Fungal endophytes from medicinal plant Bletilla striata (Thunb.) Reichb. F. promote the host plant growth and phenolic accumulation

Abstract

Endophytic fungi are capable of increasing the growth and secondary metabolite production of medicinal plants in an ecofriendly and sustainable manner. Although these responses have been demonstrated in many plant species, they are not well understood in the medicinal plant Bletilla striata (Thunb.) Reichb.F.. Co-culture of B.striata with three endofungal isolates was carried out to evaluate the effects of endophytic fungal interaction on the plant growth and accumulation of phenols. The plant growth-promoting traits of isolated fungi were investigated, and the isolates had the ability to produce indole-3-acetic acid (IAA), siderophore and cellulolytic enzyme. The fungal strain Byssochlamys spectabilis 1-N2 co-cultured with plantlets of B. striata significantly increased certain growth properties, including shoot length by 71.40%, pseudobulbs dry weight by 52.58%, number of new roots by 5.25-fold, pseudobulbs diameter by 30.94% and improved the total phenolic content of the medicinal part by 25.41%. The fungal polysaccharide elicitor prepared from B.spectabilis 1-N2 mycelium also altered the accumulation of total phenolic content at different time points. Polysaccharide elicitor treatment significantly enhanced the accumulation of nitric oxide (NO) and salicylic acid (SA), which are involved in the plant defence response and significantly upregulated the activities of phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H) and tyrosine ammonia lyase (TAL). The findings of this study contribute to our understanding of B. striata and endophytic fungi interactions and provide vital information for the use of endophytic fungi to improve plant growth and active component accumulation in B.striata cultivation.