Adaptive Horizontal Gene Transfers between Multiple Cheese-Associated Fungi
Résumé
Domestication is an excellent model for studies of
adaptation because it involves recent and strong selection
on a few, identified traits [1–5]. Few studies
have focused on the domestication of fungi, with
notable exceptions [6–11], despite their importance
to bioindustry [12] and to a general understanding
of adaptation in eukaryotes [5]. Penicillium fungi are
ubiquitous molds among which two distantly related
species have been independently selected for
cheese making—P. roqueforti for blue cheeses like
Roquefort and P. camemberti for soft cheeses like
Camembert. The selected traits include morphology,
aromatic profile, lipolytic and proteolytic activities,
and ability to grow at low temperatures, in a matrix
containing bacterial and fungal competitors [13–15].
By comparing the genomes of ten Penicillium species,
we show that adaptation to cheese was associated
with multiple recent horizontal transfers of large
genomic regions carrying crucial metabolic genes.
We identified seven horizontally transferred regions
(HTRs) spanning more than 10 kb each, flanked
by specific transposable elements, and displaying
nearly 100% identity between distant Penicillium
species. Two HTRs carried genes with functions
involved in the utilization of cheese nutrients or
competition and were found nearly identical in multiple
strains and species of cheese-associated Penicillium
fungi, indicating recent selective sweeps; they
were experimentally associated with faster growth
and greater competitiveness on cheese and contained
genes highly expressed in the early stage of
cheese maturation. These findings have industrial
and food safety implications and improve our understanding of the processes of adaptation to rapid
environmental changes.
Domaines
Sciences du Vivant [q-bio]
Origine : Publication financée par une institution
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