A major gene for grain cadmium accumulation in oat

A population of 150 F2 plants was derived from a cross between two spring oat individuals, one from cv. Aslak (Boreal Plant Breeding LTd., Finland) and the other from cv. Salo (Svalöf-Weibull AB, Sweden). Cadmium was tested by inductively coupled plasma mass spectrometry (ICP-MS) method

Template switching can create complex LTR retrotransposon insertions in Triticeae genomes

v2007okBEL/KG

Palindromic sequence-targeted (PST) PCR, version 2: an advanced method for high-throughput targeted gene characterization and transposon display

Genome walking (GW), a strategy for capturing previously unsequenced DNA fragments that exist in proximity to a known sequence tag, is currently predominantly based on PCR. Recently developed PCR-based methods allow for combining of sequence-specific primers with designed capturing primers capable of annealing to unknown DNA targets, which offer the rapidity and effectiveness of PCR. This study presents a methodological improvement to the previously described GW technique known as Palindromic Sequence-Targeted PCR (PST-PCR). Like PST-PCR, this new method (called PST-PCR v.2) relies on targeting of capturing primers to palindromic sequences arbitrarily present in natural DNA templates. PST-PCR v.2 consists of two rounds of PCR. The first round uses a combination of one sequence-specific primer with one capturing (PST) primer. The second round uses a combination of a single (preferred) or two universal primers; one anneals to a 5’ tail attached to the sequence-specific primer and the other anneals to a different 5’ tail attached to the PST primer. The key advantage of PST-PCR v.2 is the convenience of using a single universal primer with invariable sequences in GW processes involving various templates. The entire procedure takes approximately 2–3 hours to produce the amplified PCR fragment, which contains a portion of a template flanked by the sequence-specific and capturing primers. PST-PCR v.2 is highly suitable for simultaneous work with multiple samples. For this reason, PST-PCR v.2 can be applied beyond the classical task of GW for studies in population genetics, in which PST-PCR v.2 is a preferred alternative to amplified fragment length polymorphism (AFLP) or next-generation sequencing. Furthermore, the conditions for PST-PCR v.2 are easier to optimize, as only one sequence-specific primer is used. This reduces non-specific Random Amplified Polymorphic DNA (RAPD)-like amplification and formation of non-templated amplification. Importantly, akin to the previous version, PST-PCR v.2 is not sensitive to template DNA sequence complexity or quality. This study illustrates the utility of PST-PCR v.2 for transposon display, which is a method to characterize inter- or intra-specific variability related to transposon integration sites. The Ac transposon sequence in the corn (Zea mays) genome was used as a sequence tag during the transposon display procedure to characterize the Ac integration sites.Peer reviewe

Java web tools for PCR, in silico PCR, and oligonucleotide assembly and analysis

AbstractThe polymerase chain reaction is fundamental to molecular biology and is the most important practical molecular technique for the research laboratory. We have developed and tested efficient tools for PCR primer and probe design, which also predict oligonucleotide properties based on experimental studies of PCR efficiency. The tools provide comprehensive facilities for designing primers for most PCR applications and their combinations, including standard, multiplex, long-distance, inverse, real-time, unique, group-specific, bisulphite modification assays, Overlap-Extension PCR Multi-Fragment Assembly, as well as a programme to design oligonucleotide sets for long sequence assembly by ligase chain reaction. The in silico PCR primer or probe search includes comprehensive analyses of individual primers and primer pairs. It calculates the melting temperature for standard and degenerate oligonucleotides including LNA and other modifications, provides analyses for a set of primers with prediction of oligonucleotide properties, dimer and G-quadruplex detection, linguistic complexity, and provides a dilution and resuspension calculator

Retrotransposon molecular markers resolve cocoyam (Xanthosoma sagittifolium) and taro (Colocasia esculenta) by type and variety

Retrotransposon-based molecular markers were applied for the first time within the genera Xanthosoma and Colocasia to assess intraspecific variability among 27 accessions of cocoyam (Xanthosoma sagittifolium) and taro (Colocasia esulenta). Over 16 distinct retrotransposon fragments were isolated, sequenced, and LTR primers were designed to obtain Inter-Retrotransposon Amplified Polymorphism (IRAP) fingerprints. The set of six polymorphic LTR primers yielded 433 reproducible bands across a set of 20 X. sagittifolium samples. Out of the 433 bands, 400 fragments (92%) were polymorphic. In seven C. esculenta accessions, the six primers amplified a total of 354 reproducible, informative data points, of which 285 (80.5%) were polymorphic. Data concerning the number of polymorphic bands and Shannon’s index in X. sagittifolium accessions suggest that retrotransposon activity continued after Xanthosoma speciation. Cluster analysis placed all the accessions in two groups according to their species delimitation. The accessions of X. sagittifolium were further divided into two subgroups corresponding to their ploidy level. Moreover, our results showed that the genetic variability accessed by IRAP markers allows separation of X. sagittifolium and C. esculenta accessions according to their type and botanical variety respectively. These data provide a basis for better germplasm management, future systematic studies and genetic improvement, as well as for exploration of the role of retrotransposons in cocoyam and taro polyploid formation and genome dynamics.Peer reviewe

European Court of Justice delivers no justice to Europe on genome-edited crops

Non peer reviewe

Long Tandem Arrays of Cassandra Retroelements and Their Role in Genome Dynamics in Plants

Retrotransposable elements are widely distributed and diverse in eukaryotes. Their copy number increases through reverse-transcription-mediated propagation, while they can be lost through recombinational processes, generating genomic rearrangements. We previously identified extensive structurally uniform retrotransposon groups in which no member contains the gag, pol, or env internal domains. Because of the lack of protein-coding capacity, these groups are non-autonomous in replication, even if transcriptionally active. The Cassandra element belongs to the non-autonomous group called terminal-repeat retrotransposons in miniature (TRIM). It carries 5S RNA sequences with conserved RNA polymerase (pol) III promoters and terminators in its long terminal repeats (LTRs). Here, we identified multiple extended tandem arrays of Cassandra retrotransposons within different plant species, including ferns. At least 12 copies of repeated LTRs (as the tandem unit) and internal domain (as a spacer), giving a pattern that resembles the cellular 5S rRNA genes, were identified. A cytogenetic analysis revealed the specific chromosomal pattern of the Cassandra retrotransposon with prominent clustering at and around 5S rDNA loci. The secondary structure of the Cassandra retroelement RNA is predicted to form super-loops, in which the two LTRs are complementary to each other and can initiate local recombination, leading to the tandem arrays of Cassandra elements. The array structures are conserved for Cassandra retroelements of different species. We speculate that recombination events similar to those of 5S rRNA genes may explain the wide variation in Cassandra copy number. Likewise, the organization of 5S rRNA gene sequences is very variable in flowering plants; part of what is taken for 5S gene copy variation may be variation in Cassandra number. The role of the Cassandra 5S sequences remains to be established

Palindromic Sequence-Targeted (PST) PCR, Version 2: An Advanced Method for High-Throughput Targeted Gene Characterization and Transposon Display

Genome walking (GW), a strategy for capturing previously unsequenced DNA fragments that are in proximity to a known sequence tag, is currently predominantly based on PCR. Recently developed PCR-based methods allow for combining of sequence-specific primers with designed capturing primers capable of annealing to unknown DNA targets, thereby offering the rapidity and effectiveness of PCR. This study presents a methodological improvement to the previously described GW technique known as palindromic sequence-targeted PCR (PST-PCR). Like PST-PCR, this new method (called PST-PCR v.2) relies on targeting of capturing primers to palindromic sequences arbitrarily present in natural DNA templates. PST-PCR v.2 consists of two rounds of PCR. The first round uses a combination of one sequence-specific primer with one capturing (PST) primer. The second round uses a combination of a single (preferred) or two universal primers; one anneals to a 5′ tail attached to the sequence-specific primer and the other anneals to a different 5′ tail attached to the PST primer. The key advantage of PST-PCR v.2 is the convenience of using a single universal primer with invariable sequences in GW processes involving various templates. The entire procedure takes approximately 2–3 h to produce the amplified PCR fragment, which contains a portion of a template flanked by the sequence-specific and capturing primers. PST-PCR v.2 is highly suitable for simultaneous work with multiple samples. For this reason, PST-PCR v.2 can be applied beyond the classical task of GW for studies in population genetics, in which PST-PCR v.2 is a preferred alternative to amplified fragment length polymorphism (AFLP) or next-generation sequencing. Furthermore, the conditions for PST-PCR v.2 are easier to optimize, as only one sequence-specific primer is used. This reduces non-specific random amplified polymorphic DNA (RAPD)-like amplification and formation of non-templated amplification. Importantly, akin to the previous version, PST-PCR v.2 is not sensitive to template DNA sequence complexity or quality. This study illustrates the utility of PST-PCR v.2 for transposon display (TD), which is a method to characterize inter- or intra-specific variability related to transposon integration sites. The Ac transposon sequence in the maize (Zea mays) genome was used as a sequence tag during the TD procedure to characterize the Ac integration sites