Thesis (MSc (Plant Pathology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Esca is a disease affecting grapevines and is potentially devastating as there are economic
losses due to a decrease in yield, wine quality and berry quality. Vineyards also need to be
replaced earlier and therefore esca has a great impact on the wine, table grape and raisin
industries. The disease is known to affect vineyards worldwide and has been studied
extensively in Europe, but not in South Africa. Esca diseased grapevines were observed for
the first time prior to 1981 in South African vineyards. The disease is primarily caused by
Phaeoacremonium aleophilum, Phaeomoniella chlamydospora (both causing brown and
black wood streaking) and white rot basidiomycete species such as Fomitiporia mediterranea
which cause wood rot in the trunks and arms of generally older grapevines. Species of the
Botryosphaeriaceae and Phomopsis (mainly Phomopsis viticola) and Eutypa lata have also
been isolated from esca diseased vines, but their association with esca is unclear.
Some of the symptoms associated with the disease on most grapevine cultivars
include ‘tiger-stripe’ foliar symptoms, apoplexy and berry symptoms such as shriveling,
discoloration and ‘black measles’. These external symptoms as well as internal symptoms are
thought to be a result of toxin and enzyme production by the fungi involved. Symptom
expression is erratic and varies from year to year making investigations into the causal fungi
and the toxins and enzymes secreted in planta difficult.
Vines with internal or external symptoms of esca were sampled in this study from
table and wine grape cultivars in 37 towns in the Western Cape, Northern Cape and Limpopo
provinces. The majority of sampled vines were over ten years of age, but vines as young as
two to three years were also found to be infected. The external symptoms included dieback,
tiger striped leaves, berry symptoms (shriveling, insufficient colouring and black spots) and
apoplexy. These symptoms resembled those found on grapevines in Europe, Australia and the
USA. The internal symptoms found were also similar to European symptoms and included
white rot, black and brown wood streaking, brown necrosis within white rot, sectorial brown
necrosis and central brown/ red/ black margin. The fungi mostly isolated from the white rot
were the basidiomycetes. Black and brown wood streaking was primarily caused by
Phaeomoniella chlamydospora. Brown necrosis within the white rot was caused by
Phaeomoniella chlamydospora and less frequently by Phaeoacremonium spp., Eutypa lata,
Botryosphaeriaceae and Pleurostomophora richardsiae. The sectorial brown necrosis and the central/ brown/ red/ black margin were dominated by Phaeomoniella chlamydospora. The
fruiting bodies of the basidiomycetes were found on only a few grapevines.
The fungal species associated with the internal wood symptoms were characterized on
cultural growth patterns, morphology as well as phylogenetic inference. The gene areas
sequenced included the internal transcribed spacers and the 5.8S rRNA gene for the
basidiomycetes and Phomopsis isolates, the partial b-tubulin gene for Phaeoacremonium
isolates and the partial translation elongation-1a gene for the Botryosphaeriaceae isolates.
The basidiomycete isolates fell into ten taxa within the Hymenochaetales of which two could
be linked to known genera, namely Fomitiporia and Phellinus. The ten basidiomycete taxa do
not correspond to any published sequences. Eutypa lata, Diaporthe ambigua, Diplodia
seriata, Neofusicoccum australe, Neofusicoccum parvum, Phomopsis viticola, Phomopsis sp.
1, Phaeomoniella chlamydospora and six species of Phaeoacremonium including P.
aleophilum, P. alvesii, P. parasiticum, P. iranianum, P. mortoniae and P. sicilianum were
also isolated of which the latter three are reported for the first time in South Africa.
To understand the role of the basidiomycetes in the complex, toxin and enzyme
analyses was determined for these fungi. Selected basidiomycete isolates were grown up in
liquid broth and extractions performed to test for the presence of 4-hydroxy-benzaldehyde.
All of the basidiomycete isolates were able to produce this toxin which is known to be
phytotoxic. The basidiomycetes were then tested for the presence of certain wood degrading
enzymes. All of the taxa were able to produce manganese peroxidase. Laccase was produced
by all taxa, except Taxon 8. Lignin peroxidase was produced by Taxa 1, 2, 7, Fomitiporia sp.
and the Phellinus sp. All the basidiomycete isolates were able to produce cellulose and none
were able to produce xylanase. These enzyme tests showed that the basidiomycetes produce a
wide variety of enzymes which are able to degrade cellulase and lignin which are both
structural components of wood.
Given the wide distribution of esca in the grape growing regions investigated in South
Africa and the diverse amount of species found, this disease must surely be seen as a limiting
factor to the productive lifespan of vineyards and quality of produce. Preventative measures
such as sanitation and pruning wound protection contribute to the management of the disease,
but many questions still remain about the synergy of the causal fungi, epidemiology and
management of esca. / AFRIKAANSE OPSOMMING: Esca is ‘n wingerd siekte wat potensieel skade kan aanrig as gevolg van ekonomiese verliese
weens verlaagde opbrengs, wyn kwaliteit en vrug kwaliteit. Wingerde moet ook vroeër
vervang word en daarom het esca ’n groot impak op die wyn, tafeldryf en rosyne industrieë.
Esca word wêreldwyd gevind op wingerd en is al intensief nagevors in Europa, maar nog nie
in Suid-Afrika. Esca is vir die eerste keer in die 1980’s in Suid-Afrikaanse wingerde
gerapporteer. Die primêre veroorsaakende organismes van esca is Phaeoacremonium
aleophilum, Phaeomoniella chlamydospora wat bruin en swart vaatweefsel verkleuring
veroorsaak en basidiomycete spesies soos Fomitiporia mediterranea wat wit verotting
veroorsaak in die stam en arms van ouer wingerd. Spesies van die Botryosphaeriaceae en
Phomopsis (hoofsaaklik Phomopsis viticola) en Eutypa lata is ook al vanaf esca simptome
geïsoleer, maar hul assosiasie met die siekte is nie duidelik nie.
Algemene simptome wat voorkom op die meeste wingerd kultivars met esca sluit in
‘tiger-stripe’ blaar simptome, apopleksie en vrug simptome soos verdroging, verkleuring en
spikkels (black measles). Interne en eksterne simptome kan wees as gevolg van toksiene en
ensiem produksie van die swamme wat betrokke is by esca. Eksterne simptoom uitdrukking
is wisselvallig en varieer van jaar tot jaar. Dit bemoelik die bestudering van die swamme en
die toksiene en ensieme wat afgeskei word in planta.
Wingerd monsters met eksterne en interne simptome is versamel van tafel en
wyndruif kultivars in 37 dorpe in die Wes-Kaap, Noord-Kaap en Limpopo provinsies. Die
meerderheid monsters was ouer as tien jaar maar wingerde wat twee tot drie jaar oud was,
was ook gevind. Die eksterne simptome wat op hierdie kultivars gevind is het terugsterwing,
‘tiger striped’ blare, vrug simptome (verkrimping en onvoldoende verkleuring) en apopleksie
ingesluit. Hierdie simptome stem ooreen met soortgelyke simptome gevind op wingerd in
Europa, Australië en die VSA. Interne simptome was ooreenstemmend met simptome wat
gevind word in Europa. Die interne simptome het wit verotting, bruin en swart
streepvorming, bruin nekrose met wit verotting, sektoriale bruin nekrose en sentrale bruin/
rooi/ swart kante ingesluit. Basidiomycete swamme is meestal uit die wit verotting gedeeltes
geïsoleer. Swart en bruin hout streepvorming was meestal deur Phaeomoniella
chlamydospora veroorsaak. Bruin nekrose binne die wit verotting was meestal deur
Phaeomoniella chlamydospora veroorsaak en in ‘n mindere mate deur Phaeoacremonium
spp., Eutypa lata, Botryosphaeriaceae en Pleurostomophora richardsiae. Phaeomoniella
chlamydospora was die hoof veroorsakende organisme van sektoriale bruin nekrose en die sentrale bruin/ rooi/ swart kante. Vrugliggame van die basiodiomycete is op enkele wingerde
gevind.
Swam soorte wat geassosieer word met die interne hout simptome was verder
gekarakteriseer op kultuur groei, morfologiese eienskappe, en filogenetiese analise. Die geen
areas waarvan die basis paar volgorde bepaal was sluit in die interne getranskribeerde spasies
en die 5.8S rRNA geen vir die basidiomycete en Phomopsis isolate, die gedeeltelike btubulien
geen vir Phaeoacremonium isolate en die gedeeltelike translasie velenging-1a geen
vir die Botryosphaericeae isolate. Die basidiomycete isolate was versprei oor tien taksons
binne die Hymenochaetales waarvan twee genusse gekoppel kon word aan die genera
Fomitiporia en Phellinus. Die tien basidiomycete taksons kom nie ooreen met enige
gepubliseerde DNS volgordes. Eutypa lata, Phomopsis viticola, Phomopsis sp. 1, Diaporthe
ambigua, Diplodia seriata, Neofusicoccum parvum, Neofusicoccum australe, Phaeomoniella
chlamydospora en ses spesies van Phaeoacremonium insluitend P. aleophilum, P. alvesii, P.
parasiticum, P. iranianum, P. mortoniae en P. sicilianum is ook geïsoleer. Hierdie is die
eerste keer dat P. iranianum, P. mortoniae en P. sicilianum in Suid-Afrika gerapporteer
word.
Om die rol wat die basidiomycete in die siekte-kompleks speel beter te verstaan is
toksien en ensiem analises uitgevoer. Geselekteerde basidiomycete isolate is gekweek in
vloeibare groei medium en ekstraksies uitgevoer om te toets vir die teenwoordigheid van 4-
hydroxy-benzaldehyde. Al die basidiomycete isolate kon 4-hydroxy-benzaldehyde, wat
bekend is om fitotoksies te wees, produseer. Die basidiomycete isolate was verder getoets vir
die produksie van spesifieke hout afbrekende ensieme. Al die basidiomycete taksons kon
mangaan-peroksidase produseer. Lakkase was geproduseer deur al die taksons, uitsluitend
Takson 8. Lignien-peroksidase was geproduseer deur Taksons 1, 2, 7, Fomitiporia sp. en die
Phellinus sp. Al die basidiomycete isolate kon sellulose produseer, maar geen kon xilanase
produseer. Die ensiem analises het gewys dat die basidiomycete wat moontlik betrokke is by
esca ‘n wye reeks van ensieme kan produseer wat sellulose en lignien kan degradeer.
Sellulose en lignien is beide strukturele komponente van hout.
Weens die wye verspeiding van esca geaffekteerde wingerde in Suid Afrika en die
wye reeks van spesies wat betrokke is by die siekte kompleks moet esca sekerlik gesien word
as een van die beperkende faktore op die produktiewe leeftyd van wingerde en die kwaliteit
van druiwe wat geproduseer word. Sanitasie en snoeiwond beskerming is voorkomende
maatreëls wat ingestel kan word om die effek en verspreiding van esca te beperk maar daar is nog baie vrae wat antwoorde benodig oor die sinergie van die veroorsakende swamme,
epidemiologie en bestuur van esca.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5319 |
| Date | 12 1900 |
| Creators | White, Chana-Lee |
| Contributors | Mostert, L., Halleen, F., University of Stellenbosch. Faculty of Agrisciences. Dept. of Plant Pathology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 148 p. : ill. |
| Rights | University of Stellenbosch |
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