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Although chickpeas are reported to be susceptible to more than 50 pathogens, few diseases are currently recognized as significant economic constraints to production. Ascochyta blight, caused by the fungal pathogen Ascochyta rabiei, is the most serious chickpea disease worldwide. This paper describes the pathogen, symptoms of infection, biological a...
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... the initial inoculum source is airborne ascospores, the first symptoms generally seen are small necrotic specks on newer leaves or stems. Under cool, moist conditions, the necrotic specks enlarge and coalesce to form large necrotic lesions (6-12 mm in diameter) on young leaves and buds. Lesions forming on pods ( Fig. 3) and leaves (Fig. 4) are primarily circular to oval (up to 0.5 cm), containing concentric rings of pycnidia, the fruiting bodies of the anamorph (Fig. 5) which are visible with a 10× hand lens. Lesions that form on petioles and stems are usually elongate, but also will contain pycnidia arranged in circular patterns (Fig. 6). Stem lesions vary greatly in ...
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... AB was noted to be one of the most distressing diseases in North China (Sun et al. 2016), Ethiopia (Tadesse et al. 2017), Australia (Bretag et al. 2008), and Canada (Chongo et al. 2004). The characteristic symptoms of the disease include circular necrotic lesions on leaves and pods, elongated and irregular lesions on the stems and petioles, followed by stem girdling with abundant circular black/brown-colored pycnidia on the surface of the infected stems, leaves, and pods with malformed seeds or no seed setting (Akem 1999;Harveson et al. 2011). The pathogen overwinters on diseased crop residues as anamorph (asexual) in the form of pycnidia containing conidia and teleomorph as pseudothecia with ascospores (Pande et al. 2005). ...
The prevalence and distribution of pathotypes and mating types of Ascochyta rabiei (Pass.) Labr. were evaluated during the winter (October to March) seasons of 2017-18 and 2018-19. Forty-five A. rabiei isolates were obtained from six different states. From the survey results, the state of Punjab recorded the highest disease rating (Rating 9) compared with other chickpea-growing areas. The β-tubulin gene was amplified (330 bp) from all the isolates, and sequence analysis was performed. The phylogenetic tree produced by cluster analysis of β-tubulin gene sequences differentiated the 44 A. rabiei isolates . Using multiplex PCR, mating types were identified. From the mating type (MAT) study of all the A. rabiei isolates, amplification was observed at the 490-bp size, which corresponds to mating type 2 (MAT1-2). The four pathotypes (I, II, III, IV) and six physiological races were delineated based on the differential reaction of the disease. The most widely distributed pathotype was pathotype III (52.27%) among the surveyed regions of North Indian states, except Uttarakhand (where only pathotype II was recorded), followed by the least aggressive pathotype I (22.7%), highly aggressive pathotype IV (15.9%), and aggressive pathotype II (9.1%). Among the six physiological races identified, the most common races were race 5 (25%), followed by race 1 (22.73%), race 6 (18.18%), race 4 (18.18%), race 3 (9.09%), and race 2 (6.82%). Because of the prevalence of a single mating type among the surveyed locations in India, we opine that there may be less diversity in A. rabiei compared with isolates reported from other countries. However, to substantiate this conclusion, evaluation of more isolates of A. rabiei is required.
[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
... AB is a polycyclic disease and its asexual form (anamorphic) occurs every seven days under favorable environmental conditions. It may produce 100% losses, causing damage that affects yield and seed quality (Navas Cortés 2010;Chen et al. 2011;Harveson et al. 2013). ...
... Management of this disease requires a combination of cultural, chemical and genetic controls, nevertheless, there is not a 100% effective strategy for A. rabiei control (Harveson et al. 2013). Genetic resistance is the preferred tool for the management of this disease, since it is an effective and inexpensive way of controlling biotic stresses and it is the major goal of many breeding programs. ...
Chickpea is the third most important grain legume in the world after common bean and pea. Ascochyta blight (AB) of chickpea, caused by Ascochyta rabiei, is the most damaging disease of this crop worldwide. Losses may reach 100%, with damage affecting yield and seed quality. AB produces lesions to all aerial plant tissues: leaves, petioles, flowers and pods. The causal agent can survive on or in the seeds and up to four years in stubble. Genetic resistance is the preferred tool for the management of this complex disease. This is the most effective and inexpensive way of controlling biotic stresses and the major goal of many breeding programs. In Argentina, where AB was first detected in 2011, the most widely used commercial varieties, Chañaritos S-156, Norteño, Felipe UNC-INTA and Kiara UNC-INTA, are susceptible to A. rabiei. In this work, 109 genotypes carrying multiple resistance to different pathogens were evaluated against local A. rabiei under controlled conditions. The results showed that all genotypes were affected by this fungus, without occurrence of asymptomatic plants. The genotypes ranged from resistant to highly susceptible. According to disease reaction, the genotypes were classified as: resistant (2.75%),moderately resistant (32.09%), susceptible (60.55%) and highly susceptible (1.83%). This is the first research developed in Argentina to identify resistant genotypes and sources of resistance that contribute to breeding programs.
... A. rabiei is a polycyclic pathogen that completes the life cycle in 4-7 days. Once the cycle is complete, the inoculum may remain on the straws for several years as pseudothecia, contributing to the long-term survival of the pathogen and to the long-distance dispersal (Harveson et al., 2011). Ascospores produced in chickpea debris provide an important source of primary inoculum and may initiate a blight epidemic in fields located 10-15 km away from the source (Armstrong et al., 2001). ...
... Each piece was then placed in Petri dishes containing sterile water agar supplemented with streptomycin (150 ml/L) and incubated at 21°C, under a 12/12 h fluorescent light/ dark cycle (Valetti et al., 2020). After 7 days, Petri dishes were visually examined for the presence of the typical structures described for A. rabiei: pycnidia, cirrus and conidia Harveson et al., 2011). The colonies identified by light microscopy were transferred to Chickpea-Seed Meal Dextrose Agar medium (CSMDA: 40 g chickpea seed meal, 20 g dextrose, 20 g agar, 1 L distilled water) to increase their sporulation (Harveson et al., 2011;Kaiser, 1973;Pande et al., 2010). ...
... After 7 days, Petri dishes were visually examined for the presence of the typical structures described for A. rabiei: pycnidia, cirrus and conidia Harveson et al., 2011). The colonies identified by light microscopy were transferred to Chickpea-Seed Meal Dextrose Agar medium (CSMDA: 40 g chickpea seed meal, 20 g dextrose, 20 g agar, 1 L distilled water) to increase their sporulation (Harveson et al., 2011;Kaiser, 1973;Pande et al., 2010). A single spore isolate was obtained from each colony. ...
Ascochyta blight is one of the most devastating foliar diseases of chickpea. The causal agent, Ascochyta rabiei, is a heterothallic ascomycete and its sexual reproduction depends on the proximate presence of both mating types, MAT1-1 and MAT1-2. Since its first detection in Argentina in 2011, very few studies have been carried out and information on local isolates remains unknown. In this work, 12 isolates were obtained from the northern, central and southern regions of Córdoba province, Argentina. First, isolates were tentatively identified as A. rabiei based on their colony and conidial characteristics. Identity was confirmed by phylogenetic analysis of the ITS, β-tubulin and D1/D2 loci. Morphology, cultural characteristics and pathogenic variability of the isolates were compared. Likewise, 27 crosses were made to demonstrate possible sexual reproduction between the strains. The isolates showed differences in morphology (shape, texture, conidial size, colony colour, growth rate) and aggressiveness from a susceptible cultivar. All crosses were fertile and produced pseudothecia, asci and ascospores. This work is the first in Latin America to characterize isolates of A. rabiei morphologically and molecularly, examine their pathogenic variability and demonstrate the sexual reproduction between isolates carrying different mating-type idiomorphs. New levels of aggressiveness in A. rabiei or adaptive changes like resistance to fungicides or breakdown of host resistance are a distinct possibility in the future.
... Under favorable environmental conditions, the disease can cause yield losses of up to 100% on susceptible chickpea crops [8][9][10]. The rapidly increasing trend of chickpea production in many countries is limited by chickpea blight epidemics, and currently, approximately 95% of the chickpea growing areas worldwide are prone to chickpea blight epidemics [11][12][13]. ...
Ascochyta blight, also known as chickpea blight, which is caused by the fungal pathogen,
Didymella rabiei, is an important disease affecting chickpea (Cicer arietinum L.) in many countries. We studied the genetic diversity and population structure of 96 D. rabiei isolates collected from three geographic populations in Ethiopia using simple sequence repeat (SSR) markers. We confirmed the genetic identity of 89 of the D. rabiei isolates by sequencing their rRNA internal transcribed spacer region genes. The chickpea blight pathogen isolates were genetically diverse, with a total of 51 alleles identified across 6 polymorphic SSR loci, which varied from 3 to 18 (average 8.5) alleles per SSR marker. The observed heterozygosity and expected heterozygosity ranged from 0.01 to 0.92 and 0.19 to 0.86, respectively. The mean polymorphic information content value of the D. rabiei populations was 0.58, with a mean gene diversity of 0.61 among loci. Gene flow (Nm = number of migrants) for the three populations of D. rabiei isolates ranged from 1.51 to 24.10 (average 6.2) migrants/cluster. However, the genetic variation between the D. rabiei populations was small (8%), with most of the variation occurring within populations (92%). Principal component analysis to visualize genetic variation showed that the D. rabiei isolates obtained from most of the chickpea samples formed roughly three groups on a two-dimensional coordinate plane. Similarly, the clustering of individuals into populations based on multi-locus genotypes (using Clumpak) grouped isolates into three clusters but with individual isolate admixtures. Hence, no clear geographic origin-based structuring of populations could be identified. To our knowledge, this is the first report of D. rabiei diversity in Ethiopia. Virulence studies should be conducted to develop chickpea varieties that are resistant to more aggressive pathogen populations.
... The fungus affects all aboveground parts of the plant causing necrotic lesions on leaves, petioles, stems, pods, and seeds [8], which result in both yield and quality losses [9][10][11]. Yield losses can occasionally reach 100% on susceptible cultivars under favorable environmental conditions [11]. ...
... f(T) = (T − Tmin) / (Topt − Tmin) ((Tmax − T) / (Tmax − Topt)) (Tmax − Topt) / (Topt − Tmin) (8) where Tmin = minimum temperature for incubation or latency progress; Topt = optimum temperature for incubation or latency progress; Tmax = maximum temperature for incubation or latency progress; when T < Tmin or T > Tmax, f(T) = 0, and incubation or latency does not proceed. The best fit for incubation was obtained with INCmin = 150 h, Tmin = 2 °C, Topt = 21 °C, and Tmax = 34 °C. ...
Ascochyta blight caused by Ascochyta rabiei is an important disease of chickpea. By using systems analysis, we retrieved and analyzed the published information on A. rabiei to develop a mechanistic, weather-driven model for the prediction of Ascochyta blight epidemics. The ability of the model to predict primary infections was evaluated using published data obtained from trials conducted in Washington (USA) in 2004 and 2005, Israel in 1996 and 1998, and Spain from 1988 to 1992. The model showed good accuracy and specificity in predicting primary infections. The probability of correctly predicting infections was 0.838 and the probability that there was no infection when not predicted was 0.776. The model's ability to predict disease progress during the growing season was also evaluated by using data collected in Australia from 1996 to 1998 and in Southern Italy in 2019; a high concordance correlation coefficient (CCC = 0.947) between predicted and observed data was obtained, with an average distance between real and fitted data of root mean square error (RMSE) = 0.103, indicating that the model was reliable, accurate, and robust in predicting seasonal dynamics of Ascochyta blight epidemics. The model could help growers schedule fungicide treatments to control Ascochyta blight on chickpea.
... Chickpea (Cicer arietinum L.) is one of the most important food legumes around the world and is a prominent source of protein principally in central Asia and Africa (Gan et al., 2006;Harveson et al., 2011;Kanouni et al., 2011). Its cultivation area is currently approximately 11.5 million ha, primarily in developing countries (Chen et al., 2016). ...
Ascochyta blight is the major disease affecting chickpea (Cicer arietinum) around the world. Since the first report of Ascochyta rabiei's isolation in Argentina in 2012, the pathogen has caused severe economic losses in crop production; so, the detection and rapid identification of the pathogen in early stages is key for the management of the disease. In this work, a traditional PCR procedure for detection of A. rabiei directly from plant tissues has been described based on beta-tubulin gene. The TP-6/TP-9 specific primers designed, amplified only a single PCR band of 770 bp from A. rabiei. The specificity of the primers was checked using 12 isolates of A. rabiei and DNA from 10 other different fungi including common pathogens of chickpea as Alternaria alternata, Botrytis cinerea, Sclerotinia sclerotiorum and Phoma medicaginis that cause similar symptoms. The detection sensitivity with primers was 2 × 10⁴ ng μl⁻¹ genomic DNA. In inoculated plant material, PCR amplification gave a band of the expected size and no amplification was observed when DNA was from healthy and uninoculated plants. The results suggested that the assay detected the pathogen more rapidly and accurately than standard isolation methods. The PCR-based method developed here can simplify both plant disease diagnosis, and pathogen monitoring in an early phase, as well as aid in effective management practices that avoid the disease advance and minimize losses.
... Today the crop is an established, major contributor to regional agriculture in the Pacific Northwest (PNW), in the high plains of the United States and Canada, and in California (NASS 2017). Diseases are well described, and cost-effective management of A. rabiei is achieved via seed treatment, cultural practices, and partial resistance Harveson et al. 2011). In strong contrast, crop protection information on many crops still regarded as emerging continues to lag. ...
"Emerging crops" is a term typically applied to ethnic food plants or to plants used in traditional or ethnic medicine, some of which are becoming viable niche markets in North America. Information on crop protection of these plants is often scarce to lacking. Literature on diagnosis and management of fungal diseases of these crops in North America is concisely reviewed, with information gaps identified. Emphasis is placed on crops comprising recent niche markets for Asian, African, Oceanian, or Latino immigrants. Emerging crops are often tied to economic activities of immigrant populations. Crops of immigrants from Asia, Africa, Latin America, and Oceania are contrasted with crops established by immigrants of European origins, plants usually familiar to North American plant health professionals, and with Native American food and medicinal plants, some of which are experiencing a renaissance as emerging crops.
... The fungus was flat, submerged with sparse mycelium on artificial media. Based on these characteristics, the isolates were identified as Ascochyta rabiei as described earlier by various workers (Basandrai et al., 2005, Pande et al., 2010and Harveson et al., 2011. ...
Ascochyta blight caused by Ascochyta rabiei is a serious disease of chickpea world wide. Twenty five Indian isolates of A. rabiei were evaluated for their morphological variability and 91 chickpea cultivars were screened for their reactions to Ascochyta blight. The populations of A. rabiei showed variations in various morphological characters like conidia size and density, colony colour and growth rate. Colonies of the isolates on artificial media were flat, submerged with sparse mycelium. The mycelium was pale cream at first but later turned greyish white or green to greenish dark. In Chickpea dextrose agar (CDA) medium, the isolate AR1 (Delhi) grew the largest followed by the isolates AR14 (Punjab), AR5 (Himachal Pradesh), AR9 (Jammu and Kashmir) and AR20 (Rajasthan) with statistically similar colony diameter at 20 days after incubation. Thus, the growth rate was significantly highest in isolate AR1 (Delhi) followed by the isolates AR14 (Punjab), AR5 (Himachal Pradesh), AR9 (Jammu and Kashmir), and AR20 (Rajasthan). More or less similar growth patterns of the isolates were observed on PDA medium with comparatively less growth as compared to CDA. The size of the conidia in all the isolates ranged from 9.19-12.51 x 3.36-4.32 μm whereas the density of conidia in A. rabiei isolates ranged from 0.5-7.2 x 106 conidia ml-1. Three cultivars namely, ICC 76, ICC 3996 and ICC 15978 were identified as highly resistant to Ascochyta blight. Thirty cultivars showed resistant and 14 cultivars showed moderately resistant reactions against the disease. These cultivars may be used for cultivation or resistant breeding programs.
... Chickpea (Cicer arietinum, Fabaceae), also known as garbanzo bean, is an important edible leguminous crop which represents a significant source of dietary protein in many parts of central Asia and Africa (Gan et al. 2006; Harveson et al. 2011; Kanouni et al. 2011). Chickpea is the third most important pulse crop in the world. ...
Ascochyta blight is the major disease attacking chickpea (Cicer arietinum) around the world. Since its first time report of isolation in Argentina in 2012, the pathogen has caused severe economic losses and has acquired a great importance. We report here the isolation of Ascochyta rabiei from infected chickpea beans cultivated in Santa Fe, Argentina; its identification by morphological analysis and molecular biology techniques based on internal transcribed spacer (ITS) sequence alignment, its biochemical characterization regarding the capacity to produce proteinase and phospholipase enzymes, and its antifungal susceptibility to common used antifungal agents. In order to detect new inhibitors for A. rabiei from natural sources, a bioautographic method was developed. From the screening method developed, we found that extracts from cultures of Aspergillus parasiticus are active against A. rabiei.
... In this study, B fertilizer application doses increased the content of N, Ca, Mg, P, K, and Zn in both leaves and berry tissue, but decreased the content of Fe, Mn, and Cu in plant tissue. These results were similar to those obtained by Mills and Jones (1996) for grapevine, and Singh and Singh (1983 Singh ( , 1990) for chickpea (Cicer arientinum L.) and sugar beet (Beta vulgaris L.). Micronutrients, especially B, improve fruit-set, increase the fertilization of seeds, and enlarge berry size. ...
Boron (B) deficiency is widespread in the northeastern Anatolian region of Turkey. This could impact the production and quality of grapevine (Vitis vinifera L. cv. Karaerik). A field experiment was conducted for determining the optimum economic B rate (OEBR), critical soil test, and tissue B values for yield and quality response of grapevine to B fertilizer application method (foliar and soil) at 5 doses (0, 1, 3, 9, and 12 kg B/ha) for 2 years. OEBR of foliar and soil application ranged from 6.4 to 8.5 kg B/ha with an average yield of 20.2–12.8 t/ha, respectively. The average soil B content at the OEBR was 0.32–2.52 mg/kg. Leaf tissue B content amounted to 98.9 and 64.4 mg/kg, and berry B content amounted to 21.4 and 12.9 mg/kg for foliar and soil application methods, respectively. Independently of application method, B application increased tissue N, Ca, Mg, P, K, and Zn, yet decreased Fe, Mn, and Cu content. We concluded that a B addition of 6.4 kg/ha for foliar application and 8.5 kg/ha for soil application is sufficient to elevate soil B to nondeficient levels.
