but the embryo aborts a few days later. The only way to obtain hybrid plants is by the application of growth regulators to pollinated pistils to prevent initial pod abscission and to save the aborting hybrid embryos by embryo rescue techniques. Although there are a few papers on regeneration from different explants of chickpea, information on embryo rescue techniques is not available. The paper summarises the embryo rescue techniques developed for chickpea, by the use of which hybrid plants between C. arietinum and C. pinnatifidum were produced. The paper also emphasises the effect of genotype to successfully obtain hybrids. The morphology of the hybrid plants resembled the male parent in leaf structure and growth habit. The colour of the flowers produced on the hybrid plant was pale violet, resembling the male parent whose flowers were violet in colour. The flower colour of the female parent was white. This revised version was published online in August 2006 with corrections to the Cover Date.     

A partially male-sterile mutant line of soybeans,Glycine max (L.) Merr.: Characterization of the msp phenotype variation

Summary Investigations of variable expression of msp partial male sterility in soybeans (Glycine max (L.) Merr.) showed that higher temperatures promote male fertility in msp homozygotes and showed that infectious agents are not intrinsic to the sterility system. Exchange grafts failed to modify fertility levels of msp msp rootstocks, Msp Msp scions, and their self-progeny. Tests for soybean mosaic virus and tobacco ringspot virus were negative in partially male-sterile plants, in control fertile plants, and in self-progeny of grafted plants. Growth-chamber experiments and field observations manifested that male fertility of msp msp plants is higher in hot environments than in cooler ones. The unexpected aberrant ratios of fertile to partially male-sterile plants observed in 1977 (Stelly & Palmer, 1980) are explainable on the basis of msp temperature sensitivity.Our observations suggest that homogeneous msp msp populations may be increased in hot environments.Research Geneticist, SEA-AR, USDA, Iowa State University, Ames, Iowa 50011, USA.     

Interspecific hybridization in the genus Gossypium through embryo culture

Summary With embryo rescue and culture techniques interspecific hybrids have been obtained amongst diploid cultivated (Gossypium arboreum, G. herbaceum) and wild species (G. stocksii, G. anomalum) of cotton. The early abscission of the young bolls was prevented by repeated application of growth regulators followed by the culture of immature hybrid embryos (15 days after pollination). The best growth and development were obtained on modified Murashige and Skoog's medium with supplements. The plants were stouter when the cultures were first incubated in the dark for 15–25 days, followed by exposure to light. The hybrid plants transferred to soil developed further and matured, and were more or less intermediate between their respective parents.     

Transgenic fertile plants of soybean [Glycine max (L.) Merrill] obtained from bombarded embryogenic tissue

This work describes the production of transgenic, fertile plants of soybean [Glycine max (L.) Merrill]. The transformation method combines the advantages of somatic embryo genesis with the efficiency of particle bombardment of tissues that have a great capacity for in vitro proliferation and regeneration. The results described here represent the first report of transformation of soybean cultivars recommended for commercial growing in South Brazil using somatic embryogenesis, and may open the field for the improvement of this crop in this country by genetic engineering. This revised version was published online in August 2006 with corrections to the Cover Date.