Résumé
Oil palm (Elaeis guineensis) is the number one source of edible vegetable oil worldwide. Due to an annual increase in demand for human consumption and the potential use as a source of biofuel, there is increasing pressure for higher yields. One factor that limits yield is the loss due to non-synchronized fruit ripening and subsequent shedding of the ripest fruit before harvest. Previous studies indicate that the fruit shedding process in oil palm is different at the anatomical level from other species. In most species, there is a synchronized series of cell separations between the fruit and the stalk that leads to fruit shedding. The shedding of the oil palm fruit consists of at least two coordinated cell separation stages, the first within the primary abscission zone (AZ) and the second in adjacent AZs with a delay of 1-2 days between the stages. In this study we examine the primary AZ transcriptome and physiological factors that affect the cell separation processes that lead to fruit shedding in oil palm. Our results indicate that ethylene treatment induces the cell separation in the primary AZ that leads to fruit shedding. 454 based pyrosequencing generated 8.6 Mbps including 1,000 EST contigs and approximately 45,000 singleton sequences from the fruit primary AZ from E. guineensis. This represents the first data set on the AZ transcriptome related to the cell separation processes that lead to fruit abscission. From the analysis of this data, we identified gene candidates encoding cell-wall modifying enzymes and pathogen-related proteins and examined their transcript accumulation patterns in the AZ of E. guineensis. Our results provide a basis for understanding the molecular mechanisms of abscission and fruit shedding, a key agronomic character of oil palm (Texte intégral)