Résumé
Biotic plant problems are caused by living organisms, such as fungi, bacteria, viruses, nematodes, insects, mites, and animals. Plant responses to different stresses are highly complex and involve changes at the transcriptome, cellular, and physiological levels. In Theobroma cacao the main biotic stresses are cause by fungi, causing the witches' broom (Moniliophthora perniciosa) disease of cacao, Black pod (Phytophthora spp.), frost pod (Moniliophthora roreri and, recently, Ceratocysts wilt (Ceratocystis cacaofunesta). Durable resistance is the key to hamper the advance of these diseases. The OMICS with the classical phytopatological and breeding approaches have allowed: to identify putative resistance genes; to deciphering the genomics of Thebroma cacao, to discover new microsatellite and SNP markers, and to find new QTLs linked to disease resistance. These informations are being integrating in the CEPLAC' breeding program to accelerate the search for new resistance material that carries different resistant genes. In parallel, we study these diseases at the histopatological level trying to characterizing the mechanisms of resistance underneath the hosts as well gene expression in situ. The adaptability of these plant pathogens has also been considered. Advances in the understanding of the breakdown of witches´ broom resistance have been achieved. It was shown that the fungus has a high ability to evolve towards some genotypes. Partial results of these projects and the overall strategy will be presented. Work supported by CNPq, FINEP, FAPESB,RENORBIO (Texte intégral)