scholarly journals Preservation methods for isolates of ascochyta blight fungi

2014 ◽  
Vol 39 (2) ◽  
pp. 139-145
Author(s):  
Joanna Marcinkowska
Keyword(s):  
Ascochyta Blight ◽  
Mineral Oil ◽  
Mycosphaerella Pinodes ◽  
Minor Importance ◽  
Conidial Suspension ◽  
Small Space ◽  
Highly Pathogenic ◽  
Preservation Method ◽  
Ascochyta Pisi ◽  
A Minor

Isolates of ascochyta blight fungi, two of <i>Ascochyta pisi</i>, four of <i>Mycosphaerella pinodes</i> and four of <i>Phoma pinodella</i> were stored: A - on slants under mineral oil, B - on CN's medium agar disks, and as conidial suspension: C - in glycerine, D · in water. Viability and pathogenicity of recovered cultures after each consecutive year were assesed from 1991 to 1999. The compared parameters were first of all strongly influenced by the preservation method, but fungus species and number of years had a minor importance. The best for longer storage was method "A" because after 9 years the isolates were viable, highly pathogenic, and cultures recovered from them were clean. Thc method "C'' is good for short keeping (2-3 years), as conidia in vials need only small space and gave clean cultures.

The epidemiology and control of ascochyta blight in field peas: a review

2006 ◽  
Vol 57 (8) ◽  
pp. 883 ◽  
Author(s):  
T. W. Bretag ◽  
P. J. Keane ◽  
T. V. Price
Keyword(s):  
Current Knowledge ◽  
Ascochyta Blight ◽  
Mycosphaerella Pinodes ◽  
Sources Of Resistance ◽  
New Crops ◽  
Field Peas ◽  
Ascochyta Pisi ◽  
Almost All ◽  
The Cost ◽  
And Control

Ascochyta blight is one of the most important diseases affecting field peas. The disease occurs in almost all pea-growing regions of the world and can cause significant crop losses when conditions are favourable for an epidemic. Here we review current knowledge of the epidemiology of the disease. Details are provided of disease symptoms, the disease cycle and the taxonomy of the causal fungi, Ascochyta pisi, Mycosphaerella pinodes and Phoma pinodella. The importance of seed-, soil- and air-borne inoculum is discussed along with the factors that influence survival of the causal fungi in soil, on seed or associated with pea trash. Many studies have been reviewed to establish how the fungi responsible for the disease survives from year to year, how the disease becomes established in new crops and the conditions that favour disease development. Evidence is provided that crop rotation, destruction of infected pea trash and chemical seed treatments can significantly reduce the amount of primary inoculum. Later sowing of crops has been shown to reduce the incidence and severity of disease. Fungicides have been used successfully to control the disease, although the cost of their application can significantly reduce the profitability of the crop. The best long-term strategy for effective disease control appears to be the development of ascochyta blight resistant pea varieties. Reports of physiological specialisation in ascochyta blight fungi are also documented. Despite extensive screening of germplasm, relatively few sources of resistance to ascochyta blight fungi have been found in Pisum sativum. However, the discovery of much better sources of resistance in closely related species and the development of advanced breeding methods offer new possibilities for developing useful resistance.

Importance of seed-borne inoculum in the etiology of the Ascochyta blight complex of field peas (Pisum sativum L.) grown in Victoria

1995 ◽  
Vol 35 (4) ◽  
pp. 525 ◽  
Author(s):  
TW Bretag ◽  
TV Price ◽  
PJ Keane
Keyword(s):  
Pisum Sativum ◽  
Ascochyta Blight ◽  
Mycosphaerella Pinodes ◽  
Seed Infection ◽  
Seeding Rate ◽  
Pisum Sativum L ◽  
Field Peas ◽  
Ascochyta Pisi ◽  
Growing Region ◽  
Seed Infestation

Fungi associated with the ascochyta blight complex of field peas were isolated from 436 of 691 seedlots tested. Of the fungi detected, 94.8% of isolates were Mycosphaerella pinodes, 4.2% Phoma medicaginis, and 1.0% Ascochyta pisi. The levels of infestation of seed varied considerably from year to year and between seedlots, depending on the amount of rainfall between flowering and maturity. Within a particular pea-growing region, the level of seed-borne infection was often highest in seed from crops harvested latest. In addition, crops sown early were usually more severely affected by disease than late-sown crops, and this resulted in higher levels of seed infection. There was no correlation between the level of seed infestation by M. pinodes and the severity of ascochyta blight; however, where the level of seed infection was high (>11%) there was a significant reduction in emergence, which caused a reduction in grain yield. It may therefore be possible to use seed with high levels of seed-borne ascochyta blight fungi, provided the seeding rate is increased to compensate for poor emergence.

Ascochyta Blight of Peas

2011 ◽  
Vol 12 (1) ◽  
pp. 29 ◽  
Author(s):  
Linnea G. Skoglund ◽  
Robert M. Harveson ◽  
Weidong Chen ◽  
Frank Dugan ◽  
Howard F. Schwartz ◽  
...  
Keyword(s):  
North Dakota ◽  
Ascochyta Blight ◽  
Field Pea ◽  
Mycosphaerella Pinodes ◽  
Growth Stages ◽  
Southwest Asia ◽  
Cool Season ◽  
Foliar Diseases ◽  
Ascochyta Pisi ◽  
Serious Disease

Field pea is an annual, cool-season legume native to northwest to southwest Asia. It was among the first crops cultivated by man. The crop is grown primarily in North Dakota, Washington, Montana, Idaho, Oregon, and southern Canada. Ascochyta blight is a serious disease affecting above ground portions at all growth stages. Stem, crown, pod, and foliar diseases of pea are caused by a complex of Ascochyta pisi, Mycosphaerella pinodes, and Phoma pinodella. This paper reviews the disease and the pathogens involved. Accepted for publication 28 January 2011. Published 30 March 2011.

scholarly journals First Report of Ascochyta Blight of Field Pea Caused by Ascochyta pisi in South Dakota

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 789-789 ◽  
Author(s):  
F. M. Mathew ◽  
R. S. Goswami ◽  
S. G. Markell ◽  
L. Osborne ◽  
C. Tande ◽  
...  
Keyword(s):  
South Dakota ◽  
Consensus Sequence ◽  
Ascochyta Blight ◽  
Its Region ◽  
The United States ◽  
Field Pea ◽  
Conidial Suspension ◽  
First Report ◽  
Production Region ◽  
Ascochyta Pisi

Tan lesions approximately 1.7 × 0.8 cm with distinct dark brown margins and small pycnidia were observed on leaves of field peas (Pisum sativum L. ‘Agassiz’) growing in Campbell County, South Dakota (45°45.62′N, 100°9.13′W) in July 2008. Small pieces of symptomatic leaves were surface sterilized (10% NaOCl for 1 min, 70% EtOH for 1 min, and sterile distilled H2O for 2 min) and placed on potato dextrose agar (PDA) for 7 days under fluorescent lights with a 12-h photoperiod to induce sporulation. A pure culture was established by streaking a conidial suspension on PDA and isolating a single germinated spore 3 days later. The culture was grown on clarified V8 media for 10 days. Conidia were 10 to 16 × 3 to 4.5 μm and uniseptate with a slightly constricted septum, similar to those of Ascochyta pisi Lib. The exuding spore mass from pycnidia growing on the medium was carrot red. No chlamydospores or pseudothecia were observed (1,2). To confirm the identity of A. pisi, DNA was extracted from the lyophilized mycelium of the 10-day-old culture with the DNeasy Plant Mini Kit (Qiagen, Valencia, CA). Internal transcribed spacer (ITS) regions I and II were amplified with PCR primers ITS 5 and ITS 4 (3). PCR amplicons were cleaned and directly sequenced in both directions using the primers. A BLASTN search against the NCBI nonredundant nucleotide database was performed using the consensus sequence generated by alignment of the forward and reverse sequences for this region. The consensus sequence (GenBank Accession No. GU722316) most closely matched A. pisi var. pisi strain (GenBank Accession No. EU167557). These observations confirm the identity of the fungus as A. pisi. A suspension of 1 × 106 conidia/ml of the isolate was spray inoculated to runoff on 10 replicate plants of 2-week-old, susceptible green field pea ‘Sterling’. Plants were incubated in a dew chamber for 48 h at 18°C and moved to the greenhouse bench where they were maintained at 20 to 25°C with a 12-h photoperiod for 1 week. Tan lesions with dark margins appeared 7 days after inoculation and disease was assessed after 10 days (4). No symptoms were observed on water-treated control plants. A. pisi was reisolated from lesions and confirmed by DNA sequencing of the ITS region, fulfilling Koch's postulates. Currently, states bordering South Dakota (North Dakota and Montana) lead the United States in field pea production. Although acreage is limited in South Dakota, the identification of A. pisi in this region is serious. The disease is yield limiting and foliar fungicides are used for disease management (1). To our knowledge, this is the first report of Ascochyta blight on P. sativum caused by A. pisi occurring in South Dakota and the MonDak production region (the Dakotas and Montana). References: (1) T. W. Bretag et al. Aust. J. Agric. Res. 57:88, 2006. (2) A. S. Lawyer. Page 11 in: The Compendium of Pea Diseases. D. J. Hagedorn, ed. The American Phytopathological Society, St Paul, MN, 1984. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990. (4) J. M. Wroth. Can. J. Bot. 76:1955, 1998.

Dynamics of oxytocin, estrogen and progestin receptors in the bovine endometrium during the estrous cycle

1988 ◽  
Vol 118 (1) ◽  
pp. 96-104 ◽  
Author(s):  
H. H. D. Meyer ◽  
Th. Mittermeier ◽  
D. Schams
Keyword(s):  
Estrous Cycle ◽  
Luteal Phase ◽  
Oxytocin Receptor ◽  
Minor Importance ◽  
Progestin Receptors ◽  
Progestin Receptor ◽  
Nuclear Estrogen Receptor ◽  
Low Sensitivity ◽  
A Minor ◽  
Estradiol Levels

Abstract. The levels of oxytocin receptor (OTR), cytosolic progestin receptor (cPR), cytosolic and nuclear estrogen receptor (cER, nER) were measured in the endometrium of 28 heifers that had been slaughtered on a defined day of the estrous cycle, In an additional, trial endometrial tissue obtained from 78 heifers or cows at the abattoir was analyed for OTR. OTR was absent during the luteal phase (after day 6), but a minor elevation was observed after day 15. OTR increased rapidly after luteolysis on days 17–18 reaching a maximum during estrous on day 21, and decreased again during days 1–6. cER and cPR were different to OTR but followed a similar pattern with maximal levels during days 1–8 of the estrous cycle. At day 12 both receptors were minimal and increased again towards day 21. nER was maximal at day 19–21 coinciding with maximal estradiol levels and estrous. Our data indicate that owing to an increasing sensitivity of the endometrium to progesterone and estradiol after day 12, these steroids may be mainly responsible for the initiation of first PGF2α surges and luteolysis. Oxytocin seems to be of minor importance at this stage owing to low sensitivity of the endometrium for oxytocin.

scholarly journals The ADAMTS13 metalloprotease domain: roles of subsites in enzyme activity and specificity

Blood ◽  
2010 ◽  
Vol 116 (16) ◽  
pp. 3064-3072 ◽  
Author(s):  
Rens de Groot ◽  
David A. Lane ◽  
James T. B. Crawley
Keyword(s):  
Single Point ◽  
Minor Importance ◽  
Variable Regions ◽  
Cleavage Efficiency ◽  
Scissile Bond ◽  
A Minor ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

Abstract ADAMTS13 modulates von Willebrand factor (VWF) platelet-tethering function by proteolysis of the Tyr1605-Met1606 bond in the VWF A2 domain. To examine the role of the metalloprotease domain of ADAMTS13 in scissile bond specificity, we identified 3 variable regions (VR1, -2, and -3) in the ADAMTS family metalloprotease domain that flank the active site, which might be important for specificity. Eight composite sequence swaps (to residues in ADAMTS1 or ADAMTS2) and 18 single-point mutants were generated in these VRs and expressed. Swapping VR1 (E184-R193) of ADAMTS13 with that of ADAMTS1 or ADAMTS2 abolished/severely impaired ADAMTS13 function. Kinetic analysis of VR1 point mutants using VWF115 as a short substrate revealed reduced proteolytic function (kcat/Km reduced by 2- to 10-fold) as a result of D187A, R190A, and R193A substitutions. Analysis of VR2 (F216-V220) revealed a minor importance of this region. Mutants of VR3 (G236-A261) proteolysed wild-type VWF115 normally. However, using either short or full-length VWF substrates containing the P1′ M1606A mutation, we identified residues within VR3 (D252-P256) that influence P1′ amino acid specificity, we hypothesize, by shaping the S1′ pocket. It is concluded that 2 subsites, D187-R193 and D252-P256, in the metalloprotease domain play an important role in cleavage efficiency and site specificity.

Leaf Spots Induced by Ascochyta pisi and Mycosphaerella pinodes

1969 ◽  
Vol 33 (4) ◽  
pp. 657-669 ◽  
Author(s):  
MICHELE C. HEATH ◽  
R. K. S. WOOD
Keyword(s):  
Mycosphaerella Pinodes ◽  
Leaf Spots ◽  
Ascochyta Pisi

scholarly journals Identification of novel sources of resistance to ascochyta blight in a collection of wild Cicer accessions

2020 ◽  
Author(s):  
Toby E. Newman ◽  
Silke Jacques ◽  
Christy Grime ◽  
Fiona L. Kamphuis ◽  
Robert C. Lee ◽  
...  
Keyword(s):  
Genome Wide Association Study ◽  
Ascochyta Blight ◽  
Ascochyta Rabiei ◽  
Sources Of Resistance ◽  
Highly Pathogenic ◽  
Cicer Echinospermum ◽  
Genome Wide ◽  
A Genome ◽  
The Impact ◽  
Chickpea Cultivars

Chickpea production is constrained worldwide by the necrotrophic fungal pathogen Ascochyta rabiei, the causal agent of ascochyta blight (AB). In order to reduce the impact of this disease, novel sources of resistance are required in chickpea cultivars. Here, we screened a new collection of wild Cicer accessions for AB resistance and identified accessions resistant to multiple, highly pathogenic isolates. In addition to this, analyses demonstrated that some collection sites of Cicer echinospermum harbour predominantly resistant accessions, knowledge that can inform future collection missions. Furthermore, a genome-wide association study identified regions of the Cicer reticulatum genome associated with AB resistance and investigation of these regions identified candidate resistance genes. Taken together, these results can be utilised to enhance the resistance of chickpea cultivars to this globally yield-limiting disease.

Seed disinfection: III. Experiments on the germination of peas. Seed protection by the use of disinfectant dusts containing mercury

1937 ◽  
Vol 27 (1) ◽  
pp. 53-66 ◽  
Author(s):  
C. C. Brett ◽  
W. A. R. Weston Dillon ◽  
J. R. Booer
Keyword(s):  
Weather Conditions ◽  
Field Studies ◽  
Heterodera Schachtii ◽  
Mycosphaerella Pinodes ◽  
Soil Conditions ◽  
Foot Rot ◽  
Ungerminated Seed ◽  
Adverse Weather ◽  
Seed Disinfection ◽  
Ascochyta Pisi

In a previous paper(1) reference was made to the subject of seed disinfection, in particular to an investigation on disinfectant dusts containing mercury. It was shown that by the use of certain of these dusts the common seed-borne diseases of cereals (excluding the loose smuts of barley and wheat) could be controlled. The present observations record further work, chiefly greenhouse and field studies, that has been done on green peas. This crop would appear to be of increasing economic importance, since in the past ten years the acreage devoted to it has increased by approximately 49 per cent. Its successful cultivation is often much influenced by climatic and soil conditions, particularly during the first few weeks after sowing. If adverse weather conditions follow, poor germination may result although the seed sown may have been viable and not necessarily diseased. Failures of such a type are usually associated with the rotting of the ungerminated seed in the soil, but from the same bulks, samples sown under more favourable conditions may germinate well and produce a satisfactory crop. Ogilvie (2,3,4) finds that in the Western Advisory province Ascochyta Pisi and Mycosphaerella pinodes are two causes of the early failure of pea plants, and that “pea sickness” is associated with a strain of the eelworm Heterodera schachtii and with foot-rot caused by various species of Fusarium. Premature dying-off of the plants is accompanied sometimes with Heterodera schachtii and foot-rot and sometimes with foot-rot alone.

scholarly journals A Single, Plastic Population of Mycosphaerella pinodes Causes Ascochyta Blight on Winter and Spring Peas (Pisum sativum) in France

2012 ◽  
Vol 78 (23) ◽  
pp. 8431-8440 ◽  
Author(s):  
Christophe Le May ◽  
Michèle Guibert ◽  
Aurélie Leclerc ◽  
Didier Andrivon ◽  
Bernard Tivoli
Keyword(s):  
Ascochyta Blight ◽  
Plant Diseases ◽  
Mycosphaerella Pinodes ◽  
Physiological Status ◽  
Late Winter ◽  
Content Type ◽  
Evolutionary Forces ◽  
Growing Seasons ◽  
Field Peas ◽  
Pathogen Populations

ABSTRACTPlant diseases are caused by pathogen populations continuously subjected to evolutionary forces (genetic flow, selection, and recombination). Ascochyta blight, caused byMycosphaerella pinodes, is one of the most damaging necrotrophic pathogens of field peas worldwide. In France, both winter and spring peas are cultivated. Although these crops overlap by about 4 months (March to June), primary Ascochyta blight infections are not synchronous on the two crops. This suggests that the disease could be due to two differentM. pinodespopulations, specialized on either winter or spring pea. To test this hypothesis, 144 pathogen isolates were collected in the field during the winter and spring growing seasons in Rennes (western France), and all the isolates were genotyped using amplified fragment length polymorphism (AFLP) markers. Furthermore, the pathogenicities of 33 isolates randomly chosen within the collection were tested on four pea genotypes (2 winter and 2 spring types) grown under three climatic regimes, simulating winter, late winter, and spring conditions.M. pinodesisolates from winter and spring peas were genetically polymorphic but not differentiated according to the type of cultivars. Isolates from winter pea were more pathogenic than isolates from spring pea on hosts raised under winter conditions, while isolates from spring pea were more pathogenic than those from winter pea on plants raised under spring conditions. These results show that disease developed on winter and spring peas was initiated by a single population ofM. pinodeswhose pathogenicity is a plastic trait modulated by the physiological status of the host plant.

Sign in / Sign up

Export Citation Format

Share Document