LIBRO-CONGRESO-CITRUS

the nurseries, which started selling plants from this origin to growers in 1982. Since then, 103 varieties have
been propagated with a total of 150 million certified plants, with sweet oranges representing 51% of the
certified plants, clementines 27%, other mandarins 13%, lemons 6% and grapefruits 1%. Presently Carrizo
citrange is used as rootstock for 59% of the nursery plants and Citrus macrophylla for 19%. A total of 40
nurseries are presently operating and they are grouped in 7 foundation blocks. Under this program practically
all the Spanish citrus industry has been renewed with healthy plants. Today, traditional graft transmissible
pathogens do not pose any problem for our citrus industry.
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COST FA0806: Plant virus control employing RNA-based vaccines: A novel non-transgenic strategy
Voloudakis A.E.
Agricultural University of Athens (AUA), Dept. of Crop Science, Laboratory of Plant Breeding & Biometry, Greece. avoloud@aua.gr
The current virus control methods are limited in number, efficacy and environmental suitability and current EU
decisions restrict crop improvement strategies employing transgenic plants. To protect plants against existing
and emerging virus diseases new methods are urgently needed. A very promising approach is the exploitation
of RNA silencing, a natural, endogenous mechanism in plants that is a sequence-specific process leading to
viral mRNA degradation. COST Action FA0806* (http://www.aua.gr/COSTFA0806) brings together several EU
labs in order to develop suitable, efficient and cost-effective methods to induce anti-viral silencing in crops
by the transient application of dsRNA, siRNAs and/or artificial small RNAs (collectively designated as “RNAbased
vaccines”). These vaccines are produced either in vitro or in vivo in large quantities and are applied at
laboratory or large scale employing specific delivery machinery. FA0806 is structured in three Working Groups
(WGs), WG1: Development of novel non-transgenic strategies for plant virus control, WG2: Application of
novel non-transgenic strategies for plant virus control, and WG3: Socio-economic evaluation of the impact of
the novel application methods. In the frame of FA0806, Training Schools and Short Term Scientific Missions
provide instruments for scientific exchange and training for early-stage and senior researchers alike. Currently,
61 members from 28 COST countries and eight non-COST members, from Argentina, Australia, China, Mexico,
New Zealand, Peru and South Africa participate in the Action.
Contact information: Andreas Voloudakis (Action Chair): avoloud@aua.gr, Thomas Hohn (Action Vice Chair):
thomas.hohn@fmi.ch, Maria Holeva (Action Secretary): m.holeva@bpi.gr.
* COST 257/08 Memorandum of Understanding (2008). COST Action FA0806: Plant virus control employing
RNA-based vaccines: a novel non-transgenic strategy.
S14P34
Performance of Maltaise demi-sanguine sweet orange on eight rootstocks inoculated with Citrus
exocortis viroid (CEVd) and Cachexia viroid (CVIIb)
Najar A. 1 , Homri N. 2 , Bouhlel R. 3 , Ben Mimoun M. 2 , and Duran-Vila N. 4
1 Institut National de la Recherche Agronomique de Tunisie (INRAT), Plant protection, Tunisia; 2 Institut National Agronomique de Tunisie
(INAT), Agronomie et Biotechnologie végétales, Tunisia; 3 INRAT, Horticulture, Tunisia; and 4 Instituto Valenciano de Investigaciones
Agrarias (IVIA), Centro de Protección Vegetal and Biotecnología, Moncada, Valencia, Spain. asmanajara@yahoo.fr
The performance of sweet orange “Maltaise demi-sanguine” infected with two isolates of Citrus exocortis
viroid and with a cachexia inducing variant of Hop stunt viroid (citrus variant CVd-IIb) was evaluated on
eight different rootstocks (sour orange, Carrizo citrange, Citrus volkameriana, Cleopatra mandarin, Swingle
citrumelo 4447, Rangpur lime, C. macrophylla and Poncirus trifoliata) growing in an experimental field at
INRAT station in El Gobba, Cap Bon region. The trees were planted in 2005 and yield and fruit quality and size
were evaluated every year since 2007. The results obtained showed that HSVd (CVIIb) caused a significant
reduction of canopy volume and fruit yield by 20 and 30 %, respectively, of trees grafted on C. macrophylla
in comparison to non-inoculated trees. In addition, fruit quality was deteriorated. With citrumelo and C.
volkameriana, canopy volume was decreased, while with sour orange and Cleopatra mandarin, tree volume
was similar to non–inoculated trees. Similar yields were recorded for Maltaise demi-sanguine orange trees
XII INTERNATIONAL CITRUS CONGRESS 2012 - 251
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