The plant endophytic fungus Cyanodermella asteris produces the phytohormone jasmonic acid.

Abstract

Background: Cyanodermella asteris is a fungal endophyte from Aster tataricus that produces plant hormones as well as a range of specialized metabolites. The aim of our study was to explore the potential of this endophytic fungus towards plant hormones besides the auxin indole-3-acetic acid which we recently identified.

Results: Here, we identified another hormone, jasmonic acid (JA), from culture medium extracts by LC-MS/MS and NMR. JA was also found in the hyphal fraction, but its de novo biosynthesis could not be stimulated by linolenic acid, a known precursor for JA biosynthesis in plants. The growth of C. asteris in media was not inhibited by JA. Only at high concentrations of 1 mM, an inhibition of biomass production was recorded. Putative genes encoding enzymes for JA biosynthesis were identified in the genome, and expression analyses showed an induction of one thioester hydrolase, possibly catalyzing saponification of JA-CoA to free JA. We also investigated its interaction with plant jasmonate biosynthesis and signaling mutants, aoc and jar, respectively, and found that the fungus can complement the JA-deficient phenotypes.

Conclusions: Further understanding of the biology of JA biosynthesis on C. asteris as well as its interactions with plants is needed to exploit its potential use as a producer of JA.