SSR marker tightly linked to the Ti locus in Soybean [Glycine max (L.) Merr.]

Soybean is a major source of protein meal in the world. Soybean kunitz trypsin inhibitor (SKTI) protein is a responsible for the inferior nutritional quality of unheated or incompletely heated soybean meal. The primary objective of this research was to identify DNA markers linked to the Ti locus controlling presence and absence of kunitz trypsin inhibitor protein. Two mapping populations were developed. Population 1 was derived from a cross between cultivar Jinpumkong2 (TiTi) and C242 (titi). Population 2 was made from a mating between cultivar Clark (TiTi) and C242. The F₁ plants were grown in the greenhouse to produce F₂ seeds. Each F₂ seed from F₁ plants was analyzed electrophoretically to determine the presence of the SKTI protein band. One-thousand RAPD primers, 342 AFLP primer sets, and 35 SSR primers were used to map Ti locus in population 1 and 2. The presence of SKTI protein was dominant to the lack of a SKTI protein and kunitz trypsin inhibit protein band was controlled by a single locus. Twelve DNA markers (4 RAPD, 4 AFLP, and 3 SSR) and Ti locus were found to be genetically linked in population 1 consisted with 94 F₂ individual plants. Three SSR markers (Satt409, Satt228, and Satt429) were linked with Ti locus within 10 cM. Satt228 marker was tightly linked with Ti locus. Satt228 marker was tightly linked within 0–3.7 cM of the Ti locus and may be useful in a marker assisted selection program.     

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.     

Inheritance of long juvenile period under short day conditions for the BR80-6778 soybean (Glycine max (L.) Merrill) line

The long juvenile period characteristic (LJP), which delays flowering under short day conditions, has been identified in soybean cultivars (Glycine max L. Merrill). This characteristic may be especially important as it increases the range of adaptation of soybean in low latitudes and gives greater flexibility for sowing periods within the same latitude. The inheritance of the long juvenile period was studied in the BR80-6778 soybean line to provide knowledge to support the development of cultivars adapted to short day conditions. Cultivars with classic flowering, Paraná, Bossier, Bragg and Davis, which flower early under short day conditions, were also used as parents in single crosses. They were crossed among themselves and with the genotypes with LJP, BR80-6778 and MG/BR 22 (Garimpo). The study was carried out under short day conditions (early sowings) in greenhouses and in the field at Embrapa National Soybean Research Center, Londrina, PR. Flowering was assessed daily. The results indicated that the BR89-6778 line shares a pair of alleles with the Paraná cultivar, and when associated with the cc allele retards flowering under short day conditions. The following genotype constitutions were attributed to the cultivars: Paraná (aaBBCC), Bossier (AabbCC), and BR80-6778 (aaBBcc). The combination of the genes aabb and aabbcc has a pronounced effect on the manifestation of the trait. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of male fertility restoration of the cytoplasmic-nuclear male-sterile line NJCMS1A of soybean [Glycine max (L) Merr.]

At present, no report on inheritance of male fertility restoration has been released, yet more than 10 cytoplasmic-nuclear male-sterile soybean lines as well as their maintainers and restorers have been developed. Based on our previous work, 25 restorers for the male-sterile line NJCMS1A were identified and the inheritance of male fertility restoration for these restorers was studied. The results showed that F₁s between NJCMS1A and its restorers were completely male-fertile. The numbers of fertile and sterile plants in the F₂ population of Cross I (NJCMS1A × N23601) and Cross II (NJCMS1A × N23683) corresponded to a segregation ratio of 15:1, and the numbers of non-segregation lines, 3:1 segregation lines and 15:1 segregation lines in F_2:3 of the same two crosses fitted a 7:4:4 genotypic segregation ratio. The testcross BC₁F₁s between the F₁s of the above two crosses and NJCMS1A, NJCMS1B showed a 3:1 segregation ratio. Accordingly, it was inferred that two pairs of duplicate dominant genes controlled the male fertility restoration of NJCMS1A in both crosses. Meanwhile, F₂ of other 23 crosses between NJCMS1A and its 23 restorers showed a fertility segregation ratio of 3:1 or 15:1. The F₁s of the five testcrosses between NJCMS1A and the F₁s of five crosses selected from the above 23 crosses showed that fertility segregation was 3:1 in BC₁F₁s between NJCMS1A and F₁s of the crosses of which fertility segregation fitted 15:1 in F₂ population, while fertility segregation in BC₁F₁s was 1:1 for those fertility segregation fitted 3:1 in F₂ population. Allelism tests showed that restore genes of all restorers in the experiment were allelic to two pairs of dominant genes. All results showed that some restorers bore one pair of dominant restore gene and the others bore two pairs of duplicate dominant gene. The mechanism of F₁ male sterility of the cross N8855 × N2899 was discussed.     

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.     

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.     

Major QTLs associated with green stem disorder insensitivity of soybean (Glycine max (L.) Merr.)

Green stem disorder (GSD) is one of the most serious syndromes affecting soybean (Glycine max) cultivation in Japan. In GSD, stems remain green even when pods mature. When soybean plants develop GSD, seed surfaces are soiled by tissue fluid and seed quality is deteriorated during machine harvesting. We performed quantitative trait locus (QTL) analyses for GSD insensitivity using recombinant inbred lines (RILs; n = 154) derived from a cross between an insensitive line (‘Touhoku 129’) and a sensitive leading cultivar (‘Tachinagaha’) during a 6-year evaluation. Three effective QTLs were detected. The influences of these QTLs were in the following order: qGSD1 (LG_H) > qGSD2 (LG_F) > qGSD3 (LG_L). At these three QTLs, ‘Touhoku 129’ genotypes exhibited more GSD insensitivity than ‘Tachinagaha’ genotypes. The lower incidence of GSD for ‘Touhoku129’ was attributable primarily to these three QTLs because RILs harboring a ‘Touhoku 129’ genotype at the three QTLs exhibited a GSD incidence similar to that of ‘Touhoku 129.’ Although a limitation of this study is that only one mapping population was evaluated, this QTL information and the flanking markers of these QTLs would be effective tools for resolving GSD in soybean breeding programs.     

Genotype x Bradyrhizobium japonicum strain interactions in dinitrogen fixation and agronomic traits of soybean (Glycine max L. Merr.)

Summary Bradyrhizobium japonicum strain G49 has been the only inoculum used in French soils. Soybean (Glycine max L. Merr.) cultivars were selected and tested according to their performances with this rhizobial strain. The aim of the present study was to determine the consequences of strain substitution on N₂ fixation abilities of various genotypes. Three genotypes and cultivar Weber, in combination with B. japonicum strain G49 or SMGS1, were cultivated in pots and tested for nitrogenase activity under differing nitrogen nutrition conditions. The reliability of ARA (acetylene reduction activity) measurement for assessing symbiotic nitrogen fixation under the experimental conditions used was checked. Genotypic variability for symbiotic fixation activity was observed with each strain under soil culture conditions; important genotype x strain interactions were also involved. These results were corroborated for the protein yield and other yield component performances of the various genotype-strain associations. Thus, in France, the replacement of strain G49 with another one might result in the alteration of the relative agronomic performances of the soybean cultivars, since N₂ fixation is considered as a major factor of soybean productivity.     

大豆苗期耐淹性的遗传与QTL分析

涝害是世界上许多国家的重大自然灾害。耐涝性可分为耐湿(渍)性和耐淹性。以科丰1号(高度耐淹)×南农1138-2(不耐淹)衍生的RIL群体(NJRIKY)为材料, 以盆栽全淹条件下的存活率为耐淹性指标, 采用主基因+多基因混合遗传模型分离分析法进行遗传分析, 并利用WinQTL Cartographer Version 2.5程序的复合区间作图法(CIM)及多区间作图法(MIM)进行QTL定位。结果表明, 两次试验的耐淹性均存在超亲变异, 试验间、家系间以及试验与家系互作间的差异均极显著; NJRIKY大豆群体的耐淹性为3对等加性主基因遗传模型, 主基因遗传率为42.40%; 在QTL分析中, 用CIM和MIM共同检测到3个耐淹QTL, 分别位于A1、D1a和G连锁群上的Satt648~K418_2V、Satt531~A941V、Satt038~Satt275 (B53B~Satt038)区间, 表型贡献率为4.4%~7.6%。分离分析与QTL定位的结果相对一致, 可相互印证。     

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.     

吉林省大豆品种遗传改良过程中主要农艺性状的变化

以吉林省1923—2005年间育成的30个大豆品种为材料, 两年的研究结果表明, 大豆种子产量随育成年代呈线性增加, 根据回归方程计算, 产量从1923年的1 197.80 kg hm^-2到2005年的2 305.54 kg hm^-2, 82年来增加了 1 107.73 kg hm^-2, 平均每年增加14.60 kg hm^-2。随着产量的提高, 株高降低, 主茎直径增加, 节数增多, 节间缩短, 分枝减少。相关和通径分析表明, 产量与单株荚数、单株粒数、单株叶面积、叶面积指数和单株复叶数目呈显著正相关(P<0.05), 单株荚数和单株粒数对于产量的提高贡献最大; 产量与株高、单株分枝数和倒伏指数呈显著负相关(P<0.05), 表明大豆产量的遗传改良过程中, 植株抗倒伏能力提高, 库容量增加, 源器官叶片的同化能力增强。     

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.     

Association analysis for detecting significant single nucleotide polymorphisms for phosphorus-deficiency tolerance at the seedling stage in soybean [Glycine max (L) Merr.]

Tolerance to low-phosphorus soil is a desirable trait in soybean cultivars. Previous quantitative trait locus (QTL) studies for phosphorus-deficiency tolerance were mainly derived from bi-parental segregating populations and few reports from natural population. The objective of this study was to detect QTLs that regulate phosphorus-deficiency tolerance in soybean using association mapping approach. Phosphorus-deficiency tolerance was evaluated according to five traits (plant shoot height, shoot dry weight, phosphorus concentration, phosphorus acquisition efficiency and use efficiency) comprising a conditional phenotype at the seedling stage. Association mapping of the conditional phenotype detected 19 SNPs including 13 SNPs that were significantly associated with the five traits across two years. A novel cluster of SNPs, including three SNPs that consistently showed significant effects over two years, that associated with more than one trait was detected on chromosome 3. All favorable alleles, which were determined based on the mean of conditional phenotypic values of each trait over the two years, could be pyramided into one cultivar through parental cross combination. The best three cross combinations were predicted with the aim of simultaneously improving phosphorus acquisition efficiency and use efficiency. These results will provide a thorough understanding of the genetic basis of phosphorus deficiency tolerance in soybean.     

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.     

DNA fingerprinting in soybean (Glycine max (L.) Merrill) with oligonucleotide probes for simple repetitive sequences

Summary Soybean DNA fingerprints were analyzed by digoxigenin-labeled oligonucleotide probes complementary to simple repetitive sequences. The clearest and most polymorphic patterns were obtained with (AAT)₆ as a probe, with which all 47 soybean cultivars tested could be distinguished. However, DNA fingerprints of individuals within cultivars showed the same pattern. Using (CT)₈, (GAA)₅ or (AAGG)₄ as probes, clear polymorphic patterns among cultivars and accessions in the subgenus Soja (Glycine max and Glycine soja) were not observed, while quite different patterns were found in accessions in the subgenus Glycine. The results suggest that G. max and G. soja are closer in their genome structure. DNA fingerprints of reciprocal crosses between cultivars and accessions in the subgenus Soja were similar, and contained bands of both parents. In an F₂ population from these crosses, such bands segregated in a Mendelian fashion.     

Variation in the photoperiodic response on several characters in soybean,Glycine max (L.) Merrill

Summary The photoperiodic response on 12 characters in 40 soybean, Glycine max (L.) Merrill, cultivars were investigated using 10-hour (short day) and 16-hour (long day) photoperiods. Seventeen cultivars showed no significant difference between photoperiods for all 12 characters. Seven cultivars showed significant difference for only one trait. Phenotypic changes in 17 cultivars may be due to factors other than photoperiod. Number of pods per plant, days to maturity, and number of nodes per plant were highly correlated with yield per plant in both photoperiods. Invariably, the cultivars which had significant differences in the numbers of flowers produced per plant between the two photoperiods also had significant differences in the numbers of pods per plant and yield. First node to flower, plant height at flowering, days to flowering, nodes at flowering, and the 100-seed weight were least influenced by the photoperiods in most of the cultivars, while the height at maturity, number of nodes at maturity, number of days to maturity, and yield were most influenced.AVRDC Journal paper 46 (78–88).     

Genomewide association analysis of salt tolerance in soybean [Glycine max (L.) Merr.]

Salinity is a common abiotic stress causing soybean [Glycine max (L.) Merr.] yield loss worldwide. The use of tolerant cultivars is an effective and economic approach to coping with this stress. Towards this, research is needed to identify salt‐tolerant germplasm and better understand the genetic and molecular basis of salt tolerance in soybean. The objectives of this study were to identify salt‐tolerant genotypes, to search for single‐nucleotide polymorphisms (SNPs) and QTLs associated with salt tolerance. A total of 192 diverse soybean lines and cultivars were screened for salt tolerance in the glasshouse based on visual leaf scorch scores after 15–18 days of 120 mM NaCl stress. These genotypes were further genotyped using the SoySNP50K iSelect BeadChip. Genomewide association mapping showed that 62 SNP markers representing six genomic regions on chromosomes (Chr.) 2, 3, 5, 6, 8 and 18, respectively, were significantly associated with salt tolerance (p < 0.001). A total of 52 SNP markers on Chr. 3 are mapped at or near the major salt tolerance QTL previously identified in S‐100 (Lee et al., 2014). Three SNPs on Chr. 18 map near the salt tolerance QTL previously identified in Nannong1138‐2 (Chen, Cui, Fu, Gai, & Yu, 2008). The other significant SNPs represent four putative minor QTLs for salt tolerance, newly identified in this study. The results above lay the foundation for fine mapping, cloning and molecular breeding for soybean salt tolerance.     

Genetic analysis for the leaf pubescence density and water status traits in soybean [Glycine max (L.) Merr.]

Leaf pubescence density (PD) is an important component for the adaptation of soybean [ Glycine max (L.) Merr.] to drought-prone environment. Quantitative trait loci (QTL) controlling PD on the upper surface of leaf blade (PDU), PD on the lower surface of leaf blade (PDL), leaf wilting coefficient (WC) and rate of excised leaf drying (ELD) were identified using recombinant inbred lines (RILs) population from the cross between soybean cultivars 'kefeng1' and 'nannong1138-2' at the field soil drought stress stage from the mid-end of stem elongation to onset of flowering. A total of 20 QTLs were detected on molecular linkage groups (MLGs) A2, D1b, E, H, G and I with individual QTL explained 4.49–23.56% of phenotypic variation by composite interval mapping. The QTLs for PD on MLG H were mapped to near Ps locus while the QTLs on MLG D1b were located near Rsc-7 . Three genome regions for PD and water status traits on MLGs A2, D1b and H were associated. This study revealed that leaf surface PD may play an important role in the soybean drought tolerance.     

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.     

New genes for resistance to Xanthomonas campestris pv. glycines in soybean [Glycine max (L.) Merr.] and their inheritance

Bacterial leaf pustule (BLP) caused by Xanthomonas campestris pv. glycines is an important disease of soybean. A new resistant source, P-4-2, showing an immune reaction in controlled conditions to BLP was crossed with the susceptible cultivar Monetta to study the inheritance of resistance. All F1 plants were susceptible. The F2 population segregated 15 susceptible: 1 resistant plants indicating the presence of duplicate recessive genes controlling resistance. This was further confirmed in the F3 generation. Two recessive genes conferring high levels of resistance in soybean to Xanthomonas campestris pv. glycines under controlled conditions are being reported here for the first time. This revised version was published online in July 2006 with corrections to the Cover Date.