LIBRO-CONGRESO-CITRUS

S14
along the Ionian coast and the South-Eastern part of Sicily, respectively. For a better understanding of
their genetic features and spread dynamics, representative CTV isolates from each variant were used for
molecular characterization and transmission trials with local aphid biotypes. Sequencing of fragments over
the replication-related 5’UTR, and the p20, p23, p25 and p18 genomic regions have been performed, in order
to assess the genetic divergence between the two isolates and eventual alterations after aphid passage. The
latter represents one of the most significant data in virus–vector interactions. High nucleotide identity was
shown between the Apulian isolate and the Spanish mild T385 strain, and between the Sicilian isolate and
the Spanish T318A strain, respectively. Moreover, only minor variations were observed in the p18 region of
sub-isolates obtained after A. gossypii transmission of the Sicilian isolate. The two divergent CTV populations
investigated in the present work appeared to be efficiently transmitted by A. gossypii (50% of efficiency)
but they were prone to get altered after aphid transmission. These results may give indications on virus
epidemiology in the Italian citrus scenario.
S14P11
Prevalence and Epidemiology of Citrus tristeza virus in Andalucía and Murcia regions
of Spain
Gorris M.T. 1 , Muñoz C. 2 , Cano A. 3 , Hermoso de Mendoza A. 1 , Martínez M.C. 1 , Hermosilla A. 3 , Fuentes F. 3 , Bertolini E. 1 ,
Collado C. 1 , López A. 4 , and Cambra M. 1
1Instituto Valenciano de Investigaciones Agrarias (IVIA), Centro de Protección Vegetal y Biotecnología, Moncada, Valencia, Spain;
2Consejería de Agricultura y Pesca (Junta de Andalucía), Laboratorio de Sanidad Vegetal, Montequinto, Sevilla, Spain; 3Consejeria de
Agricultura y Pesca (Región de Murcia), Laboratorio de Sanidad Vegetal, La Alberca, Murcia, Spain; and 4Universidad de Valencia (UV),
Estadística e Investigación Operativa, Burjassot, Valencia, Spain. ebertoli@ivia.es
The Spanish citrus industry is based on about 310,000 ha cultivation. Andalucía (74,000 ha), mainly growing
sweet oranges, and Murcia (34,000 ha), growing lemons and mandarins, are the main citrus producing areas
after Valencia. The spread of Citrus tristeza virus (CTV) was monitored by Tissue print-ELISA (Plant Print
Diagnostics) since 1982 in Andalucía and since 1996 in Murcia to 2011 in different citrus orchards. Surveys in
different municipalities of Andalucía suggest that the disease spreads slowly (i.e. CTV prevalence increased in
a sweet orange orchard in Lora del Río/Sevilla from 0.25% in 1982 to 2.90% in 2011). In Alhama de Murcia CTV
prevalence increased in a mandarin orchard from 1.00% in 1996 to 70.00% in 2011. The aphid species landing
on the trees were monitored by the sticky shoot method during the same period. Toxoptera aurantii and Aphis
spiraecola (inefficient CTV vector species) are predominant in both regions in contrast with Valencia where A.
gossypii (efficient CTV vector) is the predominant aphid species. The different aphid species predominant in
Andalucía-Murcia and in Valencia, could justify differences in the temporal spread of CTV among these areas:
logistic model in Andalucía-Murcia versus Gompertz model in Valencia. The epidemiological data allowed
specific recommendations to the growers in order to successfully reconvert the citrus industry (already done
in almost 90% in both regions).
S14P12
Epidemiology of Citrus tristeza virus in experimental nursery blocks of citrus rootstock species
in Spain
Gorris M.T. 1 , Rodríguez A. 1 , Martínez C.M. 1 , Bertolini E. 1 , Collado C. 1 , Botella P. 2 , López A. 3 , and Cambra M. 1
1 Instituto Valenciano de Investigaciones Agrarias (IVIA), Centro de Protección Vegetal y Biotecnología, Moncada, Valencia, Spain;
2 Universidad CEU-Cardenal Herrera (CEU), Ciencias Físicas, Matemáticas y Computación, Alfara del Patriarca, Valencia, Spain; and
3 Universidad de Valencia (UV), Estadística e Investigación Operativa, Burjassot, Valencia, Spain. mcambra@ivia.es
The susceptibility to Citrus tristeza virus (CTV) natural infection of the most commonly used citrus rootstocks
in Spain (Carrizo citrange, Cleopatra mandarin, Citrus volkameriana, C. macrophylla, sour orange and
citrumelo), was studied by Tissue print-ELISA (Plant Print Diagnostics) in the Peñíscola area. The most
susceptible rootstock species was C. macrophylla followed by C. volkameriana. Cleopatra mandarin showed
an intermediate susceptibility and Carrizo citrange and sour orange very low susceptibility. Citrumelo resulted
non-susceptible. Three experimental blocks of 10,000 plants each of C. macrophylla, Cleopatra mandarin and
Carrizo citrange were established to elucidate the reasons of different susceptibility to natural CTV-infection.
242 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012