Jidongwangia sp. JTT04 as a novel bioinoculant: promoting growth and modulating the metabolic profile of Ashwagandha (Withania somnifera (L.) Dunal)

Abstract

Despite the medicinal importance of Withania somnifera (L.) Dunal (Ashwagandha), a significant knowledge gap remains regarding how endophytic microbes mechanistically reprogram host metabolism to enhance both growth and biological value. This study addresses this gap by exploring the biofortification capacity of Jidongwangia sp. JTT04, a newly isolated endophytic actinobacterium from Tribulus terrestris, in enhancing the growth, biochemical profile, and functional properties of Ashwagandha. Inoculation with JTT04 significantly improved shoot biomass and enhanced carbon assimilation provides the essential precursors for primary metabolism, driving a significant surge in glucose, fructose, and starch. These carbohydrates serve as the carbon skeleton for the accelerated synthesis of organic acids (citric and succinic) and amino acids, alongside an enriched pool of saturated and unsaturated fatty acids. This robust primary metabolic foundation subsequently fuels the shikimate and phenylpropanoid pathways, triggering the overproduction of high-value secondary metabolites, including phenolic acids (caffeic, rosmarinic) and flavonoids (rutin, kaempferol). Consequently, this integrated metabolic redirection directly translates into superior biochemical and functional values, evidenced by a 1.51-fold increase in antioxidant capacity (FRAP), potent anti-inflammatory effects (Cyclooxygenase-2 (COX-2) and lipoxygenase (LOX) inhibition), and broad-spectrum antibacterial activity. By mechanistically linking nutrient assimilation to biological value, JTT04 offers a transformative strategy for the sustainable biofortification of Ashwagandha.