Endophytic Fungi of Native Salvia abrotanoides Plants Reveal High Taxonomic Diversity and Unique Profiles of Secondary Metabolites.

Yeganeh Teimoori-Boghsani,Henry Müller,Ali Ganjeali,Gabriele Berg,Javad Asili,Tomislav Cernava

doi:10.3389/fmicb.2019.03013

Abstract

Endophytic fungi are often embedded in their host’s metabolic networks, which can result in alterations of metabolite production and higher amounts of active compounds in medicinal plants. This study reports the occurrence, diversity, and secondary metabolite profiles of endophytic fungi isolated from Salvia abrotanoides plants obtained from three geographically distinct sites in Iran. A total of 56 endophytic fungi were isolated from roots and leaves of S. abrotanoides; site-specificity and root-dominated colonization was found to be a general characteristic of the endophytes. Based on molecular identification, the endophytic fungi were classified into 15 genera. Mycelial extracts of these isolates were subjected to high-resolution mass spectrometry analyses and revealed a broad spectrum of secondary metabolites. Our results demonstrated that Penicillium canescens, P. murcianum, Paraphoma radicina, and Coniolariella hispanica are producers of cryptotanshinone, which is a main bioactive compound of S. abrotanoides. Moreover, it was shown that it can be produced independent of the host plant. The effect of exogenous gibberellin on S. abrotanoides and endophytic fungi was shown to have a positive effect on increasing the cryptotanshinone production in the plant as well as in endophytic fungi cultivated under axenic conditions. Our findings provide further evidence that endophytic fungi play an important role in the production plant bioactive metabolites. Moreover, they provide an exploitable basis to increase cryptotanshinone production in S. abrotanoides.

Highlights

Plants can be considered as holobionts that are embedded in multiple mutualistic networks connecting them with the environment and microbial communities of varying structure and diversity (Vandenkoornhuyse et al, 2015)
The results revealed isolate-specific secondary metabolite profiles, e.g., illustrated by distinct spectra obtained with Penicillium isolates
We identified a broad range of well-studied fungal secondary metabolites as well as such that were not yet described in fungi, e.g., cryptotanshinone a major bioactive diterpenoid previously isolated from Salvia species

Summary

Introduction

Plants can be considered as holobionts that are embedded in multiple mutualistic networks connecting them with the environment and microbial communities of varying structure and diversity (Vandenkoornhuyse et al, 2015). Secondary Metabolites of S. abrotanoides Endophytes bioactive compounds (Gunatilaka, 2006). Previous studies have shown that endophytic microbial communities within medicinal plants have a great potential as producers of novel bioactive compounds and have a high potential for agricultural, pharmaceutical, and other applications (Köberl et al, 2013; Rai et al, 2014). It is known that endophytes can produce distinct host plant metabolites or their precursors; e.g., taxol (Stierle et al, 1993), comptothecin (Kusari et al, 2009), azadirachtin (Kusari et al, 2012), tanshinone I/IIA (Ming et al, 2012), and maytansine (Wings et al, 2013). Despite the evident potential to improve the availability of active compounds for diverse health issues, plant-endophyte interactions and their metabolic interplay in medicinal plants are not yet fully understood

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