scholarly journals Έρευνα των παθογόνων ειδών του γένους Cryphonectria (=Endothia) στην Ευρωπαϊκή καστανιά (Castanea sativa)

2002 ◽  
Author(s):  
Χαρίκλεια Περλέρου
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Cryphonectria Hypovirus

Η ασθένεια του έλκους της καστανιάς που προκαλεί ο μύκητας Cryphonectria parasitica αποτελεί μια από τις σοβαρότερες ασθένειες που έπληξαν δασικό δένδρο του Β. Ημισφαιρίου κατά τον 20ο αιώνα. Αν και ο μύκητας πρωτοεντοπίσθηκε στην Ελλάδα το 1963 λίγο έχει μελετηθεί μέχρι σήμερα. Σχετικά πρόσφατη έρευνα στην Ευρώπη και ΗΠΑ έδειξε την ύπαρξη στη φύση ενός ιού dsRNA ο οποίος όταν προσβάλλει τις πορτοκαλόχρωμες, παθογόνες απομονώσεις του μύκητα τις μετατρέπει σε λευκές, υποπαθογόνες. Ο ιός αυτός εντάχθηκε στο γένος hypovirus, οικ. Hypoviridae και ονομάστηκε Cryphonectria hypovirus (CHV). Η μεταφορά του κυτταροπλασμικού αυτού ιού είναι εφικτή με αναστόμωση των μυκηλιακών υφών μόνον εάν οι δύο μορφές απομονώσεων ανήκουν στον ίδιο τύπο βλαστικής συμβατότητας. Η ιδιαίτερη αυτή περίπτωση μείωσης της παθογόνου ικανότητας ενός μύκητα αξιοποιήθηκε με την εφαρμογή μεθόδου βιολογικής αντιμετώπισης της ασθένειας που συνίσταται στην εισαγωγή στελεχών με CHV ιό και μειωμένη παθογόνου ικανότητα σε περιοχές όπου αυτά δεν υπάρχουν. Απαραίτητη προϋπόθεση όμως για την εφαρμογή της μεθόδου είναι η λεπτομερής γνώση και γεωγραφική διασπορά των τύπων βλαστικής συμβατότητας σε μια ευρύτερη περιοχή. Έτσι σκοπός της παρούσας έρευνας ήταν ο έλεγχος για την ύπαρξη νέων κηλίδων της ασθένειας πέραν αυτών που έχουν ήδη εντοπισθεί, ο προσδιορισμός, η γεωγραφική διασπορά και η μελέτη των τύπων βλαστικής συμβατότητας του μύκητα C. parasitica στην Ελλάδα, η διερεύνηση της ύπαρξης υποπαθογόνων στελεχών και τέλος η μελέτη της παθογόνου ικανότητας απομονώσεων του μύκητα από διάφορες περιοχές της χώρας. Κατά την έρευνα αυτή διαπιστώθηκε ότι εκτός από τις 4 περιοχές για τις οποίες υπήρχαν αναφορές ύπαρξης της ασθένειας, ήτοι όρος Πήλιο Ν. Μαγνησίας, Άνω Κεράσοβο Ν. Αιτωλοακαρνανίας, Δυτ. Τζουμέρκα Ν. Άρτας και Άγιον Όρος, η ασθένεια έχει εξαπλωθεί στις περισσότερες από τις περιοχές όπου απαντάται η καστανιά στην Ελλάδα. Από 611 απομονώσεις του μύκητα που πραγματοποιήθηκαν σε 12 Νομούς της χώρας, λευκές απομονώσεις με μειωμένη παθογόνο ικανότητα βρέθηκαν μόνο στους Νομούς Μαγνησίας, Ιωαννίνων, Αιτωλοακαρνανίας, Φθιώτιδας και Χαλκιδικής σε συνολικό ποσοστό 11,6% των απομονώσεων. Έλεγχος των ίδιων αυτών απομονώσεων έδειξε ότι στην Ελλάδα υπάρχουν τέσσερις τύποι βλαστικής συμβατότητας, ήτοι οι EU-1, EU-2, EU-10 και EU-12. Ο τύπος EU-12 βρέθηκε και στους 12 Νομούς σε συνολικό ποσοστό 88,4% των απομονώσεων ενώ ο τύπος EU-2 σε 4 Νομούς σε ποσοστό 6,4%. Οι άλλοι δύο τύποι EU-1 και EU-10 βρέθηκαν σε χαμηλότερα ποσοστά (2,1% και 3,1% αντίστοιχα) σε ένα Νομό έκαστος. Η παθογόνος ικανότητα 11 ελληνικών απομονώσεων και μιας ιταλικής προσδιορίσθηκαν από το μέγεθος των ελκών που προκάλεσαν σε πρεμνοβλαστήματα καστανιάς ηλικίας 9 ετών μετά από τεχνητή μόλυνση υπό φυσικές συνθήκες. Οι παρατηρήσεις και μετρήσεις επεκτάθηκαν σε δύο αυξητικές περιόδους (17 μήνες). Έξι πορτοκαλόχρωμες απομονώσεις συμπεριφέρθηκαν ως παθογόνες προκαλώντας εκτεταμένα έλκη που αναπτύχθηκαν και στις δύο αυξητικές περιόδους. Από τις υπόλοιπες έξι λευκές απομονώσεις με τον dsRNA ιό, οι τέσσερις προκάλεσαν μικρά έλκη κατά τους πρώτους δύο μήνες μετά την τεχνητή μόλυνση τα οποία στη συνέχεια επουλώθηκαν, παρέμειναν δε ανενεργά κατά τη δεύτερη αυξητική περίοδο. Οι άλλες δύο απομονώσεις συμπεριφέρθηκαν ως παθογόνες κατά την πρώτη αυξητική περίοδο αλλά ως υποπαθογόνες κατά τη δεύτερη καθόσον τα έλκη παρέμεινα εντελώς ανενεργά ενώ άρχισε να σχηματίζεται και επουλωτικός ιστός. Λόγω του εξαιρετικά μικρού αριθμού των τύπων βλαστικής συμβατότητας και της περιορισμένης γεωγραφικά εμφάνισης των υποπαθογόνων στελεχών του μύκητα, η εφαρμογή βιολογικής καταπολέμησης, είναι δυνατή. Η χώρα όμως θα πρέπει ταυτόχρονα να θωρακισθεί κατά της εισαγωγής και άλλων τόπων βλαστικής συμβατότητας με την αυστηρή εφαρμογή των προτάσεων φυτοελέγχου του ΕΡΡΟ.

scholarly journals Population Structure and Disease Development of Cryphonectria parasitica in European Chestnut Forests in the Presence of Natural Hypovirulence

1997 ◽  
Vol 87 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Martin Bissegger ◽  
Daniel Rigling ◽  
Ursula Heiniger
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
First Year ◽  
Mating Types ◽  
Vegetative Compatibility Groups ◽  
European Chestnut ◽  
Repeated Sampling ◽  
Cryphonectria Hypovirus ◽  
Two Populations

The Cryphonectria parasitica populations in two 6-year-old European chestnut (Castanea sativa) coppices were investigated in southern Switzerland over a period of 4 years. Occurrence of white isolates indicating an infection with Cryphonectria hypovirus, vegetative compatibility groups (VCGs), hypovirulence conversion capacity, and mating types were used to characterize the populations. Sampling of randomly chosen cankers in the first year yielded 59% white isolates in one and 40% in the other population. The distribution of the VCGs and mating types was similar among white and orange isolates, indicating a homogeneous infection of the two populations by the hypovirus. Fourteen VCGs were found in the first population, 16 VCGs in the second. Altogether, 21 VCGs were determined. The same three VCGs dominated in both populations, comprising more than 60% of all isolates. Several VCGs were represented only by white isolates. Five of the six most common VCGs were clustered in two hypovirulence conversion groups, with almost 100% hypovirus transmission within each cluster. Repeated sampling of the same cankers in 1990, 1992, and 1994 did not reveal an increase of white isolates. The portion of blighted stems rose from 37% to about 60% in both plots within 4 years. In this time, chestnut blight killed 15% and competition an additional 21% of the sprouts. Predominantly, sprouts with low diameters at breast height were killed. The growth rate of new cankers was high in their first year and decreased gradually in the following years. A role of hypovirulence in the decline of disease severity was evident since (i) cankers yielding white isolates grew slower and killed considerably fewer sprouts than cankers with orange isolates; and (ii) the majority of the cankers yielded white isolates at least once during the 4-year observation period.

scholarly journals Hail-Induced Infections of the Chestnut Blight Pathogen Cryphonectria parasitica Depend on Wound Size and May Lead to Severe Diebacks

2020 ◽  
Vol 110 (7) ◽  
pp. 1280-1293
Author(s):  
Guglielmo Lione ◽  
Luana Giordano ◽  
Massimo Turina ◽  
Paolo Gonthier
Keyword(s):  
Logistic Model ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Risk Of Infection ◽  
North West ◽  
The North ◽  
Single Location ◽  
Entry Points ◽  
Cryphonectria Hypovirus

This study combined phytosanitary surveys, laboratory analyses, and mathematical modeling to show how hail-induced wounds can foster the infections of the blight pathogen Cryphonectria parasitica, locally associated with extensive dieback of chestnut (Castanea sativa). Orchards and coppices located within and outside the assessed dieback area in a single location in the North West of Italy were inspected to appraise the abundance of hail-induced wounds and C. parasitica infections. The incidence of C. parasitica was significantly higher within the dieback area compared with outside (92% versus 60%; P < 0.05). Hail-induced wounds were observed on small branches and shoots of all trees sampled within the dieback area, whereas they were less abundant outside (20% of trees), suggesting either that the dieback was directly associated with the injuries caused by the hailstorms or that those injuries may have facilitated infections of C. parasitica. Isolations conducted on 359 branches and shoots showed that hail-induced wounds served as infection courts for C. parasitica and that infections depended on the size rather than on the number of hail wounds. We fitted a logistic model showing that hail-induced wounds whose perimeter was larger than 66 mm were at particular risk of C. parasitica infection. A newly designed geometrical-based model is proposed to relate hailstones size, hail wound perimeter, and the risk of infection. We established that hail-induced wounds are entry points for virulent and hypovirulent strains of C. parasitica, since 6.5% of isolates were infected by Cryphonectria hypovirus-1.

scholarly journals Role of Fresh Dead Wood in the Epidemiology and the Biological Control of the Chestnut Blight Fungus

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 430-438 ◽  
Author(s):  
Joana Beatrice Meyer ◽  
Loïc Chalmandrier ◽  
Fabio Fässler ◽  
Christopher Schefer ◽  
Daniel Rigling ◽  
...  
Keyword(s):  
Biological Control ◽  
Dead Wood ◽  
Biocontrol Agent ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Study Sites ◽  
Cryphonectria Hypovirus

The invasive fungus Cryphonectria parasitica, the causal agent of chestnut blight, is able to survive and sporulate on the bark of fresh dead Castanea sativa wood for at least 2 years. Here, we experimentally investigated the role of fresh dead wood in the epidemiology of chestnut blight, specifically in the spread of the hyperparasitic virus Cryphonectria hypovirus 1, which acts as biocontrol agent of C. parasitica. A total of 152 artificially initiated, virulent bark cankers in four chestnut stands were treated with virus-infected asexual spores originating either from sporulating dead wood or from a spore suspension. Molecular markers for both the virus and the fungal carrier were used to examine the spread of the applied biocontrol virus. Fourteen months after treatment, 42 to 76% of the conidial spray-treated cankers and 50 to 60% of the cankers exposed to a sporulating dead stem had been virus infected by the applied hypovirulent conidia in all four study sites. Virus infection reduced canker expansion and promoted canker healing (callusing). Thus, fresh chestnut dead wood may play an important role in supporting the successful spread of natural hypovirulence in chestnut forests. Further, combined with the application of virus-infected conidial suspensions, it may help promote the establishment of artificially released hypoviruses in chestnut stands to control chestnut blight.

scholarly journals Identification of Susceptibility Genes in Castanea sativa and Their Transcription Dynamics following Pathogen Infection

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 913
Author(s):  
Vera Pavese ◽  
Andrea Moglia ◽  
Paolo Gonthier ◽  
Daniela Torello Marinoni ◽  
Emile Cavalet-Giorsa ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Castanea Sativa ◽  
Transcript Level ◽  
Cryphonectria Parasitica ◽  
Plant Responses ◽  
Functional Domain ◽  
Loss Of Function ◽  
Pathogen Infection ◽  
Domain Identification ◽  
S Genes

Castanea sativa is one of the main multipurpose tree species valued for its timber and nuts. This species is susceptible to two major diseases, ink disease and chestnut blight, caused by Phytophthora spp. and Cryphonectria parasitica, respectively. The loss-of-function mutations of genes required for the onset of pathogenesis, referred to as plant susceptibility (S) genes, are one mechanism of plant resistance against pathogens. On the basis of sequence homology, functional domain identification, and phylogenetic analyses, we report for the first time on the identification of S-genes (mlo1, dmr6, dnd1, and pmr4) in the Castanea genus. The expression dynamics of S-genes were assessed in C. sativa and C. crenata plants inoculated with P. cinnamomi and C. parasitica. Our results highlighted the upregulation of pmr4 and dmr6 in response to pathogen infection. Pmr4 was strongly expressed at early infection phases of both pathogens in C. sativa, whereas in C. crenata, no significant upregulation was observed. The infection of P. cinnamomi led to a higher increase in the transcript level of dmr6 in C. sativa compared to C. crenata-infected samples. For a better understanding of plant responses, the transcript levels of defense genes gluB and chi3 were also analyzed.

scholarly journals Assessing the Phytosanitary Risk Posed by an Intraspecific Invasion of Cryphonectria parasitica in Europe

2019 ◽  
Vol 109 (12) ◽  
pp. 2055-2063 ◽  
Author(s):  
Francesca Dennert ◽  
Joana Beatrice Meyer ◽  
Daniel Rigling ◽  
Simone Prospero
Keyword(s):  
United States ◽  
South Korea ◽  
Plant Pathogens ◽  
Castanea Sativa ◽  
The United States ◽  
Cryphonectria Parasitica ◽  
Seedling Mortality ◽  
New Host ◽  
Phytosanitary Measures

Intraspecific cryptic invasions may occur when new strains of an invasive species are introduced into an area where this species had already been introduced previously. In plant pathogens, such invasions are not well studied, even if, potentially, they can have severe consequences. Here, we investigated the effects of a potential intraspecific invasion in Europe of Cryphonectria parasitica, the causal agent of chestnut blight. Specifically, we tested the hypotheses that (i) non-European strains are more virulent on Castanea sativa than those already present in Europe because they have never encountered this new host, and (ii) the variation in virulence among strains is higher within native than within introduced populations. In a greenhouse, 2-year-old C. sativa seedlings were inoculated with Cryphonectria parasitica strains from South Korea, the United States, and Switzerland, and lesion development and seedling mortality were recorded weekly. Additionally, growth and sporulation of the strains were measured in vitro on agar medium at 15 and 24°C. Although lesion growth was similar for all strains, seedlings inoculated with strains from South Korea and Switzerland died faster than seedlings inoculated with strains from the United States. Moreover, in vitro strains from South Korea grew faster and produced more spores at both temperatures than the strains from the other two countries. In conclusion, our results did not support the two hypotheses. All strains, regardless of their origin, were found to be highly virulent on the inoculated chestnut seedlings. Nevertheless, current phytosanitary measures to avoid the introduction of new genotypes of C. parasitica into Europe should be further implemented.

scholarly journals Diversity of microfungi on branches of Castanea sativa in Slovakia

2013 ◽  
Vol 58 (2) ◽  
pp. 741-746 ◽  
Author(s):  
Katarína Adamčíková ◽  
Gabriela Juhásová ◽  
Marek Kobza ◽  
Emília Ondrušková
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Microscopic Fungi ◽  
Chestnut Tree ◽  
New Localities ◽  
Castanea Sativa Mill

Abstract Localities in Castanea sativa Mill. plantations were visited in a study aimed at identifying the mycoflora of C. sativa in Slovakia [excluding Cryphonectria parasitica (Murr.), Barr for which much data is available]. Samples from chestnut tree branches and stems were examined visually and microscopically. Seven species of microfungi were recorded, three with their anamorphs. Coryneum modonium (Sacc.) Griffon & Maubl. and Phomopsis castaneae Woron. were the most common. Libertella quercina Tul. & C. Tul. was identified in both states (anamorph and teleomorph) at two new localities. The records of Gloniopsis praelonga (Schwein.) Underw. & Earle and Dothidotthia celtidis (Ellis & Everh.) M. E. Barr are the first for Slovakia. These species were rare, found only in one locality. Two microscopic fungi were detected: Valsa ambiens (Pers.) Fr. [Cytospora ambiens (Nitschke) Sacc.] and Diplodina castaneae Prill. & Delacr.

Cryphonectria hypovirus 1-Induced Epigenetic Changes in Infected Phytopathogenic Fungus Cryphonectria parasitica

2017 ◽  
Vol 75 (3) ◽  
pp. 790-798 ◽  
Author(s):  
Lucija Nuskern ◽  
Marin Ježić ◽  
Zlatko Liber ◽  
Jelena Mlinarec ◽  
Mirna Ćurković-Perica
Keyword(s):  
Cryphonectria Parasitica ◽  
Phytopathogenic Fungus ◽  
Epigenetic Changes ◽  
Cryphonectria Hypovirus

scholarly journals The role of production site isolation in the plant health situation of sweet chestnut (Castanea sativa)

2017 ◽  
pp. 79-82
Author(s):  
Gabriella Kovács ◽  
László Radócz
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Western Slope ◽  
Past Century ◽  
Sweet Chestnut ◽  
European Chestnut ◽  
Disease Occurrence ◽  
New Perspective ◽  
Blight Disease ◽  
Health Situation

The most destructive pathogen for the European chestnut is the blight fungus Cryphonectria parasitica (Murr.) Barr. The spread of the fungus was very fast in Europe within a few decades in the second half of the past century. During the tree-health checking in the chestnut andwalnut plantation in Romania, Hargita county, next to Homoródkarácsonyfalva village, we especially concentraded on the signs of blight disease occurrence. The grove is laying on a western slope, under a pine forest. This favourable geographical space protects it not only from pathogen attacts, but it has a special, mild microclimate for nut and chestnut trees. The European chestnut could be a valuable member of local forests, opening a new perspective under conditions of climate changes.

scholarly journals The Morphology and the Biological Control of Cryphonectria parasitica

2012 ◽  
Vol 69 (1) ◽  
Author(s):  
Carmen Emilia PUIA ◽  
Daniela Andreea GRIGORESCU ◽  
Raluca Vasilica MICLEA
Keyword(s):  
Biological Control ◽  
Virulent Strain ◽  
Morphological Characteristics ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Dual Culture ◽  
Natural Form ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Cryphonectria parasitica  (Murr.) Bar [syn. Endothia parasitica (Murr. And.] (anamorf: Endothiella sp .) is the causal agent of chestnut bark disease or chestnut blight, disease which produced great damages throughout the world, for example, in Europe, the European chestnut tree ( Castanea sativa (P.) Mill) was heavily affected. Environmental concerns have focused attention on natural forms of disease control as an effective alternative to chemical pesticides. In the chestnut blight fungus, Cryphonectria parasitica deals with a natural form of biological control in which the virulence of a fungal pathogen is attenuated by an endogenous viral RNA genetic element- the hypovirulent strain. In our researches we picked samples of chestnut bark from different areas in Maramures county. We’ve isolated the fungus on PDA medium and we’ve studied the morphological characteristics of the usual virulent strain and we looked for a possible hypovirulent strain in order to study its capacity for biological control. The fungus develops in the bark and in cambium where forms a yellowish or brownish stroma and produces both conidia and ascospores. The pycnidia stromata break through the lenticels producing conidia and later in the same stroma develop the perithecia which produce ascospores. Both strains of the fungus were found in the research area. The hypovirulent strain had a slower development, showed no sporu lation and pigmentation “white cultural strain” and was tested in vitro for the capacity to convert the virulent isolates by dual culture tests.

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