Pathogen-regulated genes in wheat isogenic lines differing in resistance to brown rust Puccinia triticina

Abstract

BackgroundInoculation of wheat plants with Puccinia triticina (Pt) spores activates a wide range of host responses. Compatible Pt interaction with susceptible Thatcher plants supports all stages of the pathogen life cycle. Incompatible interaction with TcLr9 activates defense responses including oxidative burst and micronecrotic reactions associated with the pathogen’s infection structures and leads to complete termination of pathogen development. These two contrasting host-pathogen interactions were a foundation for transcriptome analysis of incompatible wheat-Pt interaction.MethodsA suppression subtractive hybridization (SSH) library was constructed using cDNA from pathogen-inoculated susceptible Thatcher and resistant TcLr9 isogenic lines. cDNA represented steps of wheat-brown rust interactions: spore germination, haustorium mother cell (HMC) formation and micronecrotic reactions. All ESTs were clustered and validated by similarity search to wheat genome using BLASTn and sim4db tools. qRT-PCR was used to determine transcript levels of selected ESTs after inoculation in both lines.Results and discussionOut of 793 isolated cDNA clones, 183 were classified into 152 contigs. 89 cDNA clones and encoded proteins were functionally annotated and assigned to 5 Gene Ontology categories: catalytic activity 48 clones (54 %), binding 32 clones (36 %), transporter activity 6 clones (7 %), structural molecule activity 2 clones (2 %) and molecular transducer activity 1 clone (1 %).Detailed expression profiles of 8 selected clones were analyzed using the same plant-pathogen system. The strongest induction after pathogen infection and the biggest differences between resistant and susceptible interactions were detected for clones encoding wall-associated kinase (GenBank accession number JG969003), receptor with leucine-rich repeat domain (JG968955), putative serine/threonine protein kinase (JG968944), calcium-mediated signaling protein (JG968925) and 14-3-3 protein (JG968969).ConclusionsThe SSH library represents transcripts regulated by pathogen infection during compatible and incompatible interactions of wheat with P. triticina. Annotation of selected clones confirms their putative roles in successive steps of plant-pathogen interactions. The transcripts can be categorized as defense-related due to their involvement in either basal defense or resistance through an R-gene mediated reaction. The possible involvement of selected clones in pathogen recognition and pathogen-induced signaling as well as resistance mechanisms such as cell wall enforcement, oxidative burst and micronecrotic reactions is discussed.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1932-3) contains supplementary material, which is available to authorized users.

Comparative Temporal Transcriptome Profiling of Wheat near Isogenic Line Carrying Lr57 under Compatible and Incompatible Interactions

“…We identified a number of genes belonging to receptor protein kinases/receptor-like protein kinases. Most of the PRRs characterized so far are receptor like kinases (RLKs; Dmochowska-Boguta et al, 2015). Among this cysteine-rich receptor-like protein kinases were most up-regulated followed by wall-associated receptor kinase 2 and lectin-domain containing receptor kinases.…”

“…In rice, OsWAK1 was found to be induced by Magnaporthe oryzae and played a crucial role in resistance against rice blast (Li et al, 2009). Dmochowska-Boguta et al (2015) identified three wheat WAKs strongly induced by leaf rust pathogen in wheat lines differing for leaf rust resistance genes. Lectin-domain containing receptor kinase contains extracellular motifs that are known to bind various carbohydrates; they may be involved in recognition of pathogen specific carbohydrate moieties.…”

“…A number of studies have used ESTs (Manickavelu et al, 2010; Dmochowska-Boguta et al, 2015), microarrays (Fofana et al, 2007), serial analysis of gene expression (Chandra et al, 2016), and RNAseq (Zhang et al, 2014; Dobon et al, 2016) to understand the host pathogen relationship between known host genes and specific pathotypes under compatible as well as incompatible interactions.…”

TaWAK6 encoding wall-associated kinase is involved in wheat resistance to leaf rust similar to adult plant resistance

“…The full cDNA sequence of the transcript originally identified as EST JG968933 [26] was obtained as a result of 5 0 3 0 -RACE extension with the 5 0 /3 0 RACE Kit (Roche) according to the manual protocol using RNA from the TcLr9 line isolated from leaves 4 days post inoculation with spores of P. triticina isolate.…”

“…First strand cDNA was synthesized with a random hexamer primer according to the manual protocol (RevertAid First Strand cDNA Synthesis Kit, Thermo Scientific). The TaWAK6 transcript was quantified in 10 μl of PCR reaction mixture containing 1×Hot FIREPol EvaGreen qPCR Mix (Solis BioDyne), 0.4 μM of each primer: R_I_77ant, KinR_5nR [26] (S1 Table), and 1 μl of the template cDNA. Real-time PCR reactions were run in the Rotor-Gene Q cycler (Qiagen).…”