Mapping seed storage protein loci Sec-1 and Sec-3 in relation to five chromosomal rearrangements in rye (Secale cereale L.)

Summary Linkage relationships were established between the secalin loci, Sec 1 (40-K gamma and omega secalins, homologous to the wheat gliadins) and Sec 3 (HMW = high-molecular-weight secalins, homologous to the wheat HMW glutenin subunits), and five chromosomal rearrangements involving chromosome 1R of rye (Secale cereale L.). These were: interchanges T273W (1RL/5RS), T306W (1RS/5RL), and T850W (1RS/ 4RL), Robertsonian centromere split Rb1RW and the interchanged Robertsonian split Rb2R/248W. The analysis established the linkage relationships between the secalin loci and the breakpoints of the rearrangements, in addition to the quantitative effects of the rearrangements on the linkage. Sec-1 is located in the satellite at a position at least 2.5 cMorgan from the proximal border of the terminal C-band, and about 30 cMorgan from the nucleolar organizing region (NOR). The locus is also physically closer to the terminal C-band than to the NOR, but not as much as corresponds with the map distances. Similarly, the physical distance between Sec-3 and the centromere is greater than corresponds with the recombination frequency (0%–9%). Although overall recombination in 1RL remains the same, recombination between the centromere and Sec-3 is greatly reduced in the Robertsonian split combined with the interchange. This is not the case with the single Robertsonian split.     

Mapping the nucleolus organizer region,seed protein loci and isozyme loci on chromosome 1R in rye

Summary The nucleolus organizer region located on the short arm of chromosome 1R of rye consists of a large cluster of genes that code for ribosomal RNA (designated the Nor-R1 locus). The genes in the cluster are separated by spacer regions which can vary in length in different rye lines. Differences in the spacer regions were scored in two families of F₂ progeny. Segregation also occurred, in one or both of the families, at two seed protein loci and at two isozyme loci also located on chromosome 1R. The seed protein loci were identified as the Sec 1 locus controlling -secalins located on the short arm of chromosome 1R and the Sec 3 locus controlling high-molecular-weight secalins located on the long arm of 1R. The two isozyme loci were the Gpi-R1 locus controlling glucose-phosphate isomerase isozymes and the Pgd 2 locus controlling phosphogluconate dehydrogenase isozymes. The data indicated linkage between all five loci and map distances were calculated. The results indicate a gene order: Pgd 2 ... Sec 3 ... [centromere] ... Nor-R1 ... Gpi-R1 ... Sec 1. Evidence was obtained that rye possesses a minor 5S RNA locus (chromosome location unknown) in addition to the major 5S RNA locus previously shown to be located on the short arm of chromosome 1R.     

Identification and mapping of the Gli-R3 locus on chromosome 1R of rye (Secale cereale L.)

Summary The progenies of two different rye test-crosses were analyzed for secalin proteins by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) using unreduced and reduced aqueous ethanol extracts. Segregation for two high-molecular-weight secalin bands (Glu-R1 or Sec3), one -secalin band (Gli-R1 or Sec-1), two 40K -secalin bands (Gli-R1 or Sec1) and two -type secalin bands (new locus) were studied. One recombinant between - and -secalins was found in one test-cross. The new locus, designated Gli-R3 or Sec-4, was mapped between Glu-R1 and Gli-R1, more displaced towards Gli-R1. In test-cross 1 recombination between Glu-R1 and Gli-R3 was 33.80±3.22%, and between Gli-R3 and Gli-R1, 12.04±2.21%. In the other test-cross the map distances were relatively similar but smaller, likely due to less recombination within two different species of Secale. Genes coding for 40K -secalins at Gli-R1 were likely proximal to the centromere with respect to genes coding for -secalins at the same complex locus.     

Genetic linkage between cytological markers and the seed storage protein lociSec2[Gli-R2] andSec3[Glu-R1] in rye

In order to reach a higher accuracy concerning the cytological locations of the rye seed storage protein lociSec2[Gli-R2] andSec3[Glu-R1] located within chromosome arms 2RS and 1RL, respectively, the linkage relationships between the following loci were analyzed: isozyme lociGpi-R1,Mdh-R1, andPgd2, translocationT273W (Wageningen tester set, involving chromosome arms 1RS and 5RL), the telomere C-bands of chromosome arms 1RL (tL1), 2RS (tS2), and 5RS (tS5), and three interstitial C-bands in chromosome arm 1RS (iS1), in the middle of chromosome arm 1RL (iL1), and in the middle of chromosome arm 2RL (iL2), respectively. The data indicated that locusSec3 is located in the distal half of chromosome arm 1RL (between C-bandiL1 and locusPgd2), while locusSec2 is located a short distance (2.9 ± 1.4%) from the telomere C-band of chromosome arm 2RS.     

分子标记在烟草性状连锁基因定位中的应用进展简

简要综述了分子标记在烟草性状连锁基因定位中的应用进展,包括烟草化学、普通农艺和抗病性等性状,讨论了其存在的问题及应用前景,以期为分子标记应用于烟草性状连锁基因定位和特色优质烟叶育种分子标记辅助选择研究的进一步发展提供借鉴。     

Differential expression of two β-amylase genes of rye during seed development

The expression of two β-amylase loci was analysed in the developing seeds of two inbred lines of rye (Secale cereale L.), one of which was a β-amylase deficient mutant. Enzymatic activity and the contents of enzymatic protein and mRNA specific for each of an endosperm-characteristic and ubiquitous β-amylase were determined throughout the course of caryopsis development. Both loci were expressed in the developing normal line caryopses according to different temporal and quantitative patterns. The ubiquitous enzyme-specific locus β-Amy 2 was expressed earlier; both mRNA and enzymatic protein accumulated to a maximum extent at 10 to 15 days after pollination. In contrast, the highest content of mRNA for endosperm β-amylase (encoded by the β-Amy I locus) was found 20 days after pollination, and the corresponding enzymatic protein accumulated throughout seed development. The expression of the β-Amy I locus was 30- to 40-fold higher than that of the β-Amy 2 locus in terms of maximum specific mRNA accumulation. The expression product of only the β-Amy 2 locus was found in the developing mutant line caryopses. The expression pattern of this locus was similar in the developing normal and mutant line seeds in terms of the temporal accumulation of mRNA and enzymatic protein. However, an approximately 4-fold higher level of ubiquitous β-amylase-specific mRNA was found in the mutant than in the normal line caryopses, and the content of ubiquitous β-amylase protein decreased to near zero at seed maturity in the mutant line, but not in the normal line, caryopses. The enzymatic activities of both β-amylases appeared to be regulated at the level of accumulated enzymatic protein.     

Mapping of three self-fertility mutations in rye (Secale cereale L.) using RFLP, isozyme and morphological markers

 Three mutations determining self-fertility at the S, Z and S5 self-incompatibility loci on chromosomes 1R, 2R and 5R of rye, respectively, were mapped using three different F₂ populations. There was a close linkage of one isozyme and four RFLP markers, and no recombinant plants were detected. These markers are Prx7, Xiag249 and Xpsr634 for the S locus (1R), Xbcd266 for the Z locus (2R) and Xpsr100 for the S5 locus (5R). Linkage data for markers associated to the self-fertility mutations at the S, Z and S5 loci were calculated and compared with genetic maps computed by MAPMAKER multipoint analysis. Received: 8 October 1997 / Acepted: 26 November 1997     

The Fusarium wilt resistance locus Fom-2 of melon contains a single resistance gene with complex features

The soil-borne fungus Fusarium oxysporum f.sp. melonis causes significant losses in the cultivated melon, a key member of the economically important family, the Cucurbitaceae. Here, we report the map-based cloning and characterization of the resistance gene Fom-2 that confers resistance to race 0 and 1 of this plant pathogen. Two recombination events, 75 kb apart, were found to bracket Fom-2 after screening approximately 1324 gametes with PCR-based markers. Sequence analysis of the Fom-2 interval revealed the presence of two candidate genes. One candidate gene showed significant similarity to previously characterized resistance genes. Sequence analysis of this gene revealed clear polymorphisms between resistant and susceptible materials and was therefore designated as Fom-2. Analysis of susceptible breeding lines (BL) presenting a haplotype very similar to the resistant cultivar MR-1 indicated that a gene conversion had occurred in Fom-2, resulting in a significant rearrangement of this gene. The second candidate gene which shared high similarity to an essential gene in Arabidopsis, presented an almost identical sequence in MR-1 and BL, further supporting Fom-2 identity. The gene conversion in Fom-2 produced a truncated R gene, revealing new insights into R gene evolution. Fom-2 was predicted to encode an NBS-LRR type R protein of the non-TIR subfamily. In contrast to most members of this class a coiled-coil structure was predicted within the LRR region rather than in the N-terminal. The Fom-2 physical region contained retroelement-like sequences and truncated genes, suggesting that this locus is complex.     

A linkage map of rye

A linkage map of rye (Secale cereale L.) is presented which comprises 60 loci including RFLPs, RAPDs, isozyme, morphological and physiological markers. The genetics and linkage relationships of these markers were investigated in several inbred lines of rye. For the RFLP mapping a genomic library of PstI-digested DNA was constructed from which 50 size-selected clones were analysed. The portion of single-copy and multi-copy DNA and the frequency of polymorphic DNA was determined. The markers are unequally distributed over the seven chromosomes of rye. Many of them exhibit a distorted segregation. The main region of deviating segregation ratios could be localized near the self-incompatibility loci.     

The inheritance of rye seed peroxidases

Summary Genetic analyses were conducted on peroxidase of the embryo and endosperm of seeds of one open pollinated and six inbred lines of cultivated rye (Secale cereale L.), and one line of Secale vavilovii Grossh. The analyses of the individual parts of the S. cereale seed yield a total of 14 peroxidase isozymes. Isozymes m, a, b, c, d, e, f and g (in order from faster to slower migration) were found in the embryo plus scutellum, while isozymes 1, 2, 3, 4, 5 and 6 (also from faster to slower migration) were peculiar of the endosperm. S. vavilovii has isozymes m, c₁, d, e, f and g in its embryo plus scutellum, and isozyme 2 in the endosperm. Segregation data indicated that at least 13 different loci would be controlling the peroxidase of S. cereale. Isozymes a and b are controlled by alleles of the same locus, all the other loci have one active and dominant allele coding for one isozyme, and other null and recessive allele. The estimation of linkage relationships shows that five endosperm loci are linked, and tentative maps are shown. A possible dosage effect and the existence of controlling gene(s) for endosperm isozyme 4 is reported. All these data and the high frequency of null alleles found are discussed in relation to recent reports.     

Linkage and cytogenetic maps of genes controlling endosperm storage proteins and isozymes in rye (Secale cereale L.)

Summary An F₁ plant fromSecale cereale ssp.ancestrale xtelocentric substitution lines3R of the cultivated rye Petkus spring was used as female in a cross with the inbred line Riodeva (I28), which has the standard chromosome arrangement. Single plants from this backcross progeny were analyzed for chromosome constitution, storage protein, and isozymic patterns. The seed protein loci were identified asSec-1a andSec-1b loci controlling 40-K-secalins and-secalins, respectively. These loci are located on the short arm of chromosome1R. TheSec-3 locus controlling high-molecular-weight secalins is located on the long arm of chromosome1R. A further seed protein locus,Pr-3 (55-K protein), was located on the short arm of chromosome1R. A linkage was found between the6Pgd-2 isozyme locus controlling 6-phosphogluconate dehydrogenase isozymes located on the long arm of chromosome1R and the four seed protein loci. The results favor the gene order:6Pgd-2 ...Sec-3 ... [centromere] ...Pr-3 ...Sec-1b ...Sec-1a. Other linkages detected werePer-3a andPer-3b (0.33±0.33 cM),Est-8 andEst-12 (0.33±0.33 cM), andGot-3 and centromere (20.57±2.42 cM). The proxidase (Per), glutamate oxaloacetate transaminase (Got), and esterase (Est) loci were located on chromosome arms2RS,3RL, and6RL, respectively. The distances and the maps obtained are compared with data available in the literature.     

Mapping of genes controlling seed storage-proteins and cytological markers on chromosome 1R of rye

Summary Rye secalins, telomeric C-bands, and telocentric chromosomes were used as markers in the progeny of a test-cross in order to determine the position of seed storage-protein genes Glu-R1 and Gli-R1 with respect to the centromere and both telomeres of chromosome 1 R in rye. These genes were linked to the centromere (32.35±3.28% and 36.27±3.37% recombination, respectively). Glu-R1 was loosely linked to the telomere of the long arm (43.63±3.47% recombination), while Gli-R1 was closely linked to the telomere of the short arm (9.80±2.08% recombination). This finding supports the possibility that rye - and -secalin genes may be located on the satellites, as has been described in wheat for genes that code similar proteins. The importance of metaphase-I pairing failure and its consequences for the estimation of the recombination fraction are also discussed.     

一个先天性眼球震颤家系致病基因的初步定位

为确定一个X染色体显性遗传先天性眼球震颤家系的致病基因与X染色体的连锁关系, 选用X染色体上的DXS1214、DXS1068、DXS993、DXS8035、DXS1047、DXS8033、DXS1192和DXS1232共8个微卫星DNA标记对该家系进行基因扫描与基因分型,并利用LINKAGE等软件包对基因分型结果进行分析,探讨该家系致病基因与X染色体的连锁关系。 两点连锁分析时X染色体短臂4个基因座最大LOD值均小于-1,不支持与该家系致病基因连锁; X染色体长臂4个基因座中最大LOD值达到2,提示存在较大的连锁可能性。该家系的致病基因可初步定位于X染色体长臂,且提示Xq26-Xq28区间附近可能是先天性眼球震颤一个共同的致病基因座,但区间范围仍较大,仍须进一步选择合适的微卫星标记进行精确的定位以缩小候选基因的筛查范围。Abstract： To investigate the relationship between X chromosome and obligatory gene of a pedigree with congenital nystagmus,we used the following markers: DXS1214、DXS1068、DXS993、DXS8035、DXS1047、DXS8033、DXS1192 and DXS1232.Genome screening and genotyping were conducted in this pedigree of congenital nystagmus, and linkage analysis by LINKAGE package was used to determine the potential location. The linkage was not found on the Xp ( All LOD score <-1) but on Xq (the maximum LOD score=2). The related gene of this pedigree was located on the long arm of X chromosome. We demonstrate that Xq26-Xq28 is a common locus for CMN. It bring us closer to the identification of a gene responsible for X-linked CMN.     

A map of rye chromosome 2R using isozyme and morphological markers

Summary The segregation of isozymic loci for leaf peroxidases (L2Per) has been investigated in backcrosses and F₂ offspring of rye lines having purple seeds (Ps) and monstrosum ears (mo). The Ps, L2Per-3b, mo, and L2Per-2 loci were linked. The Ps and mo loci have been previously located on the 2R chromosome, and the L2Per-3b and L2Per-2 loci have been located on the 2RS chromosome arm. The results favor the gene order Ps ... L2Per-3b ... mo ... L2Per-2 or Ps ... mo... L2Per-3b ... L2Per-2. The position of the loci relative to the centromere is still not known, but the obtained results suggest that the mo locus could be located on the 2RS chromosome arm. On the basis of previously reported linkage groups, the most probable arrangement of the loci located on chromosome 2R is: dw2 ... Ps ... (L2Per-3a ... L2Per-3b ... mo) ... L2Per-2. It has not been possible to know the position of L2Per-4 loci (also located on 2RS chromosome arm) relative to L2Per-3a and L2Per-3b loci.     

The Sec-1 locus on the short arm of chromosome 1R of rye (Secale cereale)

This paper describes a detailed sequence analysis of the ω-secalin gene array at theSec-1 locus on the short arm of chromosome 1 of rye. The analysis shows that the genes are separated by 8 kb of spacer sequence and that the gene/spacer units are arranged in a head to tail fashion. The boundaries of the array are identified, and a fragment containing the majority of the genes in the array is separated by PFG analysis. The sequence data of one 9.2 kb gene unit have been determined, and because of the similarity of the gene units within the array these data provide a detailed sequence analysis of 140 kb of theSec-1 locus. Fluorescence in situ hybridization, using lambda clones isolated for the structural analysis, identifies the position of the array on the rye chromosomes relative to the 5S rRNA genes. Edited by: W. Hennig     

Genetics and molecular mapping of a male fertility restoration locus (Rfg1) in rye (Secale cereale L.)

 A gene determining the restoration of cytoplasmic genic male sterility (CMS) caused by the Gülzow (G)-type cytoplasm was mapped by analyzing an F₂ and F₃ population comprising 140 and 133 individual plants, respectively. The target gene, designated Rfg1, was mapped on chromosome 4RL distally to three RFLP (Xpsr119, Xpsr167, Xpsr899) and four RAPD (XP01, XAP05, XR11, XS10) loci. Xpsr167 and Xpsr899 are known to be located on the segment of chromosome 4RL which was ancestrally translocated and is homoeologous to the distal end of other Triticeae 6S chromosomes. It is suggested that Rfg1 may be allelic to the gene determining the restoration of rye CMS caused by the Pampa (P) cytoplasm (chromosome 4RL) and to Rfc4 that on rye addition lines of chromosome 4RL restores male fertility of hexaploid wheat with T. timopheevi cytoplasm. Homoeoallelism to two loci for cytoplasmic-male-sterility restoration on chromosomes 6AS and 6BS in hexaploid wheat is also suggested. Received: 1 December 1997 / Accepted: 10 February 1998     

矮泰引-3中半矮秆基因的分子定位

矮泰引-3的矮生性状受两对独立遗传的半矮秆基因控制,利用SSR标记将这两个矮秆基因分别定位到第1和第4染色体上。等位性测交的结果表明,位于第1染色体上的矮秆基因与sd1是等位的,所以仍然称其为sd1;而位于第4染色体上的矮秆基因是一个新基因,暂命名为sdt2。利用SSR标记将sd1定位于RM297、RM302和RM212的同一侧,而与OSR3共分离,它们之间的位置关系可能是RM297-RM302-RM212-OSR3-sd1,遗传距离分别为4．7cM、0cM、0．8cM和0cM,这与sd1在第1染色体长臂上的确切位置是基本一致的。利用已有的SSR标记和拓展的SSR标记将sdt2定位于SSR332、RM1305和RM5633、RM307、RM401之间,它们的排列位置可能是SSR332-RM1305-sdt2-RM5633-RM307-RM401,它们之间的遗传距离分别为11．6cM、3．8cM、0．4cM、0cM和0．4cM。     

葡萄无核基因定位与作图的研究

以UBC 269484和GSLP1569的序列为支点,设计合成了包括UBC 269和GSLP1在内的9条引物,以葡萄 有核亲本红地球和无核亲本红光无核的DNA为模板,对这9个引物进行筛选,结果GSLP1、39970524 5号引物和 39970524 6号引物在无核亲本红光无核上扩增出了特异标记GSLP1569、39970524 5 564、39970524 6 1538和 39970524 6 1200。用这3个特异引物在红地球、红光无核、无核白和红地球×红光无核杂交组合F1代163株杂 种的DNA样上进行PCR扩增,结果4个特异标记在F1群体中与无核主效基因共分离。4个特异标记也出现于所 用组合中无核基因原始供给者无核白上。这些标记和葡萄无核主效基因相连锁。用QTXb17遗传作图软件,对葡 萄无核主效基因S定位与作图,当P=0.01时,LOD值在32.7～46.4之间,置信界限在0.2～9.9之间。这4个 特异标记和无核主效基因S处于在同一连锁群,位于无核主效基因S的两侧,覆盖基因组12.3cM。特异标记 39970524 5 564、GSLP1569、39970524 6 1538、39970524 6 1200距S基因的遗传距离分别为0.6cM、1.2cM、 4.9cM和11.1cM。     

Partial Structure and Mapping of the Human Myelin P2 Protein Gene

Abstract: The myelin P₂ protein, a 14,800-Da cytosolic protein found primarily in peripheral nerves, belongs to a family of fatty acid binding proteins. Although it is similar in amino acid sequence and tertiary structure to fatty acid binding proteins found in the liver, adipocytes, and intestine, its expression is limited to the nervous system. It is detected only in myelin-producing cells of the central and peripheral nervous systems, i.e., the oligodendrocytes and Schwann cells, respectively. As part of a program to understand the regulation of expression of this gene, to determine its function in myelin-producing cells, and to study its role in peripheral nerve disease, we have isolated and characterized overlapping human genomic clones encoding the P₂ protein. We report here on the partial structure of this gene, and on its localization within the genome. By using a panel of human-hamster somatic cell hybrids and by in situ hybridization, we have mapped the human P₂ gene to segment q21 on the long arm of chromosome 8. This result identifies the myelin P₂ gene as a candidate gene for autosomal recessive Charcot-Marie-Tooth disease type 4A.     

Origin and genetic structure of feral rye in the western United States

Feral rye (Secale cereale) is a serious, introduced weed of dry land agricultural regions of the western United States. It closely resembles cultivated cereal rye (Secale cereale cereale L.) with the exception of having a shattering seed head. Feral rye may have originated from hybridization of cultivated rye with mountain rye, Secale strictum, as past studies of northern Californian populations suggest, or directly from volunteer cultivated rye. We characterized the genetic structure of feral rye populations across a broad geographical range and reexamined evidence for hybrid origin versus direct evolution from domesticated cultivars. Eighteen feral populations were examined from three climatically distinct regions in the western United States. Seven cultivars, four mountain rye accessions, and one wild annual relative (Secale cereale ancestrale) were included in our analysis as possible progenitors of feral rye. Individual plants were scored for 14 allozyme and three microsatellite loci. Estimates of genetic diversity in feral populations were relatively high compared to those of the possible progenitors, suggesting that the weed had not undergone a genetic bottleneck. Weed populations had no geographical structure at either a broad or a local scale, suggesting idiosyncratic colonization and gene-flow histories at each site. Feral rye populations were no more closely related to mountain rye than cultivars were. They were, however, weakly clustered as a distinct lineage relative to cultivars. Our results do not support an interspecific hybrid origin for feral rye, but do suggest that the sampled populations of feral rye share a common ancestry that may explain its weedy nature.