RESUMEN
The rice genome has proven a valuable resource for comparative approaches to address individual genomic regions in Triticeae species at the molecular level. To exploit this resource for rye genetics and breeding, an inventory was made of EST-derived markers with known genomic positions in rye, which were related with those in rice. As a first inventory set, 92 EST-SSR markers were mapped which had been drawn from a non-redundant rye EST collection representing 5,423 unigenes and 2.2 Mb of DNA. Using a BC1 mapping population which involved an exotic rye accession as donor parent, these EST-SSR markers were arranged in a linkage map together with 25 genomic SSR markers as well as 131 AFLP and four STS markers. This map comprises seven linkage groups corresponding to the seven rye chromosomes and covers 724 cM of the rye genome. For comparative studies, additional inventory sets of EST-based markers were included which originated from the rye-mapping data published by other authors. Altogether, 502 EST-based markers with known chromosomal localizations in rye were used for BlastN search and 334 of them could be in silico mapped in the rice genome. Additionally, 14 markers were included which lacked sequence information but had been genetically mapped in rice. Based on the 348 markers, each of the seven rye chromosomes could be aligned with distinct portions of the rice genome, providing improved insight into the status of the rye-rice genome relationships. Furthermore, the aligned markers provide genomic anchor points between rye and rice, enabling the identification of conserved ortholog set markers for rye. Perspectives of rice as a model for genome analysis in rye are discussed.
Asunto(s)
ADN de Plantas/química , Genómica/métodos , Secale/genética , Mapeo Cromosómico , Cromosomas de las Plantas , Etiquetas de Secuencia Expresada , Marcadores Genéticos , Genoma de Planta , Repeticiones de Minisatélite , Oryza/genética , Análisis de Secuencia de ADNRESUMEN
Genetic diversity of elite breeding material can be increased by introgression of exotic germplasm to ensure long-term selection response. The objective of our study was to develop and characterize the first two rye introgression libraries generated by marker-assisted backcrossing and demonstrate their potential application for improving the baking quality of rye. Starting from a cross between inbred line L2053-N (recurrent parent) and a heterozygous Iranian primitive population Altevogt 14160 (donor) two backcross (BC) and three selfing generations were performed to establish introgression libraries A and B. Amplified fragment length polymorphisms (AFLP markers) and simple sequences repeats (SSRs) were employed to select and characterize candidate introgression lines (pre-ILs) from BC(1) to BC2S3. The two introgression libraries comprise each 40 BC2S3 pre-ILs. For analyzing the phenotypic effects of the exotic donor chromosome segment (DCS) we evaluated the per se performance for pentosan and starch content in replicated field trials at each of four locations in 2005 and 2006. Introgression library A and B cover 74 and 59% of the total donor genome, respectively. The pre-ILs contained mostly two to four homozygous DCS, with a mean length of 12.9 cM (A) and 10.0 cM (B). We detected eight (A) and nine (B) pre-ILs with a significant (P<0.05) higher pentosan content and two pre-ILs (B) with a significant (P<0.05) higher starch content than the elite recurrent parent. Thus, our results indicate that exotic genetic resources in rye carry favorable alleles for baking quality traits, which can be exploited for improving the elite breeding material by marker-assisted selection (MAS). These introgression libraries can substantially foster rye breeding programs and provide a promising opportunity to proceed towards functional genomics.
Asunto(s)
Biblioteca de Genes , Genoma de Planta , Secale/genética , Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Cruzamiento , Mapeo Cromosómico , Marcadores Genéticos , Genómica , Hibridación Genética , Irán , Repeticiones de MinisatéliteRESUMEN
Using barley and wheat expressed sequence tags as well as rice genomic sequence and mapping information, we revisited the genomic region encompassing the self-incompatibility (SI) locus Z on rye chromosome 2RL applying a comparative approach. We were able to arrange 12 novel sequence-tagged site (STS) markers around Z, spanning a genetic distance of 32.3 cM, with the closest flanking markers mapping at a distance of 0.5 cM and 1.0 cM from Z, respectively, and one marker cosegregating with Z, in a testcross population of 204 progeny. Two overlapping rice bacterial artifical chromosomes (BACs), OSJNBa0070O11 and OSJNBa0010D21, were found to carry rice orthologs of the three rye STS markers from the 1.5-cM interval encompassing Z. The STS-marker orthologs on these rice BACs span less than 125,000 bp of the rice genome. The STS marker TC116908 cosegregated with Z in a mapping population and revealed a high degree of polymorphism among a random sample of rye plants of various origin. TC116908 was shown via Southern hybridization to correspond to gene no. 10 (OSJNBa0070O11.10) on rice BAC OSJNBa0070O11. Reverse transcription-PCR with a TC116908-specific primer pair resulted in the amplification of a fragment of the expected size from the rye pistil but not from leaf cDNA. OSJNBa0070O11.10 was found to show a highly significant sequence similarity to AtUBP22, a ubiquitin-specific protease (UBP). TC116908 likely represents a putative UBP gene that is specifically expressed in rye pistils and cosegregates with Z. Given that the ubiquitination of proteins is emerging as a general mechanism involved in different SI systems of plants, TC116908 appears to be a promising target for further investigation with respect to its relation to the SI system of the grasses.
Asunto(s)
Mapeo Cromosómico , Cromosomas de las Plantas/genética , Polimorfismo Genético , Secale/genética , Southern Blotting , Cromosomas Artificiales Bacterianos , Biología Computacional , Cruzamientos Genéticos , Cartilla de ADN , Endopeptidasas/genética , Marcadores Genéticos/genética , Oryza/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Lugares Marcados de Secuencia , Triticum/genética , Proteasas Ubiquitina-Específicas , Zea mays/genéticaRESUMEN
Three dominant resistance genes, Pr3, Pr4, and Pr5, were identified by genetic analysis of resistance to leaf rust in rye (Puccinia recondita f. sp. secalis). Each of the three genes confers resistance to a broad scale of single-pustule isolates (SPIs), but differences could be observed for specific Pr gene/SPI combinations. Resistance conferred by the three genes was effective in both detached-leaf tests carried out on seedlings and in field tests of adult plants. Molecular marker analysis mapped Pr3 to the centromeric region of rye chromosome arm 1RS, whereas Pr4 and Pr5 were assigned to the centromeric region of 1RL. Chromosomal localization and reaction patterns to specific SPIs provide evidence that the three Pr genes represent distinct and novel leaf-rust resistance genes in rye. The contributions of these genes to resistance breeding in rye and wheat are discussed.
Asunto(s)
Basidiomycota/patogenicidad , Genes de Plantas , Secale/genética , Secale/microbiología , Secuencia de Bases , Mapeo Cromosómico , Cromosomas de las Plantas/genética , Cruzamientos Genéticos , ADN de Plantas/genética , Mapeo Físico de Cromosoma , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiologíaRESUMEN
Genetic analysis of resistance to leaf rust in rye (Puccinia recondita f. sp. secalis) led to the identification of two dominant resistance genes, Pr1 and Pr2. Both genes proved to be effective against a local leaf-rust population as well as a subset of single-pustule isolates (SPIs) the latter of which comprised SPIs with very high virulence complexity. Resistance conferred by Pr1 and Pr2 was expressed in detached-leaf tests of seedlings as well as in field tests of adult plants. Molecular marker analysis allowed us to map Pr1 in the proximal part of rye chromosome 6RL, whereas Pr2 was assigned to the distal part of chromosome 7RL. These results are discussed in view of homoeology relationships among Triticeae. A proposal is submitted for the designation of resistance genes to rye leaf rust which would avoid interference with existing gene-symboling in respect to wheat leaf-rust resistances introgressed from rye into wheat or triticale.
Asunto(s)
Basidiomycota , Inmunidad Innata/genética , Enfermedades de las Plantas/genética , Proteínas de Plantas/genética , Secale/genética , Southern Blotting , Mapeo Cromosómico , Cartilla de ADN , Electroforesis en Gel de Poliacrilamida , Marcadores Genéticos , IsoenzimasRESUMEN
Rye inbred lines segregating at the S-locus and homozygous at the Z-locus were investigated by PCR with primers derived from Brassica SLG-sequences. After denaturing gradient gel electrophoresis (DGGE), a 280 bp PCR-fragment displays a polymorphism perfectly correlated to the underlying S-genotypes. This is the first report on S-related DNA polymorphism in a bifactorial self-incompatibility system of the Poaceae.