Inheritance of resistance and genetic relationships among soybean plant introductions to races of soybean cyst nematode

Summary The objectives of this study were to determine if genes for resistance to soybean cyst nematode (SCN) in soybean PI 437654 were identical or different from the genes in Peking, and PI 90763. The F₂ plants and F₃ families were studied from crosses between PI 437654, Peking, and PI 90763. The cross PI 437654 × susceptible Essex was included to determine inheritance of resistance to SCN. For Race 3, PI 437654 was found to have genes in common with Peking and PI 90763. The segregation in PI 437654 × Essex indicated the presence of one dominant and two recessive genes. For Race 5, PI 437654 indicated the presence of similar genes as those in PI 90763 and Peking whereas, PI 437654 × Essex indicated the action of the segregation ratios of two dominant and two recessive genes. For Race 14, the data from the cross PI 437654 × PI 90763 indicated monogenic inheritance with resistance being dominant; whereas PI 437654 × Peking showed a recessive gene controlling resistance. The segregation in PI 437654(R) × Essex(S) suggested one dominant and two recessive genes for Race 14 reaction.     

Identification and characterization of a RAPD/SCAR marker linked to a resistance gene for soybean mosaic virus in soybean

Soybean line `ICGR95-5383' [Glycinemax (L.) Merr.] is a newly releasedgermplasm from China and is resistant (R)to soybean mosaic virus (SMV). ICGR95-5383was crossed to the susceptible (S)cultivars `HB1', `Tiefeng21', `Amsoy', and`Williams' to investigate the inheritanceof SMV resistance. The F<sub>1</sub> and F<sub>2</sub>plants were inoculated with SMV-3 (the mostvirulent) strain from Northeast China. Theresults showed that F<sub>1</sub> plants from thefour R × S crosses were necrotic (N) andall F<sub>2</sub> populations segregated in a3(R+N):1S ratio, indicating thatICGR95-5383 carries a single gene withincomplete dominance for resistance to SMV. In a bulked segregant analysis (BSA) of theF<sub>2</sub>population from ICGR95-5383 × HB1, a codominant RAPD marker,OPN11<sub>980/1070</sub>, was found to be linkedto the resistance gene in ICGR95-5383. The980-base pair (bp) fragment OPN11<sub>980</sub>was amplified in the R parent ICGR95-5383,R bulk, and resistant F<sub>2</sub> plants. Theother 1070-bp fragment OPN11<sub>1070</sub> wasamplified in the S parent HB1, S bulk, andsusceptible F<sub>2</sub>plants.OPN11<sub>980/1070</sub> was amplified in theF<sub>1</sub> plants and the necroticF<sub>2</sub> plants from the R×S cross.Segregation analysis of the RAPD marker inthe F<sub>2</sub> population revealed that themarker OPN11<sub>980/1070</sub> is closely linkedto the resistance gene with a map distanceof 3.03 cM. OPN11<sub>980/1070</sub> was clonedand sequenced, and specific PCR primerswere designed to convertOPN11<sub>980/1070</sub> into sequencecharacterized amplified region (SCAR) makerSCN11<sub>980/1070</sub>. SCAR analysis of theF<sub>2</sub> population confirmed thatOPN11<sub>980/1070</sub> and SCN11<sub>980/1070</sub> areat the same locus linked to the SMVresistance gene. The RAPD markerOPN11<sub>980</sub> was used as RFLP probefor southern hybridization to soybeangenomic DNA. Southern analysis showed thatsoybean genome contains low-copy sequenceof OPN11<sub>980</sub>. Using a recombinant inbredmapping population of `Kefeng No.1' (R) ×Nannong1138-2'(S), OPN11_980/1070 was mapped to thesoybean molecular linkage group (MLG) Fbetween the restriction fragment lengthpolymorphism (RFLP) markers B212 (0.7 cM) and K07 (6.7 cM) and 3.03 cM apart from theSMV resistance gene.     

Resistance to soybean cyst nematode and molecular polymorphism in various sources of Peking soybean

Summary Cultivar Peking has been extensively used as a source of resistance to Race 3 and Race 5 of soybean cyst nematode, Heterodera glycines I., and Peking genes for resistance are present in a wide range of resistant soybean cultivars. Peking is also used as a host differential in the soybean cyst nematode race classification system. Thirteen Peking lines maintained in the USDA Soybean Germplasm Collection and in several breeding programs were surveyed using RFLP and RAPD markers for genetic characterization. Based on the molecular diversity combined with reaction to soybean cyst nematode, Peking genotypes from a common original source were identified. Peking lines PI 297543 (introduction from Hungary), and PI 438496A, PI 438496B and PI 438496C (introductions from Russia) represented unrelated germplasms. Identified molecular polymorphism can be used to validate the genetic purity of Peking lines used as host differentials for soybean cyst nematode classification system as well as utilization of an individual germplasm line in genetic-breeding programs.     

Employment of flanking codominant STS markers to estimate allelic substitution effects of a nematode resistance locus in carrot

In carrot, two codominant sequence-tagged site (STS) markers, flanking in tight linkage the Meloidogyne javanica resistance (Mj-1) locus, were employed to investigate the association between expression of resistance and locus dosage. Phenotypic expression of homozygous resistant (R); heterozygous; and homozygous susceptible (S) individuals in an F₂ population of 396 F₂ plants from ‘Brasília-1252’ (R) × ‘B6274’ (S) was estimated for three resistance criteria: total egg production per plant (TEP), egg production per gram of fibrous root (EPG) and root gall index (RGI). The homozygous resistant class had average values of 403.9 for TEP; 147.5 for EPG and 0.8 for RGI. The heterozygous class had 1,673; 477.3; and 0.16 whereas the homozygous susceptible class had 68,604; 11,877; and 2.54, respectively. The dominance ratio (d/a) indicated that genomic region(s) derived from the resistant parent encompass genetic factor(s) with almost complete dominance for RGI (d/a = 0.93–0.94) and incomplete dominance for transformed (TEP)^0.25 and (EPG)^0.25 (d/a = 0.63–0.65). Broad sense heritabilities were high varying from 72.9% for (EPG)^0.25 to 86.0% for RGI. Narrow sense heritability values ranged from 55.9% for RGI to 64.3%for (TEP)^0.25. Highly significant orthogonal contrasts were observed between homozygous resistant vs. heterozygous for (TEP)^0.25 and (EPG)^0.25. Marker-assisted selection could greatly facilitate the incorporation of the Mj-1 allele in both male-fertile and male-sterile counterpart lines in order to obtain F₁ hybrids with the most effective levels of resistance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic analysis of resistance to soybean cyst nematode in PI 438489B

Soybean (Glycine max L. Merr.) plant introduction PI 438489B is a unique source that has resistance to all known populations of soybean cyst nematode (Heterodera glycines Ichinohe, SCN). This PI line also has many desirable agronomic characteristics, which makes it an attractive source of SCN resistance for use in a soybean breeding program. However, characterization of SCN resistance genes in this PI line have not been fully researched. In this study, we investigated the inheritance of resistance to populations of SCN races 1, 2, 3, 5, and 14 in PI 438489B. PI 438489B was crossed to the susceptible cultivar ‘Hamilton’ to generate F₁ hybrids. The random F₂ plants and F₃ lines were evaluated in the greenhouse for reaction to these five populations of SCN races. Resistance to SCN races 1, 3, and 5 were mostly conditioned by three genes (Rhg Rhg rhg). Resistance to race 2 was controlled by four genes (Rhg rhg rgh rgh). Three recessive genes were most likely involved in giving resistance to race 14. We further concluded that resistance to different populations of SCN races may share some common genes or pleiotropic effects may be involved. This revised version was published online in July 2006 with corrections to the Cover Date.     

Incompletely dominant single resistance gene for peanut stripe virus in soybean line AGS 129

Summary Inheritance of resistance to a soybean isolate of peanut stripe virus (PStV-strain PN) was studied in three soybean varieties, AGS 129, Ankur, and PI 230971. Genetic analysis was based on necrotic, mosaic and symptomless reactions in inoculated soybeans. A single incompletely dominant gene in AGS 129 was found to confer the resistance to PStV and was tentatively designated as Pst. The homozygous parent AGS 129, possessing the genotype Pst Pst, was immune while Ankur and PI 230971, with a genotype of pst pst, were susceptible showing mosaic symptoms. The heterozygous genotype Pst pst resulting from the cross of either Ankur or PI 230971 with AGS 129 reacted with necrosis, distinctly different from either of the homozygous genotypes. This genotypic effect was confirmed through the phenotypic segregation in BC, F2, and F3.     

Breeding for resistance to cereal cyst nematode in wheat

Summary The progress of a backcross breeding programme to introduce resistance against the cereal cyst nematode into wheat is described. Methods of resistance screening and criteria for selection are detailed and the results discussed with reference to alternative procedures for the introduction of new resistance genes into major breeding programmes.     

Genetic and molecular characterization of resistance to Heterodera glycines race isolates 1, 3, and 5 in Peking

Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, has caused severe damage to soybean [Glycine max (L.) Merr.] worldwide since its discovery in 1954. ‘Peking’ is one of the most important sources in breeding SCN resistant soybean cultivars because it is resistant to Races 1, 3, and 5. Genetic information on SCN Races 1, 3, and 5 from Peking is essential to efficiently develop resistant soybean cultivars. Resistance to Race 3 in Peking was found to be controlled by three genes, but little is known on the inheritance of resistance to Races 1 and 5, and whether alleles conditioning resistance to Races 1 and 5 belong to the same linkage group and are allelic to genes giving resistance to Race 3. To determine the genetic bases of resistance to SCN Races 1, 3, and 5, Peking was crossed to the susceptible line ‘Essex’ to generate F₁ hybrids. The F₂ population and F _2:3 families were advanced from the F₁ and evaluated for resistance to SCN Race isolates 1, 3, and 5. Resistance to H. glycines Race isolates 1, 3, and 5 in Peking was found to be conditioned by three genes, one dominant and two recessive (Rhg, rhg, rhg). Peking may share similar sets of resistance loci between Races 1 and 3, but not between Races 3 and 5, or between Races 1 and 5. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inheritance of resistance in soybean PI 567516C to LY1 nematode population infecting cv. Hartwig

Worldwide, cyst nematode (SCN) Heterodera glycines is the most destructive pathogen on cultivated soybean (Glycine max (L.) Merr.). In the USA yield losses in 2001 were estimated to be nearly 60 million dollars. Crop losses are primarily reduced by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars overtime because resistance primarily traces to two soybean accessions. Recently cv. Hartwig was released which has comprehensive resistance to most SCN populations. A virulent nematode population LY1 was recently selected for its reproduction on Hartwig. LY1 population originated from a mass mating of Race 2 (HG Type 1.2.5-) females with Race 5 (HG Type 1.2-) males. LY1 nematode population infects currently known sources of resistance except PI 567516C. The female indices obtained on PI 567516C and Hartwig were 7% (resistant) and 155% (susceptible), respectively. However, the genetic basis of LY1 resistance in soybean PI 567516C is not known. Resistant PI line 567516C was crossed to susceptible cultivar Hartwig to generate 105 F_2:5 families. These families together with parents, seven indicator lines and a susceptible control cv. Lee-74 were evaluated for response to LY1 nematode population in the greenhouse. Chi-square analysis showed resistance in PI567516C to LY1 was conditioned by one dominant and two recessive genes (Rhg, rhg, rhg). Chi-square value was 0.15 and P = 0.70. This information will be useful to soybean researchers for developing resistant cultivars to nematode population that infects Hartwig.     

Characterization of resistance to Aphis glycines in soybean accessions

The soybean aphid, Aphis glycines Matsumura, is a pest of soybean [Glycine max L. (Merrill)] in Asia, and its recent establishment in North America has led to large, recurring outbreaks that have challenged pest management practitioners there to seek environmentally responsible means for its control. Growth-chamber experiments were conducted to determine and characterize host-plant resistance among several soybean accessions. Soybean plants were first screened for resistance by rating the population growth of A. glycines in two tests. All plants of PI 230977 and 25% of PI 71506 plants were resistant (≤100 aphids per plant) in the first screening test. All ‘Dowling’, PI 71506 and PI 230977 were resistant (≤150 aphids per plant), and 50% of plants of line ‘G93-9223’ were resistant in the second test. Follow-up experiments showed that antixenosis was a modality of resistance based on reduced nymphiposition by A. glycines on Dowling, PI 230977 and PI 71506 in no-choice tests and on fewer numbers of A. glycines on Dowling, PI 230977, PI 71506 and G93-5223 in distribution tests. Antixenosis in Dowling and PI 230977 was stronger in the unifoliolate leaves than in other shoot structures, whereas distribution of A. glycines within plants of PI 71506 and G93-5223 suggested comparable suitability between unifoliolate leaves and other shoot structures of these accessions. Antibiosis to A. glycines was evident as a lower proportion of aphids that reproduced on PI 230977 and from fewer progeny on PI 230977 and Dowling than on 91B91. The number of days from birth to reproduction by A. glycines did not differ among accessions. Results confirmed Dowling and PI 71506 as strong sources of resistance to A. glycines. The levels of antixenosis and antibiosis to A. glycines in PI 230977 and antixenosis to A. glycines in G93-9223 suggest that these accessions may also be valuable to soybean breeding programs as sources of resistance.     

Molecular markers linked to the Aegilops variabilis-derived root-knot nematode resistance gene Rkn-mn1 in wheat

Aegilops variabilis no. 1 is the only known source of resistance to the root‐knot nematode Meloidogyne naasi in wheat. Previous studies showed that a dominant gene, Rkn‐mn1, was transferred to a wheat translocation line from the donor Ae. variabilis. Random amplified polymorphic DNA (RAPD) analysis was performed on the wheat cultivar ‘Lutin’, on Ae. variabilis, on a resistant disomic addition line and on a resistant translocation line. For genetic and molecular studies, 114‐117 BC₃F₂ plants and F₃‐derived families were tested. Five DNA and one isozyme marker were linked to Rkn‐mn1. Three RAPD markers flanking the Rkn‐mn1 locus were mapped at 0 cM (OpY16_‐1065), 0.8 cM (OpB12_‐1320) and 1.7 cM (OpN20_‐1235), respectively. Since the Rkn‐mn1 gene remained effective, its introduction into different wheat cultivars by marker‐assisted selection is suggested.     

RAPD markers linked to resistance to downy mildew disease in soybean

To determine and utilize RAPD markers linked to resistance to downymildew incited by Peronospora manshurica in soybean, a resistantcultivar `AGS129' was crossed to a susceptible cultivar `Nakhon Sawan 1'(NS1). F₂ and BC₁ populations were advanced from the F₁ and evaluatedfor resistance to the disease. ²-test demonstrated that the resistancewas controlled by a single dominant gene (Rpmx). Near-isogenic lines(NILs) and bulked segregant analysis (BSA) were used to identify RAPDmarkers linked to the gene. Six DNA bulks namely F₅(R), F₅(S),BC₆F₃(R), BC₆F₃(S), F₂(R) and F₂(S) were set up by pooling equalamount of DNA from 8 randomly selected plants of each disease responsetype. A total of 180 random sequence decamer oligonucleotide primerswere used for RAPD analysis. Primer OPH-02 (5 TCGGACGTGA 3 andOPP-10 (5 TCCCGCCTAC 3) generated OPH-02₁₂₅₀ and OPP-10₈₃₁fragments in donor parent and resistant bulks, but not in the recurrentparent and susceptible ones. Co-segregation analysis using 102 segregatingF₂ progenies confirmed that both markers were linked to the Rpmxgene controlling downy mildew disease resistance with a genetic distance of4.9 cm and 23.1 cm, respectively. Marker OPH-02₁₂₅₀ was presentin 13 of 16 resistant soybean cultivars and absent in susceptible cultivars,thus confirming a potential for MAS outside the mapping population.     

Mapping Co, a gene controlling the columnar phenotype of apple, with molecular markers

The columnar phenotype is a very valuable genetic resource for apple breeding because of its compact growth form determined by the dominant gene Co. Using bulked segregant analysis combined with several DNA molecular marker techniques to screen the F₁ progeny of Spur Fuji × Telamon (heterozygous for Co), 9 new DNA markers (6 RAPD, 1 AFLP and 2 SSRs) linked to the Co gene were identified. A total of 500 10-mer random primers, 56 pairs of selective AFLP primers and 8 SSR primer pairs were screened. One RAPD marker S1142₆₈₂, and the AFLP marker, E-ACT/M-CTA₃₄₆, were converted into SCAR markers designated SCAR₆₈₂ and SCAR₂₁₆, respectively. These markers will enable early selection in progenies where Co is difficult to identify. The Co gene was located between the SSR markers CH03d11 and COL on linkage group 10 of the apple genetic linkage map. Finally, a local genetic map of the region around the Co gene was constructed by linkage analysis of the nine new markers and three markers developed earlier.     

Evaluation of wild perennial Glycine species for resistance to soybean cyst nematode and soybean rust

The genetic base for soybean cultivars is narrow compared to most other crop species. Twenty-seven wild perennial Glycine species comprise the tertiary gene pool to soybean that may contain many genes of economic importance for soybean improvement. We evaluated 16 accessions of G. argyrea, G. clandestina, G. dolichocarpa, and G. tomentella for resistance to Heterodera glycines (HG), also known as the soybean cyst nematode, and to multiple isolates of Phakopsora pachyrhizi, the causal fungus of soybean rust. All 16 accessions were classified as resistant to H. glycines HG Type 2.5.7, based on number of cysts per root mass with plant introductions (PIs) 483227, 509501, 563892, and 573064 (all G. tomentella) void of any cysts indicating no reproduction by this pest. All 16 accessions had an immune reaction to one isolate of P. pachyrhizi. Regardless of isolate, no sporulating uredinia were observed on G. argyrea (PI 505151) and G. tomentella (PIs 483227, 509501, and 573064). These results demonstrate that some accessions within the perennial Glycine species harbour resistance to both H. glycines and P. pachyrhizi and would be good candidates for wide hybridization programs seeking to transfer potentially unique multiple resistance genes into soybean.     

Molecular mapping and detection of the yellow rust resistance gene Yr26 in wheat transferred from Triticum turgidum L. using microsatellite markers

Yellow rust (stripe rust), caused by Puccinia striiformis Westend f. sp. tritici, is one of the most devastating diseases of wheat throughout the world. Wheat-Haynaldia villosa 6AL.6VS translocation lines R43, R55, R64 and R77, derived from the cross of three species, carry resistance to both yellow rust and powdery mildew. An F₂ population was established by crossing R55 with the susceptible cultivar Yumai 18. The yellow rust resistance in R55 was controlled by a single dominant gene, which segregated independently of the powdery mildew resistance gene Pm21 located in the chromosome 6VS segment, indicating that the yellow rust resistance gene and Pm21 are unlikely to be carried by the same alien segment. This yellow rust resistance gene was considered to beYr26, originally thought to be also located in chromosome arm 6VS. Bulked Segregation Analysis and microsatellite primer screens of the population F₂ of Yumai 18 × R55 identified three chromosome 1B microsatellite locus markers, Xgwm11, Xgwm18 and Xgwm413, closely linked to Yr26. Yr26 was placed 1.9 cM distal of Xgwm11/Xgwml8, which in turn were 3.2 cM from Xgwm413. The respective LOD values were 21 and 36.5. Therefore, Yr26 was located in the short arm of chromosome 1B. The origin and distribution of Yr26 was investigated by pedigree, inheritance of resistance and molecular marker analysis. The results indicated that Yr26 came from Triticum turgidum L. Three other 6AL.6VS translocation lines, R43, R64 and R77, also carried Yr26. These PCR-based microsatellite markers were shown to be very effective for the detection of the Yr26 gene in segregating populations and therefore can be applied in wheat breeding. This revised version was published online in July 2006 with corrections to the Cover Date.     

Breeding for resistance to cereal cyst nematode in wheat II. Use of test tube cultures in selection

Summary The use of soil. naturally infested with Heterodera avenae, to select resistant heterozygotes in backcross progenies of wheat, was tested for reliability. Selfed progenies from plants selected as resistant were cultured monoxenically in test tubes with nematodes hatched from single cysts, while backcross progenies from the same parent plants were grown in pots of naturally infested soil. Cyst counts were made after two months' growth. The results showed that over 50% of the backcross lines, screened in previous generations with naturally infested soil, had been erroneously selected as resistant. The test tube cultures clearly differentiated lines carrying resistance from those which were susceptible and corroborated results from pot tests.     

RAPD markers linked to a rust resistance gene in cultivated groundnut (Arachis hypogaea L.)

Groundnut rust (Puccinia arachidis Speg.) is an important air borne pathogen, which causes substantial losses in groundnut yield and quality. Although large numbers of accessions were identified as rust resistant in wild, interspecific derivative and cultivated groundnut species, transfer of resistance to well-adapted cultivars is limited due to linkage drag, which worsens yield potential and market acceptance. A F₂ mapping population comprising 117 individuals was developed from a cross between the rust resistant parent VG 9514 and rust susceptible parent TAG 24. Rust resistance was governed by single dominant gene in this cross. We identified 11 (out of 160) RAPD primers that exhibited polymorphism between these two parents. Using a modified bulk segregant analysis, primer J7 (5′CCTCTCGACA3′) produced a single coupling phase marker (J7₁₃₅₀) and a repulsion phase marker (J7₁₃₀₀) linked to rust resistance. Screening of the entire F₂ population using primer J7 revealed that the coupling phase marker J7₁₃₅₀ was linked with the rust resistance gene at a distance of 18.5 cM. On the other hand, the repulsion phase marker J7₁₃₀₀ was completely linked with rust resistance. Additionally, both J7₁₃₀₀ (P = 0.00075) and J7₁₃₅₀ (P < 0.00001) were significantly associated with the rust resistance. Marker J7₁₃₀₀ identified all homozygous rust resistant genotypes in the F₂ population and was present in all the eight susceptible genotypes tested for validation. Thus, J7₁₃₀₀ should be applicable for marker-assisted selection (MAS) in the groundnut rust resistance breeding programme in India. To the best of our knowledge this is the first report on the identification of RAPD markers linked to rust resistance in groundnut.     

Development of AFLP and derived CAPS markers for root-knot nematode resistance in cotton

Resistance to root-knot nematode (Meloidogyne incognita) is determined by a single major gene rkn1 in Gossypium hirsutum Acala NemX cotton. Bulked segregant analysis (BSA) combined with amplified fragment length polymorphism (AFLP) was used to identify molecular markers linked to rkn1. DNA pools from homozygous susceptible (S) and resistant (R) bulks of an F_2:3 originating from the intraspecific cross NemX × SJ-2 were screened with 128 EcoR1/Mse1 primer combinations. Putative AFLP markers were then screened with 60 F_2:7 RIL plants and four AFLP markers were found linked to rkn1. The linkage of AFLP markers to rkn1 was also confirmed in a F₂ population. The closest AFLP marker was converted to a cleaved amplified polymorphic sequence (CAPS) marker (designated GHACC1) by aligning the sequences from both susceptible and resistant parents. GHACC1 linkage to rkn1 was confirmed in the F₂ (1R:3S), F_2:7 RIL (1R:1S) and the backcross population SJ-2 × F₁ (NemX × SJ-2) (1 heterozygous: 1 homozygous). The four AFLP markers, GHACC1 plus two SSR markers (CIR316 and BNL1231) linked to rkn1 from previous work were mapped to intervals of 2.6–14.2 cM from the rkn1 locus, and the genomic region around rkn1 was spanned to about 28.2 cM in the F_2:7 population. The PCR-based GHACC1 and CIR316 markers were tested on 21 nematode resistant and susceptible cotton breeding lines and cultivars. GHACC1 was suitable for nematode resistance screening within G.␣hirsutum, but not G. barbadense, whereas CIR316 was useful in both species, indicating their␣potential for utilization in marker-assisted selection.     

Inheritance of angular leaf spot resistance in common bean line BAT 332 and identification of RAPD markers linked to the resistance gene

The existence of genetic variability for angular leaf spot (ALS) resistance in the common bean germplasm allows the development of breeding lines resistant to this disease. The BAT 332 line is an important resistance source to common bean ALS. In this work we determined the inheritance pattern and identified RAPD markers linked to a resistance gene present in BAT 332. Populations F₁, F₂,BCs and BCr derived from crosses between BAT 332 and cultivar Rudá were used. Rudá is a commercial cultivar with carioca type grains and susceptible to ALS. The resistance of BAT 332 to race 61.41 of the pathogen was confirmed. Segregation analysis of the plants indicated that a single dominant gene confers resistance. For identification of RAPD markers linked to the resistance gene, bulk segregant analysis (BSA) was used. Two RAPD markers,OPAA07₉₅₀ and OPAO12₉₅₀, linked in coupling phase at 5.10 and 5.83 cM of this gene, respectively, were identified. These molecular markers are important for common bean breeders and geneticists as source of genetic information and for marker assisted selection in breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.