How eukaryotic filamentous pathogens evade plant recognition

Zheng

Molecular Plant Pathology

2016

109

Section: The Role Of M Oryzae Effectors During the Host–pathogen Intmentioning

confidence: 99%

The Magnaporthe grisea species complex and plant pathogenesis

Zheng

Molecular Plant Pathology

2016

109

“…To date, more than 100 blast resistance (R) genes and about 500 quantitative trait loci (QTLs) have been identified (Ashkani et al, 2015), and 25 of them have been cloned (Wu et al, 2015; Zheng et al 2016). However, rice cultivars often lose their resistance to M. oryzae within 3–5 years because of the high variability of the fungus in the field (Oliveira-Garcia and Valent 2015; Devi et al 2015). In major production areas in China, for example, 174 resistant rice cultivars (disease index <4 on a scale from 0 to 9) released from 2004 to 2008 lost their blast resistance (Feng et al 2014).…”

Section: Introductionmentioning

confidence: 99%

A Genome-Wide Association Study of Field Resistance to Magnaporthe Oryzae in Rice

Zhu

Kang

et al. 2016

Rice

BackgroundBreeding of rice cultivars with long-lasting resistance to the rice blast fungus Magnaporthe oryzae is difficult, and identification of new resistance genes is essential. Most of the loci associated with blast resistance against M. oryzae in rice have been identified in controlled environments and with single isolates, and such loci may confer resistance to only a small faction of the M. oryzae strains. In the field, however, rice is commonly attacked by multiple strains. Research is therefore needed to identify loci that confer resistance in the field, i.e., “field blast resistance”. To identify loci associated with field blast resistance (LAFBRs), we conducted a genome-wide association study (GWAS) using the rice diversity panel 1 (RDP1) cultivars. These cultivars were evaluated in the field in three major rice production areas of China.ResultsGWAS identified 16 LAFBRs. Among them, 13 are novel and the other three are co-localized with known blast resistance regions. Seventy-four candidate genes are identified in the 16 LAFBR regions, which encode receptor-like protein kinases, transcription factors, and other defense-related proteins. Using the rice transcriptome data, compared with the rice-rice blast compatible interaction, we identified seven candidate genes that are significantly up-regulated and five genes that are significantly down-regulated in the incompatible interaction among the candidate genes.ConclusionsWe identified 16 LAFBRs involved in field resistance to M. oryzae and 20 cultivars that exhibit high levels of resistance in both the field and growth chamber. The resistant cultivars and the SNP markers identified in this study should be useful for marker-assisted selection of new rice cultivars that confer high levels of resistance against M. oryzae field populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-016-0116-3) contains supplementary material, which is available to authorized users.

“…The resistance responses were highly localized as only host cell close to the pathogen structures became affected, even though the response spread to adjacent cells not in direct contact with the pathogen. This spread may imply some kind of controlled signaling between host cells in the near proximity of the pathogen colony, based on either plant signaling or movement of pathogen effectors (Oliveira-Garcia and Valent, 2015). The affected cells eventually encased the fungal structures and it appeared as if some type of network was induced between them.…”

Section: Discussionmentioning

confidence: 99%

Temporal and Spatial Variability of Fungal Structures and Host Responses in an Incompatible Rust–Wheat Interaction

2017

Information about temporal and spatial variability of fungal structures and host responses is scarce in comparison to the vast amount of genetic, biochemical, and physiological studies of host–pathogen interactions. In this study, we used avirulent wild type and virulent mutant isolates of Puccinia striiformis to characterize the interactions in wheat carrying yellow rust Yr2 resistance. Both conventional and advanced microscopic techniques were used for a detailed study of morphology and growth of fungal colonies and associated host cell responses. The growth of the wild type isolates was highly restricted due to hypersensitive response (HR, plant cell death) indicated by autofluorescence and change in the shape of the affected plant cells. The host response appeared post-haustorial, but large variation in the time and stage of arrest was observed for individual fungal colonies, probably due to a delay between detection and response. Some colonies were stopped right after the formation of the primary infection hyphae whereas others formed highly branched mycelia. HR was first observed in host cells in direct contact with fungal structures, after which the defense responses spread to adjacent host cells, and eventually led to encasement of the fungal colony. Several cells with HR contained haustoria, which were small and underdeveloped, but some cells contained normal sized haustoria without signs of hypersensitivity. The growth of the virulent mutants in the resistant plants was similar to the growth in plants without Yr2 resistance, which is a strong indication that the incompatible phenotype was associated with Yr2. The interaction between P. striiformis and wheat with Yr2 resistance was highly variable in time and space, which demonstrate that histological studies are important for a deeper understanding of host–pathogen interactions and plant defense mechanisms in general.