scholarly journals Effects of Chemical Control, Cultivar Resistance, and Structure of Cultivar Root System on Black Shank Incidence of Tobacco

Plant Disease ◽  
2010 ◽  
Vol 94 (5) ◽  
pp. 613-620 ◽  
Author(s):  
Dimitrios F. Antonopoulos ◽  
Thomas Melton ◽  
Asimina L. Mila
Keyword(s):  
Partial Resistance ◽  
Adventitious Roots ◽  
Early Stage ◽  
Laboratory Studies ◽  
Critical Factors ◽  
Cultivar Resistance ◽  
Black Shank ◽  
Initial Application ◽  
Race 1 ◽  
Tobacco Growth

Black shank, caused by the hemibiotrophic oomycete Phytophthora parasitica var. nicotianae, is a major disease of tobacco (Nicotiana tabacum). The rise of race 1 in the late 1990s, after extensive cropping of cultivars possessing the Php gene, confirming immunity to race 0 of P. parasitica var. nicotianae, imposed new challenges to black shank management. The effects of tobacco cultivars and chemical controls with mefenoxam (Ridomil Gold) on black shank incidence were investigated in naturally infested fields. Twenty-five cultivars were tested and the highest resistance for races 0 and 1 of P. parasitica var. nicotianae was provided by RJR 75 and SP 227 based on field and laboratory studies. When race 1 was prevalent, mefenoxam was effective to control black shank. An initial application at an early stage of tobacco growth, such as a few days before or after transplant, was essential to successfully control the disease. In greenhouse experiments, cultivars carrying the Php gene produced fewer and shorter adventitious roots than cultivars possessing only partial resistance to all races of P. parasitica var. nicotianae. Strategies such as use of mefenoxam, especially at an early stage, when adventitious roots are emerging, and planting a cultivar with high partial resistance or possessing the Ph gene when race 1 or race 0, respectively, predominates are critical factors in reducing loss due to P. parasitica var. nicotianae.

scholarly journals Resistance to Phytophthora nicotianae in Tobacco Breeding Lines Derived from Variety Beinhart 1000

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 252-258 ◽  
Author(s):  
Kestrel McCorkle ◽  
Ramsey Lewis ◽  
David Shew
Keyword(s):  
Partial Resistance ◽  
Phytophthora Nicotianae ◽  
Sources Of Resistance ◽  
Black Shank ◽  
Breeding Lines ◽  
Stem Resistance ◽  
Race 1 ◽  
Low Levels ◽  
Dh Lines ◽  
Rapid Emergence

Black shank, caused by Phytophthora nicotianae, is managed primarily by host resistance. The rapid emergence of race 1 eliminated the usefulness of available complete resistance, leading breeders to search for new sources of resistance. Cigar tobacco ‘Beinhart 1000’ (BH) is highly resistant to all races of P. nicotianae. Doubled-haploid (DH) lines from a cross of BH and the susceptible ‘Hicks’ were evaluated for black shank resistance, and quantitative trait loci (QTL) on linkage groups (LGs) 4 and 8 accounted for >43% of the phenotypic variation in resistance. Forty-three DH lines and parents were evaluated, and genotypes with one or both QTL from BH on LGs 4 and 8 had increased incubation periods and decreased root rot but higher final inoculum levels than genotypes with neither QTL. A low level of stem resistance was observed in BH and DH lines with the QTL from BH on LG 4 but not LG 8. Low levels of leaf resistance were seen for Hicks, BH, and DH lines with both QTL from BH on LG 4 and 8. The partial resistance from BH has not been used commercially and may provide an increase in level of partial resistance in future tobacco varieties.

Adaptation of Phytophthora nicotianae to multiple sources of partial-resistance in tobacco.

Plant Disease ◽  
2021 ◽  
Author(s):  
Jing Jin ◽  
Kestrel Lannon McCorkle ◽  
Vicki Cornish ◽  
Ignazio Carbone ◽  
Ramsey Lewis ◽  
...  
Keyword(s):  
Partial Resistance ◽  
Single Gene ◽  
Field Studies ◽  
Phytophthora Nicotianae ◽  
Multiple Sources ◽  
Rapid Loss ◽  
Sources Of Resistance ◽  
Black Shank ◽  
Race 1

Host resistance is an important tool in the management of black shank disease of tobacco. While race development leads to rapid loss of single-gene resistance, the adaptation by Phytophthora nicotianae to sources of partial resistance from Beinhart 1000, Florida 301, and the Wz gene region introgressed from Nicotiana rustica is poorly characterized. In greenhouse environments, host genotypes with QTLs conferring resistance from multiple sources were initially inoculated with an aggressive isolate of race 0 or race 1 of P. nicotianae. The most aggressive isolate was selected after each of six host generations to inoculate the next generation of plants. The race 0 isolate demonstrated a continuous gradual increase in disease severity and percent root rot on all sources of resistance except the genotype K 326 Wz/--, where a large increase in both was observed between generations two and three. Adaptation by the race 0 isolate on Beinhart 1000 represents the first report of adaptation to this genotype by P. nicotianae. The race 1 isolate did not exhibit significant increases in aggressiveness over generations, but also exhibited a large increase in aggressiveness on K 326 Wz/-- between generations 3 and 4. Molecular characterization of isolates recovered during selection was completed using ddRADseq, but no polymorphisms were associated with the observed changes in aggressiveness. The rapid adaptation to Wz resistance and the gradual adaptation to other QTLs highlights the need to study the nature of Wz resistance and for conducting field studies on efficacy of resistance-gene rotation for disease management.

Clarifying the Source of Black Shank Resistance in Flue-cured Tobacco

2008 ◽  
Vol 9 (1) ◽  
pp. 15 ◽  
Author(s):  
Charles S. Johnson ◽  
Jeremy A. Pattison ◽  
Elizabeth M. Clevinger ◽  
Thomas A. Melton ◽  
Bruce A. Fortnum ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Rapd Marker ◽  
Phytophthora Nicotianae ◽  
Cultivar Resistance ◽  
Black Shank ◽  
Race 1 ◽  
Highly Correlated ◽  
Pathogen Populations ◽  
Rotation Strategy

Widespread use of resistance to race 0 of Phytophthora nicotianae in flue-cured tobacco (Nicotiana tabacum) has increased problems with race 1 in commercial fields. The RAPD marker UBC30, tightly linked to the Ph gene for resistance to race 0, was used to clarify the presence of the Ph gene in specific cultivars to enable farmers to more appropriately match cultivar resistance to the pathogen races predominating in their fields. The marker UBC30 was present in 20 of the 31 flue-cured tobacco cultivars tested, including CC 27, GL 350, NC 196, SP 220, SP 225, SP 227, and NC 810. These cultivars were previously thought to not possess the Ph gene. Presence of UBC30 was highly correlated (r = 0.93; P ≤ 0.001) with survival in fields infested primarily with race 0, and with greater survival in fields infested primarily with race 0 versus race 1 of the pathogen (r = 0.76; P ≤ 0.001). The likely presence of the Ph gene in so many currently grown flue-cured tobacco cultivars may limit farmers' ability to shift pathogen populations back to race 0 from race 1 via the recommended cultivar rotation strategy. Accepted for publication 27 February 2008. Published 18 June 2008.

scholarly journals Managing the Race Structure of Phytophthora parasitica var. nicotianae with Cultivar Rotation

Plant Disease ◽  
2005 ◽  
Vol 89 (12) ◽  
pp. 1285-1294 ◽  
Author(s):  
M. J. Sullivan ◽  
T. A. Melton ◽  
H. D. Shew
Keyword(s):  
Partial Resistance ◽  
Disease Incidence ◽  
Single Gene ◽  
Growing Season ◽  
Phytophthora Parasitica ◽  
Black Shank ◽  
Complete Resistance ◽  
Race 1 ◽  
High Level ◽  
Different Levels

Deployment of tobacco cultivars with single-gene, complete resistance to race 0 of the tobacco black shank pathogen, Phytophthora parasitica var. nicotianae, has resulted in a rapid increase in the occurrence of race 1 of the pathogen in North Carolina. Cultivar-rotation studies were conducted in three fields to assess how different levels and types of resistance affected the race structure and population dynamics of the pathogen when deployed in fields initially containing single or mixed races of the pathogen. In a field with both races present, a high level of partial resistance in cv. K 346 was most effective in reducing disease and decreasing the proportion of race 1 in the pathogen population. The deployment of complete resistance in cv. NC 71 resulted in intermediate levels of disease control and race 1 became the predominate race. The cv. K 326, with a low level of partial resistance, had the highest levels of disease, and race 0 was the dominant race recovered. In a field where no race 1 was detected initially, disease incidence was high with the use of partial resistance. Complete resistance was very effective in suppressing disease, but race 1 was recovered after only one growing season. By the end of the third growing season, race 1 was recovered from most treatments where single-gene resistance was deployed. A high level of partial resistance was most effective in suppressing disease in a field where race 1 initially was the predominant race. A rotation between cultivars with single-gene resistance and cultivars with a high level of partial resistance should provide the most effective approach to black shank management. This rotation will reduce disease incidence and minimize race shifts in the pathogen and, over time, should prolong the usefulness of the Ph gene for black shank control in commercial production of tobacco.

Components of aggressiveness in Phytophthora nicotianae during adaptation to multiple sources of partial resistance in tobacco

Plant Disease ◽  
2020 ◽  
Author(s):  
Jing Jin ◽  
H. David Shew
Keyword(s):  
Partial Resistance ◽  
Single Gene ◽  
Phytophthora Nicotianae ◽  
Root Tip ◽  
Multiple Sources ◽  
Root Tips ◽  
Black Shank ◽  
Resistance Sources ◽  
Infected Root ◽  
Race 1

Black shank is a devastating disease of tobacco caused by Phytophthora nicotianae. Host resistance has been an integral part of black shank management, but after the loss of Php single-gene resistance following its widespread deployment in the 1990s, growers have relied on varieties with varying levels of partial resistance. Partial resistance is effective in suppressing disease, but continued exposure can result in an increase in pathogen aggressiveness that threatens durability of the resistance to P. nicotianae. Aggressiveness components in P. nicotianae were characterized following adaptation on two sources of partial resistance, Fla 301 and the Wz gene from Nicotiana rustica. An aggressive isolate of the two major races of P. nicotianae, race 0 and race 1, were adapted for either ‘one/two’ or ‘five/six’ generations on the two resistance sources, giving four sets of isolates based on race, number of generations of adaptation, and source of resistance. Across the four sets of isolates, adapted isolates infected higher proportions of root tips, produced more sporangia per infected root tip, and caused larger lesions than their respective non-adapted isolates of the same race and from the same resistance source. Adapted isolates also produced more aggressive zoospore progeny than the non-adapted isolates. Adaptation to partial resistance involves multiple aggressiveness components that results in the increased aggressiveness observed for P. nicotianae. These results improve our knowledge on the nature of P. nicotianae adaptation to partial resistance in tobacco and indicate that different resistance sources are likely to select for similar aggressiveness components in the pathogen.

scholarly journals RNAseq Reveals Differential Gene Expression Contributing to Phytophthora nicotianae Adaptation to Partial Resistance in Tobacco

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 656
Author(s):  
Jing Jin ◽  
Rui Shi ◽  
Ramsey Steven Lewis ◽  
Howard David Shew
Keyword(s):  
Partial Resistance ◽  
Molecular Mechanisms ◽  
Biological Activities ◽  
Effective Means ◽  
Phytophthora Nicotianae ◽  
Economic Losses ◽  
Black Shank ◽  
Differential Gene ◽  
Go Terms

Phytophthora nicotianae is a devastating oomycete plant pathogen with a wide host range. On tobacco, it causes black shank, a disease that can result in severe economic losses. Deployment of host resistance is one of the most effective means of controlling tobacco black shank, but adaptation to complete and partial resistance by P. nicotianae can limit the long-term effectiveness of the resistance. The molecular basis of adaptation to partial resistance is largely unknown. RNAseq was performed on two isolates of P. nicotianae (adapted to either the susceptible tobacco genotype Hicks or the partially resistant genotype K 326 Wz/Wz) to identify differentially expressed genes (DEGs) during their pathogenic interactions with K 326 Wz/Wz and Hicks. Approximately 69% of the up-regulated DEGs were associated with pathogenicity in the K 326 Wz/Wz-adapted isolate when sampled following infection of its adapted host K 326 Wz/Wz. Thirty-one percent of the up-regulated DEGs were associated with pathogenicity in the Hicks-adapted isolate on K 326 Wz/Wz. A broad spectrum of over-represented gene ontology (GO) terms were assigned to down-regulated genes in the Hicks-adapted isolate. In the host, a series of GO terms involved in nuclear biosynthesis processes were assigned to the down-regulated genes in K 326 Wz/Wz inoculated with K 326 Wz/Wz-adapted isolate. This study enhances our understanding of the molecular mechanisms of P. nicotianae adaptation to partial resistance in tobacco by elucidating how the pathogen recruits pathogenicity-associated genes that impact host biological activities.

scholarly journals Enzyme-Loaded Flower-Shaped Nanomaterials: A Versatile Platform with Biosensing, Biocatalytic, and Environmental Promise

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1460
Author(s):  
Khadega A. Al-Maqdi ◽  
Muhammad Bilal ◽  
Ahmed Alzamly ◽  
Hafiz M. N. Iqbal ◽  
Iltaf Shah ◽  
...  
Keyword(s):  
Organic Matter ◽  
Metal Ions ◽  
Critical Points ◽  
Structural Integrity ◽  
Early Stage ◽  
Surface Orientation ◽  
Critical Factors ◽  
Inorganic Hybrid ◽  
Iron Based ◽  
Significant Attention

As a result of their unique structural and multifunctional characteristics, organic–inorganic hybrid nanoflowers (hNFs), a newly developed class of flower-like, well-structured and well-oriented materials has gained significant attention. The structural attributes along with the surface-engineered functional entities of hNFs, e.g., their size, shape, surface orientation, structural integrity, stability under reactive environments, enzyme stabilizing capability, and organic–inorganic ratio, all significantly contribute to and determine their applications. Although hNFs are still in their infancy and in the early stage of robust development, the recent hike in biotechnology at large and nanotechnology in particular is making hNFs a versatile platform for constructing enzyme-loaded/immobilized structures for different applications. For instance, detection- and sensing-based applications, environmental- and sustainability-based applications, and biocatalytic and biotransformation applications are of supreme interest. Considering the above points, herein we reviewed current advances in multifunctional hNFs, with particular emphasis on (1) critical factors, (2) different metal/non-metal-based synthesizing processes (i.e., (i) copper-based hNFs, (ii) calcium-based hNFs, (iii) manganese-based hNFs, (iv) zinc-based hNFs, (v) cobalt-based hNFs, (vi) iron-based hNFs, (vii) multi-metal-based hNFs, and (viii) non-metal-based hNFs), and (3) their applications. Moreover, the interfacial mechanism involved in hNF development is also discussed considering the following three critical points: (1) the combination of metal ions and organic matter, (2) petal formation, and (3) the generation of hNFs. In summary, the literature given herein could be used to engineer hNFs for multipurpose applications in the biosensing, biocatalysis, and other environmental sectors.

scholarly journals Managing Fusarium Wilt of Watermelon with Delayed Transplanting and Cultivar Resistance

Plant Disease ◽  
2019 ◽  
Vol 103 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Anthony P. Keinath ◽  
Timothy W. Coolong ◽  
Justin D. Lanier ◽  
Pingsheng Ji
Keyword(s):  
United States ◽  
South Carolina ◽  
Soil Temperature ◽  
Fusarium Wilt ◽  
Disease Incidence ◽  
Southern United States ◽  
Cultivar Resistance ◽  
Race 1 ◽  
Triploid Watermelon ◽  
Marketable Fruit

Fusarium wilt of watermelon caused by Fusarium oxysporum f. sp. niveum is a serious, widespread disease of watermelon throughout the southern United States. To investigate whether soil temperature affects disease development, three cultivars of triploid watermelon were transplanted March 17 to 21, April 7 to 11, and April 26 to May 2 in 2015 and 2016 at Charleston, SC, and Tifton, GA into fields naturally infested with F. oxysporum f. sp. niveum. Incidence of Fusarium wilt was lower with late-season than with early and midseason transplanting in all four experiments (P ≤ 0.01). Cultivar Citation had more wilted plants than the cultivars Fascination and Melody in three of four experiments (P ≤ 0.05). In South Carolina, planting date did not affect weight and number of marketable fruit ≥4.5 kg apiece. In Georgia in 2016, weight and number of marketable fruit were greater with late transplanting than with early and midseason transplanting. In both states, yield and value for Fascination and Melody were higher than for Citation. Soil temperature averaged over the 4-week period after transplanting was negatively correlated with disease incidence for all four experiments (r = –0.737, P = 0.006). Transplanting after mid-April and choosing a cultivar with resistance to F. oxysporum f. sp. niveum race 1, like Fascination, or tolerance, like Melody, can help manage Fusarium wilt of watermelon and increase marketable yields in the southern United States.

scholarly journals Fitness of Races 0 and 1 of Phytophthora parasitica var. nicotianae

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1220-1228 ◽  
Author(s):  
M. J. Sullivan ◽  
T. A. Melton ◽  
H. D. Shew
Keyword(s):  
Partial Resistance ◽  
Minor Effect ◽  
Population Declines ◽  
Phytophthora Parasitica ◽  
Growing Seasons ◽  
Incubation Periods ◽  
Race 1 ◽  
Study Population ◽  
Overwintering Survival ◽  
Pathogen Populations

Deployment of tobacco (Nicotiana tabacum) varieties with complete resistance to race 0 of Phytophthora parasitica var. nicotianae has led to a rapid increase in the field populations of race 1 in North Carolina. In a field study, population levels of race 1 decreased relative to race 0 when cultivars with partial resistance to both races were planted, suggesting that race 1 isolates were less fit than race 0 isolates. Experiments were conducted to quantify differences in aggressiveness and survivability of the two races. Tobacco varieties with low, moderate, or high levels of partial resistance were inoculated with 60 pathogen isolates, and symptom development was monitored for 3 weeks. Race 0 isolates were more aggressive than race 1 isolates on cultivars with moderate or high levels of partial resistance; incubation periods were shorter and root rot severity was greater with race 0 isolates. Isolates of race 1, however, caused greater stunting of plants with moderate and high levels of partial resistance than race 0 isolates. Field microplots were infested with either a single race or an equal mixture of each race. Soil samples were collected at the end of two growing seasons and again the following spring. Pathogen populations declined from 40 to 80% during winter months, but population declines for race 0 were lower than for race 1 in each treatment over each winter. Race shifts from race 1 to race 0 that were observed in the presence of cultivars with partial resistance appear to be primarily the result of differences in aggressiveness of the races, with a possible minor effect of enhanced overwintering survival of race 0 compared with race 1.

Application of an Evolutionary Modeling Approach to Automotive Bumper System Design and Analysis

1998 ◽  
Author(s):  
Stephen C.-Y. Lu ◽  
Christine Ping Ge ◽  
Nanxin Wang
Keyword(s):  
System Design ◽  
Early Stage ◽  
Selection Procedure ◽  
Empirical Models ◽  
Evolutionary Modeling ◽  
Modeling Approach ◽  
Initial Application ◽  
Cost Constraints ◽  
Available Information ◽  
Bumper System

Abstract Both empirical and mechanistic models are needed to design complex engineering systems. Empirical models play a particularly important role in design especially at the early stage. Large amounts of information, in terms of prior knowledge and experimental data, are needed for statistical analysis and machine learning methods to build empirical models with high quality. However, in some engineering domains, such as vehicle bumper system design, information is very limited due to the time/cost constraints and unknown physics of the problem. Methods are needed to construct reliable empirical models with limited amounts of available information. An Evolutionary Modeling Approach (EMA) has been developed as a first attempt to address this problem. In this approach, empirical model construction is viewed as a multistage, iterative learning process, in which the inaccurate and/or incomplete models gradually evolve into more accurate ones through a heuristically guided data selection procedure. This paper describes the EMA methodology and its initial application to an automotive bumper design and analysis problem.

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