Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves

Abstract

Plant volatiles play a major role in plant–insect interactions as defense compounds or attractants for insect herbivores. Recent studies have shown that endophytic fungi are also able to produce volatiles and this raises the question of whether these fungal volatiles influence plant–insect interactions. Here, we qualitatively investigated the volatiles released from 13 endophytic fungal species isolated from leaves of mature black poplar (Populus nigra) trees. The volatile blends of these endophytes grown on agar medium consist of typical fungal compounds, including aliphatic alcohols, ketones and esters, the aromatic alcohol 2-phenylethanol and various sesquiterpenes. Some of the compounds were previously reported as constituents of the poplar volatile blend. For one endophyte, a species of Cladosporium, we isolated and characterized two sesquiterpene synthases that can produce a number of mono- and sesquiterpenes like (E)-β-ocimene and (E)-β-caryophyllene, compounds that are dominant components of the herbivore-induced volatile bouquet of black poplar trees. As several of the fungus-derived volatiles like 2-phenylethanol, 3-methyl-1-butanol and the sesquiterpene (E)-β-caryophyllene, are known to play a role in direct and indirect plant defense, the emission of volatiles from endophytic microbial species should be considered in future studies investigating tree-insect interactions.

Enhancement of β-Caryophyllene Biosynthesis in Saccharomyces cerevisiae via Synergistic Evolution of β-Caryophyllene Synthase and Engineering the Chassis

“…Phytoextraction is presently the main production route of β-caryophyllene; thus, β-caryophyllene synthases from various plants have been getting attention previously. ,− Among them, β-caryophyllene synthase of A. annua was widely used for heterologous β-caryophyllene synthesis in different chassis cells due to the relatively high level of β-caryophyllene compared with other plants. ,,,, With the development of genome data mining in recent years, other genes encoding β-caryophyllene synthase were reported, such as those from plant endophyte Cladosporium sp. and Folsomia candida . Because of the relatively close relationship, we speculated that β-caryophyllene synthases originated from fungi might have higher activity when expressed in S. cerevisiae .…”

“…and Folsomia candida. 36 Because of the relatively close relationship, we speculated that β-caryophyllene synthases originated from fungi might have higher activity when expressed in S. cerevisiae. Thus, the encoding sequence of β-caryophyllene synthases from Cladosporium sp.…”