Abstract Detail

Mycology

Lemmond, Benjamin [1], Bonito, Gregory [2], Rollins, Jeffrey [1], Smith, Matthew [3].

Characterizing the mating type locus of the ‘Pecan Truffle’ (Tuber lyonii) complex.

Studies of several commercially important truffle species in the genus Tuber reveal a consistent pattern of a heterothallic mating system. This system is characterized by two idiomorphs of the MAT locus, MAT1-1 and MAT1-2, where only one idiomorph (mating type) is detected in any single haploid individual. Since truffle production therefore requires the presence of both mating types, the ability to screen for mating type is becoming an important analytical tool in commercial truffle production. Phylogenetic analysis of mating type genes is also a useful approach for delimiting species boundaries. Here, we characterize the MAT1-2 idiomorph of the commercially important Tuber lyonii species complex, commonly known as pecan truffles. Pecan truffles are native to North America and widely distributed but are most frequently collected in pecan orchards in the Southeastern US. The genome of a T. lyonii isolate was sequenced with PacBIO, assembled, and the MAT locus identified by homology with conserved genes of other Tuber species. Primer pairs were designed for three regions within the identified MAT1-2 locus: a putative MAT1-2-1 gene and two imperfect inverted repeats located at the 5' and 3' ends of the MAT1-2 idiomorph. These primer pairs were used to screen >50 collections from the T. lyonii complex. These three regions were successfully amplified and sequenced from several closely related phylotypes representing the majority of our collections. The inverted repeats were amplified from nearly all of these collections whereas only approximately 50% of the collections amplified the specific sequence of the MAT1-2-1 gene. Since these inverted regions show high similarity to genes present in both MAT1-1 and MAT1-2 regions of several other Tuber species, we hypothesize that these imperfect inverted repeat sequences are present in both idiomorphs of the Tuber lyonii complex, and that further sequencing of isolates containing the inverted repeats but lacking the MAT1-2-1 gene will allow the MAT1-1 idiomorph to be characterized. Sequences of MAT1-2-1 genes for isolates in this study also demonstrated utility in phylogenetic analysis of this species complex. A maximum likelihood phylogenetic analysis using MAT1-2-1 sequences of several phylotypes generated phylogenies with congruent topology to ITS trees and strong support for all previously delineated phylogenetic species.

1 - University of Florida, Plant Pathology, 2550 Hull Road, Gainesville, FL, 32611, USA
2 - Michigan State University, Plant, Soil, and Microbial Sciences, 1066 Bogue St., Rm A286, East Lansing, MI, 48824, United States
3 - University of Florida, Department of Plant Pathology, PO Box 110680, , Gainesville, FL, 32611, USA

Keywords:
mating type
truffle fungi
phylogenetics
Mycology.

Presentation Type: Poster
Session: MYP1, Mycology Posters I
Location: /
Date: Monday, July 19th, 2021
Time: 5:00 PM(EDT)
Number: MYP1015
Abstract ID:1033
Candidate for Awards:MSA Best Poster Presentation Award by a Graduate Student