alistair mctaggart ([email protected])...mctaggart et al. 2015. australasian plant...
TRANSCRIPT
The global movement of forestry pests and disease
Introduction of a coevolved pathogen, ora host jump of a native pathogen
Wingfield et al. (2015) Science
Acacia mearnsii in South Africa• Planted on 100,000
hectares in South Africa• Pulp and tannins
• Very few diseases• Most recent new disease
report Ceratocystis albifundus(1993)
• Outbreak of new symptomsin 2013• Slime and exudate• Stunting• Caused by rust
Slime symptoms on Acacia mearnsii
Uredinia Spermogonia
Uromycladium in South Africa• Two species of
Uromycladium are reportedfrom South Africa
• U. tepperianum• Biological control agent
introduced against A. saligna
• U. alpinum• Reported from minor
symptoms on A. mearnsii in1988
• Identification based onurediniospores
Galls and teliospores of U. tepperianum
Urediniospores on Acacia mearnsii• Urediniospores of collections in KwaZulu Natal were
morphologically similar to the first description of U. alpinum inSouth Africa (Morris et al. 1988)
Original collection of U. alpinumfrom Western Cape (PREM 48897)24–40 × 14–20 µm
Rust from KwaZulu Natal andWestern Cape(27–)32–48 × 16–26 µm
Teliospores• Species of Uromycladium are
differentiated by theirteliospores• Number of fertile cells• Presence/absence of vesicle
• The telia of rust on A.mearnsii in KZN appear aspowdery patches on stems,petioles, leaves and fruits
• The teliospores have twofertile cells and the vesicle iseither collapsed or absent
• Molecular data indicated theteliospores from KZN wereconspecific withurediniospores from the Cape
Teliospores of Uromycladium on A. mearnsii
SAR003 U. acaciae on A. mearnsiiSAR008 U. acaciae on A. mearnsii
SAR009 U. acaciae on A. mearnsiiSAR001 U. acaciae on A. mearnsii
SAR002 U. acaciae on A. decurrens
SAR017 U. acaciae on A. mearnsii
SAR015 U. acaciae on A. mearnsiiSAR016 U. acaciae on A. mearnsii
SAR019 U. acaciae on A. mearnsiiBRIP59239 U. acaciae on A. mearnsiiBRIP60092 U. acaciae on A. mearnsii
BRIP56551 U. maritimum on A. thomsoniiBRIP56556 U. maritimum on A. longifolia
DQ323921 U. fusisporumKJ632991 U. fusisporum on A. salicina
MEL235762 U. naracoortensis on A. iteaphyllaBRIP61598 U. naracoortensis on A. dealbata
KJ632990 U. simplex on A. pycnanthaKJ632977 U. tepperianum on A. acuminataKJ632978 U. tepperianum on A. acuminataKJ632985 U. tepperianum on A. salignaKJ632988 U. tepperianum on A. salignaKJ632981 U. tepperianum on A. leiocalyxKJ632982 U. tepperianum on A. leiocalyx
KJ632973 U. falcatarium on Paraserianthes falcatariaKJ632974 U. falcatarium on P. falcataria
KJ632992 U. notabile on A. dealbataKJ632989 U. robinsonii on Acacia melanoxylon
KJ862348 Ravenelia neocaledoniensis on Valchellia farnesiana
KZN
Cape
Australia
8891
100
100
74
100
100
85
Phylogram obtained from ML searchof ITS and LSU regions of rDNA
Uromycladium acaciae has been presentin South Africa for over 20 years• The original collection of Uromycladium alpinum and the
recent outbreaks of U. acaciae are conspecific• This pathogen has been in South Africa since 1988• Uredinial stage caused minor leaf symptoms
• This taxon is best named U. acaciae based onmorphology
• The telial stage causes severe symptoms• It is unknown why this stage was produced• Future studies will investigate the conditions that produced this
stage
McTaggart et al. 2015. Australasian Plant Pathology (in Press).
Observed life cycle of U. acaciae
Uredinia
Telia
Spermogonia, on uppersurface of leaflet
Basidium, germinatesfrom teliospore withone basidiospore
Future research• Why was there a change in
lifecycle of U. acaciae?• Can the lifecycle be
targeted to control thisrust?
• What is the populationdiversity of U. acaciae inSouth Africa?
• Are lifecycles plastic inother rust fungi?
Telia of U. acaciae associated withspermogonia
Calibrated to Acacia
Calibrated to Acacia
Calibrated to Angiospermsor Gymnosperms
Host jumps shaped the diversity ofextant rust fungi
• Rust fungi evolved more recently than previously thought• Previous estimates were based on coevolution of rust fungi with
their hosts
• The most recent common ancestor of rusts had a meanage 113–115 million years ago
• The familial position of Puccinia psidii (rust of Myrtaceae)was resolved in the Sphaerophragmiaceae
McTaggart et al. (2015) New Phytologist
Keeping trees healthy Keeping trees healthy Keeping trees healthy