Asian Soybean Rust Sentinel Plots

Rpp4 (Resistance to Phakopsora pachyrhizi 4) confers resistance to Phakopsora pachyrhizi Sydow, the causal agent of Asian soybean rust (ASR). By combining expression profiling and virus induced gene silencing (VIGS), we are developing a genetic framework for Rpp4-mediated resistance. We measured gene expression in mock-inoculated and P. pachyrhizi-infected leaves of resistant soybean accession PI459025B (Rpp4) and the susceptible cultivar (Williams 82) across a 12-day time course. Unexpectedly, two biphasic responses were identified. In the incompatible reaction, genes induced at 12 h after infection (hai) were not differentially expressed at 24 hai, but were induced at 72 hai. In contrast, genes repressed at 12 hai were not differentially expressed from 24 to 144 hai, but were repressed 216 hai and later. To differentiate between basal and resistance-gene (R-gene) mediated defence responses, we compared gene expression in Rpp4-silenced and empty vector-treated PI459025B plants 14 days after infection (dai) with P. pachyrhizi. This identified genes, including transcription factors, whose differential expression is dependent upon Rpp4. To identify differentially expressed genes conserved across multiple P. pachyrhizi resistance pathways, Rpp4 expression datasets were compared with microarray data previously generated for Rpp2 and Rpp3-mediated defence responses. Fourteen transcription factors common to all resistant and susceptible responses were identified, as well as fourteen transcription factors unique to R-gene-mediated resistance responses. These genes are targets for future P. pachyrhizi resistance research.

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Distinct Biphasic mRNA Changes in Response to Asian Soybean Rust Infection

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-20-8-0887 ◽

2007 ◽

Vol 20 (8) ◽

pp. 887-899 ◽

Cited By ~ 84

Author(s):

Martijn van de Mortel ◽

Justin C. Recknor ◽

Michelle A. Graham ◽

Dan Nettleton ◽

Jaime D. Dittman ◽

...

Keyword(s):

Gene Expression ◽

Time Course ◽

Expression Profiles ◽

Fungal Growth ◽

Initial Response ◽

Soybean Rust ◽

Specific Response ◽

Susceptible Genotype ◽

Rust Infection ◽

Asian Soybean Rust

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is now established in all major soybean-producing countries. Currently, there is little information about the molecular basis of ASR–soybean interactions, which will be needed to assist future efforts to develop effective resistance. Toward this end, abundance changes of soybean mRNAs were measured over a 7-day ASR infection time course in mock-inoculated and infected leaves of a soybean accession (PI230970) carrying the Rpp2 resistance gene and a susceptible genotype (Embrapa-48). The expression profiles of differentially expressed genes (ASR-infected compared with the mock-inoculated control) revealed a biphasic response to ASR in each genotype. Within the first 12 h after inoculation (hai), which corresponds to fungal germination and penetration of the epidermal cells, differential gene expression changes were evident in both genotypes. mRNA expression of these genes mostly returned to levels found in mock-inoculated plants by 24 hai. In the susceptible genotype, gene expression remained unaffected by rust infection until 96 hai, a time period when rapid fungal growth began. In contrast, gene expression in the resistant genotype diverged from the mock-inoculated control earlier, at 72 h, demonstrating that Rpp2-mediated defenses were initiated prior to this time. These data suggest that ASR initially induces a non-specific response that is transient or is suppressed when early steps in colonization are completed in both soybean genotypes. The race-specific resistance phenotype of Rpp2 is manifested in massive gene expression changes after the initial response prior to the onset of rapid fungal growth that occurs in the susceptible genotype.

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A pigeonpea gene confers resistance to Asian soybean rust in soybean

Nature Biotechnology ◽

10.1038/nbt.3554 ◽

2016 ◽

Vol 34 (6) ◽

pp. 661-665 ◽

Cited By ~ 46

Author(s):

Cintia G Kawashima ◽

Gustavo Augusto Guimarães ◽

Sônia Regina Nogueira ◽

Dan MacLean ◽

Doug R Cook ◽

...

Keyword(s):

Soybean Rust ◽

Asian Soybean Rust

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Pathogenic variation of Asian soybean rust pathogen in Bangladesh

Journal of General Plant Pathology ◽

10.1007/s10327-018-0825-0 ◽

2018 ◽

Vol 85 (2) ◽

pp. 90-100 ◽

Cited By ~ 4

Author(s):

Md. Motaher Hossain ◽

Naoki Yamanaka

Keyword(s):

Soybean Rust ◽

Asian Soybean Rust ◽

Pathogenic Variation ◽

Rust Pathogen

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Resistance to Asian soybean rust in soybean lines with the pyramided three Rpp genes

Cropp Breeding and Applied Biotechnology ◽

10.1590/s1984-70332013000100009 ◽

2013 ◽

Vol 13 (1) ◽

pp. 75-82 ◽

Cited By ~ 28

Author(s):

Naoki Yamanaka ◽

Noelle G Lemos ◽

Miori Uno ◽

Hajime Akamatsu ◽

Yuichi Yamaoka ◽

...

Keyword(s):

Genetic Background ◽

Susceptible Variety ◽

Soybean Rust ◽

Phakopsora Pachyrhizi ◽

Soybean Line ◽

Pathogen Population ◽

Resistance Level ◽

Asian Soybean Rust ◽

High Level

In this study, the influence of genetic background on the resistance level of a soybean line carrying Rpp2, Rpp4, and Rpp5 was evaluated by backcrossing it with a susceptible variety. It was also evaluated eight lines which carry these Rpp genes against five Asian soybean rust (ASR) isolates, in order to determine the likely range of resistance against ASR isolates differing in pathogenicity. The results indicated that a high level of resistance against various ASR isolates could be retained in lines carrying the three Rpp genes in susceptible genetic backgrounds, although minor influences of plant genetic background and ASR pathogenicity to the ASR resistance could occur. Thus, lines with the pyramided three Rpp genes should be effective against a complex pathogen population consisting of diverse Phakopsora pachyrhizi isolates.

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Effect of the interaction between fungicide application time and rainfall simulation interval on Asian Soybean Rust control effectiveness

Semina Ciências Agrárias ◽

10.5433/1679-0359.2016v37n6p3881 ◽

2016 ◽

Vol 37 (6) ◽

pp. 3881 ◽

Cited By ~ 1

Author(s):

Marlon Tagliapietra Stefanello ◽

Ricardo Silveiro Balardin ◽

Simone Gripa Minuzzi ◽

Diego Dalla Favera ◽

Leandro Nascimento Marques ◽

...

Keyword(s):

Disease Control ◽

Block Design ◽

Residual Activity ◽

Rainfall Simulation ◽

Soybean Rust ◽

Fungicide Application ◽

Control Effectiveness ◽

Asian Soybean Rust ◽

Randomized Block Design ◽

Negative Effect

Environmental factors affect the performance of fungicides in soybean (Glycine max (L.) Merr.). They also influence the residual activity of the products applied to the leaves. The objective of this study was to assess the control effectiveness of the interaction between fungicide application and rainfall simulation on Asian Soybean Rust (ASR). Two experiments were conducted, one in the greenhouse, in a completely randomized design, and the other in the field, in a randomized block design. Both the experiments had the same factorial arrangement of 6x5, with four replications. Factor A: Five fungicide applications time at 0400 h, 0900 h, 1400 h, 1800 h, 2300 h and, a control with no application; Factor B: four intervals of time between the application of fungicide and rainfall simulation at 0, 30, 60 and 120 min for the experiment in the greenhouse and at 2, 30, 60, 120 min for the experiment in the field. A control was included for both the experiments with no rainfall. The number of days to the appearance of the first pustules was determined, along with severity of ASR, relative chlorophyll index and productivity. It was found that the ASR control effectiveness of fungicide applications in soybean plants in sunlight was less efficient with rainfall simulation. The rainfall simulation had greater negative effect on disease control effectiveness in applications conducted at night under dew conditions. The application conducted at 0900 h showed the greatest disease control effectiveness in both greenhouse and in the field conditions. The 1400 h application showed decreased fungicide control residual and ASR control effectiveness, possibly due to a combination of the low relative humidity and high temperature. Rainfall simulation carried out at 120 min after application still had the ability to affect the ASR control effectiveness.

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