scholarly journals Growth Chamber Assay for Evaluating Resistance to Athelia rolfsii

2020 ◽  
Vol 47 (1) ◽  
pp. 25-32 ◽  
Author(s):  
R.S. Bennett
Keyword(s):  
Sclerotium Rolfsii ◽  
Growth Chamber ◽  
Lesion Length ◽  
Mycelium Growth ◽  
Arachis Species ◽  
Resistant Cultivars ◽  
Athelia Rolfsii ◽  
Commercial Cultivars ◽  
Intermediate Resistance ◽  
Resistant Genotypes

ABSTRACT Planting resistant cultivars is most sustainable method for managing Athelia rolfsii (= Sclerotium rolfsii), one of the most damaging pathogens of peanut worldwide. However, evaluating germplasm for resistance in the field can be complicated by unfavorable environmental conditions, uneven distribution of sclerotia in soil, and difficulty in growing non-standard peanut genotypes such as wild species. Thus, a growth-chamber assay was used to screen for resistance to A. rolfsii in the laboratory. Thirteen peanut genotypes were used to test the assay: cultivars Georgia-03L, Georgia-12Y, Florida-07, Georgia-07W, Tamrun OL02, FloRun ‘107′, Georgia-06G, and U.S. mini-core accessions CC038 (PI 493581), CC041 (PI 493631), CC068 (PI 493880), CC384 (PI 155107), CC650 (PI 478819), and CC787 (PI 429420). Lesion length, as well as length of visible mycelium, on the main stem and a side stem were recorded at 4, 7, 10, and 13 days after inoculation. In general, patterns of lesion and mycelium growth were similar. The most resistant genotypes, Georgia-03L and CC650, had the smallest lesions and least mycelium growth. However, Georgia-12Y, one of the most resistant cultivars available today, appeared less resistant than Georgia-03L in the assay. Other commercial cultivars were intermediate in lesion and mycelium lengths. The most susceptible entries were CC038, CC041, and CC787. Despite limitations in discriminating among genotypes with intermediate resistance to A. rolfsii, these assays may be useful for pre-screening germplasm to identify physiologically resistant and highly susceptible entries, as well as for screening Arachis species that are difficult to grow in the field.

scholarly journals A Note on a Greenhouse Evaluation of Wild Arachis Species for Resistance to Athelia rolfsii

2021 ◽  
Author(s):  
Rebecca S. Bennett ◽  
Angie D. Harting ◽  
Charles E. Simpson ◽  
Shyamalrau P. Tallury ◽  
Austin B. Pickering ◽  
...  
Keyword(s):  
Mycelial Growth ◽  
Lesion Length ◽  
Sources Of Resistance ◽  
Arachis Species ◽  
Southern Blight ◽  
Soilborne Disease ◽  
Greenhouse Evaluation ◽  
Athelia Rolfsii ◽  
Cultivated Peanut ◽  
The One

Athelia rolfsii (Curzi) C.C. Tu & Kimbr. is the one of the most damaging pathogens of cultivated peanut, causing the soilborne disease known regionally as white mold, stem rot, or southern blight. Because the genetic base for cultivated peanut is narrow, wild Arachis species may possess novel sources of disease resistance. We evaluated 18 accessions representing 15 Arachis species ( batizocoi , benensis , cardenasii , correntina , cruziana , diogoi , duranensis , herzogii , hoehnei , kempff - mercadoi , kuhlmannii , microsperma , monticola , simpsonii , williamsii ) in the greenhouse for resistance to At. rolfsii . Assays were conducted on intact plants propagated from rooted cuttings inoculated with mycelial plugs, and lesion length and mycelial growth were measured at 4, 6, 10, and 12 days after inoculation. For lesion length, Arachis batizocoi (PI 468326 and PI 468327), and A. kuhlmannii PI 468159 were the most susceptible entries with a mean lesion length >50 mm at 12 days after inoculation. Arachis microsperma (PI 666096 and PI 674407) and A. diogoi PI 468354 had the shortest lesions with mean lengths ≤16 mm at 12 days after inoculation. Arachis cruziana PI 476003 and the two A. batizocoi PIs had the highest mean area under the disease progress curves (AUDPCs), and the lowest AUDPC was obtained from the A. microsperma PI 674407. Mycelial growth was correlated with lesion length in most species except A. monticola PI 497260 . These results may be useful to peanut geneticists seeking additional sources of resistance to Athelia rolfsii .

scholarly journals Application of Bio-Friendly Formulations of Chitinase-Producing Streptomyces cellulosae Actino 48 for Controlling Peanut Soil-Borne Diseases Caused by Sclerotium rolfsii

2021 ◽  
Vol 7 (3) ◽  
pp. 167
Author(s):  
Gaber Abo-Zaid ◽  
Ahmed Abdelkhalek ◽  
Saleh Matar ◽  
Mai Darwish ◽  
Muhammad Abdel-Gayed
Keyword(s):  
Open Field ◽  
Biocontrol Agent ◽  
Sclerotium Rolfsii ◽  
Dry Weight ◽  
Culture Broth ◽  
Field Conditions ◽  
Damping Off ◽  
Mycelium Growth ◽  
Particle Size Analyzer ◽  
Cell Pellet

Of ten actinobacterial isolates, Streptomyces cellulosae Actino 48 exhibited the strongest suppression of Sclerotium rolfsii mycelium growth and the highest chitinase enzyme production (49.2 U L−1 min−1). The interaction between Actino 48 and S. rolfsii was studied by scanning electron microscope (SEM), which revealed many abnormalities, malformations, and injuries of the hypha, with large loss of S. rolfsii mycelia density and mass. Three talc-based formulations with culture broth, cell-free supernatant, and cell pellet suspension of chitinase-producing Actino 48 were characterized using SEM, Fourier transform infrared spectroscopy (FTIR), and a particle size analyzer. All formulations were evaluated as biocontrol agents for reducing damping-off, root rot, and pods rot diseases of peanut caused by S. rolfsii under greenhouse and open-field conditions. The talc-based culture broth formulation was the most effective soil treatment, which decreased the percentage of peanut diseases under greenhouse and open-field conditions during two successive seasons. The culture broth formulation showed the highest increase in the dry weight of peanut shoots, root systems, and yielded pods. The transcriptional levels of three defense-related genes (PR-1, PR-3, and POD) were elevated in the culture broth formulation treatment compared with other formulations. Subsequently, the bio-friendly talc-based culture broth formulation of chitinase-producing Actino 48 could potentially be used as a biocontrol agent for controlling peanut soil-borne diseases caused by S. rolfsii.

First report of Sclerotium rolfsii (=Athelia rolfsii) associated with root rot and leaf spot on clove basil (Ocimum gratissimum L.) in India

2021 ◽  
Author(s):  
Shivannegowda Mahadevakumar ◽  
Yelandur Somaraju Deepika ◽  
Kandikere Ramaiah Sridhar ◽  
Kestur Nagaraj Amruthesh ◽  
Nanjaiah Lakshmidevi
Keyword(s):  
Leaf Spot ◽  
Root Rot ◽  
Sclerotium Rolfsii ◽  
First Report ◽  
Ocimum Gratissimum ◽  
Athelia Rolfsii

scholarly journals Screening Oryza Species Plants for Rice Sheath Blight Resistance

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 808-812 ◽  
Author(s):  
G. C. Eizenga ◽  
F. N. Lee ◽  
J. N. Rutger
Keyword(s):  
Sheath Blight ◽  
Oryza Species ◽  
Growth Chamber ◽  
Lesion Length ◽  
Cultivated Rice ◽  
Visual Rating ◽  
Leaf Lesion ◽  
Generation Progeny ◽  
Limited Scale ◽  
Moderately Resistant

Rice wild relatives, Oryza species, are one possible source of sheath blight (Rhizoctonia solani) resistance genes. However, Oryza spp. cannot be screened in the field as is done for cultivated rice (O. sativa) because the plant canopy does not favor disease development and many plants drop mature seed. Thus, a growth chamber-greenhouse method of screening Oryza spp. and their early generation progeny is needed. Primary-secondary and ratoon tillers of rice cultivars-germplasm which ranged from moderately resistant to very susceptible were evaluated first for sheath blight susceptibility. Plants were inoculated by placing R. solani-colonized toothpicks at the leaf collar, then incubating plants in a growth chamber. After 7 days, plants were visually rated for sheath blight severity, and the lesion length of each leaf was measured. Ranking of cultivar-germplasm susceptibility by visual rating of primary-secondary tillers corresponded to the ranking from field ratings. Visual ratings correlated best with combined lesion length of the second and third leaves. For ratoon tillers, visual ratings correlated best with second-leaf lesion length. Next, this method was used with ratoon tillers to evaluate sheath blight susceptibility of 21 Oryza spp. accessions and F1 progeny from crosses between 17 accessions and cultivated rice. This method proved useful on a limited scale for screening germplasm that could not be evaluated under field conditions.

scholarly journals Evaluation of the virulence of Sclerotium rolfsii isolates on Arachis hypogaea and screening for resistant genotypes in greenhouse conditions

2015 ◽  
Vol 8 (1) ◽  
pp. 1-11 ◽  
Author(s):  
A.A. Eslami ◽  
S.A. Khodaparast ◽  
S. Mousanejad ◽  
F. Padasht Dehkaei
Keyword(s):  
Plant Height ◽  
Block Design ◽  
Sclerotium Rolfsii ◽  
Soil Surface ◽  
Lesion Length ◽  
Randomized Block Design ◽  
Wide Range ◽  
Mycelial Compatibility ◽  
Pathogenicity Tests ◽  
Plant Maturity

Summary Sclerotium rolfsii is a soil borne pathogen responsible for root and stem rot on a wide range of crops. This study was conducted to identify the virulence of different S. rolfsii isolates on a susceptible local peanut germplasm and determine the resistance of 20 peanut genotypes to the most virulent isolate and also the relationship between virulence and mycelial compatibility groups (MCGs). Seventy eight isolates of this fungus from 10 host plants and six known MCGs were used in the experiment. The experiment was done in greenhouse conditions (25±5°C) using a complete randomized block design with three replications. Pots containing sterile soil (pH=6.7) were inoculated with barley seeds colonized by each isolate separately before being seeded with the peanut germplasm. Disease severity was assessed by scoring the wilting, yellowing or death of plants, mycelia or sclerotia production on the soil surface or on plant stem, stem area affected (%) and stem lesion length, at the stage of plant maturity. Also, shoot wet weight and plant height were recorded at this stage. According to the results of the pathogenicity tests, all of the isolates were virulent on the susceptible peanut germplasm and the virulence diff ered signifi cantly between the isolates (P≤0.01). There was no relationship between the virulence of the five groups of isolates identified in the present study and the MCGs. The peanut genotype 140, which was better than the others based on seed size, plant height and the canopy size, was also the most resistant one

scholarly journals Purification and Characterization of Cellobiose Dehydrogenase from the Plant Pathogen Sclerotium(Athelia) rolfsii

2001 ◽  
Vol 67 (4) ◽  
pp. 1766-1774 ◽  
Author(s):  
Ursula Baminger ◽  
Sai S. Subramaniam ◽  
V. Renganathan ◽  
Dietmar Haltrich
Keyword(s):  
Sclerotium Rolfsii ◽  
Cation Radical ◽  
Molecular Size ◽  
Extracellular Enzyme ◽  
Cellobiose Dehydrogenase ◽  
Phytopathogenic Fungus ◽  
Athelia Rolfsii ◽  
Heme Domain ◽  
Acid Cation

ABSTRACT Cellobiose dehydrogenase (CDH) is an extracellular hemoflavoenzyme produced by several wood-degrading fungi. In the presence of a suitable electron acceptor, e.g., 2,6-dichloro-indophenol (DCIP), cytochromec, or metal ions, CDH oxidizes cellobiose to cellobionolactone. The phytopathogenic fungus Sclerotium rolfsii (teleomorph: Athelia rolfsii) strain CBS 191.62 produces remarkably high levels of CDH activity when grown on a cellulose-containing medium. Of the 7,500 U of extracellular enzyme activity formed per liter, less than 10% can be attributed to the proteolytic product cellobiose:quinone oxidoreductase. As with CDH from wood-rotting fungi, the intact, monomeric enzyme from S. rolfsii contains one heme b and one flavin adenine dinucleotide cofactor per molecule. It has a molecular size of 101 kDa, of which 15% is glycosylation, and a pI value of 4.2. The preferred substrates are cellobiose and cellooligosaccharides; additionally, β-lactose, thiocellobiose, and xylobiose are efficiently oxidized. Cytochrome c (equine) and the azino-di-(3-ethyl-benzthiazolin-6-sulfonic acid) cation radical were the best electron acceptors, while DCIP, 1,4-benzoquinone, phenothiazine dyes such as methylene blue, phenoxazine dyes such as Meldola's blue, and ferricyanide were also excellent acceptors. In addition, electrons can be transferred to oxygen. Limited in vitro proteolysis with papain resulted in the formation of several protein fragments that are active with DCIP but not with cytochrome c. Such a flavin-containing fragment, with a mass of 75 kDa and a pI of 5.1 and lacking the heme domain, was isolated and partially characterized.

scholarly journals First Report of Root and Collar Rot by Sclerotium rolfsii on Apple Trees in Italy

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 695-695
Author(s):  
L. Corazza ◽  
A. Belisario ◽  
E. Forti
Keyword(s):  
Apple Tree ◽  
Sclerotium Rolfsii ◽  
Apple Trees ◽  
Collar Rot ◽  
Athelia Rolfsii ◽  
Leaf Chlorosis ◽  
General Decline ◽  
Summer Temperatures ◽  
Ground Plate ◽  
Mycelial Strands

Sclerotium rolfsii Sacc. (teleomorph Athelia rolfsii (Curzi) Tu & Kimbrough) is a polyphagous, soilborne plant pathogen. In summer 1998, a sudden death of 2-year-old apple trees (Malus domestica Borkh.) cv. Royal Gala grafted on M9 rootstock was observed in an orchard near Rome, Italy. Symptoms were stunted vegetation, leaf chlorosis, and root and collar rot. A fungus identified as S. rolfsii was observed producing sclerotia and whitish mycelial strands on root and collar bark. Isolations from roots and at the margin of subcortical necrosis on the collar consistently yielded S. rolfsii colonies on potato dextrose agar (PDA); sclerotia developed within 7 days. Koch's postulates were fulfilled by inoculating 10 1-year-old apple tree cv. M9 rootstocks, grown in 3.5-liter pots, with an S. rolfsii isolate grown for 1 week on PDA at 25°C. One ground plate per plant was used, placed around collar and main roots. Five control plants were treated with PDA only. Rootstocks were kept in the greenhouse at 26 ± 2°C. Within 2 months, 70% of inoculated plants died, with marked necrosis girdling the collar. The other inoculated plants showed a general decline, with widespread necrosis on collars and main roots. Control plants remained healthy. S. rolfsii was reisolated from collars and roots of symptomatic plants. S. rolfsii has been recorded on apple trees in the U.S., India, China, and Israel. In Italy, it is destructive on several crops, and was recently recorded on walnut (1). This first outbreak of S. rolfsii on apple in Italy may have been favored by exceptionally warm late spring and summer temperatures. Reference: (1) A. Belisario and L. Corazza. Plant Dis. 80:824, 1996.

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