Page 162 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

Blackleg is caused primarily by the hemibiotrophic fungus Leptosphaeria maculans (Desmaz.) Ces. & De
Not., is one of the most economically significant diseases in many canola/oilseed rape (Brassica napus
L.) growing regions in the world, often causing significant yield losses. Genetic resistance has been
proven effective in mitigating blackleg infection and impact. Seedling resistance generally follows the
gene-for-gene theory. For example, the recognition of avirulence genes AvrLm3 and AvrLm9 by the
respective resistance genes Rlm3 and Rlm9 will result in a resistant reaction. However, this recognition
can be masked by the presence of AvrLm4-7 in the L. maculans isolate known as the ‘game of hide and
seek’. Recent evidence has shown that there is no direct interaction between AvrLm4-7 and AvrLm3 or
AvrLm9, or between Rlm9 and AvrLm9 or AvrLm4-7, suggesting AvrLm4-7 may conform to the guard or
decoy models and interact with unknown targets in the host that represses the recognition of AvrLm3 or
AvrLm9 by the corresponding resistance gene. To reveal the mechanisms underlying this masking effect,
we conducted RNA sequencing (NovaSeq 6000 System, Illumina) and proteomic (TMT-based
technology) studies on B. napus ‘02-22-2-1’ (Rlm3 carrier) and ‘Goéland’ (Rlm9 carrier) seedlings at 3-
and 7-days post inoculation (dpi) with L. maculans isolates carrying avrLm4-7-AvrLm3-AvrLm9 (typical
resistant reactions) and AvrLm4-7-AvrLm3-AvrLm9 (resistant reactions masked), respectively. A total of
2.33 billion pair-end reads were generated from 36 cDNA libraries (18 for each of resistant and masked
AvrLm3-Rlm3 and AvrLm9-Rlm9 interactions). On average, 72.58% of these reads were aligned to the
coding region of the reference genome of B. napus oilseed rape variety ‘Darmor-bzh’
(AST_PRJEB5043_v1). In the resistant Rlm3-AvrLm3 interactions, we detected 434 and 6611
upregulated differentially expressed genes (DEGs; P < 0.05) compared to masked interactions at 3 dpi
and 7 dpi, respectively, of which 24 upregulated DEGs were commonly found at both post-inoculation
stages. A smaller number of upregulated DEGs were found in the resistant Rlm9-AvrLm9 interaction, with
16 upregulated DEGs at three dpi and 147 at seven dpi compared to masked interactions. The GO
enrichment analysis based on the common DEGs between resistant and masked AvrLm3-Rlm3 and
AvrLm9-Rlm9 interactions indicated that biological processes, including endoplasmic reticulum to Golgi
vesicle-mediated transport, response to stress, response to endoplasmic reticulum stress, Golgi
organization, intra-Golgi vesicle-mediated transport, negative regulation of cell death, xenobiotic
transport, retrograde vesicle-mediated transport, Golgi to endoplasmic reticulum, as well as defense
response were actively involved in the ‘game of hide and seek’. Integration of RNA-sequencing and
proteome data from resistant and masked AvrLm3-Rlm3 and AvrLm9-Rlm9 interactions at 3 dpi and 7 dpi
also identified the genes that are highly correlated between RNA-sequencing and proteome data, some of
which are possibly associated with the ‘game of hide and seek’. This multi-omics study help identify key
players in the ‘game of hide and seek’ for this pathosystem and provide a tool to illuminate similar
interactions in other pathosystems.

[O119] DECIPHERING THE MOLECULAR EVENTS BEHIND SYSTEMIN-INDUCED RESISTANCE
AGAINST BOTRYTIS CINEREA IN TOMATO PLANTS. Julia Pastor-Fernández , Neus Sanmartín ,
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Maria Manresa , Cédric Cassan , Pierre Pétriacq , Yves Gibon , Jordi Gamir , Beatriz Romero
Rodriguez , Araceli G. Castillo , Miguel Cerezo , Victor Flors , and Paloma Sánchez-Bel . Metabolic
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Integration and Cell Signaling Laboratory, Biochemistry and Molecular Biology Section. Department of
Biology, Biochemistry and Natural Sciences, Universitat Jaume I. Avd Vicente Sos Baynat s/n 12071
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Castellón, Spain; Univ. Bordeaux, INRAE, UMR1332 BFP, 33882 Villenave d’Ornon, France; Bordeaux
Metabolome, MetaboHUB, PHENOME-EMPHASIS, 33140 Villenave d’Ornon, France; and Instituto de
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Hortofruticultura Subtropical y Mediterránea “La Mayora” (IHSM “La Mayora”), Universidad de Málaga-
Consejo Superior de Investigaciones Cientificas (UMA-CSIC), Campus Teatinos, 29010 Málaga, Spain.
Correspondence to: jpastorf@uwo.ca

Plant defense peptides are paramount endogenous danger signals secreted after a challenge intensifying
the plant immune response. The peptidic hormone Systemin (Sys) has been shown to participate in
resistance in several plant-pathosystems, although the mechanisms behind Sys- Induced Resistance (IR)
when exogenously applied remain elusive. We performed proteomic, metabolomic and enzymatic studies
to decipher the Sys-induced changes in tomato plants either in the absence or the presence of Botrytis
cinerea infection. Sys treatments triggered direct proteomic rearrangement mostly involved in carbon
metabolism and photosynthesis. However, the final induction of defense proteins required concurrent
challenge, triggering priming of pathogen-targeted proteins. Conversely, at the metabolomic level, Sys-
treated plants showed an alternative behaviour following a general priming profile. Out of the primed
metabolites, the flavonoids rutin and isorhamnetin and two alkaloids correlated with the proteins 4-
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