Pathogen recognition in compatible plant-microbe interactions

Abstract

Microbial infections in plant leaves remain a major challenge in agriculture. Hence an understanding of disease mechanisms at the molecular level is of paramount importance for identifying possible intervention points for their control. Whole-transcriptome changes during early disease stages in susceptible plant species are less well-documented than those of resistant ones. This study focuses on the differential transcriptional changes at 24 hours post inoculation (hpi) in tomato leaflets affected by three pathogens: (1) Phytophthora infestans, (2) Botrytis cinerea, and (3) Oidium neolycopersici. Grey mould (B. cinerea) was the disease that had progressed the most by 24 hpi, both in terms of visible symptoms as well as differential gene expression. By means of RNA-seq, we identified 50 differentially expressed tomato genes specifically induced by B. cinerea infection and 18 specifically induced by P. infestans infection at 24 hpi. Additionally, a set of 63 genes were differentially expressed during all three diseases when compared by a Bayesian approach to their respective mock infections. And Gene expression patterns were found to also depend on the inoculation technique. These findings suggest a specific and distinct transcriptional response in plant leaf tissue in reaction to B. cinerea and P. infestans invasion at 24 hpi, indicating that plants may recognize the attacking pathogen.

Transcriptome analysis and functional validation reveal a novel gene, BcCGF1, that enhances fungal virulence by promoting infection‐related development and host penetration

“…In B. cinerea pathosystems, host plant and/or pathogen transcriptomes have been investigated in Arabidopsis (Mulema and Denby, 2012), tomato (Blanco-Ulate et al, 2013;Smith et al, 2014;Vega et al, 2015;Rezzonico et al, 2017), lettuce (De Cremer et al, 2013), and cucumber (Kong et al, 2015). These reports greatly increase our understanding of the mechanisms underlying B. cinerea interaction with its diverse hosts.…”

Expression of tomato reference genes using established primer sets: Stability across experimental set‐ups

“…Seven reference genes were ranked according to their M value (geNorm, black bars) with the corresponding NormFinder values indicated by the white bars for Botrytis cinerea (a,b)‐ and Phytophthora infestans (c)‐infected tomato plants. (a), ranking of all samples from three experimental repetitions; (b), averages of separately analysed experimental repetitions with standard error of the mean as error bars; (c), reference primer sets LSM 7 and SICBL 1 compared to primer pairs targeting genes differentially regulated during disease development (Rezzonico et al., ). In (a) and (c), all qPCR replicates from the three separate experiments were analysed in a single step before relative expression values were generated leading to a single value for each gene.…”

“…In a second experiment, the two most stable reference genes identified in the B. cinerea-tomato system were tested for their stability in tomato leaves inoculated with P. infestans oospores. Four genes described previously as differentially expressed (Rezzonico et al, 2017) were included in the analysis for comparison. Their values ranged from 4.3 to 8.4 and from 6.4 to 8.9 for geNorm and NormFinder, respectively, whereas primer sets LSM7 and SlCBL1 both reached 2.6 in geNorm analysis and 3.8 and 5.2, respectively, F I G U R E 1 Ranking of candidate tomato reference genes by their expression stability over time in pathogen-and mock-inoculated leaf disc assays using the primer sets indicated in Table 1.…”

“…The geNorm and NormFinder programs do not allow the analysis of only two genes. Therefore, an additional set of four genes that were differentially expressed during disease development was included in the analysis ((Rezzonico, Rupp, & Fahrentrapp, ); putative function and accession numbers retrieved from sol genomics network ( https://doi.org/https://solgenomics.net): GDSL esterase/lipase , Solyc08 g082500.1.1; Beta‐1 3‐glucanase , Solyc01 g008610.2.1; unknown proteins, Solyc01 g105190.2.1 and Solyc07 g056210.2.1). All qPCR reactions were run in duplicates except for the primer reaction efficiency calculation, which was run in triplicate.…”

Genes for ash tree resistance to an insect pest identified via comparative genomics

“…The putative orthologue of OG47629/FRAEX38873_v2_000173180 in S. lycopersicum is Solyc09g011350 and has been identified as a "disease-specific gene" that is differentially regulated in tomato leaves at 24 hours post inoculation with three pathogens 163 . Solyc09g011350 was upregulated in the infected leaves compared with the control, specifically in response to Botrytis cinerea 163 . Table 5).…”