Lipid transfer proteins in coffee: isolation of a Coffea orthologs, Coffea arabica homeologs, expression during coffee fruit development and promoter analysis in transgenic tobacco plants

Our study aims (i) to identify different coffee nsLTPs gene homeologs corresponding to the Coffea arabica (Ca) ancestor sub-genomes: C. canephora (Cc) and C. eugenioides (Ce); (ii) to evaluate the expression of these genes during the bean development and (iii) to characterize a grain-specific nsLTP promoter. We cloned three nsLTP-encoding cDNA highly expressed in coffee fruits. By RT-qPCR assays, the expression of each nsLTP genes carried by the Cc and Ce sub-genomes of Ca was also analyzed. The results highlighted the preferential expression of these genes in endosperm at 120 and 180 days after flowering (DAF). A nsLTP promoter region (1.2 kb) was also isolated and analyzed by 5' deletions for the ability to control the expression of the uidA reporter gene in transgenic Nicotiana tabacum plants. The GUS histochemical assays showed that 1.2 kb, 1.0 kb and 0.8 kb fragments of the nsLTP promoter directed the uidA expression to all tested plant organs with different activity levels while low or null expression was detected in roots. However, the 0.4kb fragment led to the expression of the uidA gene only in seeds, fruit and floral buds. (Resume d'auteur)