Resistance to frost and tuber soft rot in near-pentaploid Solanum tuberosum - S. commersonii hybrids

The objectives of the present study were to evaluate the tolerance to low temperatures and tuber soft rot in sexual near-pentaploid hybrids between incongruent 2x (1EBN) Solanum commersonii (CMM) and 4x (4EBN) S. tuberosum (TBR). For freezing resistance, killing temperatures both under non-acclimated and un- der acclimated conditions were determined using the ion leakage procedure. Values for the hybrids were dis- tributed between the wild and cultivated parental values. Some hybrids displayed an acclimation capacity close to 2.5°C, typical of hardy species. Artificial inoculation of tubers with Pectobacterium carotovorum ssp. carotovorum (formerly Erwinia carotovora ssp. carotovora) provided evidence of variability in disease response. Highly resistant hybrids were identified. After conventional phenotypic selection, wild genome content was estimated based on the presence of CMM-specific AFLP fragments. Seven primer combinations were used (Eco-AGG/Mse-CAA; Eco-ACC/Mse-CAT; Eco-ACT/Mse-CAC; Eco-ACT/Mse-CAG; Eco- ACT/Mse-CAA; Eco-ACT/Mse-CAT; Eco-AGG/Mse-CAG). The percentages of CMM-specific AFLPs ranged from 4.3% to 56.7%, with an average value of 28.1%. AFLP analysis was employed for the selection of the hybrids to be used for further breeding objectives

Resistance traits and AFLP characterization of diploid primitive tuber-bearing potatoes.

ISSN: 0925-986

Multilevel evolution shapes the function of NB-LRR encoding genes in plant innate immunity

A sophisticated innate immune system based on diverse pathogen receptor genes (PRGs) evolved in the history of plant life. To reconstruct the direction and magnitude of evolutionary trajectories of a given gene family, it is critical to detect the ancestral signatures. The rearrangement of functional domains made up the diversification found in PRG repertoires. Structural rearrangement of ancient domains mediated the NB-LRR evolutionary path from an initial set of modular proteins. Events such as domain acquisition, sequence modification and temporary or stable associations are prominent among rapidly evolving innate immune receptors. Over time PRGs are continuously shaped by different forces to find their optimal arrangement along the genome. The immune system is controlled by a robust regulatory system that works at different scales. It is important to understand how the PRG interaction network can be adjusted to meet specific needs. The high plasticity of the innate immune system is based on a sophisticated functional architecture and multi-level control. Due to the complexity of interacting with diverse pathogens, multiple defense lines have been organized into interconnected groups. Genomic architecture, gene expression regulation and functional arrangement of PRGs allow the deployment of an appropriate innate immunity response

TomatEST database: in silico exploitation of EST data to explore expression patterns in tomato species

TomatEST is a secondary database integrating expressed sequence tag (EST)/cDNA sequence information from different libraries of multiple tomato species. Redundant EST collections from each species are organized into clusters (gene indices). A cluster consists of one or multiple contigs. Multiple contigs in a cluster represent alternatively transcribed forms of a gene. The set of stand-alone EST sequences (singletons) and contigs, representing all the computationally defined ‘Transcript Indices’, are annotated according to similarity versus protein and RNA family databases. Sequence function description is integrated with the Gene Ontologies and the Enzyme Commission identifiers for a standard classification of gene products and for the mapping of the expressed sequences onto metabolic pathways. Information on the origin of the ESTs, on their structural features, on clusters and contigs, as well as on functional annotations are accessible via a user-friendly web interface. Specific facilities in the database allow Transcript Indices from a query be automatically classified in Enzyme classes and in metabolic pathways. The ‘on the fly’ mapping onto the metabolic maps is integrated in the analytical tools. The TomatEST database website is freely available at

SolEST database: a "one-stop shop" approach to the study of Solanaceae transcriptomes

<p>Abstract</p> <p>Background</p> <p>Since no genome sequences of solanaceous plants have yet been completed, expressed sequence tag (EST) collections represent a reliable tool for broad sampling of <it>Solanaceae </it>transcriptomes, an attractive route for understanding <it>Solanaceae </it>genome functionality and a powerful reference for the structural annotation of emerging <it>Solanaceae </it>genome sequences.</p> <p>Description</p> <p>We describe the SolEST database <url>http://biosrv.cab.unina.it/solestdb</url> which integrates different EST datasets from both cultivated and wild <it>Solanaceae </it>species and from two species of the genus <it>Coffea</it>. Background as well as processed data contained in the database, extensively linked to external related resources, represent an invaluable source of information for these plant families. Two novel features differentiate SolEST from other resources: i) the option of accessing and then visualizing <it>Solanaceae </it>EST/TC alignments along the emerging tomato and potato genome sequences; ii) the opportunity to compare different <it>Solanaceae </it>assemblies generated by diverse research groups in the attempt to address a common complaint in the SOL community.</p> <p>Conclusion</p> <p>Different databases have been established worldwide for collecting <it>Solanaceae </it>ESTs and are related in concept, content and utility to the one presented herein. However, the SolEST database has several distinguishing features that make it appealing for the research community and facilitates a "one-stop shop" for the study of <it>Solanaceae </it>transcriptomes.</p

Interspecific somatic hybrids between Solanum bulbocastanum and S. tuberosum and their haploidization for potato breeding.

Protoplast fusion between incongruent Solanum bulbocastanum and S. tuberosum haploids was accomplished to produce hybrids combining elite traits from both parents. We identified 11 somatic hybrids out of 42 regenerants analyzed through ISSR markers. Some hybrids had loss or gain of fragments compared to the parents, likely due to rearrangements and deletions of chromosome segments after fusion, and/or to somaclonal variation during hybrid regeneration. Increased heterotic vigor for some traits as well as high diversity was observed as the effect of both ploidy and fusion combination. Microsporogenesis analysis indicated the occurrence of multivalent configurations and several meiotic abnormalities, such as chromosomes bridges and various spindle orientations. Since all hybrids were sterile, in vitro anther culture was employed for haploidization as a possible strategy to overcome barriers to hybridizations. Haploids were obtained from all the tetraploid S. bulbocastanum (+) S. tuberosum somatic hybrids tested, although with differences in both the number of embryos per 100 anthers cultured and the number of differentiated green plantlets. This is the first report on the successful production of haploid plants from S. bulbocastanum (+) S. tuberosum hybrids

Resistance to Ralstonia Solanacearum of sexual hybrids between Solanum commersonii and S. tuberosum

This research was carried out to study the levels of bacterial wilt resistance and genetic diversity of (near) pentaploid sexual hybrids between S. commersonii (2n = 2x = 24, 1EBN) and cultivated S. tuberosum. Following artificial inoculations with Ralstonia solanacearum, wilting degree was estimated on a scale from 0 to 4, and seven genotypes of 26 (27%) displaying a S. commersonii like behavior were identified. Latent bacterial colonizations were detected in roots of symptomless S. commersonii and hybrids, whereas no bacterial populations were detected within stems. This suggests that the movement and/or growth of the bacterium in the aerial part were strongly inhibited. A molecular study with AFLP markers clustered hybrids into nine groups and provided evidence that resistant hybrids were slightly more similar to cultivated S. tuberosum than to the wild parent. This is important in view of the re-establishment of the cultivated genetic background through backcrosses. Hybrids displayed good fertility and are being used for further breeding efforts

Genome Sequencing of Ancient Plant Remains: Findings, Uses and Potential Applications for the Study and Improvement of Modern Crops

The advent of new sequencing technologies is revolutionizing the studies of ancient DNA (aDNA). In the last 30 years, DNA extracted from the ancient remains of several plant species has been explored in small-scale studies, contributing to understand the adaptation, and migration patterns of important crops. More recently, NGS technologies applied on aDNA have opened up new avenues of research, allowing investigation of the domestication process on the whole-genome scale. Genomic approaches based on genome-wide and targeted sequencing have been shown to provide important information on crop evolution and on the history of agriculture. Huge amounts of next-generation sequencing (NGS) data offer various solutions to overcome problems related to the origin of the material, such as degradation, fragmentation of polynucleotides, and external contamination. Recent advances made in several crop domestication studies have boosted interest in this research area. Remains of any nature are potential candidates for aDNA recovery and almost all the analyses that can be made on fresh DNA can also be performed on aDNA. The analysis performed on aDNA can shed light on many phylogenetic questions concerning evolution, domestication, and improvement of plant species. It is a powerful instrument to reconstruct patterns of crop adaptation and migration. Information gathered can also be used in many fields of modern agriculture such as classical breeding, genome editing, pest management, and product promotion. Whilst unlocking the hidden genome of ancient crops offers great potential, the onus is now on the research community to use such information to gain new insight into agriculture

Fertilization fitness and offspring ploidy in 3x x 2x matings in potato.

The main objective of the current research was to study the reproductive behaviour of artificial triploid potato hybrids between wild Solanum commersonii and the cultivated potato Solanum tuberosum. When used in 3x 6 2x crosses, triploids gave aneuploid progenies with somatic chromosome number ranging from 29 to 36. Fertilization fitness data suggested that the survival rate of gametes produced by the triploid parents may be related to their chromosome number. In addition, consistent with molecular data, our results indicated that fitness of gametes and chromosome number of progenies are influenced by the genome dosage of interspecific triploids. Since a main route to polyploidy formation is via 2n gametes and triploids, our study may contribute to a better understanding of polyploid plant reproduction, evolution and breeding