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

Patricia Trotel-Aziz (1) , Guillaume Robert-Siegwald (2) , Olivier Fernandez (1) , Catarina Leal (1) , Sandra Villaume (1) , Jean-François Guise (1) , Eliane Abou-Mansour (3) , Marc-Henri Lebrun (4) , Florence Fontaine (1)

1 RIBP - Résistance Induite et Bioprotection des Plantes - EA 4707
2 Independent Researcher
3 UNIFR - Université de Fribourg = University of Fribourg
4 BIOGER - BIOlogie et GEstion des Risques en agriculture

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.

Mots clés: Np-B; Np-Bt67; Vitis vinifera cv. chardonnay; fungal plant pathogen; mutant; pathogen genotyping; plant defense responses; plant phenotyping; secondary metabolism; virulence factors

Domaines: Sciences du Vivant [q-bio]; Sciences du Vivant [q-bio]

Patricia Trotel-Aziz, Guillaume Robert-Siegwald, Olivier Fernandez, Catarina Leal, Sandra Villaume, et al.. Diversity of Neofusicoccum parvum for the Production of the Phytotoxic Metabolites (-)-Terremutin and (R)-Mellein. Journal of Fungi, 2022, 8 (3), pp.319. ⟨10.3390/jof8030319⟩. ⟨hal-03630614⟩