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Li S, Travadon R, Nouri MT, Trouillas FP. Determining the Main Infection Courts in Sweet Cherry Trees of the Canker Pathogens Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata. PLANT DISEASE 2024; 108:1695-1702. [PMID: 38173260 DOI: 10.1094/pdis-10-23-2154-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The major fungal canker pathogens causing branch dieback of sweet cherry trees in California include Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata. These pathogens have long been known to infect cherry trees mainly through pruning wounds. However, recent field observations revealed numerous shoots and fruiting spurs exhibiting dieback symptoms with no apparent pruning wounds or mechanical injuries. Accordingly, this study was conducted to assess the incidence of the three pathogens in symptomatic terminal shoots and dying fruiting spurs, in addition to the wood below pruning wounds in branches. Surveys were conducted in five sweet cherry orchards across three counties in California. We also investigated the possibility that leaf scars, bud scars, and wounds resulting from fruit picking could serve as infection courts for Cal. pulchella, Cyt. sorbicola, and E. lata by means of artificial inoculations in the field. Orchard surveys revealed that Cal. pulchella had the highest pathogen incidence below pruning wounds in branch samples, followed by Cyt. sorbicola and E. lata. Among terminal shoots with dieback symptoms and dying fruiting spurs, Cyt. sorbicola was the most prevalent, followed by Cal. pulchella. Results from field inoculations indicated that fruit-picking wounds could serve as important infection courts for Cal. pulchella, Cyt. sorbicola, and E. lata, with average pathogen recovery of 41.5, 63, and 36.2%, respectively. Results also indicated that leaf and bud scars could serve as an entry site for Cyt. sorbicola, although recovery was relatively low. The present study is the first to identify harvest-induced wounds on fruiting spurs of sweet cherry as an important infection court of Cal. pulchella, Cyt. sorbicola, and E. lata.
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Affiliation(s)
- Sampson Li
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Renaud Travadon
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Mohamed T Nouri
- University of California Cooperative Extension San Joaquin County, Stockton, CA 95206
| | - Florent P Trouillas
- Department of Plant Pathology, University of California, Davis, CA 95616
- Kearney Agricultural Research and Extension Center, Parlier, CA 93648
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Luo Y, Niederholzer F, Camiletti BX, Michailides TJ. Survey on Latent Infection of Canker-Causing Pathogens in Budwood and Young Trees from Almond and Prune Nurseries in California. PLANT DISEASE 2024; 108:550-557. [PMID: 37807086 DOI: 10.1094/pdis-07-23-1449-sr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Almond band canker and prune Cytospora canker have become more severe in the last decade, especially in young orchards, in California. To test our hypothesis that young trees from nurseries could carry the canker-causing pathogens at latency phase to new orchards through transplanting, a multiyear survey on latent infection of canker-causing pathogens of budwood and young trees of almond and prune nurseries in California was conducted. A total of more than 1,730 samples including shoots of rootstocks and scions and grafting union cuttings were collected from 11 nurseries. A real-time quantitative PCR assay was applied to quantify the latent infection levels by six canker-causing pathogen taxa: Botryosphaeria dothidea and species of Cytospora, Diplodia, Lasiodiplodia, Neofusicoccum, and Phomopsis. For almond, the average incidences of latent infection caused by Lasiodiplodia spp. (43.6%) and Neofusicoccum spp. (24.2%) were significantly greater than those by the other four pathogen taxa. The molecular severity (MS) of latent infection caused by Neofusicoccum spp. (3.6) was significantly greater than those caused by other pathogen taxa, except for Lasiodiplodia spp. (2.6). For prune, the average incidence of latent infection caused by Cytospora spp. (13.5%) was significantly higher than those caused by B. dothidea (1.5%) and Diplodia spp. (1.3%) but not significantly higher than those caused by Lasiodiplodia spp. (6.9%), Neofusicoccum spp. (6.3%), and Phomopsis spp. (7.7%), respectively. Moreover, the average MS values caused by Cytospora spp. (3.8) and Neofusicoccum spp. (3.2) were the highest followed by those caused by B. dothidea (1.4), Lasiodiplodia spp. (2.2), and Phomopsis spp. (2.3). Different almond varieties showed various levels of susceptibilities to different canker-causing pathogens. This study concluded that Lasiodiplodia and Neofusicoccum are the predominant pathogen species in almond, and Cytospora is the most important canker-causing pathogen species in prune in nurseries. These findings confirmed the observations of predominancy of canker-causing pathogens in almond and prune orchards in California.
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Affiliation(s)
- Yong Luo
- Department of Plant Pathology, Kearney Agricultural Research and Extension Center, University of California-Davis, Parlier, CA 93648
| | - Franz Niederholzer
- University of California - Cooperative Extension, Colusa/Sutter/Yuba Counties, Yuba City, CA 95991
| | - Boris X Camiletti
- Department of Plant Pathology, Kearney Agricultural Research and Extension Center, University of California-Davis, Parlier, CA 93648
| | - Themis J Michailides
- Department of Plant Pathology, Kearney Agricultural Research and Extension Center, University of California-Davis, Parlier, CA 93648
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Antón-Domínguez BI, López-Moral A, Raya MC, Lovera M, Melgar S, Roca LF, Arquero O, Trapero A, Agustí-Brisach C. Fungal Pathogens Associated with Almond Decline Syndrome, an Emerging Disease Complex in Intensive Almond Crops in Southern Spain. PLANT DISEASE 2023; 107:3737-3753. [PMID: 37486269 DOI: 10.1094/pdis-04-23-0759-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
In 2016, an almond (Prunus dulcis) decline syndrome (ADS) emerged in intensive almond plantations in the Andalusia region (southern Spain), showing branch dieback, gummosis, and general tree decline. The aim of this work was to elucidate the etiology of this disease complex. For this purpose, surveys were conducted across the Andalusia region, and a wide collection of fungi was recovered from wood samples showing gum and internal discoloration. Representative isolates were selected and identified by sequencing ITS, TEF1, TUB, ACT, LSU, and/or RPB2 genes. The following fungal species were identified to be associated with the disease: Botryosphaeria dothidea, Diplodia corticola, Di. seriata, Dothiorella iberica, Lasiodiplodia viticola, Macrophomina phaseolina, Neofusicoccum mediterraneum, N. parvum, N. vitifusiforme, Diaporthe neotheicola, Dia. rhusicola, Dia. ambigua, Eutypa lata, E. tetragona, Eutypella citricola, Eu. microtheca, Fusarium oxysporum s.l., Pleurostoma richardsiae, Phaeoacremonium iranianum, Pm. krajdenii, Pm. parasiticum, and Cytospora sp. All isolates were tested for pathogenicity by inoculating detached or attached almond shoots. Di. corticola and N. parvum were the most aggressive species, showing the largest lesions and most gummosis in attached shoots. The results suggest that the species belonging to Botryosphaeriaceae play a key role in disease development, while the remaining identified species may act as secondary pathogens or endophytes. However, further research to determine the interaction between all these fungal species and other biotic and abiotic factors in the ADS progress is needed.
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Affiliation(s)
- Begoña I Antón-Domínguez
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
| | - Ana López-Moral
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
| | - María Carmen Raya
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
| | - María Lovera
- Departamento de Fruticultura Mediterránea, IFAPA, Alameda del Obispo, 14004 Córdoba, Spain
| | - Samara Melgar
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
| | - Luis F Roca
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
| | - Octavio Arquero
- Departamento de Fruticultura Mediterránea, IFAPA, Alameda del Obispo, 14004 Córdoba, Spain
| | - Antonio Trapero
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
| | - Carlos Agustí-Brisach
- Departamento de Agronomía (Unit of Excellence 'María de Maeztu' 2020-24), ETSIAM, Universidad de Córdoba, 14071 Córdoba, Spain
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Drais MI, Gusella G, Mazzaglia A, Polizzi G. A quantitative PCR assay for the detection and quantification of Septoria pistaciarum, the causal agent of pistachio leaf spot in Italy. PLoS One 2023; 18:e0286130. [PMID: 37205697 DOI: 10.1371/journal.pone.0286130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/09/2023] [Indexed: 05/21/2023] Open
Abstract
Septoria leaf spot is one of the most widespread diseases affecting pistachio (Pistacia vera) in countries of the Mediterranean region. Septoria pistaciarum was recently confirmed as the causal agent of this disease in Italy. Currently, the detection of S. pistaciarum relies on isolation techniques. These require significant amounts of labor, and time for completion. Also, a reliable identification requires the sequencing of at least two housekeeping genes, in addition to the morphological observations. To accurately detect the presence and quantify S. pistaciarum in pistachio tissues, a molecular tool was necessary. We designed applicable primers that allow reliable amplification of the β-tubulin gene. The amplification of target DNA was highly efficient, with a 100% success rate, and the assay was able to detect as little as 100 fg/rxn of pure fungal DNA. When tested in artificial mixtures of plant and pathogen DNAs, the assay was able to detect the pathogen consistently at a limit of detection of 1 pg/rxn. The assay was also effective in identifying the pathogen in naturally infected samples, providing rapid detection in all symptomatic specimens. The resulting qPCR assay is an improved detection tool for accurate diagnosis of S. pistaciarum that can also contribute to better understand the population dynamics of the pathogen in the orchard.
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Affiliation(s)
- Mounira Inas Drais
- Dipartimento di Scienze Agrarie e Forestali, Università degli Studi della Tuscia, Viterbo, Italy
| | - Giorgio Gusella
- Dipartimento di Agricoltura, Alimentazione e Ambiente, Sezione di Patologia Vegetale, University of Catania, Catania, Italy
| | - Angelo Mazzaglia
- Dipartimento di Scienze Agrarie e Forestali, Università degli Studi della Tuscia, Viterbo, Italy
| | - Giancarlo Polizzi
- Dipartimento di Agricoltura, Alimentazione e Ambiente, Sezione di Patologia Vegetale, University of Catania, Catania, Italy
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Luo Y, Ma R, Barrera E, Gusella G, Michailides TJ. Effects of Temperature on Development of Canker-Causing Pathogens in Almond and Prune. PLANT DISEASE 2022; 106:2424-2432. [PMID: 35171640 DOI: 10.1094/pdis-01-22-0048-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Between 2000 and 2020, canker diseases of nut and stone fruit trees have become very widespread and severe in California. This study determined the effects of temperature on the development of canker-causing pathogens of almond and prune. Five pathogen taxa, Botryosphaeria dothidea, Cytospora leucostoma, Diaporthe (Phomopsis) neotheicola, Lasiodiplodia citricola, and Neofusicoccum mediterraneum, were used. Colony growth on medium and canker lesion development on detached shoots were measured at 10, 15, 20, 25, 30, and 35°C. The effects of temperature on colony growth differed among different pathogen taxa, although 25°C was the optimal temperature for most of the pathogens tested. The patterns of lesion growth as response to temperature were different among the different pathogens and tree crops. On almond, the highest growth rates appeared at 30°C for B. dothidea and L. citricola, but at 20°C for N. mediterraneum. The growth rates for C. leucostoma were lower than those of the other three pathogen taxa, with the highest rates recorded at 25°C. However, on prune, C. leucostoma showed greater lesion growth rates at different temperatures than the other pathogen taxa and maximum growth at 30 to 35°C. Similar trends were observed for L. citricola. The growth rates of B. dothidea and N. mediterraneum were comparatively lower than those of C. leucostoma and L. citricola.
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Affiliation(s)
- Y Luo
- Department of Plant Pathology, University of California Davis/Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
| | - R Ma
- College of Forestry and Horticulture, Xinjiang Agricultural University, Urumqi 830052, China
| | - E Barrera
- Department of Plant Pathology, University of California Davis/Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
| | - G Gusella
- Department of Plant Pathology, University of California Davis/Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
- University of Catania Department of Agriculture Food and Environment, Catania, Italy
| | - T J Michailides
- Department of Plant Pathology, University of California Davis/Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
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Avenot HF, Jaime-Frias R, Travadon R, Holland LA, Lawrence DP, Trouillas FP. Development of PCR-Based Assays for Rapid and Reliable Detection and Identification of Canker-Causing Pathogens from Symptomatic Almond Trees. PHYTOPATHOLOGY 2022; 112:1710-1722. [PMID: 35240867 DOI: 10.1094/phyto-08-21-0351-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Trunk and scaffold canker diseases (TSCDs) of almond cause significant yield and tree losses and reduce the lifespan of orchards. In California, several pathogens cause TSCDs, including Botryosphaeriaceae, Ceratocystis destructans, Eutypa lata, Collophorina hispanica, Pallidophorina paarla, Cytospora, Diaporthe, and Phytophthora spp. Field diagnosis of TSCDs is challenging because symptom delineation among the diseases is not clear. Accurate diagnosis of the causal species requires detailed examination of symptoms and subsequent isolation on medium and identification using morphological criteria and subsequent confirmation using molecular tools. The process is time-consuming and difficult, particularly as morphological characteristics are variable and overlap among species. To facilitate diagnosis of TSCD, we developed PCR assays using 23 species-specific primers designed by exploiting sequence differences in the translation elongation factor, β-tubulin, or internal transcribed spacer gene. Using genomic DNA from pure cultures of each fungal and oomycete species, each primer pair successfully amplified a single DNA fragment from the target pathogen but not from selected nontarget pathogens or common endophytes. Although 10-fold serial dilution of fungal DNA extracted from either pure cultures or infected wood samples detected as little as 0.1 pg of DNA sample, consistent detection required 10 ng of pathogen DNA from mycelial samples or from wood chips or drill shavings from artificially or naturally infected almond wood samples with visible symptoms. The new PCR assay represents an improved tool for diagnostic laboratories and will be critical to implement effective disease surveillance and control measures.
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Affiliation(s)
- Herve F Avenot
- Kearney Agricultural Research & Extension Center, Parlier, CA 93648
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Rosa Jaime-Frias
- Kearney Agricultural Research & Extension Center, Parlier, CA 93648
| | - Renaud Travadon
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Leslie A Holland
- Department of Plant Pathology, University of Wisconsin, Madison, WI 53706
| | - Daniel P Lawrence
- Department of Plant Pathology, University of California, Davis, CA 95616
| | - Florent P Trouillas
- Kearney Agricultural Research & Extension Center, Parlier, CA 93648
- Department of Plant Pathology, University of California, Davis, CA 95616
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Gusella G, Lawrence DP, Aiello D, Luo Y, Polizzi G, Michailides TJ. Etiology of Botryosphaeria Panicle and Shoot Blight of Pistachio ( Pistacia vera) Caused by Botryosphaeriaceae in Italy. PLANT DISEASE 2022; 106:1192-1202. [PMID: 34752130 DOI: 10.1094/pdis-08-21-1672-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Pistachio (Pistacia vera) is an important crop in Italy, traditionally cultivated in Sicily (southern Italy) for several decades now. In recent years, new orchards have been planted in new areas of the island. Field surveys conducted in 2019 revealed the presence of symptomatic trees showing shoot dieback, cankers, fruit spots, and leaf lesions. Isolations from symptomatic samples consistently yielded fungal species in the Botryosphaeriaceae family. Identification of collected isolates was conducted using morphological and molecular analyses. Morphological characterization was based on conidia measurements of representative isolates and also effects of temperatures on mycelial growth was evaluated. DNA data derived from sequencing the ITS, tef1-α, and tub2 gene regions were analyzed via phylogenetic analyses (maximum parsimony and maximum likelihood). Results of the analyses confirmed the identity of Botryosphaeria dothidea, Neofusicoccum hellenicum, and N. mediterraneum. Pathogenicity tests were conducted on detached twigs and in the fields both on shoots as well as on fruit clusters using the mycelial plug technique. The inoculation experiments revealed that among the Botryosphaeriaceae species identified in this study N. hellenicum (occasionally detected) and N. mediterraneum were the most aggressive based on lesion length on shoots and fruits. N. mediterraneum was the most widespread among the orchards while B. dothidea can be considered a minor pathogen involved in this complex disease of pistachio. Moreover, to our knowledge, this is the first report of N. hellenicum in Italy.
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Affiliation(s)
- Giorgio Gusella
- Dipartimento di Agricoltura, Alimentazione e Ambiente, Sezione di Patologia vegetale, University of Catania, Catania, 95123, Italy
- Department of Plant Pathology, University of California, Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
| | - Daniel P Lawrence
- Department of Plant Pathology, University of California, Davis, Davis, CA 95616, U.S.A
| | - Dalia Aiello
- Dipartimento di Agricoltura, Alimentazione e Ambiente, Sezione di Patologia vegetale, University of Catania, Catania, 95123, Italy
| | - Yong Luo
- Department of Plant Pathology, University of California, Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
| | - Giancarlo Polizzi
- Dipartimento di Agricoltura, Alimentazione e Ambiente, Sezione di Patologia vegetale, University of Catania, Catania, 95123, Italy
| | - Themis J Michailides
- Department of Plant Pathology, University of California, Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648, U.S.A
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Fiorenza A, Aiello D, Costanzo MB, Gusella G, Polizzi G. A New Disease for Europe of Ficus microcarpa Caused by Botryosphaeriaceae Species. PLANTS (BASEL, SWITZERLAND) 2022; 11:727. [PMID: 35336609 PMCID: PMC8953617 DOI: 10.3390/plants11060727] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/04/2022] [Accepted: 03/06/2022] [Indexed: 06/14/2023]
Abstract
The Indian laurel-leaf fig (Ficus microcarpa) is an important ornamental tree widely distributed in the urban areas of Italy. Surveys conducted in 2019 and 2020 on several tree-lined streets, squares, and public parks in Catania and Siracusa provinces (Sicily, southern Italy) revealed the presence of a new disease on mature trees. About 9% of approximately 450 mature plants showed extensive branch cankers and dieback. Isolations from woody tissues obtained from ten symptomatic plants consistently yielded species belonging to the Botryosphaeriaceae family. The identification of the recovered fungal isolates was based on a multi-loci phylogenetic (maximum parsimony and maximum likelihood) approach of the ITS, tef1-α, and tub2 gene regions. The results of the analyses confirmed the presence of three species: Botryosphaeria dothidea, Neofusicoccum mediterraneum, and N. parvum. Pathogenicity tests were conducted on potted, healthy, 4-year-old trees using the mycelial plug technique. The inoculation experiments revealed that all the Botryosphaeriaceae species identified in this study were pathogenic to this host. Previous studies conducted in California showed similar disease caused by Botryosphaeriaceae spp., and the pathogenic role of these fungi was demonstrated. To our knowledge, this is the first report of Botryosphaeriaceae affecting Ficus microcarpa in Europe.
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Luo Y, Niederholzer FJA, Lightle DM, Felts D, Lake J, Michailides TJ. Limited Evidence for Accumulation of Latent Infections of Canker-Causing Pathogens in Shoots of Stone Fruit and Nut Crops in California. PHYTOPATHOLOGY 2021; 111:1963-1971. [PMID: 33829854 DOI: 10.1094/phyto-01-21-0009-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Prevalence of latent infections of the canker-causing fungi Botryosphaeria dothidea and species of Cytospora, Diplodia, Lasiodiplodia, Neofusicoccum, and Phomopsis in young shoots of almond, prune, and walnut trees in California was studied to test the hypotheses that latent infections accumulate from current-season shoots to 1-year-old shoots in the orchard and there are distinct associations among pathogen taxa present as latent infections in the same shoot. Samples of newly emerged and 1-year-old shoots were periodically collected in each almond, prune, and walnut orchard for two growing seasons. A real-time quantitative PCR assay was used to quantify latent infection with three parameters: incidence, molecular severity, and latent infection index. Diplodia spp. were absent from most samples. For almond, Lasiodiplodia spp. and Cytospora spp. were detected with a maximum incidence >90%, while B. dothidea and Neofusicoccum spp. incidence was <20% in most cases. In prune orchards, the incidence levels of B. dothidea were >50% in most cases, while those of Cytospora spp. and Lasiodiplodia spp. were 30 to 60% and 30 to 100%, respectively. For walnut, many samplings showed higher incidence in 1-year-old (30 to 80%) than in newly emerged shoots (10 to 50%). Accumulation of latent infection between the two shoot age classes was detected in only a few cases. The percentages of samples showing coexistence of two, three, and four pathogen taxa in the same shoot were 20 to 25, <10, and <5%, respectively. Pairwise associations among pathogen taxa in the same shoot were significant in many cases.
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Affiliation(s)
- Yong Luo
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648
| | - Franz J A Niederholzer
- University of California Cooperative Extension, Colusa/Sutter/Yuba Counties, Yuba City, CA 95991
| | - Dani M Lightle
- University of California Cooperative Extension, Butte/Glenn/Tehama Counties, Orland, CA 95963
| | - Dan Felts
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648
| | - John Lake
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648
| | - Themis J Michailides
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648
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Garcia JF, Lawrence DP, Morales-Cruz A, Travadon R, Minio A, Hernandez-Martinez R, Rolshausen PE, Baumgartner K, Cantu D. Phylogenomics of Plant-Associated Botryosphaeriaceae Species. Front Microbiol 2021; 12:652802. [PMID: 33815343 PMCID: PMC8012773 DOI: 10.3389/fmicb.2021.652802] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/25/2021] [Indexed: 11/29/2022] Open
Abstract
The Botryosphaeriaceae is a fungal family that includes many destructive vascular pathogens of woody plants (e.g., Botryosphaeria dieback of grape, Panicle blight of pistachio). Species in the genera Botryosphaeria, Diplodia, Dothiorella, Lasiodiplodia, Neofusicoccum, and Neoscytalidium attack a range of horticultural crops, but they vary in virulence and their abilities to infect their hosts via different infection courts (flowers, green shoots, woody twigs). Isolates of seventeen species, originating from symptomatic apricot, grape, pistachio, and walnut were tested for pathogenicity on grapevine wood after 4 months of incubation in potted plants in the greenhouse. Results revealed significant variation in virulence in terms of the length of the internal wood lesions caused by these seventeen species. Phylogenomic comparisons of the seventeen species of wood-colonizing fungi revealed clade-specific expansion of gene families representing putative virulence factors involved in toxin production and mobilization, wood degradation, and nutrient uptake. Statistical analyses of the evolution of the size of gene families revealed expansions of secondary metabolism and transporter gene families in Lasiodiplodia and of secreted cell wall degrading enzymes (CAZymes) in Botryosphaeria and Neofusicoccum genomes. In contrast, Diplodia, Dothiorella, and Neoscytalidium generally showed a contraction in the number of members of these gene families. Overall, species with expansions of gene families, such as secreted CAZymes, secondary metabolism, and transporters, were the most virulent (i.e., were associated with the largest lesions), based on our pathogenicity tests and published reports. This study represents the first comparative phylogenomic investigation into the evolution of possible virulence factors from diverse, cosmopolitan members of the Botryosphaeriaceae.
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Affiliation(s)
- Jadran F Garcia
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Daniel P Lawrence
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Abraham Morales-Cruz
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States.,Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Renaud Travadon
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Andrea Minio
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | | | - Philippe E Rolshausen
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - Kendra Baumgartner
- Crops Pathology and Genetics Research Unit, United States Department of Agriculture - Agricultural Research Service, Davis, CA, United States
| | - Dario Cantu
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
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11
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Luo Y, Niederholzer FJA, Felts DG, Puckett RD, Michailides TJ. Inoculum quantification of canker-causing pathogens in prune and walnut orchards using real-time PCR. J Appl Microbiol 2020; 129:1337-1348. [PMID: 32406554 DOI: 10.1111/jam.14702] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 11/30/2022]
Abstract
AIMS A real-time quantitative PCR (qPCR) assay was established to quantify the inoculum densities in the air and rainwater for six canker-causing pathogen groups in prune and walnut orchards in California. METHODS AND RESULTS The previously published DNA primers to target six pathogen groups including Botryosphaeria dothidea, Cytospora spp., Diplodia spp., Lasiodiplodia spp., Neofusicoccum spp. and Phomopsis spp. were used in a qPCR assay. Air samples from Burkard spore traps and rain samples from special rain collector devices were collected periodically from various prune and walnut orchards. Using the qPCR approach, we were able to quantify the concentrations of these pathogen groups in rainwater and air samples and study the dynamics of pathogen inoculum in orchards showing severe canker potential. Phomopsis spp. and Diplodia spp. were not found in all rain samples in prune orchards, although they were detected in the 2016 in the walnut orchard. The other four pathogen groups were quantified at varying concentrations in the prune and walnut orchards. Cytospora spp. in some cases showed higher concentrations in the rainwater in prune orchards. CONCLUSIONS The rainy season during winter and early spring is a highly risky period of time for infection by the pathogens when the inoculum of these pathogens can easily spread by air and rain water, thus serving as an important inoculum source for disease initiation. The different studied pathogen groups showed different concentrations during the growing season, indicating the complexity of the components of canker-causing species in various tree crops. SIGNIFICANCE AND IMPACT OF THE STUDY This study showed the applicability of the qPCR assay in the quantification of inoculum in tree orchards to help reveal the mechanisms of canker disease epidemics and to help design disease management strategies.
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Affiliation(s)
- Y Luo
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA, USA
| | | | - D G Felts
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA, USA
| | - R D Puckett
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA, USA
| | - T J Michailides
- Department of Plant Pathology, University of California-Davis, Kearney Agricultural Research and Extension Center, Parlier, CA, USA
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