Journal of Plant Pathology (2010), 92 (4, Supplement ... - Sipav.org

Journal of Plant Pathology (2010), 92 (4, Supplement), S4.71-S4.105 S4.103
tique et Ecophysiologie de la Qualite des Agrumes–GEQA, INRA,
Route de l’INRA, San Giuliano-Corse, France. 3 Dipartimento di
Scienze Entomologiche, Fitopatologiche, Microbiologiche, Agrarie e
Zootecniche, Sezione di Patologia Vegetale e Microbiologia Agraria,
Università degli Studi, Viale delle Scienze, 90128 Palermo, Italy. Email:
mtessitori@unict.it
Tristeza disease, caused by Citrus tristeza virus (CTV), is the
one of the most important viral diseases of citrus species. Several
strains of CTV have been studied all over the world. Two isolates
have been previously identified in Corsica, the K strain from
Marumi kumquat, known to determine no symptoms on Mexican
lime, and the Cal-1 from calamondin that induces stem pitting on
the same indicator. Few sequence data of both isolates are published
or available in GenBank. Recently additional CTV strains
were found in Corsica. The isolates LA5 and CO3 were detected
in two different 40-year-old orchards of Clementine on sour orange
that did not show decline or other tristeza symptoms. CTV
was identified in young shoots collected in the field by RT-PCR
using primers specific for the p20 and p23 proteins. The amplicons
obtained were analyzed by SSCP, cloning and sequencing.
Both CTV isolates showed the same SSCP patterns for both proteins
which differed from control patterns (DS1, DS2 and T36).
Sequences analysis diclosed a high similarity between the two isolates
(98%) for both p20 and p23. Multiple alignment analysis of
LA5 and CO3 showed a similarity of 98% with CTV isolates deposited
in GenBank. Moreover, with respect to the already described
groups of CTV isolates, mild, severe and atypical, phylogenetic
analysis revealed a new cluster that includes both LA5
and CO3 isolates
SYNERGISTIC INTERACTION BETWEEN POTATO
SPINDLE TUBER VIROID AND CUCUMBER MOSAIC
VIRUS IN TOMATO. E.M. Torchetti, B. Navarro, F. Cillo, F.
Di Serio. Istituto di Virologia Vegetale del CNR, Via Amendola
165/A, 70126 Bari, Italy. E-mail: em.torchetti@ba.ivv.cnr.it
Potato spindle tuber viroid (PSTVd), a nuclear replicating viroid
included in the EPPO A2 list of quarantine pests, causes severe
diseases to potato and tomato. In the last few years, this viroid
has been detected in several symptomless ornamental solanaceous
species in many European countries, producing a general
alert on the risk of possible PSTVd outbreaks in horticultural
crops. The recent report of symptomatic tomato plants infected
by PSTVd in Italy has increased such concerns. Since tomato is
also a natural host of Cucumber mosaic virus (CMV), its response
to mixed infections by this virus and PSTVd was investigated.
Here, we report the synergistic interaction of contemporary infections
by a mild strain of PSTVd and the Fny strain of CMV in
tomato cvs. Micro-Tom and UC82. Plants infected by both
pathogens showed severe stunting, delay of flowering, and frequent
systemic necrotic lesions that completely impaired plant
growth. These symptoms were never observed in PSTVd and
CMV single-infected plants, which only showed slight stunting
and leaf deformation, respectively. Data about the accumulation
levels of each pathogen in single- and mix-infected hosts will be
discussed in the context of a possible role of RNA silencing in the
synergistic interaction. These findings highlight the need of implementing
control measures to restrain PSTVd spread in Europe.
ALTERNARIA LEAF SPOT ON OKRA IN TANZANIA:
PROSPECTS FOR BIOLOGICAL CONTROL IN SUSTAIN-
ABLE AGRICULTURE. E. Turco 1 , M. Galla 2 , D. Bocciolini 3 , S.
Tofani 3 , A. Ragazzi 2 . 1 Istituto per la Protezione delle Piante del
CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI),
Italy. 2 Dipartimento di Biotecnologie Agrarie, Sezione di Protezione
delle Piante, Università degli Studi, Piazzale delle Cascine
28, 50144 Firenze, Italy. 3 Cooperativa Agricola di Legnaia, Via di
Sollicciano 13a, 50142 Firenze. E-mail: e.turco@ipp.cnr.it
The “Progetto Tanzania” was funded in 2006 by the Cooperativa
Agricola di Legnaia, the oldest and largest agricultural cooperative
in Tuscany. In 2007, the Faculty of Agriculture of the Universisity
of Florence joined the project. Besides the humanitarian
and economical assistance to “Villaggio della Speranza” in
Dodoma and San Gaspare hospital in Itigi, the project is involved
in improving and upgrade livestock and crop plants (mainly vegetables)
of local communities. Okra (Abelmoschus esculentus L.) ,
a traditional food plant in Africa with a high nutritive value, is essential
to the daily diet of local population, consisting almost exclusively
of carbohydrates. Eco-compatible measures to control
and eradicate fungal diseases are therefore required to manage
sustainable agriculture and rural development. Periodical surveys
of the health status of okra plantations in the area of Itigi (Manyoni
discrict, 5°42’S 34°29’E, 1300 m a.s.l.) revealed leaf spots and
blight caused by Alternaria alternata. The biological control of
the disease by the application of Trichoderma viride and Epicoccum
nigrum is the scope of this report. Field experiments were
carried out during the rainy season of 2009. Leaf spots and
blight, before and after treatment with the two fungal antagonists,
were scored and DI (disease score index) using a three class
scale was assessed over 8 weeks. DI above 2 was observed starting
6 weeks after pathogen inoculation. Leaf symptoms caused by
A. alternata were not significantly reduced by the presence of either
T. viride or E. nigrum. The efficacy of fungal antagonists and
validity of the experimental protocol are discussed in relation to
the environmental and climatic conditions.
PRELIMINARY RESULTS ON THE EFFECT OF GOSSY-
POL ON FEW AUSTRALIAN FUSARIUM OXYSPORUM f.
sp. VASINFECTUM ISOLATES. E. Turco 1 , A. Ragazzi 2 , B.
Wang 3 , C.L. Brubaker 4 . 1 Istituto per la Protezione delle Piante del
CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy.
2 Dipartimento di Biotecnologie Agrarie, Sezione di Protezione delle
Piante, Università degli Studi, Piazzale delle Cascine 28, 50144
Firenze, Italy. 3 Centre for Plant Biodiversity Research, CSIRO Plant
Industry, Clunies Ross Street and Barry Drive, GPO Box 1600, Canberra
ACT 2601, Australia. 4 Bayer CropScience, Technologiepark 38,
B-9052, Gent, Belgium. E-mail: e.turco@ipp.cnr.it
The Australian cotton industry is an important component of
the Australian economy. Researchers and farmers are working to
build sustainable production based on new cotton cultivars with
high fibre quality and yield coupled with improved pest and disease
resistance. Fusarium wilt of cotton (caused by Fusarium oxysporum
f.sp. vasinfectum or FOV) appeared unexpectedly in Australia
in 1995 and represents a considerable threat to the sustainability
of cotton production. Therefore, considerable efforts are
directed toward developing and obtaining new cotton varieties
with enhanced levels of FOV tolerance. In some breeding programs
attention as turned to native Australian Gossypium species
with variable concentrations of gossypol, a terpenoid aldehyde
with a suspected potential to improve resistance to Fusarium wilt
in cotton cultivars. Because the Australian FOV isolates are genetically
distinct from FOV isolates found outside Australia and the
probable co-evolution pathogen and wild cotton cultivars, the susceptibility
of FOV conidia to varying levels of gossypol was deter-