Journal of Fungi (Mar 2022)

Diversity of <i>Neofusicoccum parvum</i> for the Production of the Phytotoxic Metabolites (-)-Terremutin and (<i>R</i>)-Mellein

  • Patricia Trotel-Aziz,
  • Guillaume Robert-Siegwald,
  • Olivier Fernandez,
  • Catarina Leal,
  • Sandra Villaume,
  • Jean-François Guise,
  • Eliane Abou-Mansour,
  • Marc-Henri Lebrun,
  • Florence Fontaine

DOI
https://doi.org/10.3390/jof8030319
Journal volume & issue
Vol. 8, no. 3
p. 319

Abstract

Read online

Two Neofusicoccumparvum isolates and a UV mutant were characterized for their phytotoxin production in vitro, their pathogenicity on grapevine, and their genome sequenced. The isolate Np-Bt67 produced high level of (-)-terremutin, but almost no (R)-mellein, and it was the most aggressive on grapevine, triggering apoplexy. Similar symptoms were not induced by purified (-)-terremutin. The isolate Bourgogne S-116 (Np-B) produced 3-fold less (-)-terremutin and high amounts of (R)-mellein, but it was less aggressive on grapevine than Np-Bt67. The UV9 mutant obtained from Np-B (NpB-UV9) no longer produced (-)-terremutin but overproduced (R)-mellein by 2.5-fold, and it was as pathogenic as its parent. NpB-UV9 differed from its parent by simple mutations in two genes (transcription factor UCR-NP2_6692, regulatory protein UCR-NP2_9007), not located neither near (R)-mellein, nor (-)-terremutin biosynthetic genes, but likely involved in the control of (-)-terremutin biosynthesis. Grapevine immunity was disturbed upon challenge with these pathogens or purified phytotoxins, leading to an upregulation of SA-dependent defenses, while (-)-terremutin interfered with host JA/ET-dependent defenses. Our results suggest that neither (-)-terremutin nor (R)-mellein alone is essential for the pathogenicity of N. parvum on grapevine, since isolate/mutant non-producing these toxins in vitro is pathogenic. However, these phytotoxins could play a quantitative role in the infection process.

Keywords