AUTHOR=Badet Thomas , Peyraud Rémi , Raffaele Sylvain 

TITLE=Common protein sequence signatures associate with Sclerotinia borealis lifestyle and secretion in fungal pathogens of the Sclerotiniaceae

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00776

DOI=10.3389/fpls.2015.00776

ISSN=1664-462X

ABSTRACT=<p>Fungal plant pathogens produce secreted proteins adapted to function outside fungal cells to facilitate colonization of their hosts. In many cases such as for fungi from the <italic>Sclerotiniaceae</italic> family the repertoire and function of secreted proteins remains elusive. In the <italic>Sclerotiniaceae</italic>, whereas <italic>Sclerotinia sclerotiorum</italic> and <italic>Botrytis cinerea</italic> are cosmopolitan broad host-range plant pathogens, <italic>Sclerotinia borealis</italic> has a psychrophilic lifestyle with a low optimal growth temperature, a narrow host range and geographic distribution. To spread successfully, <italic>S. borealis</italic> must synthesize proteins adapted to function in its specific environment. The search for signatures of adaptation to <italic>S. borealis</italic> lifestyle may therefore help revealing proteins critical for colonization of the environment by <italic>Sclerotiniaceae</italic> fungi. Here, we analyzed amino acids usage and intrinsic protein disorder in alignments of groups of orthologous proteins from the three <italic>Sclerotiniaceae</italic> species. We found that enrichment in Thr, depletion in Glu and Lys, and low disorder frequency in hot loops are significantly associated with <italic>S. borealis</italic> proteins. We designed an index to report bias in these properties and found that high index proteins were enriched among secreted proteins in the three <italic>Sclerotiniaceae</italic> fungi. High index proteins were also enriched in function associated with plant colonization in <italic>S. borealis</italic>, and in <italic>in planta</italic>-induced genes in <italic>S. sclerotiorum</italic>. We highlight a novel putative antifreeze protein and a novel putative lytic polysaccharide monooxygenase identified through our pipeline as candidate proteins involved in colonization of the environment. Our findings suggest that similar protein signatures associate with <italic>S. borealis</italic> lifestyle and with secretion in the <italic>Sclerotiniaceae</italic>. These signatures may be useful for identifying proteins of interest as targets for the management of plant diseases.</p>