Algal peptides: diversity, roles, relation to plant peptide science, and applications in crop improvement

Algae are an emerging and promising source of bioactive peptides, with significant potential in biotechnology and agriculture. As the predecessors of photosynthetic life in water (aquatic plants) and on land, algae share evolutionary similarities with land plants, particularly in their peptide signaling systems. These similarities provide valuable insights into the evolution and diversification of peptide systems in terrestrial plants. Bioactive peptides derived from algae are identified to have several properties, like antimicrobial, antifungal, antiinflammatory, antiproliferative, antiviral properties, etc. Due to such diverse functions, they could have potential applications in plant science and agriculture as well. Though the application of algal extracts in agriculture is widely studied, the use of algal protein hydrolysates and their peptides remains underexplored. Therefore, this chapter provides an overview of algal peptides, their features and their applications in plant science. It discusses the unique features of algal peptides, such as structural diversity, processing methods like extraction, purification, and characterization, functional diversity, and their mode of action. Additionally, the chapter discusses the applications of algal extracts and peptides in agriculture. Furthermore, this chapter introduces the evolutionary relationship between algal and plant peptides, with specific examples from the literature. The chapter also outlines how modern techniques could be helpful to unlock the peptide evolution. In addition, challenges in the production and commercialization of algal peptides are discussed here. Finally, the future possibilities to improve algal peptide scale-up through genetic engineering techniques and how algal peptides can be integrated into sustainable agricultural practices are introduced here.