Molecular mapping of 36 soybean male-sterile, female-sterile mutants

Mutability of the w ( 4 ) flower color locus in soybean [Glycine max (L.) Merr.] is conditioned by an unstable allele designated w ( 4 ) -m. Germinal revertants, purple-flower plants, recovered among self-pollinated progeny of mutable flower plants were associated with the generation of necrotic root, chlorophyll-deficiency, and sterility mutations. Thirty-seven male-sterile, female-sterile mutant lines were generated from 37 independent reversion events at the w ( 4 ) -m locus. The first germinal revertant study had one male-sterile, female-sterile mutant (st8, T352), located on Molecular Linkage Group (MLG) J. The second study had 36 germinal-revertant derived sterility mutants descended from four mutable categories of w ( 4 ) -m. The mutable categories were designated; (1) low frequency of early excisions, (2) low frequency of late excisions, (3) high frequency of early excisions, and (4) high frequency of late excisions. The objectives of the present study were to; (1) molecularly map the 36 male-sterile, female-sterile mutants, and to (2) compare map locations of these mutants with T352 (st8), identified from the first germinal revertant study. Thirty-three of 36 male-sterile, female-sterile mutations were derived from germinal reversions that were classified in the late excision categories. Thirty-five male-sterile mutants mapped to the st8 region on MLG J. The only exception mapped to MLG G. Most likely mutants were generated through insertion of a putative transposon that was excised from the w ( 4 ) locus. The location of 36 of 37 mutations to a single chromosomal region suggests preference for sequence-dependent insertion.     

Genetics and cytology of a genic male-sterile, female-sterile mutant from a transposon-containing soybean population

A male-sterile, female-sterile soybean mutant (w4-m sterile) was identified among progeny of germinal revertants of a gene-tagging study. Our objectives were to determine the genetics (inheritance, allelism, and linkage) and the cytology (microsporogenesis and microgametogenesis) of the w4-m sterile. The mutant was inherited as a single recessive nuclear gene and was nonallelic to known male-sterile, female-sterile mutants st2 st2, st3 st3, st4 st4, st5 st5, and st6 st6 st7 st7. No linkage was detected between the w4-m sterile and the w4w4, y10 y10, y11 y11, y20 y20, fr1 fr1, and fr2 fr2 mutants. Homologous chromosome pairing was complete in fertile plants. Chromosome pairing, as observed in squash preparation, was almost completely absent in sterile plants. Developmentally microsporogenesis proceeded normally in both the fertile and the w4-m sterile through the early microspore stage. Then the tapetal cells of the w4-m sterile surrounding the young microspores developed different-size vacuoles. These tapetal cells became smaller in size and separated from each other. Some of the microspores of the w4-m sterile also became more vacuolate prematurely and sometimes they collapsed, usually by the late microspore stage. In the w4-m sterile the microspore walls remained thinner and structurally different from the microspore walls of fertile plants. No pollen was formed in the mutant plants, even though some of the male cells reached the pollen stage, although without normal filling. The w4-m sterile was designated st8st8 and assigned Soybean Genetic Type Collection number T352.     

Molecular mapping of the reverse thermo-sensitive genic male-sterile gene (rtms1) in rice

TGMS (thermo-sensitive genic male-sterile) rice is widely used in hybrid rice production. Because of a specific temperature requirement, it can be used only in a narrow rice-growing zone in Asia. A newly discovered reverse thermo-sensitive genic male-sterile line, J207S, has an opposite phynotype compared to the normal TGMS lines. J207S is completely sterile when the temperature is lower than 31°C. Thus, it can be widely used in a larger area. Genetic analysis indicated that the sterility of J207S was controlled by a single recessive gene which was first named as rtms1. An F₂ population from the cross between J207S and E921 was developed and used for molecular mapping of the rtms1 gene. The AFLP (amplified fragment length polymorphism) technique, combined with BSA (bulked segregant analysis), was used to screen markers linked to the target gene, and eight polymorphic AFLP loci were identified. Co-segregating analysis using the F₂ population showed that two of them, Rev1 and Rev7, were closely linked to the target gene with a recombinant rate of 3.8% and 7.7%, respectively. Both Rev1 and Rev7 were found to be single-copy sequences through Southern analysis. Rev1 was subsequently mapped on chromosome 10 with a doubled-haploid mapping populations derived from the cross CT9993 × IR62266 available at Texas Tech University. RM222 and RG257 were linked to Rev1 at a distance of 11.8 cM and 4.6 cM, respectively. Additional SSR markers from the rice map of Cornell University, RFLP markers from the map of RGP in Japan and the map of Texas Tech University were selected from the region surrounding Rev1 on chromosome 10 to conduct the fine-mapping of the rtms1 gene. Presently, rtms1 was mapped between RM239 and RG257 with genetic distance of 3.6 cM and 4.0 cM, respectively. The most-closely linked AFLP marker, Rev1, 4.2 cM from the rtms1 gene, was sequenced and converted into a SCAR (sequence characterized amplified region) marker which could facilitate marker-assisted selection of the rtms1 gene. Received: 2 November 2000 / Accepted: 21 November 2000     

A new and distinctive male-sterile,female-fertile desynaptic mutant in soybean (Glycine max)

A spontaneous desynaptic mutation, affecting only microsporogenesis and causing pollen sterility, has been detected in BR97-12986H, a line of the official Brazilian soybean breeding program. In this male-sterile, female-fertile mutant, up to metaphase II, the meiotic behavior was similar to that described for the st series of synaptic mutants previously reported in soybean. Besides many univalents, few or total absence of bivalents were recorded in diakinesis. Bivalents presented one or two terminal chiasmata, while univalents retained the sister chromatid cohesion. Bivalents and most univalents congregated at the equatorial metaphase plate, although univalents frequently migrated to the poles prematurely. Laggards resulting from delay in chiasmata terminalization were also recorded. Distinctly different in their behavior from st series soybean mutants, telophase I-originated micronuclei of different sizes organized their own spindle in the second division. This behavior contributed towards an increase in genome fractionation. Several microspores and microcytes of different sizes were recorded at the end of meiosis. Pollen sterility was estimated at 91.2%. Segregation ratio for sterility in this line and its progenies reached 3:1. Allelism tests with st series of synaptic mutants are in progress. The importance of male-sterile, female-fertile mutations for soybean breeding programs is discussed.     

Molecular mapping of the fasciation mutation in soybean, Glycine max (Leguminosae)

The spontaneous fasciation mutation generates novel developmental diversity in cultivated soybean, Glycine max (L.) Merrill. An increased apical dominance in the mutant inhibits axillary buds, causes a branchless phenotype, and restricts reproduction to shoot apices. The fasciation mutation is encoded by a recessive (f) allele at a single locus. The mutation, despite its importance in soybean development, has no locus assignment on previously reported molecular maps of soybean. A population of 70 F(2) progeny was derived from a cross between 'Clark 63' and the fasciation mutant. More than 700 molecular markers (amplified restriction fragment length polymorphisms [AFLPs], random amplified polymorphic DNAs [RAPDs], restriction fragment length polymorphisms [RFLPs], and simple sequence repeats [SSRs]) were used in mapping of the fasciation phenotype. Twenty linkage groups (LGs) corresponding to the public soybean molecular map are represented on the Clark 63 × fasciation mutant molecular map that spans 3050 centimorgans (cM). The f locus was mapped on LG D1b+W and linked with two AFLPs and four SSR markers (Satt005, Satt141, Satt600, and Satt703). No linkage was found between the f locus and several cDNA polymorphic loci between the wild type and the mutant. The known map position of the f locus and demonstration of the mutant phenotype from early postembryonic throughout reproductive stages provide an excellent resource for investigations of molecular mechanisms affecting soybean ontogeny.     

Genetic analysis,molecular tagging and mapping of the thermo-sensitive genic male-sterile gene (wtms1) in wheat

A thermo-sensitive genic male-sterile (TGMS) wheat line ( Triticum aestivum L.) BNY-S was obtained from the spontaneous mutant of BNY-F. Its fertility was decided by the temperature during the differentiation stage of the spikelets. BNY-S was completely sterile when the temperature was lower than 10 degrees C during the differentiation stage of the spikelets, but fertile when the temperature was higher than 10 degrees C. Genetic analysis indicated that the sterility of BNY-S was controlled by a single recessive gene, which was named as wtms1. An F(2) population, consisting of 3,000 individuals from the cross between BNY-S and Lankao 52-24, was used for genetic analysis and statistical analysis of the TGMS and, out of them, 158 sterile and 93 fertile extremes were present for molecular tagging and mapping of the wtms1 gene. SSR (simple sequence repeat) and AFLP (amplified fragment length polymorphism) techniques combined with BSA (bulked segregant analysis) were used to screen markers linked to the target gene. As a result, wtms1 was preliminarily mapped on chromosome 2B according to SSR analysis. In AFLP analysis, 14 polymorphic AFLP loci were identified with a linkage relation to the wtms1 gene. Then linkage analysis using the F(2) population showed that three of them, E: AAG/M: CTA(163), E: AGG/M: CTC(220) and E: ACA/M: CTA(160), were linked to the wtms1 gene relatively close to a genetic distance of 6.9 cM, 6.9 cM and 13.9 cM, respectively. Finally, the wtms1 gene was mapped between the SSR marker Xgwm 374 and the AFLP marker E: AAG/M: CTA(163) with the distance of 4.8 cM and 6.9 cM, respectively. A partial linkage map was constructed according the SSR and AFLP data.     

Fine mapping of the recessive genic male-sterile gene (Bnms1) in Brassica napus L.

A recessive genic male sterility (RGMS) system, S45 AB, has been developed from spontaneous mutation in Brassica napus canola variety Oro, and is being used for hybrid cultivar development in China. The male sterility of S45 was controlled by two duplicated recessive genes, named as Bnms1 and Bnms2. In this study, a NIL (near-isogenic line) population from the sib-mating of S45 AB was developed and used for the fine mapping of the Bnms1 gene, in which the recessive allele was homozygous at the second locus. AFLP technology combined with BSA (bulked segregant analysis) was used. From a survey of 2,560 primer combinations (+3/+3 selective bases), seven AFLP markers linked closely to the target gene were identified, of which four were successfully converted to sequence characterized amplified region (SCAR) markers. For further analysis, a population of 1,974 individuals was used to map the Bnms1 gene. On the fine map, Bnms1 gene was flanked by two SCAR markers, SC1 and SC7, with genetic distance of 0.1 cM and 0.3 cM, respectively. SC1 was subsequently mapped on linkage group N7 using doubled-haploid mapping populations derived from the crosses Tapidor × Ningyou7 and DH 821 × DHBao 604, available at IMSORB, UK, and our laboratory, respectively. Linkage of an SSR marker, Na12A02, with the Bnms1 gene further confirmed its location on linkage group N7. Na12A02, 2.6 cM away from Bnms1, was a co-dominant marker. These molecular markers developed from this research will facilitate the marker-assisted selection of male sterile lines and the fine map lays a solid foundation for map-based cloning of the Bnms1 gene.     

Cytological evidence of a new male-sterile mutant in soybean (Glycine max (L.) Merr.)

Summary From one plant of soybean (Glycine max (L.) Merr.) with only two one-seeded pods, found in an F₄ population maintained by single-seed descent procedure, two fully fertile plants were obtained which, in turn, produced two progeny segregating for male sterility. Segregation ratios, observed on progeny from fertile plants in three successive generations, indicated that the male-sterility trait was under the control of a single recessive gene. Cytological observations made on malesterile, female-fertile plants showed the occurrence of a complete and properly timed cytokinesis with the formation of tetrad cells whose size was very variable, one of which sometimes had two nuclei. During pollen maturation binucleate microspores and grains with reduced size (micropollens) were frequently observed. Massive pollen degeneration occurred at a rather later stage. Structural evidence points to a normally functioning tapetum.On the basis of these cytological observations we conclude that the abnormalities observed in the mutant we studied have to be considered to be different from those caused by any other known ms allele. Tests of allelism with other sources of male sterility are in progress.     

Characterization of the female-sterile mutant Almondex of Drosophila melanogaster

Drosophila melanogaster females homozygous for the sex-linked recessive mutation almondex (amx) are completely sterile when mated to amx males. Matings of amx X+ yield low numbers of heterozygous female offspring, which frequently show abnormalities of the thorax and abdominal sternites, and an occasional non-disjunctional, non-mutant (XO) male offspring. The results of mating experiments reported here can be explained by assuming that the cytoplasm of eggs produced by amx females is deficient for some material that is necessary for normal development.Homozygous amx females have apparently normal reporductive organs and a high egg yield. Eggs are usually fertilized. In matings to amx males, all zygotes die as embryos; in matings to non-amx males, all ordinary (XY) male zygotes and most female zygotes die as embryos. Survival to the adult stage is more frequent at higher temperatures and, surprisingly, increases also with maternal age.     

Molecular cloning, mapping and characterization of the human neurocalcin delta gene (NCALD)

We identified a new human gene that encodes a cognate of the bovine neurocalcin delta from a human fetal brain cDNA library; hence we named it human neurocalcin delta (NCALD) gene. The deduced polypeptide product of the cDNA is 22 kDa in size, and its amino acid sequence is 100% and 99% identical to that of the bovine and chicken neurocalcin, respectively. Northern blots showed that the NCALD gene is more abundantly expressed in brain, testis, ovary and small intestine. Tissue in situ hybridization confirmed the existence of the NCALD mRNA in the adult human testis. Radiation hybrid panel mapping localized the gene to chromosome 8 between molecular markers D8S270 and D8S257.     

Fine mapping the soybean aphid resistance gene Rag1 in soybean

The soybean aphid (Aphis glycines Matsumura) is an important soybean [Glycine max (L.) Merr.] pest in North America. The dominant aphid resistance gene Rag1 was previously mapped from the cultivar ‘Dowling’ to a 12 cM marker interval on soybean chromosome 7 (formerly linkage group M). The development of additional genetic markers mapping closer to Rag1 was needed to accurately position the gene to improve the effectiveness of marker-assisted selection (MAS) and to eventually clone it. The objectives of this study were to identify single nucleotide polymorphisms (SNPs) near Rag1 and to position these SNPs relative to Rag1. To generate a fine map of the Rag1 interval, 824 BC₄F₂ and 1,000 BC₄F₃ plants segregating for the gene were screened with markers flanking Rag1. Plants with recombination events close to the gene were tested with SNPs identified in previous studies along with new SNPs identified from the preliminary Williams 82 draft soybean genome shotgun sequence using direct re-sequencing and gene-scanning melt-curve analysis. Progeny of these recombinant plants were evaluated for aphid resistance. These efforts resulted in the mapping of Rag1 between the two SNP markers 46169.7 and 21A, which corresponds to a physical distance on the Williams 82 8× draft assembly (Glyma1.01) of 115 kilobase pair (kb). Several candidate genes for Rag1 are present within the 115-kb interval. The markers identified in this study that are closely linked to Rag1 will be a useful resource in MAS for this important aphid resistance gene.     

甘蓝型油菜花瓣缺失基因的图谱定位

在无花瓣品系APT02和正常有花瓣品种中双4号构建的的F2分离群体中,运用AFLP和SRAP两种标记技术对甘蓝型油菜花瓣缺失基因进行分子标记和图谱定位。在两亲本间筛选20对AFLP引物和170对SRAP 引物,进一步通过BSA法筛选,获得了与甘蓝型油菜花瓣缺失基因WHB连锁的1个SRAP标记e8m3_4（600bp）和1个AFLP标记E3247_15（150bp）,标记与基因WHB之间的遗传距离分别为5 cM和13.5cM;构建了一个甘蓝型油菜(Brassica napus.L )的分子标记遗传连锁图谱,该图谱共包含213个AFLP标记、56个SRAP标记和1个形态标记,分布于17个主要连锁群、两个三联体和4个连锁对中,遗传图距总长2487.1cM,标记间平均距离为10.09 cM。通过图谱定位,控制花瓣缺失性状的基因WHB被定位到第4连锁群(LG4)上。     

Assessment of selection mapping near the myostatin gene (GDF-8) in cattle

Domestic species provide a unique opportunity to examine the effects of selection on the genome. The myostatin gene ( GDF-8 ) has been under strong selection in a number of cattle breeds because of its influence on muscle conformation and association with the 'double-muscling' phenotype. This study examined genetic diversity near this gene in a set of breeds including some nearly fixed for the allele associated with double-muscling (MH), some where the allele is segregating at intermediate frequency and some where the allele is absent. A set of microsatellites and SNPs were used to examine patterns of diversity at the centromeric end of bovine chromosome 2, the region where GDF-8 is located, using various statistical methods. The putative position of a selected gene was moved across the genomic region to determine, by regression, a best position of reduced heterozygosity. Additional analyses examined extended homozygous regions and linkage disequilibrium patterns. While the SNP data was not found to be very informative for selection mapping in this dataset, analyses of the microsatellite data provided evidence of selection on GDF-8 in several breeds. These results suggested that, of the breeds examined, the allele was most recently introduced into the South Devon. Limitations to the selection-mapping approach were highlighted from the analysis of the SNP data and the situation where the MH allele was at intermediate frequency.     

Molecular characterization of a Siglec8 variant containing cytoplasmic tyrosine-based motifs, and mapping of the Siglec8 gene

Through efforts to investigate the CD33-like subgroup of sialic acid binding immunoglobulin-like lectins (Siglecs), which are believed to be located on chromosome 19q13.4, we have identified the precise genomic region containing the Siglec8 gene. It is located on chromosome 19q13.4, approximately 330 kb downstream of the Siglec9 gene. Further, we have identified a novel Siglec8 variant, named Siglec8-Long (Siglec8-L), which differs in its last two exons from the previously published mRNA sequence of Siglec8 (GenBank Accession No. AF195092). Both Siglec8 and Siglec8-L are comprised of seven exons, of which the first five are identical, followed by marked differences in exon usage and mRNA splicing. The 499 amino acid protein encoded by the Siglec8-L open reading frame has a molecular weight of 54 kDa. Like the other members of the CD33-like subgroup of Siglecs, except for the previously published Siglec8, Siglec8-L also contains the two tyrosine-based motifs that have been found to recruit both SH2 domain-containing tyrosine and inositol phosphatases.     

Anthocyanin accumulation in the hypocotyl of an ABA-over producing male-sterile tomato (Lycopersicon esculentum) mutant

Anthocyanin accumulation is known to be regulated by light and plant hormones but its occurrence varies with plant species and/or organ and tissue, and it has been negatively correlated with male sterility. In this study, we have examined the light responsive changes in anthocyanin in an abscisic acid (ABA) over-producer, male-sterile 7B-1 mutant and wild-type (WT) tomato hypocotyls. The results show that light-induced anthocyanin accumulation in the hypocotyl was more in WT compared with the 7B-1 mutant and more so under white light (W) compared with blue light (B) or red light (R). In contrast, the chlorophyll content was greater in the mutant than in WT. Exogenous ABA caused a transitory increase in anthocyanin content in WT but a reduction in 7B-1 , both in W and B. The high level of anthocyanin in WT under light conditions was not correlated with increased mRNA levels of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and dihydroflavonol 4-reductase (DFR), some of the anthocyanin biosynthetic genes. However, the activity of PAL (EC 4.3.1.5) was higher in the WT than in 7B-1 hypocotyls, and exogenous ABA caused an increase in PAL activity in the WT but a reduction in the mutant. The results presented show that high ABA negatively affects anthocyanin accumulation and that in the 7B-1 mutant it is related, in part, to reduced PAL activity. The results also support the view that the 7B-1 mutant has a defect in light perception and ABA sensitivity.     

Molecular gene mapping of human aldolase A (ALDOA) gene to chromosome 16

Summary Mapping of human aldolase A (ALDOA) gene was performed by molecular hybridization techniques using a panel of human-mouse cell hybrids and sorted fractions of human metaphase chromosomes besides in situ hybridization. For the purpose, three kinds of DNA probes derived from the coding region (probe-1), the 3 noncoding region (probe-2), and the coding and 3 noncoding regions (probe-3) of human aldolase A cDNA clone, pHAAL116-3, were selectively employed. The results of RNA and DNA blot analyses indicated that the human ALDOA gene is located on chromosome 16. The in situ hybridization experiment also indicated that the ALDOA gene was localized to 16q22–q24.     

Fine mapping of the soybean aphid-resistance gene Rag2 in soybean PI 200538

The discovery of biotype diversity of soybean aphid (SA: Aphis glycines Matsumura) in North America emphasizes the necessity to identify new aphid-resistance genes. The soybean [Glycine max (L.) Merr.] plant introduction (PI) 200538 is a promising source of SA resistance because it shows a high level of resistance to a SA biotype that can overcome the SA-resistance gene Rag1 from ‘Dowling’. The SA-resistance gene Rag2 was previously mapped from PI 200538 to a 10-cM marker interval on soybean chromosome 13 [formerly linkage group (LG) F]. The objective of this study was to fine map Rag2. This fine mapping was carried out using lines derived from 5,783 F₂ plants at different levels of backcrossing that were screened with flanking genetic markers for the presence of recombination in the Rag2 interval. Fifteen single nucleotide polymorphism (SNP) markers and two dominant polymerase chain reaction-based markers near Rag2 were developed by re-sequencing target intervals and sequence-tagged sites. These efforts resulted in the mapping of Rag2 to a 54-kb interval on the Williams 82 8× assembly (Glyma1). This Williams 82 interval contains seven predicted genes, which includes one nucleotide-binding site-leucine-rich repeat gene. SNP marker and candidate gene information identified in this study will be an important resource in marker-assisted selection for aphid resistance and for cloning the gene.     

Molecular mapping of four ovule lethal mutants in soybean

We report genetic mapping of four soybean ovule lethal mutants, PS-1, PS-2, PS-3, and PS-4, which had been identified as female partial-sterile mutants from a gene-tagging study. The four mutants had been classified into two mutation classes: (1) PS-1—sporophytic mutation affects sporophytically expressed genes; and (2) PS-2, PS-3, and PS-4 mutants—female gametophyte-specific mutations affect gametophytically expressed genes and are transmitted through the male, but not the female gametes. Molecular mapping demonstrated that these four mutant genes and previously reported female-partial sterile gene, Fsp1, are located independently on soybean molecular linkage groups (MLG-) using SSR markers. PS-1, designated as Fsp2 and Genetic Type Collection number T364, is located between SSR markers Satt170 and Satt363 on MLG-C2 and linked by 13.9 cM and 12.1 cM, respectively. PS-2, designated as Fsp3 and Genetic Type Collection number T365H, is located between SSR markers Satt538 and Satt429 on MLG-A2 and linked by 13.3 cM and 25.4 cM, respectively. PS-3, designated as Fsp4 and Genetic Type Collection number T366H, is located on the terminus of MLG-F and linked to Sat 152 by 13.1 cM. PS-4, designated as Fsp5 and Genetic Type Collection number T367H, is located between SSR markers Satt324 and Satt138 on MLG-G and linked by 19.6 cM and 7.5 cM, respectively. SSR markers adjacent to Fsp3, Fsp4, and Fsp5 were distorted from a 1:2:1 ratio and fit a 1:1 ratio. The segregation distortions of SSR markers adjacent to Fsp3, Fsp4, and Fsp5 are in support of male, but not female transmission of the Fsp3, Fsp4, and Fsp5 gametes.This is a joint contribution of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 3769 and from the USDA, Agricultural Research Service, Corn Insects and Crop Genetics Research Unit, and supported by Hatch Act and State of Iowa. The mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by Iowa State University or the USDA, and the use of the name by Iowa State University or the USDA implies no approval of the product to the exclusion of others that may also be suitable.Communicated by J. Dvorak     

Molecular mapping of the genomic region conferring resistance to soybean stem canker in Hutcheson soybean

Genetic resistance to soybean stem canker, caused by the fungus Diaporthe phaseolorum var. meridionalis (Dpm), is controlled by five major, dominant, nonallelic genes Rdm1 to Rdm5. A genomic region containing the Rdm4 and Rdm5 genes was first described in Hutcheson soybean, where they were found to confer specific resistance to Argentinean physiological races of Dpm. Here, we report the genetic mapping of Rdm4 and Rdm5 loci using two pheno- and genotypically characterized F_2:3 populations derived from Hutcheson cultivar. The mapping populations were screened with amplified fragment length polymorphism (AFLP) markers using bulk segregant analysis, and with simple sequence repeat (SSR) markers. Linkage analysis indicated that the Rdm4 and Rdm5 resistance loci were located in a genomic region collinear with the molecular linkage group (MLG) A2 (chromosome 8) of the soybean genetic map. The linkage group contains two SSR markers, Sat_162 and Satt233, flanking the Rdm4 and Rdm5 loci. These SSR will be useful to increase the efficiency of selection in breeding programs aimed to incorporate Rdm4 and Rdm5 genes into soybean elite germplasm.