Rapid bioassays to evaluate the plant growth promoting activity of Ascophyllum nodosum (L.) Le Jol. using a model plant, Arabidopsis thaliana (L.) Heynh

Abstract

Ascophyllum nodosum extract products are used commercially in the form of liquid concentrate and soluble powder. These formulations are manufactured from seaweeds that are harvested from natural habitats with inherent environmental variability. The seaweeds by themselves are at different stages of their development life-cycle. Owing to these differences, there could be variability in chemical composition that could in turn affect product consistency and performance. Here, we have tested the applicability of using Arabidopsis thaliana as a model to study the activity of two different extracts from A. nodosum. Three different bioassays: Arabidopsis root-tip elongation bioassay, Arabidopsis liquid growth bioassay and greenhouse growth bioassay were evaluated as growth assays. Our results indicate that both extracts promoted root and shoot growth in comparison to controls. Further, using Arabidopsis plants with a DR5:GUS reporter gene construct, we provide evidence that components of the commercial A. nodosum extracts modulates the concentration and localisation of auxins which could account, at least in part, for the enhanced plant growth. The results suggest that A. thaliana could be used effectively as a rapid means to test the bioactivity of seaweed extracts and fractions.

Effect of seaweed saps on growth and yield improvement of green gram

“…Apart from the above organic and inorganic constituents, there is an evidence of existence of different other stimulatory and antibiotic substances. These findings are in agreement with Jeannin et al (1991), Vernieri et al (2005), Kowalski et al (1999), Zhang and Ervin (2008), Mancuso et al (2006), Norrie and Keathley (2006) and Rayorath et al (2008). Thus, being a wealthy source of versatile plant nutrients, phytohormones, amino acids, vitamins, stimulatory and antibiotic substances, the liquid sea weed extract enhances root volume and proliferation, bio-mass accumulation, plant growth, flowering, distribution of photosynthates from vegetative parts to the developing fruits and promotes fruit development, reduces chlorophyll degradation, disease occurrence etc.…”

Agricultural uses of plant biostimulants

“…Recent studies have shown enhanced growth and yield in agricultural and horticultural crops such as wheat (Kumar and Sahoo 2011), winter rapeseed (Jannin et al 2013), apple (Malus domestica) (Basak 2008), strawberry (Alam et al 2013), tomato (Kumari et al 2011;Zodape et al 2011), spinach (Fan et al 2013), okra (Zodape et al 2008), olive (Olea europaea) (Chouliaras et al 2009), broccoli (Mattner et al 2013), and geranium (Pelargonium spp) (Krajnc et al 2012). Root and shoot growth of the model plant Arabidopsis was also enhanced by treatment with algal extracts (Rayorath et al 2008). Leaf chlorophyll content was increased following seaweed extract application in a number of studies (Blunden et al 1997;Mancuso et al 2006;Sivasankari et al 2006;Spinelli et al 2010;Fan et al 2013;Jannin et al 2013).…”

“…These extracts are reported to act as chelators, improving the utilization of mineral nutrients by plants and improving soil structure and aeration, which may stimulate root growth (Milton 1964). Seaweed extracts also act as biostimulants, enhancing seed germination and establishment, improving plant growth, yield, flower set and fruit production, increasing resistance to biotic and abiotic stresses, and improving postharvest shelf life (Mancuso et al 2006;Norrie and Keathley 2006;Hong et al 2007aHong et al , 2007bRayorath et al 2008;Khan et al 2009;Craigie 2011;Mattner et al 2013). The biostimulant effects often have been attributed to the presence of plant growth hormones and related low molecular weight compounds present in the extracts (Stirk and van Staden 1997;Tarakhovskaya et al 2007), but other research suggests that larger molecules including unique polysaccharides and polyphenols may also be important as biostimulants, as allelochemicals, and for enhancing resistance to stress (Klarzynski et al 2003;Zhang et al 2006;Rioux et al 2007;González et al 2013).…”

“…Plant nutrient uptake, growth, and yield Studies have shown that foliar application of seaweed extract leads to enhanced root development in a variety of species, including maize (Jeannin et al 1991), tomato (Crouch and van Staden 1992), Arabidopsis (Rayorath et al 2008), grape (Mancuso et al 2006;Mugnai et al 2008), strawberry (Alam et al 2013), winter rapeseed (Jannin et al 2013), Norway spruce (Picea abies) (Slávik 2005), and lodgepole pine (Pinus contorta) (MacDonald et al 2012). Increases in lateral root formation (Vernieri et al 2005), total root volume (Slávik 2005;Mancuso et al 2006), and root length (Zodape et al 2011) have been observed and attributed to the presence of phytohormones such as auxins and cytokinins in seaweed extracts (Khan et al 2011a(Khan et al , 2011b.…”

Efeitos do extrato de Ascophyllum nodosum sobre o desenvolvimento e produção de cultivos

“…Tabela 1 -Efeito das doses (mL) do extrato de A. nodosum sobre o crescimento radicular diário (CR), em centímetros (cm), de plântulas do milho 'Impacto' em rizotrons , do primeiro (D1) ao décimo dia de avaliação ( , 1947;OLSEN et al, 1998) e, para tal, foi identificado que uma amilase independente da giberelina é induzida pelo extrato de A. nodosum (RAYORATH et al, 2008b).…”