AOBPreview published online on June 8, 2007
Annals of Botany, doi:10.1093/aob/mcm092
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Comparative Analysis of Expressed Genes from Cacao Meristems Infected by Moniliophthora perniciosa
,*
1 DCB/UESC, Laboratório de Genômica e Expressão Gênica, Ilhéus, Bahia, Brasil
2 CIRAD-CP, UMR PIA, Montpellier, France
3 DCB/UESC, LABBI, Ilhéus, Bahia, Brasil
4 CEPLAC/CEPEC, Cocoa Research Center, Itabuna, Bahia, Brasil
5 COODETEC, Cascavel, Paraná, Brasil
6 Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Genética e Evolução-UNICAMP, Campinas, São Paulo, Brasil
* For correspondence. E-mail fabienne.micheli{at}cirad.fr
Received: 24 October 2006 Returned for revision: 31 January 2007 Accepted: 21 March 2007
Background and Aims: Witches' broom disease is caused by the hemibiotrophic basidiomycete Moniliophthora perniciosa, and is one of the most important diseases of cacao in the western hemisphere. Because very little is known about the global process of such disease development, expressed sequence tags (ESTs) were used to identify genes expressed during the Theobroma cacao–Moniliophthora perniciosa interaction.
Methods: Two cDNA libraries corresponding to the resistant (RT) and susceptible (SP) cacao–M. perniciosa interactions were constructed from total RNA, using the DB SMART Creator cDNA library kit (Clontech). Clones were randomly selected, sequenced from the 5' end and analysed using bioinformatics tools including in silico analysis of the differential gene expression.
Key Results: A total of 6884 ESTs were generated from the RT and SP cDNA libraries. These ESTs were composed of 2585 singlets and 341 contigs for a total of 2926 non-redundant sequences. The redundancy of the libraries was low and their specificity high when compared with the few other cacao libraries already published. Sequence analysis allowed the assignment of a putative functional category for 54 % of sequences, whereas approx. 22 % of sequences corresponded to unknown function and approx. 24 % of sequences did not show any significant similarity with other proteins present in the database. Despite the similar overall distribution of the sequences in functional categories between the two libraries, qualitative differences were observed. Genes involved during the defence response to pathogen infection or in programmed cell death were identified, such as pathogenesis related-proteins, trypsin inhibitor or oxalate oxidase, and some of them showed an in silico differential expression between the resistant and the susceptible interactions.
Conclusions: As far as is known this is the first EST resource from the cacao–M. perniciosa interaction and it is believed that it will provide a significant contribution to the understanding of the molecular mechanisms of the resistance and susceptibility of cacao to M. perniciosa, to develop strategies to control witches broom, and as a source of polymorphism for molecular marker development and marker-assisted selection.
Key words: Theobroma cacao, Moniliophthora perniciosa, ESTs, resistance, programmed cell death, witches' broom disease
These authors contributed equally to this work.
Present address: Centro de Pesquisas Gonçalo Moniz, Salvador, Bahia, Brasil.
Present address: Centro de Biotecnologia Molecular Estrutural (CBME), Instituto de Fisica de Sao Carlos, São Carlos, São Paulo, Brasil.