Millora genètica de plantes assistida amb marcadors

En els darrers trenta anys s'ha fet un gran progrés en el desenvolupament i ús dels marcadors moleculars en plantes. Els marcadors, que detecten la variació de la seqüència del DNA, permeten la predicció de molts caràcters, com ara la forma, mida, color, resistència a les malalties, productivitat, etc., d'una manera sovint més precoç, eficient i barata que la mesura del caràcter quan aquest es manifesta en la planta. La millora genètica ha anat integrant progressivament els marcadors en el procés de selecció i en el control de qualitat de llavors i planters, de manera que actualment s'han convertit en eines d'ús generalitzat i sovint imprescindible que ajuden i potencien els mètodes clàssics d'obtenció de noves varietats. En aquest article es resumeixen les característiques dels principals tipus de marcadors i es descriuen les seves principals aplicacions en la selecció de gens majors, de caràcters quantitatius i en la incorporació de gens d'interès a partir d'individus exòtics o d'espècies silvestres properes als conreus.The last three decades have witnessed an enormous progress in the development and use of molecular markers for plant breeding. Molecular markers are based on the DNA variation and allow the prediction of many characters related with form, color, size, disease resistance, yield, etc., often quicker, more efficiently and cheaper than field measurements when these characters are expressed on the plant. Markers have been progressively integrated in the process of selection and have become a useful and often necessary tool for breeders to select the best individuals and for quality control of seed and nursery plants. This chapter summarizes the characteristics of the main marker types and their application for the selection of major genes, quantitative characters and for the exploitation of genes of interest from wild or exotic sources in cultivated species

Agriculture of the future : science and technology for sustainable agricultural development

Guaranteeing access to food for a growing human population - based on sustainability criteria and in the face of the climate change threat - is the main challenge for twenty-first-century agriculture. The solutions are inevitably complex, require a variety of coordinated measures, and essentially, are dependent on the progress of science and the development of technologies to make more efficient use of available resources to increase crop yields and food quality to feed the world. Technologies such as genomics, computing, robotics, and nanotechnology, along with their correct application - which will require highly qualified users - will also be crucial elements to reach these objectives

The Extensin from Prunus amygdalus

2 pages, 1 figure, 1 table.-- PMID: 16653168 [PubMed].-- PMCID: PMC1075830.Peer reviewe

Generation of a BAC-based physical map of the melon genome

13 páginas, 4 figuras, 3 tablas.[Background]: Cucumis melo (melon) belongs to the Cucurbitaceae family, whose economic importance among horticulture crops is second only to Solanaceae. Melon has high intra-specific genetic variation, morphologic diversity and a small genome size (450 Mb), which make this species suitable for a great variety of molecular and genetic studies that can lead to the development of tools for breeding varieties of the species. A number of genetic and genomic resources have already been developed, such as several genetic maps and BAC genomic libraries. These tools are essential for the construction of a physical map, a valuable resource for map-based cloning, comparative genomics and assembly of whole genome sequencing data. However, no physical map of any Cucurbitaceae has yet been developed. A project has recently been started to sequence the complete melon genome following a whole-genome shotgun strategy, which makes use of massive sequencing data. A BAC-based melon physical map will be a useful tool to help assemble and refine the draft genome data that is being produced. [Results]: A melon physical map was constructed using a 5.7 × BAC library and a genetic map previously developed in our laboratories. High-information-content fingerprinting (HICF) was carried out on 23,040 BAC clones, digesting with five restriction enzymes and SNaPshot labeling, followed by contig assembly with FPC software. The physical map has 1,355 contigs and 441 singletons, with an estimated physical length of 407 Mb (0.9 × coverage of the genome) and the longest contig being 3.2 Mb. The anchoring of 845 BAC clones to 178 genetic markers (100 RFLPs, 76 SNPs and 2 SSRs) also allowed the genetic positioning of 183 physical map contigs/singletons, representing 55 Mb (12%) of the melon genome, to individual chromosomal loci. The melon FPC database is available for download at http://melonomics.upv.es/static/files/public/physical_map/ webcite. [Conclusions]: Here we report the construction of the first physical map of a Cucurbitaceae species described so far. The physical map was integrated with the genetic map so that a number of physical contigs, representing 12% of the melon genome, could be anchored to known genetic positions. The data presented is already helping to improve the quality of the melon genomic sequence available as a result of a project currently being carried out in Spain, adopting a whole genome shotgun approach based on 454 sequencing data.This project was funded by the Plan Nacional de Investigación Científica of the Spanish Ministerio de Educación y Ciencia (Project BIO2007-61789) and by the Consolider-Ingenio 2010 Programme of the Spanish Ministerio de Ciencia e Innovación (CSD2007-00036 "Center for Research in Agrigenomics").Peer reviewe

Fine mapping and identification of candidate genes for the peach powdery mildew resistance gene Vr3

Powdery mildew is one of the major diseases of peach (Prunus persica), caused by the ascomycete Podosphaera pannosa. Currently, it is controlled through calendar-based fungicide treatments starting at petal fall, but an alternative is to develop resistant peach varieties. Previous studies mapped a resistance gene (Vr3) in interspecific populations between almond (‘Texas’) and peach (‘Earlygold’). To obtain molecular markers highly linked to Vr3 and to reduce the number of candidate genes, we fine-mapped Vr3 to a genomic region of 270 kb with 27 annotated genes. To find evidence supporting one of these positional candidate genes as being responsible of Vr3, we analyzed the polymorphisms of the resequences of both parents and used near-isogenic lines (NILs) for expression analysis of the positional candidate genes in symptomatic or asymptomatic leaves. Genes differentially expressed between resistant and susceptible individuals were annotated as a Disease Resistance Protein RGA2 (Prupe2G111700) or an Eceriferum 1 protein involved in epicuticular wax biosynthesis (Prupe2G112800). Only Prupe2G111700 contained a variant predicted to have a disruptive effect on the encoded protein, and was overexpressed in both heterozygous and homozygous individuals containing the Vr3 almond allele, compared with susceptible individuals. This information was also useful to identify and validate molecular markers tightly linked and flanking Vr3. In addition, the NILs used in this work will facilitate the introgression of this gene into peach elite materials, alone or pyramided with other known resistance genes such as peach powdery mildew resistance gene Vr2.info:eu-repo/semantics/publishedVersio

Molecular markers for plant genetics and breeding

Els marcadors moleculars han permès un dels majors avenços recents en la comprensió de la base genètica de la diversitat fenotípica i la mesura de la variació genètica en plantes silvestres i cultivades. En els darrers 50 anys hem passat d'unes desenes d'isoenzims a un nombre virtualment il·limitat de marcadors d'ADN altament polimòrfics, codominants, presents a tot arreu del genoma i que poden ser obtinguts amb tecnologies senzilles i barates. Els marcadors han introduït el lligament com una nova dimensió en l'anàlisi genètica, permetent la construcció de mapes, la dissecció de caràcters quantitatius, la genètica d'associació, el clonatge posicional de gens d'interès i l'estudi de l'evolució dels genomes basada en la comparació de mapes. Els marcadors han estat també útils per la millora genètica, permetent la identificació molecular de genotips, la selecció assistida amb marcadors de gens majors i QTLs (loci de caràcters quantitatius), la selecció de tot el genoma en programes de retroencreuament i la selecció genòmica, que han estat adoptats com eines que augmenten l'eficiència dels mètodes convencionals. Aquest article resumeix la recerca realitzada a Catalunya en aquest àmbit que ha estat pionera a nivell internacional, en particular als fruiters i hortalisses.The development of molecular markers has been a major step forward in understanding the genetic basis of phenotypic diversity, and in measuring the amount and organization of genotypic polymorphisms in wild and cultivated plant species. The progress in molecular technologies of the last 50 years has lead from a few isozyme markers to a virtually unlimited number of DNA-based markers that are highly polymorphic, codominant, ubiquitous in the genome, and can be obtained by relatively cheap and simple technologies. With markers it has been possible to introduce linkage as a new dimension in genetic analysis, allowing map construction, dissection of quantitative traits, association genetics, positional cloning of genes of interest and the study of genome evolution based on the comparison of the genome positions of homologous markers. These developments have led to multiple applications for plant breeding, including cultivar fingerprinting, major gene or QTL (quantitative trait loci) assisted selection, whole-genome selection in backcross programs, and genomic selection, which have been adopted by most breeders as tools to enhance the efficiency of conventional methods of plant improvement. This paper summarizes the research conducted in Catalonia that has been pioneering in this area at the international level, particularly for horticultural crops

Resynthesis: Marker-Based Partial Reconstruction of Elite Genotypes in Clonally-Reproducing Plant Species

We propose a method for marker-based selection of cultivars of clonally-reproducing plant species which keeps the basic genetic architecture of a top-performing cultivar (usually a partly heterozygous genotype), with the addition of some agronomically relevant differences (such as production time, product appearance or quality), providing added value to the product or cultivation process. The method is based on selecting a) two complementary nearly-inbred lines from successive selfing generations (ideally only F2 and F3) of large size, that may generate individuals with most of their genome identical to the original cultivar but being homozygous for either of the two component haplotypes in the rest, and b) individuals with such characteristics already occurring in the F2. Option a) allows for introgressing genes from other individuals in one or both of these nearly-inbred lines. Peach, a woody-perennial, clonally-reproduced species, was chosen as a model for a proof of concept of the Resynthesis process due to its biological characteristics: self-compatibility, compact and genetically well-known genome, low recombination rates and relatively short intergeneration time (3–4 years). From 416 F2 seedlings from cultivar Sweet Dream (SD), we obtained seven individuals with 76–94% identity with SD, and selected five pairs of complementary lines with average homozygosity of the two parents ≥0.70 such that crossing would produce some individuals highly similar to SD. The application of this scheme to other species with more complex genomes or biological features, including its generalization to F1 hybrids, is discussed.info:eu-repo/semantics/publishedVersio

Biochemical and genetic implications of the slow ripening phenotype in peach fruit

The peach [Prunus persica L. (Batsch)] slow ripening (SR) trait is a mutation preventing the normal fruit ripening process. It is determined by a single Mendelian gene (Sr/sr) located on linkage group 4, where only homozygous individuals for a recessive allele (sr) show the SR phenotype and are generally discarded from breeding programs. Ripening-related traits such as fruit weight, firmness loss, ethylene production, ACO activity, sugars and organic acids composition, malondialdehyde, antioxidant capacity and total phenolic content were evaluated in a segregating population for the SR trait during two consecutive harvest seasons and at different maturity stages. Although there is no commercial value for the slow ripening (srsr) individuals, our results demonstrate that a heterozygous combination involving sr and another allele at this locus (Sr2) showed interesting traits including a longer harvest window and improved postharvest behaviour if harvested at the appropriate maturity (IAD ≥ 2). All these traits seem to be linked to a delayed ripening behaviour mediated, in turn, by a lower ethylene production capacity and an altered sugar (mainly sucrose) and organic acid accumulation/utilisation on-tree. The selection of this allelic combination could be an easy and efficient strategy to obtain new peach cultivars with potentially improved shelf life.info:eu-repo/semantics/acceptedVersio