Beneficial biota or bugs of burden?

The microbial dilemma at the heart of seed conservation

OPINION

By Abdul Shango

Research Associate – Seed Quality and Conservation

Office location: Arusha, Tanzania

Abelmoschus esculentus – okra, Uli Westphal, 2024

When we store seeds in genebanks, we store plant life. But sometimes the seeds host additional lifeforms – such as microbes both good and bad.

Fungi like Fusarium or Aspergillus can threaten germination, while others support early root development, enhance stress tolerance, or offer protection against soil pathogens. Together, they form an invisible ecology; asleep while the seed is in cold storage but ready to awaken when the conditions are right.

As a seed scientist at the World Vegetable Center’s Regional Genebank in Arusha, Tanzania, my colleagues and I have spent countless hours examining the microbial life that lies dormant beneath the seed coat.

This hidden world became the focus of one of our recent studies, in which we explored the prevalence of seed-borne fungi in conserved soybean. While the cool, dry storage conditions preserved seed viability (germination rate) relatively well, it also preserved potentially devastating fungi. Sordaria, Mucor, Fusarium, and others, were all quietly awaiting their moment – these fungi can cause root rot, poor seedling growth and reduced yields.

Sterilizing the surface of the seed could mitigate their spread, but only up to a point: These fungi have adapted to survive and, in some cases, returned with vigor when conditions shifted.

In a follow-up study on okra – yet to be published – we tested various seed health treatments to reduce fungal incidence. The idea was simple: eliminate the bad guys before they wake up. But while dramatically curbing fungal growth, all the treatments  saw seed viability and seed longevity drop significantly.

That was sobering because for genebanks, germination and longevity are sacred. A seed that cannot grow is a loss not just of a plant, but potentially of a lineage, a variety, or a future solution to climate challenges or food insecurity. But if we over-sterilize seeds, we risk losing opportunities for sustainable pest management and nutrition enhancement. At the same time, if we allow contaminated seeds to go unchecked, we risk distributing seed-borne pathogens across borders or damaging trust in both genebanks and seed systems more broadly.

So, what’s the path forward?

Abdul Shango, Research Associate – Seed Quality and Conservation

For me, this is where the One Health approach serves as a compass. The idea that plant health, human health, and environmental health are inseparable is not theoretical in a genebank—it’s lived reality.

It means we need more research into the functional roles of seed-associated microbes, as well as learning more about how seeds and their associated microbiomes perform under different environmental conditions. After all, we can’t protect what we don’t fully understand. We also need to develop seed treatment protocols to preserve beneficial microorganisms while eliminating harmful ones, together with exploring gentler, less chemically harsh seed health treatments.

Importantly, it also means we should change the narrative about seeds: They are not sterile objects, nor should they be. They are complex ecosystems. Protecting them is about more than viability percentages—it’s about preserving both seed longevity and the delicate microbial relationships that can help plants thrive. In doing so, we protect not just the future of agriculture, but the health of soils, people, and the planet.