Page 70 - EER-2-2

Explora: Environment
and Resource Application of Algae for seed priming

Nitrogen metabolism is also significantly influenced algal extracts serve as metabolic enhancers during the
by algal priming. Algal extracts contain amino acids, germination process.
peptides, and nitrogen-rich compounds that enhance
nitrogen assimilation during early seedling development. 6. Algal priming affecting the rhizosphere
145
The upregulation of nitrate reductase and glutamine through beneficial microbiome interactions
synthetase activities in response to algal priming facilitates Algal extracts play a crucial role in fostering beneficial
the conversion of inorganic nitrogen into organic forms, microbiome interactions during seed germination,
which are essential for protein biosynthesis. The significantly enhancing seedling vigor, nutrient acquisition,
146
presence of amino acids, such as glutamine, asparagine, and resistance to soil-borne pathogens (Figure 10).
148
and proline in algal extracts provides a direct substrate The rhizosphere microbial communities associated with
for protein synthesis, ensuring rapid cell division and germinating seeds – particularly PGPR and mycorrhizal
tissue differentiation. 5,102 Priming with S. platensis extract fungi – contribute to early seedling establishment by
– known for its high protein content – has been shown
to increase total soluble protein levels in seedlings, improving nutrient bioavailability, modulating root
supporting enhanced metabolic activity and biomass architecture, and inducing systemic resistance to stress
accumulation. 123,124 Lipid metabolism also plays a critical factors. Algal-based seed priming enhances these
role during seed germination by maintaining membrane interactions by providing bioactive compounds, organic
integrity and providing additional energy storage. matter, and signaling molecules that create a favorable
149
Algal extracts supply essential fatty acids, including microenvironment for beneficial microbes. Notably,
omega-3 (α-linolenic acid) and omega-6 (linoleic acid), algal extracts contain bioactive metabolites, such as
which are fundamental for membrane biogenesis and polyphenols, flavonoids, and phlorotannins, which
structural stability. These fatty acids improve membrane exhibit antimicrobial properties that selectively suppress
fluidity and facilitate nutrient transport and signal pathogenic fungi and bacteria while allowing beneficial
transduction processes necessary for cellular expansion microbes to thrive. For example, seed priming with
and division. 107,108 Furthermore, sterols and phospholipids S. wightii extract has been shown to reduce the incidence
present in algal extracts enhance mitochondrial stability, of fungal pathogens, such as Fusarium and Rhizoctonia,
150
thereby optimizing ATP synthesis through oxidative both of which are major threats to seedling survival.
phosphorylation. Extracts from D. salina, S. platensis, and Simultaneously, the bioactive compounds present in brown
N. oculata have been reported to improve seedling vigor and red algae create a conducive environment for PGPR
by enriching lipid profiles that support cellular function species, such as Azospirillum, Pseudomonas, and Bacillus,
under varying environmental conditions. 28,105,106 which enhance nitrogen fixation and produce growth-
promoting phytohormones, such as IAA. 151,152
In addition to supporting macronutrient metabolism,
algal priming also modulates secondary metabolic Algal priming also facilitates mycorrhizal symbiosis, a
pathways that safeguard and sustain primary metabolism. crucial interaction during early seedling development that
Algal extracts are rich in polyphenols, flavonoids, and improves phosphorus and water uptake. Many algal extracts
carotenoids, which act as antioxidants, protecting contain compounds that mimic plant signaling molecules,
metabolic intermediates from oxidative damage. These such as strigolactones, which stimulate mycorrhizal
153
bioactive compounds help maintain cellular redox balance, spore germination and hyphal branching. Seaweed
ensuring uninterrupted progression of glycolysis, the TCA and microalgal-derived compounds have been reported
cycle, and amino acid biosynthesis. Sulfur metabolism to enhance AMF colonization in root tissues, leading
3,4
also contributes to primary metabolic regulation, as to improved nutrient absorption and stress tolerance in
sulfur-rich microalgae, such as C. vulgaris enhance germinating seeds. This symbiotic interaction is particularly
glutathione biosynthesis—an essential antioxidant beneficial under nutrient-deficient or drought-stressed
defense mechanism. The presence of sulfur-containing conditions, where mycorrhizal fungi help extend the root’s
147
amino acids, such as methionine and cysteine in algal absorptive surface area. Furthermore, algal extracts
154
extracts further supports protein synthesis and enzymatic influence microbial quorum sensing, a communication
functions essential for metabolic stability. 5,102 Collectively, mechanism used by bacteria to regulate gene expression and
the regulatory effects of algal priming on primary biofilm formation. Sulfated polysaccharides and specific
metabolism establish a favorable biochemical environment secondary metabolites in algae act as quorum-sensing
that promotes seedling establishment and early growth. By modulators, allowing beneficial microbes to coordinate
modulating carbohydrate hydrolysis, nitrogen assimilation, their activities in response to metabolic cues during seed
lipid biosynthesis, and antioxidant defense mechanisms, germination. This interaction supports the persistence

Volume 2 Issue 2 (2025) 17 doi: 10.36922/EER025120025