Overcoming Polysaccharides and Polyphenols: Improving Plant DNA and RNA Extraction Reliability

Abstract

Plant nucleic acid extraction is rarely a one protocol fits all process. In routine laboratory work, many laboratories encounter recurring problems such as low yield, highly viscous lysates, or poor downstream performance when working with plant samples. In most cases, these issues can be traced back to polysaccharides and polyphenols naturally present in plant tissues ^[1].

Although both are common plant derived inhibitors, polysaccharides and polyphenols affect DNA and RNA extraction in fundamentally different ways. Understanding these differences is essential for selecting appropriate extraction workflows and achieving reproducible results across diverse plant materials ^[2].

Two Common Inhibitors, Two Distinct Challenges

Polysaccharide Rich Plant Samples

Polysaccharides are frequently encountered in soybean and other legumes, seaweed and algae, starch rich crops such as potato and cassava, as well as dry or powdered seeds. These compounds significantly increase lysate viscosity and tend to co precipitate with nucleic acids, reducing binding efficiency and interfering with washing steps.

Even when nucleic acid concentration appears sufficient, residual polysaccharides often inhibit PCR, qPCR, and sequencing reactions, leading to misleading quality assessments.

Polyphenol Rich Plant Samples

Polyphenols are abundant in cotton leaves and bolls, woody plant tissues, medicinal plants, fruits, and some vegetables. During extraction, polyphenols oxidize readily and bind irreversibly to nucleic acids. This typically results in dark colored lysates, nucleic acid degradation, and poor downstream performance.

This effect is particularly problematic for RNA extraction, where oxidation reactions and endogenous RNase activity further compromise RNA integrity and reproducibility.

Representative Inhibitor Rich Plant and Non Plant Sample Categories

Table. Representative inhibitor rich sample categories validated in nucleic acid extraction workflows

Figure. Representative inhibitor rich plant and non plant sample categories commonly encountered in nucleic acid extraction workflows. Polysaccharide rich materials, polyphenol rich tissues, and fungal samples frequently require specialized extraction strategies to achieve reproducible results.

Why Plant RNA Extraction Is Especially Challenging

Compared with DNA, plant RNA extraction from inhibitor rich samples is significantly more difficult. RNA is inherently sensitive to oxidation and RNase activity ^[3], and the presence of polysaccharides and polyphenols further amplifies these effects during extraction.

Repeated protocol tuning quickly becomes impractical in routine workflows. Laboratories attempting to optimize methods manually often need to prepare additional reagents, adjust lysis chemistry, and repeatedly modify purification steps for different plant species. This trial and error approach is time consuming, difficult to standardize, and often inconsistent.

For these reasons, many laboratories gradually move away from repeated manual optimization and instead adopt more standardized extraction chemistries. Automated magnetic bead based RNA workflows are increasingly used to reduce variability while maintaining broad sample compatibility.

Choosing the Right Workflow Based on Sample Characteristics

For particularly difficult plant samples, especially those with extremely high polysaccharide content or highly viscous lysates, manual column based extraction workflows are often preferred. These approaches tolerate extreme viscosity more effectively and allow hands on adjustment during processing.

For laboratories handling large numbers of plant samples from diverse sources, automated magnetic bead based workflows offer clear advantages. Standardized automation reduces operator dependent variation and improves overall consistency. However, extremely viscous samples may still exceed the practical limits of magnetic bead handling.

Recommended Workflows

• GDP441 – Column Based Plant RNA Extraction Kit
  Suitable for extremely difficult or highly viscous plant samples
• GDP672 – Magnetic Bead–Based Plant RNA Extraction Kit
  Designed for standardized, high throughput extraction across diverse plant materials

References

1. Doyle JJ, Doyle JL. Rapid and efficient isolation of high quality nucleic acids from plant tissues rich in polyphenols and polysaccharides. BMC Biology. 2010;8:95.

2. Kumar S, et al. DNA free high quality RNA extraction from difficult plant species. Plant Methods. 2023.

3. Gopinath SCB, et al. RNA stability: structural features and environmental conditions. Molecules. 2024;29(24):5978.