AUTHOR=Malvestiti Michele C. , Steentjes Maikel B. F. , Beenen Henriek G. , Boeren Sjef , van Kan Jan A. L. , Shi-Kunne Xiaoqian 

TITLE=Analysis of plant cell death-inducing proteins of the necrotrophic fungal pathogens Botrytis squamosa and Botrytis elliptica

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.993325

DOI=10.3389/fpls.2022.993325

ISSN=1664-462X

ABSTRACT=<p>Fungal plant pathogens secrete proteins that manipulate the host in order to facilitate colonization. Necrotrophs have evolved specialized proteins that actively induce plant cell death by co-opting the programmed cell death machinery of the host. Besides the broad host range pathogen <italic>Botrytis cinerea</italic>, most other species within the genus <italic>Botrytis</italic> are restricted to a single host species or a group of closely related hosts. Here, we focused on <italic>Botrytis squamosa</italic> and <italic>B. elliptica</italic>, host specific pathogens of onion (<italic>Allium cepa</italic>) and lily (<italic>Lilium</italic> spp.), respectively. Despite their occurrence on different hosts, the two fungal species are each other’s closest relatives. Therefore, we hypothesize that they share a considerable number of proteins to induce cell death on their respective hosts. In this study, we first confirmed the host-specificity of <italic>B. squamosa</italic> and <italic>B. elliptica</italic>. Then we sequenced and assembled high quality genomes. The alignment of these two genomes revealed a high level of synteny with few balanced structural chromosomal arrangements. To assess the cell death-inducing capacity of their secreted proteins, we produced culture filtrates of <italic>B. squamosa</italic> and <italic>B. elliptica</italic> that induced cell death responses upon infiltration in host leaves. Protein composition of the culture filtrate was analysed by mass spectrometry, and we identified orthologous proteins that were present in both samples. Subsequently, the expression of the corresponding genes during host infection was compared. RNAseq analysis showed that the majority of the orthogroups of the two sister species display similar expression patterns during infection of their respective host. The analysis of cell death-inducing proteins of <italic>B. squamosa</italic> and <italic>B. elliptica</italic> provides insights in the mechanisms used by these two <italic>Botrytis</italic> species to infect their respective hosts.</p>