Open AccessTranscriptome analysis highlights preformed defences and signalling pathways controlled by the pr A e1 quantitative trait locus ( QTL ), conferring partial resistance to A phanomyces euteiches in M edicago truncatula
Author(s) -
Badis Yacine,
Bonhomme Maxime,
Lafitte Claude,
Huguet Stéphanie,
Balzergue Sandrine,
Dumas Bernard,
Jacquet Christophe
Publication year - 2015
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/mpp.12253
Subject(s) - biology , oomycete , medicago truncatula , transcriptome , quantitative trait locus , gene , locus (genetics) , genetics , microbiology and biotechnology , botany , gene expression , symbiosis , bacteria
Summary To gain an insight into the molecular mechanisms of quantitative disease resistance in M edicago truncatula to the root‐infecting oomycete A phanomyces euteiches , we selected two near‐isogenic lines ( NILs ), NR and NS , partially resistant and susceptible, respectively, differing in the allelic state of the quantitative resistance locus ( QRL ) pr A e1 (partially resistant to A . euteiches 1 ). Complementary molecular and cytological phenotyping methods showed that pr A e1 alone confers quantitative resistance to A . euteiches . Root and stem tissues were colonized in NS plants and 80% of NS plants died by 21 days post‐inoculation (dpi). In contrast, A . euteiches mycelium was restricted to the root cortex and the spread of symptoms was arrested in aerial parts of NR plants. A transcriptome analysis performed at 0, 1 and 6 dpi identified 1198 differentially expressed genes ( DEGs ) between NR and NS lines. More than 87% of the DEGs were significantly more expressed in NR . The highest number of DEGs was found in control conditions, with 723 genes over‐expressed in NR versus 85 in NS . Genes belonging to secondary metabolism, pathogenesis‐related ( PR ) proteins and kinases were significantly enriched. The significant role of the flavonoid pathway in resistance was corroborated by the detection of larger amounts of flavonoids in NR roots and the inhibition of A . euteiches zoospore germination by 2′‐ O ‐methyl‐isoliquiritigenin, a compound synthesized by enzymes specifically induced in NR . Our study revealed that pr A e1 ‐dependent resistance relies mainly on the constitutive expression of defence‐related pathways and signalling elements, which can be re‐amplified in later time points of the infection.