Frankia‑actinorhizal symbiosis: a non‑chemical biological assemblage for enhanced plant growth, nodulation and reclamation of degraded soils

Actinorhizal symbiosis naturally harbours beneficial categories of diverse plant growth promoting microorganisms (PGPMs),
including the Frankia species. The beneficial microorganisms can be used as efficient, non-chemical and sustainable alterna
tives for adopting effective soil restoration programmes and revegetation schedules in chemical and industrial-contaminated
sites, including treating degraded lands contaminated with toxic chemicals and pesticides. It has been proposed that the
interactions between the microbial gene pool are of immense agricultural significance that would facilitate an improvement in
the health, hygiene and nutrient acquisition pathway of native soil. The present review is focused on exploiting the hitherto
unexplored Frankia-actinorhizal symbiosis with due interest for their application in soil restoration programmes, including
the reclamation of degraded lands. This opens up new insights for the development of sustainability in forestry and plantation
research. Additionally, it would promise an improvement in plant growth and vigour, hygiene, and other parameters related
to crop yield, such as plant biomass, root/shoot ratio, crop yield, and so on. Novel and putative microorganisms isolated
from the actinorhizal may be used for bio-transformation of allelochemicals and toxic heavy metals into compounds with
modified biological properties, opening up novel avenues for mediating microbial degradation of putative allelochemicals
that would otherwise accumulate at phytotoxic levels in soil. Endophyte-host specificities, the phylogeny of Frankia, and
the conservation of unique endemic plant genetic resources like actinorhizal plants, are of paramount significance in the
advancement of genomics, metabolomics and phenomics