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Nones S, Sousa E, Holighaus G. Symbiotic Fungi of an Ambrosia Beetle Alter the Volatile Bouquet of Cork Oak Seedlings. PHYTOPATHOLOGY 2022; 112:1965-1978. [PMID: 35357159 DOI: 10.1094/phyto-08-21-0345-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In Portugal, fungal symbionts of the ambrosia beetle Platypus cylindrus affect tree vigor of cork oak (Quercus suber) and are linked with the cork oak decline process. Fungal symbionts play crucial roles in the life history of bark and ambrosia beetles and recent work indicates complex interactions on the fungal and plant metabolic level. Colonized trees may respond with an array of currently unknown volatile metabolites being indicative of such interactions, acting as infochemicals with their environment. In this study, we examined volatile organic compounds (VOCs) of cork oak seedlings wound inoculated with strains of three fungal associates of P. cylindrus (Raffaelea montetyi, R. quercina, and Ceratocystiopsis sp. nov.) over a 45-day period by means of thermodesorption gas chromatography-mass spectrometry techniques. Fungal strains induced largely quantitative but species-specific changes among the 58 VOCs characterized. Overall, monoterpenes-the major volatiles of cork oak foliage-were significantly reduced, possibly a result of fungal biotransformation. Acetophenone, sulcatone, and nonanal-volatiles known for mediating ambrosia beetle behavior-increased in response to fungal inoculation. Qualitative VOC profiles of excised tissue of wood lesions (21 VOCs) and pure fungal cultures (60 VOCs) showed little overlap with seedling VOCs, indicating their plant-derived but fungal-induced origin. This chemoecological study expands on the limited knowledge of VOCs as infochemicals emitted from oak trees threatened by oak decline in relation to beetle-vectored ophiostomatoid fungi. It opens new avenues of research to clarify mutualistic or pathogenic aspects of these complex symbiotic interactions and develop new control strategies for P. cylindrus, including its mycobiota.
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Affiliation(s)
- Stefano Nones
- Agrarian and Forestry Systems and Vegetal Health Unit, National Institute for Agricultural and Veterinary Research (INIAV, I.P.), Av. da República, Quinta do Marquês, 2780-159 Oeiras, Portugal
- GREEN-IT Bioresources for Sustainability, ITQB NOVA, Av. da República, 2780-157 Oeiras, Portugal
- Institute of Chemical and Biological Technology António Xavier, NOVA University of Lisbon, Av. da República, 2780-157 Oeiras, Portugal
| | - Edmundo Sousa
- Agrarian and Forestry Systems and Vegetal Health Unit, National Institute for Agricultural and Veterinary Research (INIAV, I.P.), Av. da República, Quinta do Marquês, 2780-159 Oeiras, Portugal
- GREEN-IT Bioresources for Sustainability, ITQB NOVA, Av. da República, 2780-157 Oeiras, Portugal
| | - Gerrit Holighaus
- Department of Forest Zoology and Forest Conservation, Büsgen Institute, Georg-August-University Göttingen, Büsgenweg 3, 37077 Göttingen, Germany
- Northwest German Forest Research Institute, Department of Forest Protection, Grätzelstraße 2, 37079 Göttingen, Germany
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Oak Decline Syndrome in Korean Forests: History, Biology, and Prospects for Korean Oak Wilt. FORESTS 2022. [DOI: 10.3390/f13060964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Oak decline syndrome has been observed in South Korea and Japan and variously referred to as Korean oak wilt (KOW) and Japanese oak wilt (JOW). We reviewed aspects of the historical occurrence of KOW, disease cycle, and its potential causes. KOW has been seen principally in Mongolian oak (Quercus mongolica Fisch. ex Ledeb.). The first occurrence of KOW was in 2004 in Seongnam, South Korea. KOW is associated with the fungus Raffaelea quercus-mongolicae, which is vectored by the ambrosia beetle Platypus koryoensis. In addition, it has been suggested that yeasts have evolved a symbiotic relationship with the vector without antagonism for the pathogenic fungus. The number of trees in Korea killed by KOW increased to about 331,000 in 2011, but then decreased to about 157,000 in 2019. We hypothesized that trees infected by R. quercus-mongolicae accumulate phenolic compounds in the sapwood and the vector (P. koryoensis) beetles then avoid these trees. Therefore, the number of hosts available for the beetle after a KOW outbreak decrease due to accumulation of phenolic compounds in the wood, although most oak trees survive outbreaks. Therefore, P. koryoensis beetles move longer distances after outbreaks to find susceptible host trees. Novel occurrence of KOW in Korea may be due to either (1) an increase in tree age (size) in Korean oak stands, for which the beetle has a known preference or (2) climate change, which may be increasing the number of weakened or stressed trees, for which P. koryoensis also shows a preference.
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Inácio ML, Marcelino J, Lima A, Sousa E, Nóbrega F. Ceratocystiopsis quercina sp. nov. Associated with Platypus cylindrus on Declining Quercus suber in Portugal. BIOLOGY 2022; 11:biology11050750. [PMID: 35625478 PMCID: PMC9139077 DOI: 10.3390/biology11050750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/12/2022] [Accepted: 05/12/2022] [Indexed: 11/16/2022]
Abstract
Platypus cylindrus is the most common ambrosia beetle in stands of Quercus suber in Portugal. This insect farms specialized fungi in sapwood galleries, using its mycangia to carry and store these organisms. Some ectosymbiotic fungi carried by P. cylindrus are phytopathogenic and cause extensive tree mortality and severe economic losses. To understand the role of P. cylindrus fungal symbionts in stands of Q. suber we examined beetle galleries present in declining and/or dying cork oak trees during field surveys. Logs with active galleries were obtained in situ and from captured emerging beetles. Insects were aseptically dissected, and their mycangia and intestine were retrieved. Morphological and molecular profiles of fungal isolates obtained from cultured insect parts were carried out to accurately characterize and identify isolated fungi. Molecular characterizations were performed with DNA sequence data from four loci, i.e., LSU, SSU, 5.8S-ITS2-28S, and TUB. Morphological results consistently showed a collection of Ophiostoma-like fungal axenic isolates, while phylogenies inferred that this collection constitutes an undescribed taxon reported herein for the first time in association with P. cylindrus in Portuguese cork oak stands. The novel species was erected as Ceratocystiopsis quercina sp. nov. and constitutes a new phytopathogenic fungal species associated with symptoms of vegetative cork oak decline.
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Affiliation(s)
- Maria L. Inácio
- Instituto Nacional de Investigação Agrária e Veterinária, Quinta do Marquês, 2780-159 Oeiras, Portugal; (E.S.); (F.N.)
- GREEN-IT Bioresources for Sustainability, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa (ITQN NOVA), Av. da República, 2780-157 Oeiras, Portugal
- Correspondence:
| | - José Marcelino
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32608, USA;
| | - Arlindo Lima
- LEAF—Linking Environment Agriculture and Food, Instituto Superior de Agronomia (ISA), University of Lisbon, Tapada de Ajuda, 1349-017 Lisbon, Portugal;
- LPVVA—Laboratório de Patologia Vegetal “Veríssimo de Almeida”, Instituto Superior de Agronomia (ISA), University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal
| | - Edmundo Sousa
- Instituto Nacional de Investigação Agrária e Veterinária, Quinta do Marquês, 2780-159 Oeiras, Portugal; (E.S.); (F.N.)
- GREEN-IT Bioresources for Sustainability, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa (ITQN NOVA), Av. da República, 2780-157 Oeiras, Portugal
| | - Filomena Nóbrega
- Instituto Nacional de Investigação Agrária e Veterinária, Quinta do Marquês, 2780-159 Oeiras, Portugal; (E.S.); (F.N.)
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Pires D, Vicente CSL, Inácio ML, Mota M. The Potential of Esteya spp. for the Biocontrol of the Pinewood Nematode, Bursaphelenchus xylophilus. Microorganisms 2022; 10:microorganisms10010168. [PMID: 35056617 PMCID: PMC8781088 DOI: 10.3390/microorganisms10010168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/07/2022] [Accepted: 01/12/2022] [Indexed: 01/21/2023] Open
Abstract
The pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease (PWD) and a quarantine organism in many countries. Managing PWD involves strict regulations and heavy contingency plans, and present climate change scenarios predict a spread of the disease. The urgent need for sustainable management strategies has led to an increasing interest in promising biocontrol agents capable of suppressing the PWN, like endoparasitic nematophagous fungi of the Esteya genus. Here, we review different aspects of the biology and ecology of these nematophagous fungi and provide future prospects.
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Affiliation(s)
- David Pires
- Instituto Nacional de Investigação Agrária e Veterinária (INIAV, I.P.), 2780-159 Oeiras, Portugal;
- Mediterranean Institute for Agriculture, Environment and Development (MED), University of Évora, Pólo da Mitra, Apartado 94, 7006-554 Evora, Portugal;
| | - Cláudia S. L. Vicente
- Mediterranean Institute for Agriculture, Environment and Development (MED), University of Évora, Pólo da Mitra, Apartado 94, 7006-554 Evora, Portugal;
- Correspondence: (C.S.L.V.); (M.L.I.)
| | - Maria L. Inácio
- Instituto Nacional de Investigação Agrária e Veterinária (INIAV, I.P.), 2780-159 Oeiras, Portugal;
- GREEN-IT Bioresources for Sustainability, ITQB NOVA, Av. da República, 2780-157 Oeiras, Portugal
- Correspondence: (C.S.L.V.); (M.L.I.)
| | - Manuel Mota
- Mediterranean Institute for Agriculture, Environment and Development (MED), University of Évora, Pólo da Mitra, Apartado 94, 7006-554 Evora, Portugal;
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