Inheritance and gene tagging of male fertility restoration of cytoplasmic-nuclear male-sterile line NJCMS1A in soybean

The F₁, F₂ and F_2:3 of the NJCMS1A × 'Zhongdou 5' cross were used to analyse the inheritance of the male fertility restoration of the cytoplasmic-nuclear male-sterile line NJCMS1A in soybean. The results of genetic analysis showed two pairs of dominant genes conferring the male fertility restoration of NJCMS1A, which further confirmed previous results. The F₂ population from the NJCMS1A × 'Zhongdou 5' cross was used for tagging the restorer genes for NJCMS1A with 664 pairs of simple sequence repeat primers selected randomly from the genetic linkage map of soybean published by Cregan et al. (1999) . Satt626 on linkage group M and Satt300 on linkage group A1 of the integrated linkage map by Song et al. (2004) were found to link to the two restorer genes of NJCMS1A. The maximum-likelihood estimates of the genetic distance between the two markers, Satt626 and Satt300, and the two restorer genes of 'Zhongdou 5' were 9.75 and 11.18 cM, respectively.     

Discovery of new male-sterile cytoplasm sources and development of a new cytoplasmic-nuclear male-sterile line NJCMS3A in soybean

Most of the cytoplasmic-nuclear male-sterile (CMS) lines of soybean were developed only from a limited cytoplasm sources and performed not as good as required in hybrid seed production, therefore, to explore new male-sterile cytoplasm sources should be one of the effective ways to improve the pollination and hybridization for a better pod-set in utilization of heterosis of soybeans. In the present study, total 80 crosses between 70 cultivated and annual wild soybean accessions and three maintainers (N2899, N21249, and N23998) of NJCMS1A were made for detecting potential new sources with male-sterile cytoplasm. The results showed that in addition to the crosses with N8855.1 (the cytoplasm donor parent of NJCMS1A) and its derived line NG99-893 as cytoplasm parent, there appeared three crosses, including N21566 × N21249 and N23168 × N21249, with male-sterile plants in their progenies. According to the male fertility performance of backcrosses and reciprocal crosses with the tester N21249, the landrace N21566 and annual wild soybean accession N23168 were further confirmed to have male-sterile cytoplasm. Accordingly, it was understood that the source with male-sterile cytoplasm in soybean gene pool might be not occasional. The results also showed that the genetic system of male sterility of the newly found cytoplasm source N21566 was different from the old cytoplasm source N8855.1, while N23168 was to be further studied. Based on the above results, the derived male-sterile plants from [(N21566 × N21249) F₁ × N21249] BC₁F₁ were back-crossed with the recurrent parent N21249 for five successive times, and a new CMS line and its maintainer line, designated as NJCMS3A and NJCMS3B, respectively, were obtained. NJCMS3A had normal female fertility and stable male sterility. Its microspore abortion was mainly at middle uninucleate stage, earlier than that of NJCMS1A and NJCMS2A. The male fertility of F₁s between NJCMS3A and 20 pollen parents showed that 7 accessions could restore its male fertility and other 13 could maintain its male sterility. The male sterility of NJCMS3A and its restoration were controlled by one pair of gametophyte male-sterile gene according to male fertility segregation of crosses between NJCMS3A and three restorers. The nuclear gene(s) of male sterility in NJCMS3A appeared different from the previously reported CMS lines, NJCMS1A and NJCMS2A. The development of NJCMS3A demonstrated the feasibility to discover new CMS system through choosing maintainers with suitable nuclear background.     

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.     

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.     

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。     

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.     

Development of a cytoplasmic male‐sterile line NJCMS4A for hybrid soybean production

Cytoplasmic male‐sterile (CMS) lines are being used to produce hybrid seeds. Thus far, four CMS sources in soybean [Glycine max (L.) Merr.] have been reported in China. However, they are not sufficient or efficient in meeting the requirements of commercial soybean hybrid seed production. In this study, 33 varieties were tested for CMS using 45 crosses among 37 landraces and 17 annual wild soybean accessions (Glycine soja Sieb. et Zucc.). The cross of N23661 × N23658 showed partial to complete male sterility in backcross generations, while the corresponding reciprocal cross showed normal male fertility. Thus, the cytoplasm of N23661 is male‐sterile, the continuously backcrossed line is a male‐sterile line (designated NJCMS4A), and N23658 is its maintainer (designated NJCM4B). The male fertility of NJCMS4A was restored by another accession, Nansheng9403. Accordingly, NJCMS4A along with its maintainer and restorer composes a complete set of three lines for producing hybrid soybean. Using mitochondrial markers and sequence analyses, NJCMS4A is a CMS line with its cytoplasm not identical to the four previously reported CMS sources in soybean.     

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。     

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.     

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.     

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.     

大豆不同生育时期叶绿素含量QTL的定位及其与产量的关联分析

利用来自波高×南农94-156的151个RI家系检测与4个不同生育时期叶绿素含量（累积量、净增量）有关的QTL,并分析其与籽粒产量、表观生物学产量和表观收获指数的关系。结果表明,与叶绿素累积量有关的QTL位于D1a+Q、F、G、H、L和M连锁群上,每个QTL可解释表型变异的6.9%~23.4%。V6和R2期没有检测到2个年份均表达的QTL,而在R4期检测到4个在2个年份均表达的QTL（qccF.1、qccG.2、qccH.1和qccM.1）,R6期仅检测到1个QTL（qccH.1）在2个年份均表达,该QTL在R4也表达。与叶绿素含量净增量有关的QTL位于B2和L连锁群上,在V6-R2时期没有检测到与叶绿素净增量有关的QTL,在B2和L连锁群上的两个QTL（qccB2-1.1和qccL.1）在R2-R4和R4-R6时期均表达,qccB2-1.1可解释表型变异的6.4%~9.8%,而qccL.1所解释表型变异达29.5%~31.3%。但这两个QTL在R2-R4和R4-R6时期表达的性质不同,且与2年均表达的籽粒产量QTL共位。这印证了生育后期叶绿素含量与籽粒产量间存在的极显著正相关。     

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.     

大豆根区逆境耐性的种质鉴定及其与根系性状的关系

依根系类型从黄淮海和长江中下游地区301份代表性材料中选取62份，以株高、叶龄、地上部干物重、地下部干物重为指标，采用平均隶属函数值方法鉴定了苗期耐旱性、苗期耐铝毒性，加上主茎节数、分枝数、单株荚数、单株粒数、百粒重等性状鉴定了后期耐旱性，并通过钒钼黄比色法测定植株P含量鉴定了苗期耐低磷性。筛选出1级苗期     

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.     

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.     

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.     

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.     

Inheritance of fertility restoration in sunflower (helianthus annuus L.)

Summary Fertility restoration in the cross between a cytoplasmic male sterile line, 2 cm 183, and the restorer line, BCZ 111, (both obtained from France) was dominant in F₁ and segregated in a 9:7 ratio in the F₂ generation and thus suggested the action of two independent, complementary dominant genes controlling restoration. The behaviour of F₃ families broadly confirmed the F₂ ratio. The reasons underlying this pattern of inheritance has been discussed and the genetic symbols rf ₁ rf ₁ rf₂ rf₂and Rf ₁ Rf ₁ Rf ₂ Rf ₂ have been suggested for the male sterile and the restorer parents respectively.     

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.