scholarly journals Pathotype IV, a New and Highly Virulent Pathotype of Didymella rabiei, Causing Ascochyta Blight in Chickpea in Syria

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1192-1192 ◽  
Author(s):  
M. Imtiaz ◽  
M. M. Abang ◽  
R. S. Malhotra ◽  
S. Ahmed ◽  
B. Bayaa ◽  
...  
Keyword(s):  
Rating Scale ◽  
Wide Spectrum ◽  
Major Gene ◽  
Block Design ◽  
Ascochyta Blight ◽  
Gene Pools ◽  
Sources Of Resistance ◽  
Host Genotype ◽  
Single Spore ◽  
Highly Virulent

The causal agent of Ascochyta blight disease of chickpea (Cicer arietinum L.) is highly variable because of the presence of a sexual phase (Didymella rabiei). There is also selection pressure on the pathogen due to wide adoption of improved resistant chickpea cultivars in some countries. The pathogen is able to produce pathotypes with specific virulence on particular cultivars. Three pathotypes, I, II, and III, have been reported (3). In this study, we confirmed the presence of a new and highly virulent pathotype that we designate as pathotype IV. To test the pathogenicity of the isolates collected and maintained at ICARDA, 10 isolates representing a wide spectrum of pathogenic variation, including those classified by S. M. Udupa et al. (3) and a putatively identified more virulent type, which was collected from a chickpea production field in the Kaljebrine area, Syria, were inoculated onto a set of differential chickpea genotypes. The differential genotypes, ILC 1929, ILC 482, ILC 3279, and ICC 12004, were sown in individual 10-cm-diameter pots containing potting mix and arranged in a randomized block design with three replications in a plastic house maintained at 18 to 20°C. Each differential genotype was inoculated individually with the 10 isolates following the methodology of S. M. Udupa et al. (3). DNA was extracted from single-spored isolates to compare the genotypes of the isolates using three simple sequence repeat (SSR) markers (ArA03T, ArH05T, and ArH06T) (2) and to determine the frequency of mating types (MAT) through the use of MAT-specific PCR primers for MAT1-1 and MAT1-2 (1). Host genotype reactions were measured on a 1 to 9 rating scale (1 = resistant and 9 = plant death). On the basis of the pathogenicity tests, the isolates were classified into four pathotypes: I (least virulent, killed ILC 1929 but not ILC 482, ILC 3279, or ICC12004); II (virulent, killed ILC 1929 and ILC 482 but not ILC 3279 or ICC12004); III (more virulent, killed ILC 1929, ILC 482, and ILC 3279 but not ICC12004); and IV (highly virulent, killed all four host differentials). Of 10 single-spore isolates tested, four showed similar disease reactions unique to pathotype I, four revealed pathotype II reactions, and one isolate each behaved like pathotype III or pathotype IV. SSR fingerprinting of these isolates provided evidence for genetic diversity since SSR ArH05T was highly polymorphic and amplified five bands, including pathotypes III- and IV-specific bands, which need further investigation to discern if this locus has any role to play in the virulence. MAT-type analysis showed that seven isolates were MAT1-1 while the remaining three isolates were MAT1-2. Only pathotype I showed the profile of MAT1-2 and the other three pathotypes were MAT1-1. Initially, a number of chickpea wild relatives were screened to identify sources of resistance to pathotype IV, but none of the accessions tested showed resistance. However, efforts are underway to combine minor and major gene(s) available in the breeding program in addition to a further search of the wild gene pools to control pathotype IV. References: (1) M. P. Barve et al. Fungal Genet. Biol. 39:151, 2003. (2) J. Geistlinger et al. Mol. Ecol. 9:1939, 2000. (3) S.M. Udupa et al. Theor. Appl. Genet. 97:299, 1998.

scholarly journals Differential resistance reaction of maize genotypes to maize stem borer (Chilo partellus Swinhoe) at Chitwan, Nepal

2016 ◽  
Vol 2 (1) ◽  
pp. 133-143
Author(s):  
Ghanashyam Bhandari ◽  
Bhuddhi Bahadur Achhami ◽  
Saraswati Neupane ◽  
Shila Devi Sharma
Keyword(s):  
Chilo Partellus ◽  
Rating Scale ◽  
Block Design ◽  
Insect Pest ◽  
Stem Borer ◽  
Research Field ◽  
Tunnel Length ◽  
Sources Of Resistance ◽  
Maize Genotypes ◽  
Foliar Damage

Maize stem borer (MSB), Chilo partellus Swinhoe, Lepidoptera: Pyralidae is one of the most important insect pest of maize in Nepal. Host plant resistance is the cost-effective, ecologically sound and stable approach to reduce damage by stem borers. Forty four maize genotypes were screened for resistance to maize stem borer at the research field of National Maize Research Program, Rampur during spring seasons (March to June) of two consecutive years 2013 and 2014. The maize genotypes were evaluated in randomized complete block design with three replications and data were collected on foliar damage rating, tunnel length and number of exit holes made by the borer. The foliar damage and tunnel length damage were significant for genotypes for both the years. The exit holes were not significant in 2013 but significant in 2014 ranging from 2-6 scale. The foliar rating ranged from 2 to 5.5 in 2013 and 1.1 to 4.5 in 2014 on a 1-9 rating scale. The highly resistant genotypes (<2.0 score) were R-POP-2 and RML-5/RML-8. The tunnel length ranged from 3.2 to 22.5 cm in 2013 and 4.2 to 20.4 cm in 2014 on 0- >10 cm scale. The least susceptible genotypes (<5 cm) were RampurSO3F8, RampurSO3FQ02 and RampurS10F18. The genotypes having least exit holes (2.0) in 2014 were RampurSO3F8, RampurSO3FQ02, RampurS10F18. Thus less damage parameters were observed in R-POP-2, RML-5/RML-8, RampurSO3F8, RampurSO3FQ02 and RampurS10F18 and therefore they can be used as parents or as sources of resistance in breeding program.

Sources of resistance to Fusarium wilt and root-knot nematode in indigenous chickpea germplasm

2012 ◽  
Vol 10 (3) ◽  
pp. 258-260 ◽  
Author(s):  
Mohar Singh ◽  
Z. Khan ◽  
Krishna Kumar ◽  
M. Dutta ◽  
Anju Pathania ◽  
...  
Keyword(s):  
Fusarium Wilt ◽  
Rating Scale ◽  
Resistance Breeding ◽  
Practical Method ◽  
Root Knot Nematode ◽  
Sources Of Resistance ◽  
Chickpea Wilt ◽  
Breeding Programmes ◽  
Race 1 ◽  
Moderately Resistant

Fusarium wilt caused by Fusarium oxysporum, Schlecht. emend. Snyd. & Hans. f. sp. ciceri is prevalent in most chickpea-growing countries and is a major devastating disease. Host plant resistance is the most practical method of disease management. Indigenous chickpea germplasm reveals a heterogeneous genetic make-up and the response of resistance to wilt is an unexplored potential source for disease resistance. There are 70 indigenous germplasm lines selected on the basis of their agronomic performance and diverse areas of collections in the country. Of these, four accessions had a highly resistant score of 1 and six had a score of 3 using a 1–9 rating scale, indicating their level of resistance to Fusarium wilt (race 4). Other germplasm accessions of chickpea were found to be moderately resistant to highly susceptible disease reaction. Likewise, the same set of germplasm was also screened for Meloidogyne incognita (race 1) using pot culture under controlled condition. Only one accession was found to be resistant to this pest. These resistant gene sources can be utilised effectively for race-specific chickpea wilt and root-knot resistance breeding programmes.

Responses of genotypes from species ofTrifolium,Ornithopus,BiserrulaandHedysarumto a highly virulent race ofPhytophthora clandestinaand new sources of resistance

2009 ◽  
Vol 155 (2) ◽  
pp. 259-265 ◽  
Author(s):  
H. Li ◽  
S. Han ◽  
P.G.H. Nichols ◽  
C.K. Revell ◽  
K. Sivasithamparam ◽  
...  
Keyword(s):  
Sources Of Resistance ◽  
Highly Virulent

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.

scholarly journals Identification and characterization of maize lines resistant to leaf diseases

2019 ◽  
Vol 40 (2) ◽  
pp. 517
Author(s):  
Kaian Albino Corazza Kaefer ◽  
Adilson Ricken Schuelter ◽  
Ivan Schuster ◽  
Jonatas Marcolin ◽  
Eliane Cristina Gruszka Vendruscolo
Keyword(s):  
Genetic Diversity ◽  
Leaf Spot ◽  
Block Design ◽  
Snp Markers ◽  
Gray Leaf Spot ◽  
Leaf Blight ◽  
Yield Reduction ◽  
Northern Leaf Blight ◽  
Sources Of Resistance ◽  
White Leaf

Among the maize leaf diseases, white leaf spot, northern leaf blight, gray leaf spot, and southern rust are recognized not only by the potential for grain yield reduction but also by the widespread occurrence in the producing regions of Brazil and the world. The aim of this study was to characterize common maize lines for resistance to white leaf spot, northern leaf blight, gray leaf spot, and southern rust and suggest crosses based on the genetic diversity detected in SNP markers. The experiment was conducted in a randomized block design with three replications in order to characterize 72 maize lines. Genotypic values were predicted using the REML/BLUP procedure. These 72 lines were genotyped with SNP markers using the 650K platform (Affymetrix®) for the assessment of the genetic diversity. Genetic diversity was quantified using the Tocher and UPGMA methods. The existence of genetic variability for disease resistance was detected among maize lines, which made possible to classify them into three large groups (I, II, and III). The maize lines CD 49 and CD50 showed a good performance and can be considered sources of resistance to diseases. Therefore, their use as gene donors in maize breeding programs is recommended. Considering the information of genetic distance together with high heritability for leaf diseases, backcrossing of parent genotypes with different resistance levels, such as those of the lines CD49 x CD69 and CD50 x CD16, may result in new gene combinations, as they are divergent and meet good performances.

scholarly journals Natural Variation in Portuguese Common Bean Germplasm Reveals New Sources of Resistance Against Fusarium oxysporum f. sp. phaseoli and Resistance-Associated Candidate Genes

2020 ◽  
Vol 110 (3) ◽  
pp. 633-647 ◽  
Author(s):  
Susana T. Leitão ◽  
Marcos Malosetti ◽  
Qijan Song ◽  
Fred van Eeuwijk ◽  
Diego Rubiales ◽  
...  
Keyword(s):  
Common Bean ◽  
Fusarium Oxysporum ◽  
Candidate Genes ◽  
Fusarium Wilt ◽  
Functional Markers ◽  
Gene Pools ◽  
Primary Metabolism ◽  
Sources Of Resistance ◽  
Wilt Resistance ◽  
Fusarium Wilt Resistance

Common bean (Phaseolus vulgaris) is one of the most consumed legume crops in the world, and Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. phaseoli, is one of the major diseases affecting its production. Portugal holds a very promising common bean germplasm with an admixed genetic background that may reveal novel genetic resistance combinations between the original Andean and Mesoamerican gene pools. To identify new sources of Fusarium wilt resistance and detect resistance-associated single-nucleotide polymorphisms (SNPs), we explored, for the first time, a diverse collection of the underused Portuguese common bean germplasm by using genome-wide association analyses. The collection was evaluated for Fusarium wilt resistance under growth chamber conditions, with the highly virulent F. oxysporum f. sp. phaseoli strain FOP-SP1 race 6. Fourteen of the 162 Portuguese accessions evaluated were highly resistant and 71 intermediate. The same collection was genotyped with DNA sequencing arrays, and SNP–resistance associations were tested via a mixed linear model accounting for the genetic relatedness between accessions. The results from the association mapping revealed nine SNPs associated with resistance on chromosomes Pv04, Pv05, Pv07, and Pv08, indicating that Fusarium wilt resistance is under oligogenic control. Putative candidate genes related to phytoalexin biosynthesis, hypersensitive response, and plant primary metabolism were identified. The results reported here highlight the importance of exploring underused germplasm for new sources of resistance and provide new genomic targets for the development of functional markers to support selection in future disease resistance breeding programs.

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.

Genetic diversity of Colombian landraces of common bean as detected through the use of silver-stained and fluorescently labelled microsatellites

2011 ◽  
Vol 9 (01) ◽  
pp. 86-96 ◽  
Author(s):  
Lucy M. Díaz ◽  
Héctor F. Buendía ◽  
Myriam C. Duque ◽  
Matthew W. Blair
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Microsatellite Markers ◽  
Common Bean ◽  
Gene Pool ◽  
Major Gene ◽  
Gene Pools ◽  
Silver Stain ◽  
Fluorescent Marker ◽  
Fluorescent Markers

Colombia, situated at the northern end of the Andes mountains of South America and in proximity to Central America, is an important centre of diversity for common bean (Phaseolus vulgarisL.) that has a mix of cultivated germplasm from both major gene pools (Andean and Mesoamerican) for the species. Microsatellites are a useful marker system for analyzing genetic diversity of this crop and can be analyzed with manual (silver-stain) or automated (ABI) detection systems and using unlabelled or fluorescently labelled markers, respectively. The objectives of this research were to evaluate the genetic diversity of 92 Colombian landraces and gene pool controls with 36 fluorescent and 30 non-fluorescent microsatellite markers and to determine the extent of introgression between the Andean and Mesoamerican gene pools for this germplasm. A comparison of fluorescentversusnon-fluorescent marker systems was performed with 14 loci, which were evaluated with both methods; the fluorescent markers were found to be more precise than the non-fluorescent markers in determining population structure. A combined analysis of 52 microsatellites using the 36 fluorescent markers and 16 non-overlapping, silver-stained markers produced an accurate population structure for the Andean gene pool that separated race Nueva Granada and race Peru genotypes and clearly identified introgression between these races and the gene pools. The results of this research are important for the application of microsatellite markers to diversity analysis in common bean and for the conservation of landraces in Colombia and neighbouring countries of Latin America, where similar germplasm exists and where gene pool or race mixtures also occur.

Variation in pathogenicity among and within Mycosphaerella pinodes populations collected from field pea in Australia

1998 ◽  
Vol 76 (11) ◽  
pp. 1955-1966 ◽  
Author(s):  
J M Wroth
Keyword(s):  
Cluster Analysis ◽  
Pisum Sativum ◽  
Host Resistance ◽  
Ascochyta Blight ◽  
Mycosphaerella Pinodes ◽  
Environment Interaction ◽  
Pathogen Population ◽  
Host Genotype ◽  
Host Pathogen Interaction ◽  
The Relationship

Ninety-nine single ascospore isolates of Mycosphaerella pinodes (Berk. & Blox.) Vestergr. from widely separated locations in southern Australia varied greatly in their ability to cause disease in leaves and stems of 10 host genotypes when assayed at two inoculum pressures. There were highly significant differences between the infection pressures, isolates, and host genotypes that accounted for most of the variance. A small proportion of the variance included a highly significant host genotype beta isolate interactions in leaves and stems and a highly significant host genotype beta isolate beta environment interaction in leaves. The continuous variation in disease responses among isolates precluded classification into distinct pathotypes. A cluster analysis of the data revealed that many isolates were closely related irrespective of the host cultivar or location from which they were collected. The relationship between mean host resistance and the variation among isolates was assessed, and it was concluded that increasing host resistance was unlikely to increase variation in the pathogen population; therefore, resistance should be relatively stable.Key words: Ascochyta blight, Pisum sativum, host-pathogen interaction, cluster analysis.

Impact of tillage and crop rotation on ascochyta blight (Ascochyta lentis) of lentil

2003 ◽  
Vol 83 (2) ◽  
pp. 411-415 ◽  
Author(s):  
B. D. Gossen ◽  
D. A. Derksen
Keyword(s):  
Crop Rotation ◽  
Seed Quality ◽  
Block Design ◽  
Ascochyta Blight ◽  
Conventional Tillage ◽  
Crop Species ◽  
Ascochyta Lentis ◽  
Main Plot ◽  
The Impact ◽  
Rotation Study

Two trials were conducted from 1996 to 1999; one at Indian Head, SK, to examine the impact of tillage management on the severity of ascochyta blight of lentil, caused by Ascochyta lentis (teleomorph Didymella lentis), and a second at Saskatoon, SK, to assess the impact of crop rotation. In 1995, the blight-susceptible lentil cv. Eston was seeded across both sites and later inoculated with blight-infested lentil residue to provide a uniform level of infection. Treatments were initiated in the spring of 1996. Ascochyta blight severity was assessed on each lentil plot during the growing season. Seed quality and yield were assessed each year. A split-block design was used to minimize movement of inoculum among plots over years. In the tillage management trial at Indian Head, the main plot treatments were 0, 1, or 2 yr between lentil crops, with spring wheat as the alternate crop; the subplot treatments were zero-till vs. conventional tillage. Ascochyta blight severity was substantially higher under zero-till than under conventional tillage in the continuous lentil treatment when conditions were conducive to blight development. However, tillage management had little effect on severity when there were 2 yr between successive lentil crops. We conclude that tillage management is unlikely to have an important impact on blight severity, except in rotations with short re-cropping intervals. In the crop rotation study at Saskatoon, the main plot treatments were two rotation sequences and the subplot treatments were three crop species (canola, barley, pea) planted in 1996. Rotation 1 was seeded to cv. Eston in 1997 and barley in 1998; Rotation 2 was seeded to barley in 1997 and cv. Eston in 1998. Both rotations were seeded to cv. Eston in 1999. Also, a plot seeded continuously to cv. Eston was included at one end of each replicate block as a control. Blight was more severe in continuous lentil than in the other crop rotations, and ascochyta blight levels in 1999 were lowest where barley followed the 1996 lentil crop for both Rotation 1 and 2. However, the intervening nonhost crop had little impact on seed infection or seed yield. We conclude that at least two nonhost crops between successive lentil crops are required to substantially reduce inoculum of A. lentis following a disease outbreak. Key words: Didymella lentis, zero-till management, fusarium root rot, Lens culinaris, barley, canola, field pea

Sign in / Sign up

Export Citation Format

Share Document