Complexities underlying the breeding and deployment of Dutch elm disease resistant elms

Martín, Juan A.; Domínguez, Jorge Domínguez; Solla, Alejandro; Brasier, C. M.; Webber, Joan; Santini, Alberto; Martínez‐Arias, Clara; Bernier, Louis; Gil, Luís

doi:10.1007/s11056-021-09865-y

Cited by 21 publications

(19 citation statements)

References 145 publications

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“…Therefore, effects of U. minor infection on stream ecosystem are likely to be small. However, many trees survive as sprouts and root suckers suffering recurrent Dutch elm disease symptoms (Brasier & Webber, 2019), and elm breeding programmes have permitted selection of resistant elm varieties currently used for reforestation of riparian areas (Martín, Domínguez, et al., 2021; Martín et al., 2019).…”

Section: Discussionmentioning

confidence: 99%

Invasive forest pathogens affect the characteristics, microbial colonisation, and decomposition of leaf litter in streams

2021

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Invasive tree pathogens threaten forests worldwide, but their effects on streams are poorly understood. Nevertheless, tree infections that lead to changes in the characteristics of litter inputs to streams may affect stream communities and ecosystem processes. We studied cross‐ecosystem effects derived from Phytophthora cinnamomi, Phytophthora ×alni, and Ophiostoma novo‐ulmi infection on Castanea sativa (chestnut), Alnus lusitanica (alder), and Ulmus minor (elm) trees, respectively, by assessing physical and chemical characteristics of senescent leaves from healthy, symptomatic, and highly symptomatic individuals. Leaf litter from the three health statuses per tree species was then incubated in laboratory microcosms and the effects of tree infection on microbial decomposers and leaf litter decomposition were assessed. Tree infection significantly affected leaf litter characteristics, microbial decomposers and leaf litter decomposition, and the health status of trees conditioned these effects differently depending on the tree species. In C. sativa, leaf litter of highly symptomatic trees had higher toughness, higher polyphenolic concentration and slower decomposition than leaf litter of symptomatic and healthy trees. In A. lusitanica, leaf litter of highly symptomatic trees had higher phosphorus concentration, lower carbon:phosphorus ratio and faster decomposition than leaf litter of symptomatic and healthy trees. Finally, in U. minor, leaf litter of highly symptomatic trees had higher nitrogen concentration and lower carbon:nitrogen ratio than leaf litter of healthy trees, and faster decomposition than leaf litter of symptomatic and healthy trees. Effects of changes in litter characteristics on litter decomposition were mediated by changes in microbial decomposer colonisation and activity. The composition of the aquatic hyphomycetes communities associated with C. sativa and U. minor litter varied depending on the tree health status. Most striking was the two‐fold higher aquatic hyphomycetes species richness in litter of U. minor trees infected with O. novo‐ulmi than in litter of healthy U. minor trees. Tree infection alters the nutritional quality of leaf litter, potentially affecting the functioning of aquatic ecosystems strongly dependent on riparian litter inputs.

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Section: Discussionmentioning

confidence: 99%

Invasive forest pathogens affect the characteristics, microbial colonisation, and decomposition of leaf litter in streams

2021

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“…In the present work, we aim to deepen the knowledge regarding the role of fungal endophytes of forest trees as inducers of defense mechanisms against pathogens by exploring the Dutch elm disease (DED) pathosystem. DED is a vascular wilt disease that has caused massive deaths of Ulmus species populations in Europe and North America in the last 100 years [38][39][40]. The causal agents are several species in the genus Ophiostoma, being O. novo-ulmi Brasier responsible of the current pandemic [41,42].…”

Section: Introductionmentioning

confidence: 99%

Priming of Plant Defenses against Ophiostoma novo-ulmi by Elm (Ulmus minor Mill.) Fungal Endophytes

Martínez‐Arias

Sobrino-Plata

Gil

et al. 2021

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Some fungal endophytes of forest trees are recognized as beneficial symbionts against stresses. In previous works, two elm endophytes from the classes Cystobasidiomycetes and Eurotiomycetes promoted host resistance to abiotic stress, and another elm endophyte from Dothideomycetes enhanced host resistance to Dutch elm disease (DED). Here, we hypothesize that the combined effect of these endophytes activate the plant immune and/or antioxidant system, leading to a defense priming and/or increased oxidative protection when exposed to the DED pathogen Ophiostoma novo-ulmi. To test this hypothesis, the short-term defense gene activation and antioxidant response were evaluated in DED-susceptible (MDV1) and DED-resistant (VAD2 and MDV2.3) Ulmus minor genotypes inoculated with O. novo-ulmi, as well as two weeks earlier with a mixture of the above-mentioned endophytes. Endophyte inoculation induced a generalized transient defense activation mediated primarily by salicylic acid (SA). Subsequent pathogen inoculation resulted in a primed defense response of variable intensity among genotypes. Genotypes MDV1 and VAD2 displayed a defense priming driven by SA, jasmonic acid (JA), and ethylene (ET), causing a reduced pathogen spread in MDV1. Meanwhile, the genotype MDV2.3 showed lower defense priming but a stronger and earlier antioxidant response. The defense priming stimulated by elm fungal endophytes broadens our current knowledge of the ecological functions of endophytic fungi in forest trees and opens new prospects for their use in the biocontrol of plant diseases.

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“…It appears that the differences in tolerance among various elm trees are caused by the fact that the fungus and toxins can spread easily through wide vessels and, simultaneously, narrow vessels are more effectively and faster blocked by tyloses or other materials which prevent the spread of the fungus. In narrow vessels, the formation of these blocking structures has only a limited impact on the overall hydraulic conductivity [ 7 ].…”

Section: Discussionmentioning

confidence: 99%

“…In addition to DED tolerance, some of these newly released cultivars also possessed high ornamental value, exhibited fast growth and were tolerant to variable edaphic or climatic factors [ 6 ]. Many of the benefits previously conceded to elms still show both aesthetic and high-quality material values, which maintain the procedures of breeding and selection of new resistant hybrids in progress [ 7 ]. Besides the common breeding techniques, genetic engineering approaches were recently applied.…”

Section: Introductionmentioning

confidence: 99%

Different Responses in Vascular Traits between Dutch Elm Hybrids with a Contrasting Tolerance to Dutch Elm Disease

Moravčík

Mamoňová

Račko

et al. 2022

JoF

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The ascomycetous fungus Ophiostoma novo-ulmi is the causative agent of the current Dutch elm disease (DED) pandemic, which has ravaged many tens of millions of European and North American elm trees. Host responses in vascular traits were studied in two Dutch elm hybrids, ‘Groeneveld’ and ‘Dodoens’, which show different vascular architecture in the secondary xylem and possess contrasting tolerances to DED. ‘Groeneveld’ trees, sensitive to DED, possessed a high number of small earlywood vessels. However, these trees showed a poor response to DED infection for the earlywood vascular characteristics. Following infection, the proportion of least vessels with a vessel lumen area less than 2500 µm2 decreased from 65.4% down to 53.2%. A delayed response in the increasing density of vessels showing a reduced size in the latewood prevented neither the rapid fungal spread nor the massive colonisation of the secondary xylem tissues resulting in the death of the infected trees. ‘Dodoens’ trees, tolerant to DED, possessed a low number of large earlywood vessels and showed a prominent and fast response to DED infection. Vessel lumen areas of newly formed earlywood vessels were severely reduced together with the vessel size : number ratio. Following infection, the proportion of least vessels with a vessel lumen area less than 2500 µm2 increased from 75.6% up to 92.9%. A trend in the increasing density of vessels showing a reduced size was maintained not only in the latewood that was formed in the year of infection but also in the earlywood that was formed in the consecutive year. The occurrence of fungal hyphae in the earlywood vessels that were formed a year following the infection was severely restricted, as revealed by X-ray micro-computed tomography imaging. Possible reasons responsible for a contrasting survival of ‘Groeneveld’ and ‘Dodoens’ trees are discussed.

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Complexities underlying the breeding and deployment of Dutch elm disease resistant elms

Cited by 21 publications

References 145 publications

Invasive forest pathogens affect the characteristics, microbial colonisation, and decomposition of leaf litter in streams

Invasive forest pathogens affect the characteristics, microbial colonisation, and decomposition of leaf litter in streams

Priming of Plant Defenses against Ophiostoma novo-ulmi by Elm (Ulmus minor Mill.) Fungal Endophytes

Different Responses in Vascular Traits between Dutch Elm Hybrids with a Contrasting Tolerance to Dutch Elm Disease

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