scholarly journals Resistance to rust (Puccinia arachidis Speg.) identified in nascent allotetraploids cross-compatible with cultivated peanut (Arachis hypogaea L.)

2021 ◽  
Author(s):  
Chandler Maddox Levinson ◽  
Eric Antepenko ◽  
Soraya C. M. Leal-Bertioli ◽  
Ye Chu ◽  
Albert K. Culbreath ◽  
...  
Keyword(s):  
United States ◽  
Leaf Area ◽  
Interspecific Hybrids ◽  
Rust Resistance ◽  
The United States ◽  
Plant Management ◽  
Arachis Species ◽  
Puccinia Arachidis ◽  
Cultivated Peanut ◽  
Peanut Cultivars

Peanut rust, caused by Puccinia arachidis Speg., is a foliar disease that plagues peanut production along with early and late leaf spots, Passalora arachidicola (Hori) U. Braun and Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash, Videira & Crous, respectively. Rust can cause up to 80% yield losses without control and is widespread in tropical countries but is also a sporadic problem in the United States. An integrative plant management strategy with rust resistant peanut cultivars is needed to decrease dependence on costly fungicides and increase yields for farmers who cannot afford or do not have access to fungicides. Only moderate levels of rust resistance have been found in cultivated peanut germplasm, but fortunately, high resistance to rust has been identified in wild Arachis species that can be introgressed into peanut cultivars. In this study, 16 diploid, wild Arachis species, five diploid, interspecific hybrids, 11 unique, allotetraploid interspecific hybrids, and two cultivated peanut controls were tested for resistance to rust. Resistance was evaluated in vitro by incubation time, susceptibility index (calculated based on the number of lesions of different diameters)/ leaf area, total number of lesions/ leaf area, and total number of sporulating lesions/ leaf area. All wild Arachis species tested were very highly resistant to rust, except for A. ipaënsis , the B-genome progenitor of cultivated peanut. Additionally, all interspecific hybrids and synthetic allotetraploids not produced with A. ipaënsis as a parent did not show symptoms for rust. Any of these nine synthetic allotetraploids, BatCor , BatDur 1, BatDur 2, BatSten 1, GregSten , MagCard , MagDio , MagDur , and ValSten 1 are recommended for progression to QTL mapping of rust resistance. These resistance QTLs can be pyramided into peanut cultivars to protect yields in the United States and to increase yields in tropical, developing countries for farmers that cannot afford, or do not have access to, costly fungicides.

scholarly journals First Report of Leaf Spot of Sesame Caused by Xanthomonas sp. In the United States

Plant Disease ◽  
2012 ◽  
Vol 96 (8) ◽  
pp. 1222-1222 ◽  
Author(s):  
T. Isakeit ◽  
B. T. Hassett ◽  
K. L. Ong
Keyword(s):  
United States ◽  
Leaf Area ◽  
Its Region ◽  
The United States ◽  
Pcr Analysis ◽  
Sterile Water ◽  
First Report ◽  
Genomic Dna Isolation ◽  
Leaf Spots ◽  
Mist Chamber

In July 2010 in Texas, extensive leaf spots (10 to 30% leaf area affected) occurred on a commercial planting of sesame (Sesamum indicum L.) in Hidalgo County and to a lesser extent (1 to 5% leaf area) on leaves of several varieties in experimental trials in Colorado and Victoria Counties. The leaf spots were light to dark brown, somewhat circular, and 1 to 3 mm in diameter. A symptomatic leaf from each of three to five plants per county was sampled for isolations. Leaves were sprayed with 70% ethanol and immediately blotted dry with a paper towel. The margins of spots (2 mm2) were excised with a scalpel and placed in a drop of sterile water for 5 min. Drops were streaked on nutrient agar (NA) and incubated at 30°C. The 12 isolations consistently yielded gram-negative, rod-shaped bacteria with yellow, translucent colonies that were visible after 2 days of incubation. The DNA of 11 isolates was extracted with the Norgen (Thorold, ON) Bacterial genomic DNA isolation kit (Cat. #17900) and the ITS region was amplified by 16S uni 1330 and 23S uni 322 anti primers (1). PCR products were treated with the ZymoResearch (Irvine, CA) DNA clean & concentrator kit (Cat. #D4003) and sequenced. With the NCBI database, a BLAST search of the 1,100 bp amplicons showed 93 to 99% identity with pathovars of either Xanthomonas oryzae or X. axonopodis (GenBank Accession Nos. CP003057.1 and CP002914.1, respectively). Amplicon sequences of the sesame isolates were deposited in GenBank as Accession Nos. JQ975037 through JQ975047. The reported species on sesame is X. campestris pv. sesami (2). To fulfill Koch's postulates, potted sesame plants (var. Sesaco 25), 15 to 20 cm tall, were sprayed until runoff with a suspension of bacteria (106 to 107 CFU/ml) from a 2-day-old NA culture. All 12 isolates were evaluated, with five to seven plants per isolate. Plants were maintained in a mist chamber in a greenhouse at 27 to 30°C and 100% relative humidity. The pathogenicity trial was repeated once. Leaf spots were first seen 7 days after inoculation and were prevalent 14 days after inoculation. All 12 isolates were pathogenic. There were no symptoms on leaves sprayed with sterile water. Bacteria that produced colonies consistent with Xanthomonas were reisolated on NA from symptomatic leaves but not from controls. The identities of three isolates were reconfirmed with PCR analysis and sequencing. In 2007, more than 2,000 ha of sesame were grown in the continental United States, with 80% of that in Texas. Currently, acreage of shatter-free varieties of sesame is increasing in arid areas of Texas, Oklahoma, and Kansas. In such areas, the yield impact of this disease is likely to be minimal, except in years with above-average rainfall. To our knowledge, this is the first report of this disease in the United States. References: (1) E. R. Gonçalves and Y. B. Rosato. Int. J. Syst. Evol. Microbiol. 52:355, 2002. (2) J. M. Young et al., New Zealand J. Agric. Res. 21:153, 1978.

Commercial Runner Peanut Cultivars in the United States: Tocopherol Composition

2009 ◽  
Vol 57 (21) ◽  
pp. 10289-10295 ◽  
Author(s):  
Eui-Cheol Shin ◽  
Yue-Zhong Huang ◽  
Ronald B. Pegg ◽  
R. Dixon Phillips ◽  
Ronald R. Eitenmiller
Keyword(s):  
United States ◽  
The United States ◽  
Tocopherol Composition ◽  
Peanut Cultivars

scholarly journals Differentiation of Molecular Genotypes and Virulence Phenotypes of Puccinia triticina from Common Wheat in North America

2009 ◽  
Vol 99 (6) ◽  
pp. 750-758 ◽  
Author(s):  
M. E. Ordoñez ◽  
J. A. Kolmer
Keyword(s):  
United States ◽  
North America ◽  
Leaf Rust ◽  
Resistance Genes ◽  
Rust Resistance ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
The United States ◽  
Rust Resistance Genes ◽  
Leaf Rust Resistance Genes

Wheat leaf rust caused by Puccinia triticina is widely distributed in the wheat growing regions of the United States and Canada, and is subject to selection for virulence phenotype by leaf rust resistance genes in wheat cultivars. The objective of this study was to determine the number of genetically differentiated groups of P. triticina that are currently present in North America. In total, 148 isolates of P. triticina from the 1980s to 2005 were collected from wheat-growing regions of the United States and Canada and tested for virulence on 20 lines of wheat with single genes for leaf rust resistance and for molecular genotype with 23 simple sequence repeat (SSR) markers. In total, 91 virulence phenotypes and 65 SSR genotypes were found. After removal of isolates with identical virulence and SSR genotypes, 125 isolates were included for further analysis. Bayesian cluster analysis indicated five different groups of isolates based on SSR genotypes that also differed for virulence to leaf rust resistance genes Lr2a, Lr2c, Lr3bg, Lr17, and Lr28. Isolates avirulent to Lr14a and Lr20 that have increased since 2003 had SSR genotypes identical or similar to older isolates in one of the five groups, indicating that these isolates were derived by mutation from the previously existing population of P. triticina. The representative collection of P. triticina isolates had characteristics consistent with an asexual dikaryotic population of genetically differentiated groups of SSR genotypes with high levels of heterozygosity and disequilibrium within which stepwise mutation at avirulence or virulence loci regularly occurs.

scholarly journals Florida Crop/Pest Profile: Sugarcane

EDIS ◽  
2018 ◽  
Vol 2018 (3) ◽  
Author(s):  
Philippe Charles Rott ◽  
Dennis Calvin Odero ◽  
Julien Beuzelin ◽  
Richard N. Raid ◽  
Matthew VanWeelden ◽  
...  
Keyword(s):  
United States ◽  
Interspecific Hybrids ◽  
The United States ◽  
Crop Pest ◽  
Sugarcane Crop ◽  
The World ◽  
Cultivation Techniques

Sugarcane (Saccharum interspecific hybrids) is the main source of sugar in the world. It is grown in more than 90 countries in tropical and subtropical regions. Cultivation techniques and production challenges vary by location (Rott 2017; Rott 2018). This 19-page document discusses characteristics of the sugarcane crop and pests affecting its production in Florida, which is the largest producer of sugarcane in the United States. Written by P. Rott, D. C. Odero, J. M. Beuzelin, R. N. Raid, M. VanWeelden, S. Swanson, and M. Mossler, and published by the UF/IFAS Agronomy Department, revised May 2018. https://edis.ifas.ufl.edu/pi207

scholarly journals Characterizing leaf area index (LAI) and vertical foliage profile (VFP) over the United States

2016 ◽  
Vol 13 (1) ◽  
pp. 239-252 ◽  
Author(s):  
H. Tang ◽  
S. Ganguly ◽  
G. Zhang ◽  
M. A. Hofton ◽  
R. F. Nelson ◽  
...  
Keyword(s):  
United States ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Canopy Structure ◽  
The United States ◽  
Data Set ◽  
Area Index ◽  
Continental Scale ◽  
Comparison Results ◽  
Waveform Lidar

Abstract. Leaf area index (LAI) and vertical foliage profile (VFP) are among the important canopy structural variables. Recent advances in lidar remote sensing technology have demonstrated the capability of accurately mapping LAI and VFP over large areas. The primary objective of this study was to derive and validate a LAI and VFP product over the contiguous United States (CONUS) using spaceborne waveform lidar data. This product was derived at the footprint level from the Geoscience Laser Altimeter System (GLAS) using a biophysical model. We validated GLAS-derived LAI and VFP across major forest biomes using airborne waveform lidar. The comparison results showed that GLAS retrievals of total LAI were generally accurate with little bias (r2 =  0.67, bias  =  −0.13, RMSE  =  0.75). The derivations of GLAS retrievals of VFP within layers were not as accurate overall (r2 =  0.36, bias  =  −0.04, RMSE  =  0.26), and these varied as a function of height, increasing from understory to overstory – 0 to 5 m layer: r2 =  0.04, bias  =  0.09, RMSE  =  0.31; 10 to 15 m layer: r2 =  0.53, bias  =  −0.08, RMSE  =  0.22; and 15 to 20 m layer: r2 =  0.66, bias  =  −0.05, RMSE  =  0.20. Significant relationships were also found between GLAS LAI products and different environmental factors, in particular elevation and annual precipitation. In summary, our results provide a unique insight into vertical canopy structure distribution across North American ecosystems. This data set is a first step towards a baseline of canopy structure needed for evaluating climate and land use induced forest changes at the continental scale in the future, and should help deepen our understanding of the role of vertical canopy structure in terrestrial ecosystem processes across varying scales.

scholarly journals Additional Sources of Broad-Spectrum Resistance to Puccinia coronata f. sp. avenae from Canadian Accessions of Avena barbata

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1405-1410 ◽  
Author(s):  
M. L. Carson
Keyword(s):  
United States ◽  
Broad Spectrum ◽  
Rust Resistance ◽  
The United States ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
Adult Plant ◽  
United States Department ◽  
Ploidy Levels ◽  
Broad Spectrum Resistance

Crown rust (Puccinia coronata f. sp. avenae) is considered the most damaging disease of oat and the use of race-specific seedling (Pc) genes for resistance has been the primary means of control. As these resistance genes from cultivated oat, Avena sativa, and the wild hexaploid animated oat, A. sterilis, were deployed in oat cultivars, corresponding virulence in the U.S. crown rust population increased rapidly, such that the effective lifespan of a resistant cultivar in the United States is now 5 years or less. Introgression of resistance from diploid and tetraploid Avena spp. into hexaploid oat has been difficult due to the difference in ploidy levels and the lack of pairing of homeologous chromosomes between species. The wild tetraploid slender oat, A. barbata, has been a source of powdery mildew and stem rust resistance in cultivated oat but has largely been unexploited for crown rust resistance. A relatively high percentage of A. barbata accessions from the United States Department of Agriculture (USDA) National Small Grains Collection were resistant to a highly diverse crown rust population in recent tests. Tests of 1,099 A. barbata accessions from the Canadian Plant Gene Resources Center not represented in the USDA collection revealed that a similar percentage (11.4%) were at least moderately resistant at the seedling and adult plant stage when tested with a highly diverse bulk inoculum derived from the St. Paul buckthorn nursery. Eighteen accessions were rated as highly resistant or a mix of highly resistant and resistant plants in both seedling and adult plant tests. Three accessions (CN21531 from Italy and CN26271 and CN26305 from Spain) displayed a unique “blotchy” resistant reaction as adult plants. Resistant accessions were found from throughout much of the natural range of A. barbata but the Western Mediterranean and Lebanon had the highest frequency of accessions with broad-spectrum resistance.

scholarly journals Races of Puccinia graminis Identified in the United States During 2003

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1125-1127 ◽  
Author(s):  
Y. Jin
Keyword(s):  
United States ◽  
Resistance Genes ◽  
Stem Rust ◽  
Rust Resistance ◽  
The United States ◽  
Stem Rust Resistance ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Stem Rust Resistance Genes ◽  
Rust Resistance Genes

Stem rust of small grain cereals, caused by Puccinia graminis, is a major disease of wheat, barley, and oat. In order to effectively utilize stem rust resistance in the improvement of small grain cereals, it is necessary to monitor the virulence composition and dynamics in the stem rust population. Races of P. graminis from barberry, wheat, barley, and oat were surveyed across the United States during 2003. Aecial infections on barberry were primarily due to P. graminis f. sp. secalis, as inoculations using aeciospores failed to produce infection on wheat and oat. Race QFCS of P. graminis f. sp. tritici was the most common race identified from wheat and barley. Race QFCS has virulence on stem rust resistance genes Sr5, 8a, 9a, 9d, 9g, 10, 17, and 21 that are used for race identification. Race TTTT was identified in 2003. This race possesses virulence to all 16 stem rust resistance genes present in the wheat stem rust differentials and should be targeted in breeding for stem rust resistance. Race QFCN appeared to be a new race in the U.S. stem rust population. Races QCCJ and MCCF were identified, but at low frequencies. Seven races of P. graminis f. sp. avenae were identified from oat, and races NA-27, NA-29, and NA-67 were the predominant races. Race NA-76 was identified for the first time in the United States.

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