AUTHOR=Shiller Jason , Van de Wouw Angela P. , Taranto Adam P. , Bowen Joanna K. , Dubois David , Robinson Andrew , Deng Cecilia H. , Plummer Kim M. 

TITLE=A Large Family of AvrLm6-like Genes in the Apple and Pear Scab Pathogens, Venturia inaequalis and Venturia pirina

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00980

DOI=10.3389/fpls.2015.00980

ISSN=1664-462X

ABSTRACT=<p><italic>Venturia inaequalis</italic> and <italic>V. pirina</italic> are Dothideomycete fungi that cause apple scab and pear scab disease, respectively. Whole genome sequencing of <italic>V. inaequalis</italic> and <italic>V. pirina</italic> isolates has revealed predicted proteins with sequence similarity to AvrLm6, a <italic>Leptosphaeria maculans</italic> effector that triggers a resistance response in <italic>Brassica napus</italic> and <italic>B. juncea</italic> carrying the resistance gene, <italic>Rlm6</italic>. <italic>AvrLm6</italic>-like genes are present as large families (&gt;15 members) in all sequenced strains of <italic>V. inaequalis</italic> and <italic>V. pirina</italic>, while in <italic>L. maculans</italic>, only <italic>AvrLm6</italic> and a single paralog have been identified. The <italic>Venturia AvrLm6</italic>-like genes are located in gene-poor regions of the genomes, and mostly in close proximity to transposable elements, which may explain the expansion of these gene families. An <italic>AvrLm6</italic>-like gene from <italic>V. inaequalis</italic> with the highest sequence identity to <italic>AvrLm6</italic> was unable to trigger a resistance response in <italic>Rlm6</italic>-carrying <italic>B. juncea</italic>. RNA-seq and qRT-PCR gene expression analyses, of in planta- and <italic>in vitro</italic>-grown <italic>V. inaequalis</italic>, has revealed that many of the <italic>AvrLm6</italic>-like genes are expressed during infection. An <italic>AvrLm6</italic> homolog from <italic>V. inaequalis</italic> that is up-regulated during infection was shown (using an eYFP-fusion protein construct) to be localized to the sub-cuticular stroma during biotrophic infection of apple hypocotyls.</p>