AUTHOR=von Dahlen Janina K. , Schulz Kerstin , Nicolai Jessica , Rose Laura E. 

TITLE=Global expression patterns of R-genes in tomato and potato

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1216795

DOI=10.3389/fpls.2023.1216795

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>As key-players of plant immunity, the proteins encoded by resistance genes (<italic>R</italic>-genes) recognize pathogens and initiate pathogen-specific defense responses. The expression of some <italic>R</italic>-genes carry fitness costs and therefore inducible immune responses are likely advantageous. To what degree inducible resistance driven by <italic>R</italic>-genes is triggered by pathogen infection is currently an open question.</p></sec><sec><title>Methods</title><p>In this study we analyzed the expression of 940 <italic>R</italic>-genes of tomato and potato across 315 transcriptome libraries to investigate how interspecific interactions with microbes influence <italic>R</italic>-gene expression in plants.</p></sec><sec><title>Results</title><p>We found that most <italic>R</italic>-genes are expressed at a low level. A small subset of <italic>R</italic>-genes had moderate to high levels of expression and were expressed across many independent libraries, irrespective of infection status. These <italic>R</italic>-genes include members of the class of genes called NRCs (NLR required for cell death). Approximately 10% of all <italic>R</italic>-genes were differentially expressed during infection and this included both up- and down-regulation. One factor associated with the large differences in <italic>R</italic>-gene expression was host tissue, reflecting a considerable degree of tissue-specific transcriptional regulation of this class of genes.</p></sec><sec><title>Discussion</title><p>These results call into question the widespread view that <italic>R</italic>-gene expression is induced upon pathogen attack. Instead, a small core set of <italic>R</italic>-genes is constitutively expressed, imparting upon the plant a ready-to-detect and defend status.</p></sec>