Endophyte inoculation enhances Ulmus minor resistance to Dutch elm disease

AbstractThe main objective of this research was to assess the genetic diversity of 5 natural field elm populations in Croatia. The study results suggest that the observed populations are characterized by a satisfactory amount of heterozygosity, and that the impact of the Dutch elm disease on the amount of genetic diversity in the sampled populations is currently negligible. However, one population displayed a significant excess of heterozygosity, implying a genetic bottleneck. The existence of a very clear genetic differentiation between the continental and the Mediterranean populations of Ulmus minor in Croatia was noticed.

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Endophyte inoculation enhances Ulmus minor resistance to Dutch elm disease

10.1101/2020.05.04.076349 ◽

2020 ◽

Author(s):

C Martínez-Arias ◽

J Sobrino-Plata ◽

S Ormeño-Moncalvillo ◽

L Gil ◽

J Rodríguez-Calcerrada ◽

...

Keyword(s):

Fungal Endophytes ◽

Nutrient Utilization ◽

Dutch Elm Disease ◽

Total Phenolic ◽

Phenotypic Traits ◽

Total Phenolic Compounds ◽

Biotic Stresses ◽

Ulmus Minor ◽

Utilization Patterns

AbstractCertain fungal endophytes are known to improve plant resistance to biotic stresses in forest trees. In this study, three stem fungal endophytes belonging to classes Cystobasidiomycetes, Eurotiomycetes and Dothideomycetes were selected from 210 isolates for their potential as enhancers of Ulmus minor resistance to Ophiostoma novo-ulmi. We evaluated phenotypic traits of these endophytes that could be beneficial for inhibiting O. novo-ulmi in the host plant. Under in vitro conditions, the Dothideomycetous isolate YCB36 strongly inhibited O. novo-ulmi growth, released antipathogenic VOCs, chitinases and siderophores, and overlapped with the pathogen in nutrient utilization patterns. These functional traits could explain the 40% reduction in leaf wilting due to O. novo-ulmi in elm trees pre-inoculated with this endophyte. Ulmus minor trees inoculated with this endophyte showed increased leaf stomatal conductance and higher concentrations of flavonoids and total phenolic compounds in xylem tissues, suggesting induction of defence metabolism.

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Cellulose Nanofibers from a Dutch Elm Disease-Resistant Ulmus minor Clone

Polymers ◽

10.3390/polym12112450 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2450 ◽

Cited By ~ 1

Author(s):

Laura Jiménez-López ◽

María E. Eugenio ◽

David Ibarra ◽

Margarita Darder ◽

Juan A. Martín ◽

...

Keyword(s):

Cellulose Nanofibers ◽

Barrier Properties ◽

Dutch Elm Disease ◽

Ulmus Minor ◽

Mechanical Pretreatment ◽

Pfi Refining ◽

First Time ◽

Mediated Oxidation ◽

Potential Use ◽

Selection Of

The potential use of elm wood in lignocellulosic industries has been hindered by the Dutch elm disease (DED) pandemics, which have ravaged European and North American elm groves in the last century. However, the selection of DED-resistant cultivars paves the way for their use as feedstock in lignocellulosic biorefineries. Here, the production of cellulose nanofibers from the resistant Ulmus minor clone Ademuz was evaluated for the first time. Both mechanical (PFI refining) and chemical (TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation) pretreatments were assessed prior to microfluidization, observing not only easier fibrillation but also better optical and barrier properties for elm nanopapers compared to eucalyptus ones (used as reference). Furthermore, mechanically pretreated samples showed higher strength for elm nanopapers. Although lower nanofibrillation yields were obtained by mechanical pretreatment, nanofibers showed higher thermal, mechanical and barrier properties, compared to TEMPO-oxidized nanofibers. Furthermore, lignin-containing elm nanofibers presented the most promising characteristics, with slightly lower transparencies.

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Current status of the Dutch elm disease pathogen populations affecting Ulmus minor in Greece

Forest Pathology ◽

10.1111/efp.12323 ◽

2016 ◽

Vol 47 (2) ◽

pp. e12323 ◽

Cited By ~ 2

Author(s):

G. T. Tziros ◽

Z. G. Nakopoulou ◽

C. Perlerou ◽

S. Diamandis

Keyword(s):

Dutch Elm Disease ◽

Current Status ◽

Ulmus Minor ◽

Pathogen Populations

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Exogenous phenol increase resistance of Ulmus minor to Dutch elm disease through formation of suberin-like compounds on xylem tissues

Environmental and Experimental Botany ◽

10.1016/j.envexpbot.2008.05.004 ◽

2008 ◽

Vol 64 (1) ◽

pp. 97-104 ◽

Cited By ~ 20

Author(s):

Juan A. Martín ◽

Alejandro Solla ◽

M. Rosário Domingues ◽

Manuel A. Coimbra ◽

Luis Gil

Keyword(s):

Dutch Elm Disease ◽

Ulmus Minor

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Influence of water stress on Dutch elm disease symptoms in Ulmus minor

Canadian Journal of Botany ◽

10.1139/b02-067 ◽

2002 ◽

Vol 80 (8) ◽

pp. 810-817 ◽

Cited By ~ 26

Author(s):

A Solla ◽

L Gil

Keyword(s):

Water Stress ◽

Water Relations ◽

Spore Suspension ◽

Large Vessel ◽

Dutch Elm Disease ◽

Disease Symptoms ◽

Vessel Formation ◽

Ulmus Minor ◽

Influence Of Water

The response of Ulmus minor Miller to Dutch elm disease was observed under combined heavy and light watering regimes. Ramets of two clones, planted in pots, were divided into two groups and each group underwent a different watering regime: heavy initial watering followed by light watering and light initial watering followed by heavy watering. The changeover in watering took place on May 29, 1998, 15 days after plants had been inoculated with a Ophiostoma novo-ulmi Brasier spore suspension. Greater wilting was evident in elms subjected to the heavy initial watering followed by light watering regime than those subjected to light initial watering followed by heavy watering. Non-inoculated plants subjected to heavy initial watering followed by light watering developed large vessel diameters during the heavy watering period and showed approximately 20% wilting during the light watering period. Non-inoculated plants subjected to light initial watering followed by heavy watering developed vessels with smaller diameters during the light watering period, and showed no wilting. The evidence suggests that large vessel formation prior to inoculation associated with water stress after infection increases Dutch elm disease symptoms. The role of water stress in the development of Dutch elm disease symptoms and the implications for elm resistance and breeding are discussed.Key words: field elm, Dutch elm disease, water relations, xylem vessels, breeding, Ophiostoma novo-ulmi.

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Influence of Plant Age on Symptom Development in Ulmus minor Following Inoculation by Ophiostoma novo-ulmi

Plant Disease ◽

10.1094/pd-89-1035 ◽

2005 ◽

Vol 89 (10) ◽

pp. 1035-1040 ◽

Cited By ~ 29

Author(s):

A. Solla ◽

J. A. Martín ◽

G. B. Ouellette ◽

L. Gil

Keyword(s):

Positive Relationship ◽

Dutch Elm Disease ◽

Screening Tests ◽

Host Age ◽

Symptom Development ◽

Relative Resistance ◽

Breeding Programs ◽

Ulmus Minor ◽

Growing Conditions ◽

Old Trees

In American and European breeding programs, numerous elm trees from many species (Ulmus spp.) and hybrids have been inoculated annually with the fungus Ophiostoma novo-ulmi (the Dutch elm disease pathogen) in screening tests for resistance. Because trees were inoculated at different ages, it appeared necessary to study the influence of host age on the symptoms shown. Four Ulmus minor trees and one U. minor × U. pumila tree were cloned annually from 1994 to 1999. The replicates obtained (usually n = 6) were inoculated on 17 May 2000 with an O. novoulmi strain. At the end of the season, 2-year-old U. minor trees showed average wilting of 8 ± 3% (ES), significantly less than that of 3-year-old trees (34 ± 5%) (P ≤ 0.01). Elms that were 4, 5, 6, and 7 years old showed wilting values of around 50%. A positive relationship between the symptoms shown and the diameter of the elm xylem vessels was observed, and the implications for elm resistance and breeding are discussed. Breeders and pathologists should use trees of the same age and physiological phase when determining the relative resistance among elm clones. It is concluded that under the growing conditions of this experiment, the optimal age for U. minor screening was 4-year-old plants.

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Characterizing offspring of Dutch elm disease-resistant trees (Ulmus minor Mill.)

Forestry An International Journal of Forest Research ◽

10.1093/forestry/cpaa040 ◽

2020 ◽

Author(s):

Juan A Martín ◽

Alejandro Solla ◽

Tomasz Oszako ◽

Luis Gil

Keyword(s):

Resistance Mechanisms ◽

High Variability ◽

Dutch Elm Disease ◽

Xylem Anatomy ◽

Vessel Size ◽

Ulmus Minor ◽

Tree Resistance ◽

Breeding Programmes ◽

Earlywood Vessels ◽

Selection Of

Abstract Populations of Ulmus minor in Europe were severely damaged by Dutch elm disease (DED) pandemics. However, elm breeding programmes have permitted selection of resistant elm varieties currently used for reforestation. In restored elm forests, resistant (R) and susceptible (S) trees interbreed, but little is known about resistance in their offspring. In this work, growth, DED resistance and xylem anatomy in the offspring of two resistant U. minor trees (R1 and R2) were studied. To verify whether transmission of traits in offspring is determined by maternal or paternal trees, a complete randomized plot was established with clonal material from controlled crosses (R1 × S and R2 × S) and parent trees (R1, R2 and S). Trees were inoculated with O. novo-ulmi firstly at age 4 years and again at 5 years. Growth, susceptibility to DED and vessel size in offspring were closer to the traits of maternal than of paternal trees. This association disappeared after the second inoculation when symptoms increased. The more resistant trees in R1 × S and R2 × S had wide and narrow earlywood vessels, respectively, suggesting that water-conducting strategies and resistance mechanisms vary in offspring. Tylosis formation was related to resistance only in R2 × S offspring, possibly due to the narrow earlywood vessles of trees. Latewood vessels were normally narrower in the more resistant trees. This study sheds light on anatomical resistance mechanisms of elms against DED: (1) offspring exhibit high variability in responses among individuals, (2) narrow earlywood vessels are not a prerequisite for DED resistance and (3) barrier zones are not fully associated with tree resistance in offspring.

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

Journal of Fungi ◽

10.3390/jof7090687 ◽

2021 ◽

Vol 7 (9) ◽

pp. 687

Author(s):

Clara Martínez-Arias ◽

Juan Sobrino-Plata ◽

Luis Gil ◽

Jesús Rodríguez-Calcerrada ◽

Juan Antonio Martín

Keyword(s):

Host Resistance ◽

Current Knowledge ◽

Fungal Endophytes ◽

Antioxidant Response ◽

Plant Diseases ◽

Dutch Elm Disease ◽

Forest Trees ◽

Variable Intensity ◽

Defense Priming ◽

Ulmus Minor

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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First report of Geosmithia langdonii and Geosmithia spp. isolated from a decaying elm (Ulmus minor) in Geneva, Switzerland

Folia Forestalia Polonica ◽

10.1515/ffp-2016-0011 ◽

2016 ◽

Vol 58 (2) ◽

pp. 96-102 ◽

Cited By ~ 1

Author(s):

Martine Hänzi ◽

Bastien Cochard ◽

Romain Chablais ◽

Julien Crovadore ◽

François Lefort

Keyword(s):

Bark Beetle ◽

Fungal Species ◽

Dutch Elm Disease ◽

Beetle Species ◽

Opportunistic Pathogens ◽

First Report ◽

Ulmus Minor ◽

Rdna Sequences ◽

Nucleotide Database ◽

First Time

Abstract The mortality of a young elm Ulmus minor in 2014 in Geneva prompted a search for the microorganisms potentially involved. Symptoms included foliar chlorosis and wilting followed by defoliation of branches. Wood symptoms included a brown streaking of sap wood and brown stains in trunk and branches. The comparison of the resulting ITS rDNA sequences to the NCBI Nucleotide database allowed to identify 10 different organisms. The genus Geosmithia represented 48% of the isolates belonging to three species: Geosmithia langdonii (7 isolates) and 2 unknown morphologically and genetically different Geosmithia sp. 1 and sp. 2 (4 isolates). Geosmithia species are very little known ascomycetes, which have been recently shown to be opportunistic pathogens on broadleaved trees and conifers, living as saprobes in galleries of many bark beetle species. In the case described here, Geosmithia langdonii, and the unknown Geosmithia species were found in symptomatic wood while bark beetle galleries were found in close regions of the symptomatic wood. Geosmithia langdonii was the major fungus retrieved from the symptomatic wood and could have contributed, along with other identified fungal species, to a pathogenic complex producing symptoms similar to the ones of the Dutch Elm Disease and led to the dieback of this elm tree. Geosmithia langdonii and 2 yet unknown Geosmithia species (sp. 1 and sp. 2), different from any other reported Geosmithia species are reported from an elm tree in Switzerland for the first time.

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