Dataset Information

Concerted action of two avirulent spore effectors activates Reaction to Puccinia graminis 1 (Rpg1)-mediated cereal stem rust resistance.

ABSTRACT: The barley stem rust resistance gene Reaction to Puccinia graminis 1 (Rpg1), encoding a receptor-like kinase, confers durable resistance to the stem rust pathogen Puccinia graminis f. sp. tritici. The fungal urediniospores form adhesion structures with the leaf epidermal cells within 1 h of inoculation, followed by hyphae and haustorium formation. The RPG1 protein is constitutively expressed and not phosphorylated. On inoculation with avirulent urediniospores, it is phosphorylated in vivo within 5 min and subsequently degraded. Application of arginine-glycine-aspartic acid peptide loops prevented the formation of adhesion structures for spore attachment, the phosphorylation of RPG1, and germination of the viable spores. Arginine-glycine-aspartic acid affinity chromatography of proteins from the ungerminated avirulent rust spores led to the purification and identification of a protein with fibronectin type III and breast cancer type 1 susceptibility protein domains and a vacuolar protein sorting-associated protein 9 with a coupling of ubiquitin to endoplasmic reticulum degradation domain. Both proteins are required to induce in vivo phosphorylation and degradation of RPG1. Combined application of both proteins caused hypersensitive reaction on the stem rust-resistant cultivar Morex but not on the susceptible cultivar Steptoe. Expression studies indicated that mRNA of both genes are present in ungerminated urediniospores and are constitutively transcribed in sporelings, infected leaves, and haustoria in the investigated avirulent races. Evidence is presented that RPG1, in yeast, interacts with the two protein effectors from the urediniospores that activate cooperatively the stem rust resistance protein RPG1 long before haustoria formation.

SUBMITTER: Nirmala J

PROVIDER: S-EPMC3167542 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Concerted action of two avirulent spore effectors activates Reaction to Puccinia graminis 1 (Rpg1)-mediated cereal stem rust resistance.

Nirmala Jayaveeramuthu J Drader Tom T Lawrence Paulraj K PK Yin Chuntao C Hulbert Scot S Steber Camille M CM Steffenson Brian J BJ Szabo Les J LJ von Wettstein Diter D Kleinhofs Andris A

Proceedings of the National Academy of Sciences of the United States of America 20110822 35

The barley stem rust resistance gene Reaction to Puccinia graminis 1 (Rpg1), encoding a receptor-like kinase, confers durable resistance to the stem rust pathogen Puccinia graminis f. sp. tritici. The fungal urediniospores form adhesion structures with the leaf epidermal cells within 1 h of inoculation, followed by hyphae and haustorium formation. The RPG1 protein is constitutively expressed and not phosphorylated. On inoculation with avirulent urediniospores, it is phosphorylated in vivo within ...[more]

PMID: 21873196

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Project description:BackgroundStem rust is an economically important disease of wheat and barley. However, studies to gain insight into the molecular basis of these host-pathogen interactions have primarily focused on wheat because of its importance in human sustenance. This is the first extensive study utilizing a transcriptome-wide association mapping approach to identify candidate Puccinia graminis f. sp. tritici (Pgt) effectors/suppressors that elicit or suppress barley stem rust resistance genes. Here we focus on identifying Pgt elicitors that interact with the rpg4-mediated resistance locus (RMRL), the only effective source of Pgt race TTKSK resistance in barley.ResultsThirty-seven Pgt isolates showing differential responses on RMRL were genotyped using Restriction Site Associated DNA-Genotyping by Sequencing (RAD-GBS), identifying 24 diverse isolates that were used for transcript analysis during the infection process. In planta RNAseq was conducted with the 24 diverse isolates on the susceptible barley variety Harrington, 5 days post inoculation. The transcripts were mapped to the Pgt race SCCL reference genome identifying 114 K variants in predicted genes that would result in nonsynonymous amino acid substitutions. Transcriptome wide association analysis identified 33 variants across 28 genes that were associated with dominant RMRL virulence, thus, representing candidate suppressors of resistance. Comparative transcriptomics between the 9 RMRL virulent -vs- the 15 RMRL avirulent Pgt isolates identified 44 differentially expressed genes encoding candidate secreted effector proteins (CSEPs), among which 38 were expressed at lower levels in virulent isolates suggesting that they may represent RMRL avirulence genes. Barley transcript analysis after colonization with 9 RMRL virulent and 15 RMRL avirulent isolates inoculated on the susceptible line Harrington showed significantly lower expression of host biotic stress responses specific to RMRL virulent isolates suggesting virulent isolates harbor effectors that suppress resistance responses.ConclusionsThis transcriptomic study provided novel findings that help fill knowledge gaps in the understanding of stem rust virulence/avirulence and host resistance in barley. The pathogen transcriptome analysis suggested RMRL virulence might depend on the lack of avirulence genes, but evidence from pathogen association mapping analysis and host transcriptional analysis also suggested the alternate hypothesis that RMRL virulence may be due to the presence of suppressors of defense responses.

Project description:Wheat is one of the high-value major crops in the world. However, wheat stem rust is considered one of the determinant threats to wheat production in Ethiopia and the world. So this study was conducted to assess the disease intensity, seasonal distribution dynamics pattern, the genetic variability of Puccinia graminis f. sp. tritici, and to determine the virulence spectrum in the irrigated ecology of the Awash River Basin. Totally 137 wheat farms were evaluated, from 2014/15-2019/20 in six districts representing the Upper, Middle, and Lower Awash River Basin. Farm plots were assessed, in every 5-10 km intervals, with 'X' fashion, and data on disease incidence, severity, healthy plants were counted and recorded. Diseased samples were collected from the diseased wheat stem by Puccinia graminis physiological and genetic race analysis. The seasonal trend of stem rust disease progress showed its importance to infer the future progresses of the disease for the country's potential production plan of irrigated wheat. The result revealed that the disease prevalence, disease incidence, and severity were significantly varied; among the different districts and seasons in the two regions. The survey results also indicated that about 71.7% of the wheat fields were affected by stem rust during the 2018/19 growing period. The disease's overall incidence and mean severity during the same season were 49.02% and 29.27%, respectively. In 2019/20, about 63.7% of the wheat fields were affected by stem rust, disease incidence 30.97%, and severity 17.22% were lower than the previous season. In 2019/20, even though seasonal disease distribution decreased, the spatial distribution was expanding in Afambo and Dubti districts. Four, stem rust dominant races were identified (TTTTF, TKTTF TKKTF, and TTKTF) by physiological and genetic race analysis during 2018/19 and one additional race (TKPTF) in 2019/20, production year. The result indicated that the races are highly virulent and affect most Sr genes except Sr31 and Sr24. From the race analysis result, TTTTF, and TKKTF have the broadest virulence spectrum race, which affects 90% of the Sr genes. Generally, we can conclude that the spatial and seasonal distribution of the disease is expanding. Most of the races in the irrigated areas in the Basin were similar to that of rain-fed wheat production belts in Ethiopia, so care must be given, to effective management of the diseases, in both production ecologies towards controlling the spore pressure than race variability. Therefore, these findings provide inputs for wheat producers to reduce the spread and disease' damage in the irrigated ecologies of Ethiopia. Also, it gives an insight for breeders to think about the breeding program in their crossing lines.

Dataset Information

Concerted action of two avirulent spore effectors activates Reaction to Puccinia graminis 1 (Rpg1)-mediated cereal stem rust resistance.

Publications

Concerted action of two avirulent spore effectors activates Reaction to Puccinia graminis 1 (Rpg1)-mediated cereal stem rust resistance.

Similar Datasets

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