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Explora: Environment
and Resource Application of Algae for seed priming

3.3. Proteins and amino acids leading to enhanced metabolic readiness for germination.

Algal extracts provide essential amino acids, such as In addition, algal-derived antioxidants help mitigate
glutamate, proline, and methionine, which are vital oxidative stress during the early stages of seedling
for protein synthesis and stress adaptation in seeds. establishment. The subsequent sections will delve into
the key mechanisms by which algal extracts exert their
Proline, in particular, functions as an osmoprotectant, priming effects.
helping seeds withstand drought and salinity stress
during germination. 5,102 In addition, microalgal proteins 4.1. Enhancing water uptake and hydration
contribute to nitrogen metabolism, enhancing seedling
growth and vigor. 103 Algal extracts enhance water uptake and hydration during
seed priming through multiple synergistic mechanisms,
3.4. Polyphenols and antioxidants ensuring efficient imbibition, reducing imbibitional
damage, and promoting uniform germination (Figure 4).
Seaweeds and microalgae are rich in polyphenolic One key pathway involves their rich composition of
compounds, such as flavonoids, phenolic acids, and polysaccharides, such as alginate, fucoidan, laminarin,
tannins, which exhibit strong antioxidant properties. These and carrageenan, which function as hydrophilic agents
compounds mitigate oxidative stress in seeds by scavenging that improve seed water absorption and retention. These
reactive oxygen species (ROS), thereby protecting cellular polysaccharides form a protective gel-like layer around
structures and improving overall seed viability. Algal- seeds, preventing rapid dehydration and maintaining
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derived polyphenols from Sargassum and Gracilaria moisture availability. 86,88 For example, A. nodosum, a
species have been found to boost seed germination and brown seaweed, is known for its high alginate content,
early seedling growth under abiotic stress conditions. 83,104 which enhances water-binding capacity, while U. lactuca,

3.5. Fatty acids and lipid metabolites a green seaweed, produces sulfated polysaccharides that
improve seed coat permeability, allowing for faster water
Certain algal species produce beneficial fatty acids, uptake. 4,96,115 In addition, algal bioactive compounds
including omega-3 and omega-6 PUFAs, which contribute modify the seed coat structure, making it more permeable
to membrane stability and stress resistance in germinating and facilitating uniform hydration. Microalgae, such as C.
seeds. 105,106 Microalgae, such as Spirulina and D. salina vulgaris release bioactive exopolysaccharides that improve
are known for their lipid-rich composition, which aids in seed coat flexibility, while K. alvarezii, a red seaweed,
energy supply during early seedling growth. 107,108 contains carrageenan that softens the seed coat, further

3.6. Vitamins and essential minerals enhancing water absorption. 72,116
Algal extracts contain a variety of vitamins, including Another crucial mechanism involves the activation
Vitamin C, Vitamin E, and B-complex Vitamins, which of aquaporins – specialized water-channel proteins that
play crucial roles in enzymatic reactions and metabolic regulate water transport across cell membranes. Algal-
pathways in seeds. 109,110 In addition, macroalgae and derived phytohormones, particularly GAs, and cytokinins,
microalgae supply essential minerals, such as iron, zinc, play a vital role in upregulating aquaporin gene expression,
selenium, and magnesium, which enhance enzymatic leading to rapid water influx into the embryo and
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activities and promote nutrient uptake in seedlings. 111,112 endosperm. For example, S. platensis is rich in cytokinins
that enhance aquaporin activity, ensuring efficient water
3.7. Secondary metabolites and stress modulators uptake, while brown algae, such as Laminaria, Sargassum,
Turbinaria, Spatoglossum, Rosenvingea, and Chnoospora
Algae also produce unique secondary metabolites, such as contain GAs that facilitate aquaporin activation, reducing
betaines, sterols, and alkaloids, which contribute to stress the lag phase in seed germination. 77,81 Moreover, algal
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tolerance and seedling vigor. These compounds help in extracts mitigate imbibitional damage and cell membrane
osmotic adjustment, reinforce plant cell walls, and activate rupture caused by sudden water influx by supplying
defense-related genes, thereby enhancing resistance to osmoprotectants, such as betaines and proline, which
environmental challenges. 114 stabilize cellular structures and allow gradual water

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4. Mechanistic insights into algal extract- absorption. D. salina, a microalga, is known for its
mediated seed priming high betaine content, which protects seeds from osmotic
stress during hydration, while G. edulis, a red seaweed,
Algal extracts are rich in bioactive compounds, and these contains proline that prevents osmotic shock, leading
molecules improve water uptake, activate enzymatic to synchronized germination. 118,119 Together, these
machinery, and modulate stress-responsive pathways, mechanisms contribute to improved seed hydration

Volume 2 Issue 2 (2025) 11 doi: 10.36922/EER025120025