Genetic mapping of quantitative trait loci in rye (Secale cereale L.)

Using the marker information of 275 F₂ plants quantitative traits determining morphological and yield characters were studied analyzing F₃progenies grown in four different experiments at three sites. The map constructed contains 113 markers including the major dwarfing gene Ddw1 with an average distance of about 10 cM between adjacent markers. Of the 21 QTLs detected ten were found to map on chromosome 5RL in the region of Ddw1. Beside the expected effects on plant height and peduncle length that are most probably due to the presence of the major dwarfing gene, additional effects on yield characters and flowering time were discovered in that region which may be caused by pleiotropic effects of Ddw1. An additional supposed gene cluster consisting of four QTLs controlling flowering time and yield components was discovered in the centromere region of chromosome 2R. Further loci are distributed on chromosomes 1R (1), 4R (1) 6R (3) and 7R (1). The map positions of the quantitative trait loci detected in rye are discussed in relation to major genes or QTLs determining agronomically important traits in other cereals. This revised version was published online in July 2006 with corrections to the Cover Date.     

Intrachromosomal mapping of genes for dwarfing (Rht12) and vernalization response (Vrn1) in wheat by using RFLP and microsatellite markers

For intrachromosomal mapping of the dominant GA-sensitive dwarfing gene Rht12 and the vernalization response gene Vrn1 on chromosome 5 A, an F₂ population was established using a wide (synthetic) wheat cross. In addition to restriction fragment length polymorphism (RFLP) probes four microsatellite markers were incorporated. Rht12 was mapped distally to four RFLP loci (Xmwg616, Xpsr164, Xwg114, Xpsr1201) and three microsatellite markers (Xgwm179, Xgwm410, Xgwm291), known to be located on the segment of chromosome SAL which was ancestrally translocated and is homoeologous to Triticeae 4 L. The map position of Rht12 suggests that it is homoeologous to the dominant GA-sensitive dwarfing gene Ddw1, present on chromosome 5RL. The vernalization response gene Vrn1 showed linkage to Xwg644, as might be expected from comparative maps.     

Localization of Genes in Rye that Restore Male Fertility to Hexaploid Wheat with timopheevi Cytoplasm

Four sets of wheat-rye addition lines were screened to localize genes in rye that restore male fertility to hexaploid wheat with timopheevi cytoplasm. One gene, designated Rfc3, was physically located in the distal 40 % of the long arm of chromosome 6R. No allelic variation at Rfc3 was found; normal male fertility was consistently observed in all F₁ hybrid combinations tested. A second gene, designated Rfc4, was located on the long arm of chromosome 4R. Variation between chromosomes 4R in the level of restoration was observed; fertility in hybrids ranged from 0 % to about 50 % of normal. Attempts to genetically map Rfc4 were inconclusive but suggested it was located 16.1 cM from the telomere of the long arm and at least 8.0 cM from the centromere. These restorers, particularly Rfc3, may have potential in hybrid wheat breeding programs and can be manipulated for production of male sterile triticale lines.     

Mapping of the Vrn-B1 gene in Triticum aestivum using microsatellite markers

An F₂ population segregating for the dominant gene Vrn‐B1 was developed from the cross of the substitution line ‘Diamant/'Miro‐novskaya 808 5A’ and the winter wheat cultivar ‘Bezostaya 1′. Microsatellite markers (Xgwm and Xbarc) with known map locations on chromosome 5B of common wheat were used for mapping the gene Vrn‐B1. Polymorphism between parental varieties was observed for 28 out of 34 microsatellite markers (82%). Applying the quantitative trait loci mapping approach, the target gene was mapped on the long arm of chromosome 5B, closely linked to Xgwm408. The map position of Vrn‐B1 suggests that the gene is homoeologous to other vernalization response genes located on the homoeologous group 5 chromosomes of wheat, rye and barley.     

Telosomic mapping of the homoeologous genes for the long glume phenotype in tetraploid wheat

Triticum turgidum ssp. polonicum and T. ispahanicum were characterized by the long glume phenotype. P ₁ gene determines the long glume phenotype of T. polonicum, and locates on chromosome 7A. T. ispahanicum has shorter glume than T. polonicum and the long glumephenotype is determined by P ₂ gene located on chromosome 7B. In the present study, aneuploid stocks of `Langdon' durum wheat were used to map the genes, P ₁ and P ₂. P ₁ located on the long arms of chromosome 7A and its map distances from the centromere was 14.5 cM. On chromosome 7B, four loci located as cc (chocolate black chaff) – Pc (purple culm) – centromere – P ₂ – cn-BI (chlorina). P ₂ located on the long arms of chromosome 7B and its map distances from the centromere was 11.7 cM. It was suggested that a paralogous gene set conditions long glume phenotype in the homoeologous group 7 chromosomes. The P ₁ and P ₂ genes may be useful as genetic markers in tetraploid wheat.     

Mapping genes controlling anthocyanin pigmentation on the glume and pericarp in tetraploid wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> L.)

A novel gene, designated Pg (purple glume), controlling anthocyanin pigmentation of the glume was identified and mapped in an F₂ population from the durum wheat (Triticum durum) cross TRI 15744/TRI 2719. This gene was close to one of the two complementary dominant genes, controlling anthocyanin pigmentation of the pericarp (gene Pp3) in the centromere region of chromosome 2A; the other Pp gene (Pp1) was mapped on the short arm of chromosome 7B, near gene Pc controlling anthocyanin pigmentation of the culm and co-segregating with Pls (purple leaf sheath) and Plb (purple leaf blade). On the basis of the mapping results, the Pp3, Pc, Pls and Plb genes of T. durum were regarded as allelic to the T. aestivum Pp3, Pc-B1, Pls-B1 and Plb-B1 loci. The likely allelism of Pp1 in T. durum and T. aestivum remains in dispute, the present durum Pp gene mapped to the short arm of chromosome 7B, whereas in common wheat it was reportedly located on the long arm.     

Embryo lethality in wheat × rye hybrids—mode of inheritance and the identification of a complementary gene in wheat

Crosses between hexaploid wheat and rye can only succeed when pre- and post-zygotic barriers have been overcome. A rye gene determining embryo lethality (Eml-R1), which is involved in post-zygotic isolation, has been mapped to chromosome 6R. In the present paper the mode of inheritance of Eml-R1 was studied by employing a wheat/rye chromosome 6R addition line. We show that Eml-R1 exists in at least two alternative forms, with the mutant allele Eml-R1b being dominant with respect to wild-type Eml-R1a. Furthermore, we have exploited nulli-tetrasomic lines of wheat to detect a complementary wheat gene present on chromosome 6A. This gene has been designated Eml-A1.     

Clustering of amplified fragment length polymorphism markers in a linkage map of rye

Amplified fragment length polymorphisms (AFLPs) are now widely used in DNA fingerprinting and genetic diversity studies, the construction of dense genetic maps and in fine mapping of agronomically important traits. The AFLP markers have been chosen as a source to extend and saturate a linkage map of rye, which has previously been generated by means of restriction fragment length polymorphism, random amplified polymorphic DNA, simple sequence repeat and isozyme markers. Gaps between linkage groups, which were known to be part of chromosome 2R, have been closed, thus allowing the determination of their correct order. Eighteen EcoRI‐MseI primer combinations were screened for polymorphism and yielded 148 polymorphic bands out of a total of 1180. The level of polymorphism among the different primer combinations varied from 5.7% to 33.3%. Eight primer combinations, which revealed most polymorphisms, were further analysed in all individuals of the F₂ mapping population. Seventy‐one out of 80 polymorphic loci could be integrated into the linkage map, thereby increasing the total number of markers to 182. However, 46% of the mapped AFLP markers constituted four major clusters located on chromosomes 2R, 5R and 7R, predominantly in proximity to the centromere. The integration of AFLP markers caused an increase of 215 cM, which resulted in a total map length of almost 1100 cM.     

Genetical Studies of Gibberellic Acid Insensitivity in Rye (Secale cereale L.)

Genetic analysis of three semi-dwarf genotypes of rye (Secale cereale L.)—‘Moskowskij Karlik’, ‘Gülzow kurz’ and ‘R 18’, which were shown to be insensitive to applied gibberellic acid (GA₃), has been carried out by using a seedling test. It could be demonstrated that all of the three genotypes are carrying recessive alleles for GA-insensitivity. Whereas the alleles of ‘Moskowskij Karlik’ and ‘R 18’ seem to have the same locus on chromosome 5R, the GA-insensitivity of ‘Gülzow kurz’ is governed by a different gene, most probably located on chromosome 7R. The relationship between the genes (alleles) for GA-insensitivity and semi-dwarfness, including the symbolization of the Gai-genes as well as their utilization in rye breeding is discussed.     

水稻半矮秆基因iga-1的鉴定及精细定位

在前期通过空间诱变获得半矮秆隐性突变基因iga-1的基础上,进一步对iga-1进行鉴定。农艺性状调查表明携带iga-1的矮秆株系CHA-2、CHA-2N与原种特籼占13相比存在明显变异。节间长度测量显示CHA-2、CHA-2N节间比例正常,属dn型。外源GA₃处理、内源GA₃测定和α-淀粉酶活性检测揭示iga-1与GA₃调控无关。利用CHA-2与粳稻品种02428杂交获得的F₂群体将iga-1定位在水稻第5染色体两个InDel标记DL18和DL19间32.01 kb的物理距离内。该区域有5个阅读框架,其中包括赤霉素信号传导调控基因D1。序列分析表明CHA-2、CHA-2N和特籼占13在D1位点上基因组序列不存在差异,推测D1并非iga-1的候选基因。比较水稻第5染色体上其他矮秆基因发现iga-1可能与半矮秆基因sd-7来自同一位点。     

Genetic control of esterase-6 isozymes in hexaploid wheat and rye

Summary The EST-6 leaf esterase phenotypes from euploid, nullisomic-tetrasomic and rye chromosome addition and substitution lines of common wheat were determined using polyacrylamide gel electrophoresis. Evidence is presented to demonstrate that Est-6 is a new set of genes, that are expressed in the leaf. The Est-6 gene set were clearly distinguished from the Est-5 genes which are expressed in the grain. The three homoeoallelic loci, Est-A6, Est-B6 and Est-D6, were located on chromosomes 3A, 3B and 3D. An Est-R6 gene was located on chromosome 6R is involved in rye. Some considerations concerning homoeology between homoeologous group 3 of wheat and the rye chromosome 6R are made.     

Dosage Response of Rye Genes in a Wheat Background

Wheat (Triticum aestivum L.) breeders often utilize alien sources to supply new genetic variation to their breeding programs. However, the alien gene complexes have not always behaved as desired when placed into a wheat background. The introgressed genes of interest may be linked to undesirable genes, expressed at low levels or not at all. The short arm of rye (Secale cereale L.) chromosome one (1RS) contains many valuable genes for wheat improvement. In order to study rye gene response to varying copy number, wheat lines were constructed which contained zero, two or four doses of 1RS. The meiotic behavior of rye chromosome 1R, and wheat/rye translocation chromosomes, 1AL/1RS and 1BL/1RS was studied in the F₁ hybrids between wheat lines carrying 1R or the translocation chromosomes. The IRS arm was transmitted at a very high frequency; 98 % of the F₂ plants had at least one of the chromosomes with a IRS arm. In addition, 44 % of the F₂ plants received at least one copy of the chromosomes from each parent. Analysis of the meiotic behavior of the IRS arm suggested that few euploid wheat gametes were formed. Therefore, most of the pollen must have contained IRS. It is unknown whether the lack of euploid wheat pollen could account for the high transmission frequency of the rye chromosomes. There may have been differential survival of the embryos receiving the rye chromosome as well.     

Using a wheat-rye amphihaploid population to map a rye gene responsible for dwarfness

Gene identification in cross-pollinating plants such as rye can be arduous and time consuming because of the difficulties involved with genetic population construction. Here, we provide an alternative approach for the construction of mapping populations to rapidly map genes in cross-pollinated cereal rye. The aim of the present experiments was to genetically analyze the dwarf stature expressed by a germplasm accession of rye. The dwarf phenotype was reversible when the seedlings were exposed to gibberellic acid; the reductions in plant height occurred via reductions in cell size. A mapping population was constructed by generating a set of wheat-rye amphihaploids bred from a single rye plant heterozygous for the dwarfing gene(s). The dwarfness phenotype was expressed in the amphihaploid background, and segregation in the mapping population was consistent with the presence of a single gene. Using rye SSR markers, the gene responsible was located on chromosome arm 1RL, which is also the location of the known rye dwarfing gene Ddw3. This gene is valuable for dwarf breeding of wheat as well as rye.     

Genetic analysis of ion-beam induced extremely late heading mutants in rice

Two extremely late heading mutants were induced by ion beam irradiation in rice cultivar ‘Taichung 65’: KGM26 and KGM27. The F₂ populations from the cross between the two mutants and Taichung 65 showed clear 3 early: 1 late segregation, suggesting control of late heading by a recessive gene. The genes identified in KGM26 and KGM27 were respectively designated as FLT1 and FLT2. The two genes were mapped using the crosses between the two mutants and an Indica cultivar ‘Kasalath’. FLT1 was located on the distal end of the short arm of chromosome 8. FLT2 was located around the centromere of chromosome 9. FLT1 might share the same locus as EHD3 because their chromosomal location is overlapping. FLT2 is inferred to be a new gene because no gene with a comparable effect to that of this gene was mapped near the centromere of chromosome 9. In crosses with Kasalath, homozygotes of late heading mutant genes showed a large variation of days to heading, suggesting that other genes affected late heading mutant genes.     

小麦EST-SSR标记的开发和染色体定位及其在追踪黑麦染色体中的应用

根据小麦盐胁迫诱导和茎秆组织相关EST序列开发了81对EST-SSR引物, 其中67、46、18和61对分别在小麦、黑麦、簇毛麦和大麦基因组中稳定扩增, 在不同小麦和大麦品种间具有多态性的引物分别有22和23对。利用小麦缺体-四体系共定位了43对引物的81个位点, 其中A、B和D染色体组上分别有29、30和22个位点, 涉及除4B、3D和6D外的18条染色体。此外30对引物在黑麦基因组中具有特异扩增, 其中8对分别在黑麦1R、4R、5R和R7染色体上具有特异扩增, 7对在多条黑麦染色体具有相同扩增。这些新标记可有效用于小麦及其近缘物种的遗传作图与比较遗传研究。     

Mapping of rhizoctonia root rot resistance genes in sugar beet using pathogen response‐related sequences as molecular markers

Rhizoctonia root and crown rot caused by the fungus Rhizoctonia solani is a serious disease of sugar beet. An F_2:3 population from a cross between a resistant and a susceptible parent has been tested for R. solani resistance and a genetic map has been constructed from the corresponding F₂ parents. The map encompasses 38 expressed sequence tags (ESTs) with high similarity to genes which are involved in resistance reactions of plants (R‐ESTs) and 25 bacterial artificial chromosomes (BACs) containing nucleotide binding site (NBS)‐motifs typical for disease resistance genes. Three quantitative trait loci (QTL) for R. solani resistance were found on chromosomes 4, 5 and 7 collectively explaining 71% of the total phenotypic variation. A number of R‐ESTs were mapped in close distance to the R. solani resistance QTL. In contrast, the NBS‐BACs mapped to chromosomes 1, 3, 7 and 9 with two major clusters of NBS‐BACs on chromosome 3. No linkage between NBS‐BACs and R. solani resistance QTL was found. The data are discussed with regard to using R‐ESTs and NBS markers for mapping quantitative disease resistances.     

A novel barley scald resistance gene: genetic mapping of the Rrs15 scald resistance gene derived from wild barley, Hordeum vulgare ssp. spontaneum

Most genes for resistance to barley leaf scald map either to the Rrs1 locus on the long arm of chromosome 3H, or the Rrs2 locus on the short arm of chromosome 7H. Other loci containing scald resistance genes have previously been identified using lines derived from wild barley, Hordeum vulgare ssp. spontaneum. A single dominant gene conditioning resistance to scald was identified in a third backcross (BC3F3) line derived from an Israeli accession of wild barley. The resistance gene is linked to three microsatellite markers that map to the long arm of chromosome 7H; the closest of these loci, HVM49, maps 11.5 cM from the resistance gene. As no other scald resistance genes have been mapped to this chromosome arm, it is considered to be a novel scald resistance locus. As the Acp2 isozyme locus is linked to this scald resistance locus, at 17.7 cM, Acp2 is assigned to chromosome 7H. Molecular markers linked to the novel scald resistance gene, designated Rrs15, can be used in breeding for scald resistance.     

A polymorphic microsatellite in the 3'end of 'waxy' genes of wheat, Triticum aestivum

Potential polymorphism of an (AT)_N microsatellite at the 3’end of waxy genes in bread wheat was examined. Primers were designed from a published cDNA sequence of a wheat waxy gene. Polymerase chain reaction (PCR) amplification of genomic DNA from 135 mainly Australian cultivars revealed eight alleles on chromosome 7A. This polymorphic microsatellite is a potential codominant marker for the Wx-A1 locus in breeding programmes. A distinguishable fragment was also amplified from chromosome 7D. This fragment was absent where a plant was null for the waxy gene on chromosome 7D, being a dominant marker for the Wx-D1 locus. The primers were also useful for amplifying genomic DNA from barley, rye and triticale and can be used to detect potential polymorphism in these species.     

Comparative molecular marker-based genetic mapping of flavanone 3-hydroxylase genes in wheat,rye and barley

The F3 h gene encoding flavanone 3-hydroxylase, one of the key enzymes of the flavonoid biosynthesis pathway, is involved in plant defense response, however, it has not yet been genetically mapped in such important crop species as wheat, barley and rye. In the current study, the F3 h genes were for the first time genetically mapped in these species, using microsatellite and RFLP markers. The three wheat F3 h homoeologous copies F3 h-A1, F3 h-B1 and F3 h-D1, and rye F3 h-R1 were mapped close to the microsatellite loci Xgwm0877 and Xgwm1067 on chromosomes 2AL, 2BL, 2DL, and 2RL, respectively. Wheat F3 h-G1 and barley F3 h-H1 were also mapped at the homoeologous F3 h-1 position on chromosomes 2GL and 2HL, respectively. The non-homoeologous F3 h gene (F3 h-B2) was mapped on wheat chromosome 2BL about 40 cM distal to the F3 h-1 map position. The results obtained in the current study are important for further studies aimed on manipulation with F3 h expression (and, hence, plant defense) in wheat, barley and rye.     

Transfer of new dwarfing genes from the weed species Avena fatua into cultivated oat A. byzantina

New sources of dwarfing genes were identified from accessions of Avena fatua in Japan and Korea. The dwarfing genes were transferred from backcrossed and self‐pollinated relatives to the cultivated oat ‘Kanota’. In the cultivated form, the dominant dwarfing gene Dw8 showed a relatively lower transmission rate than recessive, semi‐dominant and nondwarfing genes and was characterized by a distinct link with wild gene cluster. This was also supported by the high transmission rate of wild specific SSR alleles. Four dwarf inbred lines (L153, L169a, L169b and L812) were identified as involving a single recessive dwarfing gene(s). The recessive dwarfing genes that showed normal and stable transmission rates in BC₁F₃ were first reported in hexaploid oats. The L169 segregated two different recessive dwarf lines in BC₁, which were selected as semi‐ (L169a) and extreme‐ (L169b) dwarf lines. The L169a was a good genotype with a high grain yield. L288 is a semi‐dwarf line conditioned by a semi‐dominant dwarfing gene, with a unilateral panicle, large florets and good grain quality due to strong resistance to lodging. L342 had a short peduncle, making the panicle compact, and its phenotype was similar to the dwarfness controlled by Dw7, but the dwarfing genes were different.