LIBRO-CONGRESO-CITRUS

suppression subtractive hybridization (SSH) was applied on two lemon cultivars exhibiting differences in
resistance to Mal Secco and cold, namely ‘Lisbon’ (susceptible to both stresses) and ‘Adamopoulou’ (tolerant
Greek cultivar), which is believed to have derived from ‘Lisbon’. Two subtractions were performed resulting
in two subtractive cDNA libraries: ‘Adamopoulou-Lisbon’ containing sequences expressed preferentially in
‘Adamopoulou” and ‘Lisbon-Adamopoulou’ containing genes expressed in ‘Lisbon’. A total of 587 clones
were sequenced and the obtained sequences were edited resulting in 81 non-redundant ESTs that have been
deposited in GenBank EST database. The analysis of these sequences using BLAST software (NCBI) revealed
homology to previously identified genes involved in defense mechanisms against biotic and abiotic stresses.
ESTs from each subtractive library were selected for further analysis of their expression in both cultivars by
performing semi-quantitative RT-PCR reactions. The results of this experiment will be discussed.
S03P02
Transcriptome profile analysis of Citrus Canker resistance of Chinese citron (Citrus medica) via
massively parallel mRNA sequencing
Li D.Z. 1 , Dai S.M. 2 , Li N. 2 , and Deng Z.N. 2
1 Provincial Key Laboratory of Crop Germplasm Innovation and Utilization (PKLCGIU), Hunan Agricultural University, China; and
2 National Center for Citrus Improvement, (NCCI), Hunan Agricultural University, China. ldazhi@163.com
Citrus Canker (Xanthomonas axonopodis pv. citri) has brought great damage to citrus industry worldwide. To
control the disease, it seems the use of resistant genotypes is the only choice. A total of 14 accessions from
three species were investigated by artificial inoculation on leaves with the pathogen, and it was found that
only Chinese citron (Citrus medica) showed complete and active resistance to canker disease. Comparative
transcript profiling of leaves after inoculating pathogen on resistant Chinese citron by using massively parallel
signature sequencing (MPSS) was performed. Samples from 3 stages (RC1,RC2,RC3) according to the symptom
development were chosen and they were divided into the susceptible stage (SS) and the resistant stage (RS). A total
of 13,396,168,12,747,212 and 13,491,020 high quality clean reads were obtained for the samples, respectively.
Interpretation of the MPSS signatures revealed that the total number of transcribed genes in the SS (18,045) was
larger than that in the RS (17,394). Further comparison of the transcripts revealed that 2554 genes had nearly
twofold expression difference in the RS compared with the SS (1409). Especially, the number of down-regulated
genes in the RS (1984) is much higher than that in the SS (470), suggesting that many genes were restrained in the
RS. In addition, we identified more than 20 genes that were involved in the plant-pathogen interaction pathway.
These genes are highly conserved in citrus and other species, suggesting that the function of the related proteins
in resistance to bacterial disease may be conserved as well. Our results provide a foundation for comparative
gene expression studies about the incursive development of that citron was inoculated by pathogen. Additionally,
a number of candidate genes that were involved in resistance to disease were identified. These results provide
new insight into the molecular processes regulating resistance to Citrus Canker.
S03P03
Characterization of genes associated with two agronomically important traits in citrus: drought
tolerance and fruit color
Costa M.G.C. 1 , Cidade L.C. 1 , de Oliveira T.M. 1 , Martins C.P.S. 1 , Mendes A.F.S. 1 , Pereira S.L.S. 1 , Pedrosa A.M. 1 , Gesteira
A.S. 2 , Girardi E.A. 2 , Coelho-Filho M.A. 2 , Soares Filho W.S. 2 , and Machado M.A. 3
1State University of Santa Cruz (UESC), Center for Biotechnology and Genetics, Brazil; 2Embrapa Cassava & Fruits (EMBRAPA-CNPMF),
Brazil; and 3Instituto Agronômico de Campinas, Centro APTA Citros Sylvio Moreira, Brazil. marciogc.costa@gmail.com
Drought tolerance and fruit color are important traits to citrus producers and consumers. Because citrus
cultivation is mainly located in regions subjected to long periods of water shortage, drought is one of the
main factors affecting citrus productivity worldwide. On the other hand, the color of citrus fruits provided
by carotenoid pigments is one of the most important attributes of fruit quality and consumer acceptance.
Within the scope of the National Science and Technology Institute of Genomics for Citrus Breeding, with
support of Embrapa Cassava & Fruits, our group has focused on functional characterization of genes affecting
drought tolerance and fruit color in citrus. To this end, we are using the tools of genomics, molecular biology,
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