Plant Science

Isolation of pure RNA is the basic requisite for most molecular biology work. Plants contain polyphenols and polysaccharides, which can interfere with isolation of pure RNA from them. Especially hardwood tree species like Paulownia elongata have surplus amount of RNA-binding alkaloids, proteins and secondary metabolites that can further complicate the process of RNA extraction. Paulownia elongata is a fast-growing tree species which is known for its role in environmental adaptability and biofuel research. Here we describe an economical, efficient and time-saving method (2 h) to extract RNA from leaf tissues of the tree Paulownia elongata. Lack of DNA contamination and good RNA integrity were confirmed using RNA Gel electrophoresis. The purity of RNA was confirmed using Nanodrop spectrophotometer that revealed an A₂₆₀:A₂₈₀ ratio of about 2.0. The purified RNA was successfully used in the downstream applications such as RT-PCR (Reverse Transcription PCR) and qPCR (quantitative PCR). This method could be used for RNA extraction from several other recalcitrant tree species.

Chromochloris zofingiensis is a unicellular green alga that is an emerging model species for studies in fields such as biofuel production, ketocarotenoid biosynthesis and metabolism. The recent availability of a high-quality genome assembly facilitates systems-level analysis, such as RNA-Seq. However, cells of this alga have a tough cell wall, which is a challenge for RNA purification. This protocol was designed specifically to breach the cell wall and isolate high-quality RNA suitable for RNA-Seq studies.

Gene expression is dynamically regulated on many levels, including chromatin accessibility and transcription. In order to study these nuclear regulatory events, we describe our method to purify nuclei with Isolation of Nuclei in TAgged Cell Types (INTACT). As nuclear RNA is low in polyadenylated transcripts and conventional pulldown methods would not capture non-polyadenylated pre-mRNA, we also present our method to remove ribosomal RNA from the total nuclear RNA in preparation for nuclear RNA-Seq.

Extraction of high quality RNA is an essential step for quantitative reverse transcription PCR (qRT-PCR) and microarray analysis. However, it is not easy to extract high quality RNA from fruit materials, which contain high amounts of polysaccharides, lipids and secondary metabolites. Wan and Wilkins (1994) had developed ‘Hot Borate Method’ to isolate high quality RNA. Here, we describe a modified protocol of the ‘Hot Borate Method’ to isolate high quality RNA from grape berry skin for qRT-PCR and microarray analysis (Suzuki et al., 2015a; Suzuki et al., 2015b).

Polysome profile analysis is a frequently performed task in translational control research that not only enables direct monitoring of the efficiency of translation but can easily be extended with a wide range of downstream applications such as Northern and western blotting, genome-wide microarray analysis or qRT-PCR. Here, we describe a method for the isolation and quantification of high-quality polysome-bound mRNA complexes from small quantities of liquid-nitrogen-frozen solid tissue samples of rice shoots/roots. The mRNA obtained can be further analyzed by methods that evaluate polysomal mRNA abundance at the individual transcript or global level.

mRNAs surrounded by polysomes are ready for translation into proteins (Warner et al., 1963); these mRNAs are defined as polysomal-mRNAs (Mustroph et al., 2009). The process is affected by various growth conditions or surrounding situations. Microarray analysis is a powerful tool for detecting genome-wide gene expression. Therefore, using polysomal-mRNAs for microarray analysis can reflect the gene translation information (the translatome) under different developmental stages or environmental conditions from eukaryotes. Polysomal-mRNAs can be collected from the polysomal fraction by sucrose-gradient separation for further quantitative PCR or microarray assay. We modified a protocol (Mustroph et al., 2009) for collecting polysomal-mRNAs via sucrose-gradient separation to eliminate monosomal-mRNA contamination from pLAT52:HF:RPL18 Arabidopsis. This transgenic Arabidopsis uses a pollen-specific promoter (ProLAT52) to generate epitope-tagged polysomal-RNA complexes that could be purified with a specific antigen (Lin et al., 2014). The polysomal-mRNAs we obtained via sucrose-gradient separation and antibody purification underwent in vivo translation in pollen tubes grown from self-pollinated gynoecia of Arabidopsis thaliana.

Isolation of intact, full-length high quality RNAs is essential for RNA sequencing, reverse transcription PCR analysis of gene expression as well as RNA gel blot analysis. This simple yet easy protocol is developed to meet this need; in addition to regular samples, this protocol is especially good for isolating RNAs from RNase-rich samples such as senescing leaves and ripening fruits (from which RNAs isolated using standard method are generally degraded to certain degree). The total RNA yield varies from 900 μg total RNA/g non-senescing leaves to 200 μg total RNA/g senescent leaves.