Goñi et al., (2016) Journal of Agricultural and Food Chemistry 64(14)
Comparative Transcriptome Analysis of Two Ascophyllum nodosum Extract Biostimulants: Same Seaweed but Different
https://pubs.acs.org/doi/abs/10.1021/acs.jafc.6b00621
Summary
Ascophyllum nodosum, a type of brown seaweed, is renowned for being extensively researched and remarkable biostimulating properties. These properties have made it a widely used component in various biostimulant products. But not all Ascophyllum nodosum products are made the same nor do they elicit the same stimulating effects to crops.
Our scientist at Brandon Bioscience have formulated two unique proprietary extraction process for our Ascophyllum nodosum biostimulants. One extracted at neutral pH, using an aqueous process (ANE A), the other using an alkaline process at an alkaline pH (ANE B). These biostimulants are used to enhance the growth, quality, and stress tolerance of plants. Despite being sourced from the same seaweed, the two biostimulants have distinct effects on plants. Our scientists conducted a comparative investigation of the transcriptomes of the two biostimulant products. The study aims to understand the molecular mechanisms underlying these differences.
Initially, we performed a chemical compositional analysis to quantify the overall solid content in the ANE samples. Our findings indicated that ANE B exhibited a greater solid content and higher polyphenol levels, while ANE A displayed a higher concentration of bioactive seaweed carbohydrates. These results highlight that the total solid content alone does not serve as an accurate indicator of the chemical composition.
Next, general growth test were preformed to investigate the effects the ANEs had on phenotypic traits using Arabidopsis thaliana, a model plant. Results proved the capability of the biostimulants to enhance plant growth and development. Increased rosette numbers and longer stems highlighted the ANEs influence over vegetative growth, while inducing earlier flowering signalled the impact of adding biostimulants had on reproductive growth.
Delving into the molecular framework, we conducted transcriptome analysis on 21-day-old plants. The results revealed that ANE A caused dysregulation in the expression of approximately 4.47% of the total genes, with an upregulation of 599 genes and a downregulation of 412 genes. The Mapman data illustrated an overrepresentation of transcriptome changes in genes associated with transport, signaling, carbohydrate metabolism, and lipid metabolism.
In contrast, ANE B induced dysregulation in the expression of about 0.87% of the total genes, upregulating 127 genes, of which 98 were common with ANE A, and downregulating 69 genes, with 64 of them overlapping with ANE A. The Mapman data indicated an overrepresentation of transcriptome changes in genes related to sulfur assimilation, nitrogen metabolism, and nucleotide metabolism.
When we examined defense genes, ANE A exhibited a higher expression of dysregulated defense genes, with 78 stress-related genes being affected, as opposed to 18 stress-related genes in ANE B.
Moreover, we performed a Principal Component Analysis (PCA) to investigate the connection between gene expression and chemical composition. Our analysis revealed that fluctuations in the levels of fucoidan, laminarin, and mannitol were associated with the dysregulation of five commonly expressed genes. Notably, as the concentration of these bioactive compounds increased, so did the expression of these genes. This finding underscores the notion that the variations in the biostimulant effects of the products may, in part, be attributed to their chemical composition.
In summary, the paper investigates the molecular differences between two biostimulant products derived from the same seaweed species, Ascophyllum nodosum, to understand why they have different effects on plants. Through transcriptome analysis, the study identifies gene expression variations that contribute to the distinct outcomes of these biostimulants. The findings provide insights into the molecular mechanisms underlying their divergent impacts on plant growth and stress tolerance.
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