Discovery of genes affecting resistance of barley to adapted and non-adapted powdery mildew fungi

Abstract

BackgroundNon-host resistance, NHR, to non-adapted pathogens and quantitative host resistance, QR, confer durable protection to plants and are important for securing yield in a longer perspective. However, a more targeted exploitation of the trait usually possessing a complex mode of inheritance by many quantitative trait loci, QTLs, will require a better understanding of the most important genes and alleles.ResultsHere we present results from a transient-induced gene silencing, TIGS, approach of candidate genes for NHR and QR in barley against the powdery mildew fungus Blumeria graminis. Genes were selected based on transcript regulation, multigene-family membership or genetic map position. Out of 1,144 tested RNAi-target genes, 96 significantly affected resistance to the non-adapted wheat- or the compatible barley powdery mildew fungus, with an overlap of four genes. TIGS results for QR were combined with transcript regulation data, allele-trait associations, QTL co-localization and copy number variation resulting in a meta-dataset of 51 strong candidate genes with convergent evidence for a role in QR.ConclusionsThis study represents an initial, functional inventory of approximately 3% of the barley transcriptome for a role in NHR or QR against the powdery mildew pathogen. The discovered candidate genes support the idea that QR in this Triticeae host is primarily based on pathogen-associated molecular pattern-triggered immunity, which is compromised by effector molecules produced by the compatible pathogen. The overlap of four genes with significant TIGS effects both in the NHR and QR screens also indicates shared components for both forms of durable pathogen resistance.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-014-0518-8) contains supplementary material, which is available to authorized users.

Evolutionary Dynamics of the Cellulose Synthase Gene Superfamily in Grasses

“…While the data of Schweizer and Stein (2011), which implicate the barley HvCslD2 gene in nonhost resistance, might argue against the observed low dN:dS (Fig. 8), if the HvCslD2 gene plays a central role in multilayered nonhost resistance (Douchkov et al, 2014), one might predict a stationary or purifying selection operating on this gene.…”

Discovery of genes affecting resistance of barley to adapted and non-adapted powdery mildew fungi

“…Primary transcript-regulation data of this study, or obtained from the public domain, were used [25,26] (PlexDB, [81]). Transcripts were assumed to be significantly regulated if normalized signal intensities (inoculated versus control samples) exceeded 2.0 in at least one of the analyzed time points after inoculation, and if the…”

An LRR/Malectin Receptor-Like Kinase Mediates Resistance to Non-adapted and Adapted Powdery Mildew Fungi in Barley and Wheat

“…Transient silencing of HvLEMK1 was reported to weaken non-host resistance of barley to the wheat powdery mildew fungus Bgt , and therefore we searched for the presence of an orthologous protein in wheat, which is the natural host for Bgt (Douchkov et al, 2014). By PCR we identified two genes, TaLEMK1_1 (Acc.…”

“…KX529077), differing by five predicted amino acids in the LRR domain ( Figure 1B ; Supplementary Figure S2). Comparison of the full length sequences of TaLEMK1 to the wheat chromosomes on URGI database 3 revealed that the gene is located on the group 5 chromosomes, in syntenic position to the barley orthologous gene (Douchkov et al, 2014). Although exhibiting 94% nucleotide identify to HvLEMK1 , evolutionary separation of the genus Hordeum and Triticum approximately 12 MY ago led to the accumulation of a total of 31 non-conservative amino-acid exchanges between the wheat and barley orthologs, which corresponds to approximately 3% of the protein (Supplementary Figure S2).…”

“…HvLEMK1 was discovered in a transient-induced gene silencing (TIGS) screen for candidate genes of non-host resistance in barley to the non-adapted wheat powdery mildew fungus (Douchkov et al, 2014). The gene was silenced in transgenic barley plants and also transiently expressed in barley and wheat epidermal cells that were challenge-inoculated by adapted or non-adapted powdery mildew pathogens.…”