scholarly journals Characterizing Resistance to Soybean Aphid (Hemiptera: Aphididae): Antibiosis and Antixenosis Assessment

Author(s):  
Raman Bansal ◽  
M A Rouf Mian ◽  
Andy Michel

Abstract Host-plant resistance (HPR) remains a vital tool to manage soybean aphid (Aphis glycines Matsumura), a major pest of soybean in Midwestern United States and southern Canada. HPR can be overcome by virulent biotypes of A. glycines; thus, in order to increase the durability of resistant cultivars, HPR needs to be deployed strategically. To improve the strategic deployment, a complete understanding of HPR in existing resistant germplasm will help ensure HPR success. In this study, we characterized HPR soybean to determine antibiosis and antixenosis categories of resistance to different biotypes of A. glycines. No-choice and free-choice tests were performed on 11 previously reported plant introductions (PIs) possessing resistance to at least one A. glycines biotype (1, 2, and 3). Overall, we found that the PIs manifested differences of a particular resistance category in response to infestation by different biotypes. Our data from no-choice tests indicate that all tested PIs possess antibiosis-based resistance to three biotypes. However, the strength of antibiosis was variable as some PIs showed stronger antibiosis toward a given biotype than others. All tested PIs manifested antixenosis, in addition to antibiosis. Furthermore, detached leaf assays revealed that resistance to A. glycines was not retained in excised soybean leaves. Characterization of resistance in this study can contribute to develop strategies for future deployment of resistant cultivars developed from these PIs.

2019 ◽  
Vol 112 (5) ◽  
pp. 2407-2417 ◽  
Author(s):  
Sophia R Conzemius ◽  
Louis S Hesler ◽  
Adam J Varenhorst ◽  
Kelley J Tilmon

Abstract Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), infestations of soybean, Glycine max (L.) Merr. (Fabales: Fabaceae), and the associated yield loss have led to a large dependence on insecticidal management in soybean throughout the Midwestern United States. However, several populations of pyrethroid-resistant soybean aphids have recently been found in Iowa, Minnesota, North Dakota and South Dakota, which highlights the importance of alternative management approaches. One such alternative method is host-plant resistance, which uses naturally occurring plant defenses in crop cultivars to reduce the potential for yield loss from a pest population. Current soybean aphid-resistant cultivars do not protect against all soybean aphids due to the presence of virulent biotypes. In particular, soybean aphid biotype 4 is virulent to Rag1 and Rag2 resistance genes both individually and in combination. However, we hypothesized that resistance to biotype 4 may exist in previously identified, but uncharacterized resistant soybean plant introductions (PIs). To test this, we evaluated 51 previously identified but uncharacterized soybean aphid-resistant PIs for their resistance to colonies of soybean aphid biotype 4 collected in separate site-years (Lomira, WI 2013; Volga, SD 2015, 2016). Free-choice tests identified 14 PIs with putative resistance to ‘Lomira13’, two to ‘Volga15’, and eight to ‘Volga16’ soybean aphid colonies. Follow-up, no-choice tests corroborated two to three resistant PIs per colony, and PI 437696, which was resistant to each of the three colonies and could aid in breeding efforts and an integrated approach to soybean aphid management.


Author(s):  
S J Bhusal ◽  
R L Koch ◽  
A J Lorenz

Abstract Soybean aphid (Aphis glycines Matsumura (Hemiptera: Aphididae)) has been a major pest of soybean in North America since its detection in this continent in 2000 and subsequent spread. Although several aphid resistance genes have been identified, at least four soybean aphid biotypes have been discovered, with three of them being virulent on soybean cultivars with certain soybean aphid resistance genes. These biotypes are known to vary across years and locations, but information on their variation within single fields is limited. An investigation was conducted to study the variation of soybean aphid biotypes within single townships and fields in Minnesota. Screening of 28 soybean aphid isolates collected from seven soybean fields (six soybean fields in Cairo and Wellington Townships of Renville County, MN and one field in Wilmar Township of Kandiyohi County, MN) revealed the existence of multiple known biotypes of soybean aphid within single fields of soybean. We found up to three biotypes of soybean aphid in a single field. Two biotypes were found in five fields while only one field had only a single biotype. Three isolates presented reactions on a panel of resistant and susceptible indicator lines that were different from known biotypes. These results highlight the importance of characterizing soybean aphid biotypes in small geographical areas and utilizing generated knowledge to develop soybean cultivars pyramided with multiple resistance genes. The outcome will be decreased use of insecticides, thereby improving economic and environmental sustainability of soybean production.


Genome ◽  
2007 ◽  
Vol 50 (12) ◽  
pp. 1104-1111 ◽  
Author(s):  
Charles Y. Chen ◽  
Cuihua Gu ◽  
Clarice Mensah ◽  
Randall L. Nelson ◽  
Dechun Wang

The soybean aphid ( Aphis glycines Matsumura) has become a major pest of soybean in North America since 2000. Seven aphid resistance sources, PI 71506, Dowling, Jackson, PI 567541B, PI 567598B, PI 567543C, and PI 567597C, have been identified. Knowledge of genetic relationships among these sources and their ancestral parents will help breeders develop new cultivars with different resistance genes. The objective of this research was to examine the genetic relationships among these resistance sources. Sixty-one lines were tested with 86 simple sequence repeat (SSR) markers from 20 linkage groups. Non-hierarchical (VARCLUS) and hierarchical (Ward’s) clustering and multidimensional scaling (MDS) were used to determine relationships among the 61 lines. Two hundred and sixty-two alleles of the 86 SSR loci were detected with a mean polymorphism information content of 0.36. The 61 lines were grouped into 4 clusters by both clustering methods and the MDS results consistently corresponded to the assigned clusters. The 7 resistance sources were clustered into 3 different groups corresponding to their geographical origins and known pedigree information, indicating genetic differences among these sources. The largest variation was found among individuals within different clusters by analysis of molecular variance.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Kaitlin M. Chapman ◽  
Lia Marchi-Werle ◽  
Thomas E. Hunt ◽  
Tiffany M. Heng-Moss ◽  
Joe Louis

Author(s):  
Valeria Moreno Heredia

Yellow rust is caused by the fungus Puccinia striiformis f.sp.tritici (Pst), which due to its great migratory capacity, adaptation to different environments, and high levels of mutation; is one of the most devastating wheat diseases worldwide. Due to this, several strategies have been implemented to control the disease, the best being genetic improvement. The key to develop resistant cultivars is understanding the interactions between wheat and Pst. Therefore, this work synthesizes the most important investigations carried out in the last 30 years regarding: cellular, histological, and molecular interactions between wheat and Pst. This will allow a deeper and more complete understanding of the interaction between resistance and virulence genes in the yellow rust disease. The results of this work revealed that the early stage of infection, in susceptible and resistant cultivars, is the same qualitatively, but not quantitatively. However, a clear difference at the histological and molecular level, in terms of the amount and type of genes expressed, begins 48 hours after infection. It was also found that the haustorium, in addition to absorbing nutrients from the host; can also manipulate its metabolism to benefit itself, and can make some nutrients on its own. Keywords: haustorio, Puccinia striiformis f.sp.tritici, histological, resistance genes, virulence genes. Resumen La roya amarilla es causada por el hongo Puccinia striiformis f.sp.tritici (Pst), el cual debido a su gran capacidad migratoria, adaptación a diferentes ambientes, y niveles altos de mutación; es la enfermedad más devastadoras del trigo a nivel mundial. Debido a esto, varias estrategias han sido implementadas para controlar la enfermedad, siendo la mejor, el mejoramiento genético. La clave para desarrollar cultivares resistentes, es el entendimiento de las interacciones entre el trigo y Pst. Por lo tanto, este trabajo sintetiza las investigaciones más importantes realizadas en los últimos 30 años, en cuanto a interacciones celulares, histológicas y moleculares entre el trigo y Pst. Esto permitirá un entendimiento más profundo y completo de la interacción entre los genes de resistencia y virulencia, en la enfermedad de la roya. Los resultados revelaron que la fase temprana de infección en cultivares susceptibles y resistentes, es igual cualitativamente, pero no cuantitativamente. Sin embargo, una diferencia clara a nivel histológico y molecular, en cuanto a la cantidad y al tipo de genes expresados, empieza 48 hr post infección. También, se halló que el haustorio además de absorber nutrientes del huésped, también manipula el metabolismo de éste para su beneficio y puede elaborar algunos nutrientes por sí mismo. Palabras Clave: haustorio, Puccinia striiformis f.sp.tritici, histológico, genes de resistencia, genes de virulencia.


2013 ◽  
Vol 14 (1) ◽  
pp. 31 ◽  
Author(s):  
Imana L. Power ◽  
Albert K. Culbreath ◽  
Barry L. Tillman

Peanut rust, caused by Puccinia arachidis Speg, is an important foliar disease of peanut (Arachis hypogaea L.) in tropical countries. The best option for disease management is host resistance. The objectives of this project included characterizing peanut genotypes for resistance to P. arachidis, assessing the genetic variation of newly developed Collaborative Research and Support Program (CRSP) peanut breeding lines, and assessing genetic variability among P. arachidis populations. In field studies conducted over 2010-2011, several CRSP breeding lines demonstrated varying levels of rust resistance. Detached leaf assays were used to examine the components of resistance to P. arachidis. Few significant differences were observed in these studies. We used SSR markers to characterize newly developed CRSP breeding lines, plant introductions, and commonly grown cultivars. The SSR markers used detected polymorphisms but were not able to distinguish resistant from susceptible peanut genotypes. Sequences of the 5.8S-ITS2-28S region of P. arachidis isolates collected from different regions in the United States and other countries do not indicate high genetic variability among the populations. Accepted for publication 23 September 2013. Published 25 November 2013.


2019 ◽  
Vol 113 (2) ◽  
pp. 940-948
Author(s):  
Ashley N Dean ◽  
Shelby Pritchard ◽  
John C Tyndall ◽  
Erin W Hodgson ◽  
Matthew E O’Neal

Abstract Farmers face many choices when selecting seed for soybean (Glycine max (L.) Merr.) production, including highly desired herbicide tolerance traits. Despite the convenience of herbicide tolerance, resistant weeds and technology fees may reduce utility and profitability of these varieties, especially when commodity prices are low. Sporadic outbreaks of soybean aphid (Aphis glycines Matsumura, Hemiptera: Aphididae) that require insecticide use for optimal yield can be a further complication for farmers in Iowa. Soybean aphid-resistant varieties are commercially available, but in limited genetic backgrounds without herbicide tolerance. We hypothesized yield and value of resistance traits will vary based on the environment. We established plots at two locations with different risks of soybean aphid outbreaks and used two planting dates at each location to mimic different yield environments. In 2016 and 2017, we planted four varieties that varied in their susceptibility to soybean aphids and glyphosate, and applied insecticides if aphid populations reached an economic threshold. Regardless of genetic background, aphid-resistant varieties prevented populations from reaching the economic threshold at all environments. We observed no significant difference in yield between resistant and susceptible varieties, revealing this trait is as effective at protecting yield as an insecticide application on susceptible varieties at the high-risk location. We also explored the value of each variety in different environments. Resistant varieties produced greater potential net revenue than susceptible varieties at the high-risk location, while the opposite occurred at the low-risk location. Resistant varieties with herbicide tolerance, if made available, would be the most valuable across all environments.


Many attempts have been made in the past to bring order to the near-bewildering array of eutectic morphologies. These have met with limited success due mainly to the fact that the morphology of a particular eutectic may be highly dependent on both chemical composition and the rate of freezing. This paper shows for binary alloys, at least, that a more complete understanding of eutectic growth may be obtained by applying a few simple ‘rules’. With these it is possible to so characterize eutectic growth that the unknown structure of a particular eutectic may be prodicted at a given growth rate if the entropy of solution and re­lative volume of each phase are known. The characterization scheme embraces the growth behaviour of the thirty or so systems for which thermodynamic data are more readily available.


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