Five years investigation of female and male genotypes in Périgord black truffle (Tuber melanosporumVittad.) revealed contrasted reproduction strategies

Abstract

Summary 22The Périgord black truffle (Tuber melanosporum Vittad.) is a heterothallic ascomycete that 23 establishes ectomycorrhizal symbiosis with trees and shrubs. Small-scale genetic structures of 24 female genotypes in truffle orchards are known, but it has not yet been studied in male 25 genotypes. In this study, our aim was to characterize the small-scale genetic structure of both 26 male and female genotypes over five years in an orchard to better understand the T. suggesting an important turnover due to ascospore recruitment. Larger and perennial female 33 and male genotypes were also detected. Only three genotypes (1.5 %) were found as both 34 female and male genotypes (hermaphrodites) while most were detected only as female or 35 male genotype (dioecy). Our results suggest that germinating ascospores act as male 36 genotypes, but we also proposed that soil mycelium could be a reservoir of male genotypes. 38All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.

Ascoma genotyping and mating type analyses of mycorrhizas and soil mycelia of Tuber borchii in a truffle orchard established by mycelial inoculated plants

“…S5). This result confirms that also in T. borchii a single mating type tends to dominate in a single soil patch, as found for T. melanosporum and T. aestivum in natural and cultivated truffle ground, and confirms that in field conditions only one strain or multiple strains of the same mating type tend to colonize one single plant (Rubini et al ., ; Linde and Selmes, ; Zampieri et al ., ; Murat et al ., ; Rubini et al ., ; Molinier et al ., ; De la Varga et al ., ). This can be explained by considering that a vegetative incompatibility (VI) system exists in T. borchii , which prevents hyphal interactions between hyphae of different strains (Sbrana et al ., ).…”

“…Several works demonstrated that in Tuber species the maternal tissue of ascomata and surrounding ECMs have the same genotype (Rubini et al ., , Murat et al ., ; Molinier et al ., ; Taschen et al . ; De la Varga et al ., ). Moreover, a physical and nutritional link between these fungal structures has been proved (Le Tacon et al ., ; Deveau et al ., ).…”

“…melanosporum ) but never on T . borchii (Rubini et al ., ; Riccioni et al ., ; Murat et al ., ; Molinier et al ., , ; Taschen, et al ., ; De la Varga et al ., ; Schneider‐Maunory et al ., ). In this study, T .…”

“…Most of the studies on the genetic structure of truffle population have been conducted in human‐made or natural truffle grounds where the identity of the strains colonizing roots was not known (Murat et al ., ; Molinier et al ., ; Taschen, et al ., ; De la Varga et al ., ). On the contrary, the T. borchii plantation under investigation was established with plants inoculated with five different mycelial strains without knowing their mating type.…”

“…The haploid maternal genotype of truffles forms the sterile tissues of the fruiting body, and it is fed from the surrounding mycorhizas throughout the maturation time (Rubini et al ., ; Le Tacon et al ., ; Murat et al ., ). On the contrary, the paternal genes are confined to the asci and, indeed, the paternal genotypes were rarely found to form mycorrhizas (Taschen et al ., ; De la Varga et al ., ).…”