Characterization and Quantification of Fungal Colonization of <i>Phakopsora pachyrhizi</i> in Soybean Genotypes

Ramya, V.; Paul, C.; Hill, Curtis B.; Hartman, G. L.

doi:10.1094/phyto-12-12-0334-r

Cited by 21 publications

(31 citation statements)

References 34 publications

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“…In the case of P. gossypii at 42 hai the uredospores germinated, produced a germ tube and an appressorium that might directly allow the fungus to penetrate the leaf cuticle ( Figure 1A). According to Vittal et al (2014), the early events of uredospore germination, appressorium formation, and penetration of P. pachyrhizi on the soybean leaf occurred by 24 hai. The formation of appressoria is a pivotal event that allows a number of fungi to penetrate the leaf cuticle and establish a successful infection in their hosts (Chang et al, 2014;Dean, 1997;Loehrer et al, 2014;Ludwig et al, 2014;Mendgen and Deising, 1993).…”

Section: Resultsmentioning

confidence: 99%

“…Medice et al (2007) reported that the uredia of P. pachyrhizi on soybean leaves became completely open at 36 dai. Generally, the small and closed uredia of P. pachyrhizi on soybean leaves were associated with reduced Asian soybean rust symptoms because they produced fewer uredospores (Cruz et al, 2012;Medice et al, 2007;Vittal et al, 2014). The results from the present study strongly indicate that control managements against tropical rust, such as fungicides should be implemented up to a maximum of 20 days after the infection took place because from this time onwards, the uredia start to open and release the first uredospores.…”

Section: Resultsmentioning

confidence: 99%

“…Based on SEM observations, Cruz et al (2012) reported that the parenchyma cells in the soybean leaves next to the uredia of P. pachyrhizi were densely colonized by fungal hyphae. Vittal et al (2014) reported that for a compatible soybean-P. pachyrhizi interaction, fungal hyphae need to massively colonize the mesophyll. Edwards and Bonde, (2011) used transmission electron microscopy and observed the hyphae and haustorial mother cells of P. pachyrhizi developed in soybean mesophyll between 14 and 21 dai.…”

Section: Resultsmentioning

confidence: 99%

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Infection process of Phakopsora gossypii in cotton leaves

Araújo

Guerra

Berger

et al. 2016

Sci. agric. (Piracicaba, Braz.)

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ABSTRACT:Tropical rust caused by the biotrophic fungus Phakopsora gossypii is an emerging disease in cotton that has caused significant yield losses of crop/cotton cultivated in Brazil.Considering the current importance of tropical rust and the need to obtain additional basic information about its causal agent to better control this disease, the present study aimed to determine the infection process of P. gossypii in cotton leaves using scanning electron microscopy (SEM). Thirty-day-old plants were inoculated with a suspension of P. gossypii uredospores, and leaf fragments were collected 42 h after inoculation (hai) as well as 20, 25 and 35 days after inoculation (dai) for SEM observations. By 42 hai, the uredospores of P. gossypii had germinated and produced a germ tube and an appressorium that may directly penetrate the leaf cuticle.At 20 dai, closed uredia containing uredospores were observed on the abaxial leaf surface. At 25 dai, the uredia started to open and became fully open by 35 dai and contained many uredospores. By 25 dai, fungal hyphae were growing abundantly in the mesophyll next to the uredia that formed in the leaf fragments with total or partial removal of the epidermis. The results of the present study provide novel information regarding the infection process of P. gossypii in cotton leaves, which might be useful for the development of new and more effective strategies for tropical rust control.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Infection process of Phakopsora gossypii in cotton leaves

Araújo

Guerra

Berger

et al. 2016

Sci. agric. (Piracicaba, Braz.)

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“…An appressorial cone initiates the penetration into the epidermal cell by turgor pressure independent of melanin accumulation (Chang et al 2014). Penetration hyphae grow through the epidermal cell and intercellular space, first forming primary invading hyphae, then secondary hyphae populating intercellular spaces (Bonde et al 1976;Edwards and Bonde 2011;Koch et al 1983;Vittal et al 2014). In compatible interactions, primary haustoria form in the mesophyll cells, secondary haustoria form within 12 days, and a domed-shaped eruption occurs in the epidermis to form uredinia that often have a rusty appearance on infected leaves of both kudzu and soybean (Fig.…”

Section: Classification Infection Host Range and Virulencementioning

confidence: 99%

“…In an incompatible interaction, branching of fungal hyphae in the mesophyll is not common, and is associated with mesophyll cell necrosis (McLean 1979). During the 24 h after inoculation, spore germination, appressorium formation, and fungal penetration of the epidermis in susceptible and resistant soybean genotypes are similar but, within 2 days, more hyphae occur in the mesophyll tissue of susceptible than in resistant genotypes, and mesophyll cell death is greater in soybean genotype with an immune response, demonstrating that an incompatible soybean-P. pachyrhizi interaction restricts hyphal development in the mesophyll cell tissue (Vittal et al 2014). A very similar response was observed in kudzu as well, where the resistant interactions had early onset of a multicell hypersensitive response, while immune interactions were the result of a cell wall deposition that blocked penetration in combination with early onset of a hypersensitive response (Jordan et al 2010) (Fig.…”

Section: Classification Infection Host Range and Virulencementioning

confidence: 99%

From Select Agent to an Established Pathogen: The Response to Phakopsora pachyrhizi (Soybean Rust) in North America

et al. 2015

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The pathogen causing soybean rust, Phakopsora pachyrhizi, was first described in Japan in 1902. The disease was important in the Eastern Hemisphere for many decades before the fungus was reported in Hawaii in 1994, which was followed by reports from countries in Africa and South America. In 2004, P. pachyrhizi was confirmed in Louisiana, making it the first report in the continental United States. Based on yield losses from countries in Asia, Africa, and South America, it was clear that this pathogen could have a major economic impact on the yield of 30 million ha of soybean in the United States. The response by agencies within the United States Department of Agriculture, industry, soybean check-off boards, and universities was immediate and complex. The impacts of some of these activities are detailed in this review. The net result has been that the once dreaded disease, which caused substantial losses in other parts of the world, is now better understood and effectively managed in the United States. The disease continues to be monitored yearly for changes in spatial and temporal distribution so that soybean growers can continue to benefit by knowing where soybean rust is occurring during the growing season.

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Soybean rust detection and disease severity classification by remote sensing

Negrisoli

Silva

et al. 2022

Agronomy Journal

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The detection and monitoring of soybean rust (SBR) through remote sensing is promising because of the importance of the crop and the aspects of the disease.We evaluated the effects of different levels of SBR severity on soybean [Glycine max (L.) Merr.] leaflets reflectance aiming for the construction of a disease classification model. Leaflet reflectance was evaluated on two cultivars (susceptible and partially resistant) at four disease severity levels: healthy, low, moderate, and high.Leaflets were collected in the field and taken to the laboratory for spectral evaluation through the spectrophotometer UV 2700 coupled with Integrating Sphere Attachment ISR-603, in the range of 270-1000 nm. The feasibility of using a collection of vegetation indices (VIs) and data dimensionality reduction through multiple factor analysis (MFA) was evaluated, and a classification model was constructed. Ten algorithms were assessed based on precision, sensibility, and accuracy parameters, using 80% of the dataset as training data and 20% as testing dataset. The visible range and red edge region contributed more significantly to the disease prediction and classification model. The MFA performed satisfactorily in the dimensionality reduction and unveiled the effect of specific wavelengths on the classification of each class. Most of the VIs studied had high correlation performance across the severity classes. Classification accuracy and precision were >70% for all models. Linear support vector machine with the collection of VIs achieved the best results. This study provides a practical path for developing a detection model to be integrated into SBR management programs.

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Characterization and Quantification of Fungal Colonization of Phakopsora pachyrhizi in Soybean Genotypes

Cited by 21 publications

References 34 publications

Infection process of Phakopsora gossypii in cotton leaves

Infection process of Phakopsora gossypii in cotton leaves

From Select Agent to an Established Pathogen: The Response to Phakopsora pachyrhizi (Soybean Rust) in North America

Soybean rust detection and disease severity classification by remote sensing

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