Molecular Biology

We present a safe and low-cost method suitable for DNA extraction from mycelium and tree tissue samples. After sample preparation, the extraction takes about 60 min. Method performance was tested by extracting DNA from various tree tissue samples and from mycelium grown on solid and liquid media. DNA was extracted from juvenile and mature host material (Picea abies, Populus trichocarpa, Pseudotsuga menziesii) infected with different pathogens (Heterobasidion annosum, Heterobasidion parviporum, Leptographium wagenerii, Sphaerulina musiva). Additionally, DNA was extracted from pure cultures of the pathogens and several endophytic fungi. PCR success rate was 100% for young poplar material and fungal samples, and 48-72% for conifer and mature broadleaved plant samples. We recommend using 10-50 mg of fresh sample for the best results. The method offers a safe and low-cost DNA extraction alternative to study tree-fungus interactions, and is a potential resource for teaching purposes.

The purification of nucleic acids is one of the most common procedures employed in modern molecular biology laboratories. Typically, commercial column-based protocols are utilized to isolate DNA or RNA from various sources. However, these methods not only require specialized equipment, but are also extremely expensive for high-throughput applications. Although an elegant answer to this issue can be provided by paramagnetic beads, bead-based open-source protocols have been limited in the past. Here, we provide an easy to follow step-by-step manual for the synthesis of paramagnetic beads, as well as their functionalization with either a silica- or a carboxyl-surface that can be used to replace the commercial columns with self-made magnetic beads. Together with a variety of detailed protocols for their use in high-throughput nucleic acids extractions, this bead synthesis method forms the recently published open platform Bio-On-Magnetic-Beads (BOMB), which is available on PLOS Biology (Oberacker et al., 2019). Updated protocols can be found on the associated webpage (https://bomb.bio).

Fusarium graminearum, the major causal agent of Fusarium head blight (FHB), causes serious wheat yield losses and a threat to human and animal health. The main efforts to combat the disease are the research of pathogenesis mechanisms and breeding for disease resistance plants. The efficiency of these actions could be evaluated by reliable inoculation assay, which is performed by accurate and repeatable inoculation methods. Hence, a standard procedure of effective wheat inoculation should improve the accuracy of pathogenicity evaluation. Here, we present a protocol for wheat spike inoculation with fungal conidial suspensions or fungus agar discs. These methods show highly reproducibility and accuracy on wheat infection experiment in laboratory conditions.

As the sister clade of seed plants, ferns are significant materials for plant phylogeny research. However, the genomic DNA extraction protocol for fern samples like modified CTAB method still lacks robustness. Here, we found that the amount and condition of the pinnae samples are critical for gDNA extraction in fern, Adiantum capillus-veneris L. In 500 μl CTAB solution, the recommended amount of pinnae is about 10-20 mg (2-3 pieces). The condition of the pinnae must be instantly-picked from a plant cultivated in a suitable environment. With these factors under control, it is highly reproducible to get the high-quality gDNA with low degradation rate

Since the first discovery of badnaviruses (family Caulimoviridae, genus Badnavirus) in yam (Dioscorea spp.) germplasm in the 1970s (Harrison and Roberts, 1973), several hundred partial badnavirus reverse transcriptase (RT)-ribonuclease H (RNaseH) sequences have been characterised (Kenyon et al., 2008; Bousalem et al., 2009), but only a few complete Dioscorea bacilliform virus (DBV) genome sequences have been reported (Phillips et al., 1999; Seal and Muller, 2007; Bömer et al., 2016 and 2017; Sukal et al., 2017; Umber et al., 2017). We have optimised a workflow involving total nucleic acid extractions and rolling circle amplification (RCA) combined with restriction enzyme analysis for the detection and amplification of DBVs present in yam germplasm. We have employed this approach successfully revealing three novel episomal yam badnaviruses (Bömer et al., 2016). We proposed this to be a complementary method to denaturing gradient gel electrophoresis, which enables a rapid indication of badnavirus diversity as well as the identification of potentially integrated badnavirus sequences in the host genome (Turaki et al., 2017). Here, we describe the step-by-step protocol to screen yam germplasm for badnavirus infections using RCA as an efficient research tool in the amplification and characterization of novel badnavirus genomes.

This technique allows for efficient, highly purified cytoplasmic and nuclear-associated compartment fractionation utilizing NP-40 detergent in mammalian cells. The nuclear membrane is not disturbed during the fractionation thus leaving all nuclear and perinuclear associated components in the nuclear fraction. This protocol has been modified from Sambrook and Russell (2001) in order to downscale the amount of cells needed. To determine the efficiency of fractionation, we recommend using qPCR to compare the subcellular compartments that have been purified with equivalent amount of control whole cell extracts.

The plant phyllosphere, which represents all plant parts that are above the ground, is considered one of the most extensive ecosystems to be colonized by microorganisms, both at the surface as epiphytes or as endophytes within the plant. These plant-associated microbial communities are reservoirs of microbial diversity and they can be important for plant health. The characterization of microbial communities in diverse plants, such as Espeletia plants that are endemic to the Paramo ecosystem in the Andes Mountains, can shed light regarding possible interactions among microorganisms and microbial functional properties. Obtaining DNA from plant endophytic microbial communities involves various steps to ensure that samples are free of contamination from microorganisms present on the plant surface (epiphytes). Plant leaves are first surface sterilized, cut into pieces, homogenized using glass beads, and then used for DNA extraction using a commercially available kit. DNA samples are then quantified and analyzed using Qubit^® 2.0 for use in PCR amplification of 16S rRNA genes.

dA^6m DNA immunoprecipitation followed by deep sequencing (DIP-Seq) is a key tool in identifying and studying the genome-wide distribution of N⁶-methyldeoxyadenosine (dA^6m). The precise function of this novel DNA modification remains to be fully elucidated, but it is known to be absent from transcriptional start sites and excluded from exons, suggesting a role in transcriptional regulation (Koziol et al., 2015). Importantly, its existence suggests that DNA might be more diverse than previously believed, as further DNA modifications might exist in eukaryotic DNA (Koziol et al., 2015). This protocol describes the method to perform dA^6m DNA immunoprecipitation (DIP), as was applied to characterize the first dA^6m methylome analysis in higher eukaryotes (Koziol et al., 2015). In this protocol, we describe how genomic DNA is isolated, fragmented and then DNA containing dA^6m is pulled down with an antibody that recognizes dA^6m in genomic DNA. After subsequent washes, DNA fragments that do not contain dA^6m are eliminated, and the dA^6m containing fragments are eluted from the antibody in order to be processed further for subsequent analyses.

Establishing a reservoir of polymorphic markers is an important key for marker-assisted breeding. Many crops are still lack of such genomic infrastructure. Single nucleotide polymorphisms (SNPs) and simple sequence repeats (SSRs) are useful as markers because they are widespread over the genome and many technologies were developed for high throughput genotyping. We present here a pipeline for developing a reservoir of SNP and SSR markers for Mangifera indica L. as an example for fruit tree crops having no genomic information available. Our pipeline includes de novo assembly of reference transcriptome with MIRA and CAP3 based on reads produced by 454-GS FLX technology; Polymorphic loci discovery by alignment of Illumina resequencing to the transcriptome reference; Identifying a subset of loci that are polymorphic in the entire germplasm collection for downstream diversity analysis by genotyping with Fluidigm technology.

This protocol describes the extraction, fractionation, and recovery of cytoplasmic nucleic acids (e.g., cytoplasmic RNA) versus nucleic acids in the cell nucleus (including genomic DNA, gDNA) from single cells with a microfluidic system. The method enables independent, sequence-specific analyses of these critical markers (Kuriyama et al., 2015). The system uses a microfluidic chip with a simple geometry and four end-channel electrodes, and completes the entire process in less than 5 min, including lysis, purification, fractionation, and delivery to two output reservoirs: One for the nucleus (including gDNA and nuclear RNA) and one for cytoplasmic RNA. Each reservoir then contains high quality and purity aliquots with no measurable cross-contamination of cytoplasmic RNA versus nucleic acids in nucleus. As described here, our protocol focuses on the analysis of cytoplasmic RNA versus gDNA from the nucleus. We have tested this protocol with mouse and human cells but not with walled cells such as plant cells.