Molecular Microbiology Research 2024, Vol.14, No.5, 226-235 http://microbescipublisher.com/index.php/mmr 228 sequencing has been employed to explore the composition and diversity of endophytic fungi in Alpinia zerumbet seeds, identifying a wide range of taxa and functional guilds (Yan et al., 2022). Combining culturing with molecular techniques, such as 16S rDNA sequencing and terminal restriction fragment length polymorphism (TRFLP), can provide a more comprehensive understanding of endophyte communities. This integrated approach was used to study the seed endophytes of Zea, showing that a core microbiota is conserved across different genotypes and geographical locations (Oita et al., 2021). These molecular and genomic methods are indispensable for characterizing the full spectrum of endophytic diversity and understanding their ecological roles and potential applications. 4 Functional Roles of Seed-Associated Endophytes Seed-associated endophytes play crucial roles in the growth, development, and health of plants. These microorganisms, which include bacteria and fungi, are vertically transmitted from one generation to the next, ensuring their presence in the early stages of plant development. The functional roles of these endophytes can be categorized into several key areas: enhancement of seed germination and vigor, protection against pathogens, and nutrient acquisition and symbiosis. 4.1 Enhancement of seed germination and vigour Seed-associated endophytes significantly contribute to the enhancement of seed germination and vigor. These microorganisms can produce phytohormones such as auxins and gibberellins, which promote seed germination and seedling growth (Truyens et al., 2015; Langill et al., 2023). For instance, the presence of endophytes in seeds of Noccaea caerulescens has been shown to increase germination rates and plant size, highlighting their role in early plant development. Additionally, endophytes can improve seedling establishment by enhancing root growth and nutrient uptake, which are critical for the early stages of plant growth (Rodríguez et al., 2020). 4.2 Protection against pathogens 4.2.1 Production of antimicrobial compounds Endophytes can produce a range of antimicrobial compounds that inhibit the growth of pathogenic microorganisms. These compounds include antibiotics, enzymes, and secondary metabolites that target specific pathogens (Shahzad et al., 2018; Yan et al., 2022). For example, endophytic fungi such as Alternaria and Fusarium, found in Alpinia zerumbet seeds, produce antimicrobial compounds that can act as biocontrol agents against plant pathogens. 4.2.2 Induction of systemic resistance Endophytes can induce systemic resistance in plants, enhancing their ability to defend against pathogens. This process involves the activation of the plant's immune system, leading to the production of defense-related proteins and compounds (Rodriguez et al., 2009; Shahzad et al., 2018). The presence of endophytes in seeds can prime the plant's immune system, providing long-term protection against a range of pathogens. 4.2.3 Competitive exclusion of pathogens Endophytes can also protect plants by occupying ecological niches within the seed and plant tissues, thereby preventing the colonization of pathogenic microorganisms. This competitive exclusion is a crucial mechanism by which endophytes maintain plant health (Truyens et al., 2015). For instance, the core microbiota of endophytes conserved in Zea seeds across different genotypes can outcompete potential pathogens, ensuring the plant's health and productivity. 4.3 Nutrient acquisition and symbiosis Seed-associated endophytes play a vital role in nutrient acquisition and symbiosis, which are essential for plant growth and development. These microorganisms can solubilize phosphate, fix nitrogen, and sequester iron, making these nutrients more available to the plant. For example, endophytes isolated fromZea seeds have shown the ability to solubilize phosphate and produce acetoin/butanediol, which are important for plant growth.
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