Seed associated bacterial and fungal endophytes: Diversity, life cycle, transmission, and application potential

Exponential upsurge in the global population growth rate claims sustainable means to fulfill their food requirements. Therefore, the collaboration of beneficial microorganisms with their host plants have been of interest for years as these associations can be helpful in the development of sustainable agriculture. However, the endophytic microorganisms develop a strong and persistent interaction with the host plants compared to epiphytic microbes. The origin of plant-associated endophytes was supposed to be from seeds as the endophytic microbes were found inside seeds of several plant species although, endophytes do not necessarily come from seeds only but can also enter the roots or other parts during plant growth. In any case, the richness of seed with the microbes and their dynamics can edify innovative research potentials in the field of plant-microbe associations. Yet, the seed microbiome is often underrepresented in plant microbial studies and is least studied up till now compared to phyllospheric or rhizospheric microbial population. The revival of exploring the seed microbiome is stimulating new insights related to the dynamics and diversity of seed microbiome along with their interconnectedness with the soil and plant microbial community as well as the microbes associated with pollinators and dispersers. This review is an effort to acknowledge the research on seed associated microbial community including bacteria and fungi. It focuses on ecology of seed microbiome from sources to diversity, their association with the host plant, and their life cycle including mode of colonization, localization, and transmission. Both the horizontal and vertical means of transmission have been discussed in this paper whereas the significance of vertical transmission for rapid infection of beneficial microbial community to next generations of plants through seeds is emphasized. Moreover, the applications of seed endophytes for growth promotion of plants, as biocontrol agents and in phytoremediation are discussed. Finally, the association of seed endophytes with seed quality is linked.

Automated summary

The interaction between seed-associated microbes and host plants plays a significant role in promoting plant growth and can be crucial for the sustainability of agriculture. The potential of seed microbiome research is immense, yet often overlooked compared to other plant microbial studies. The complex life cycle and transmission dynamics of seed-associated microbes provide ample research opportunities for exploring their impact on plant health and development.