Genome-Wide Identification of the Gene Family Involved in Fruitlet Abscission in L

Fruitlet abscission frequently occurs in L. and causes considerable production loss. However, the inducement mechanism of fruitlet abscission remains mysterious. In this study, we observed that the cell architecture in the abscission zone (AZ) was distinct with surrounding tissues, and varied obviously before and after abscission. Transcriptome analysis of the "about-to-abscise" and "non-abscised" AZs were performed in , and the genes encoding the plant-specific DOF (DNA-binding with one finger) transcription factors showed a uniform up-regulation in AZ, suggesting a role of the DOF transcription in fruitlet abscission. In total, 36 members of the gene family distributed in 13 chromosomes were identified from the genome. The 36 genes were classified into nine subgroups based on phylogenic analysis. Six of them showed an AZ-specific expression pattern, and their expression levels varied according to the abscission process. In total, nine types of phytohormone response -elements and five types of abiotic stress related -elements were identified in the promoter regions of the genes. In addition, histochemical staining showed that lignin accumulation of vascular bundles in AZ was significantly lower than that in pedicel and mesocarp, indicating the specific characteristics of the cell architecture in AZ. Our data suggests that the DOF transcription factors might play a role in fruitlet abscission regulation in .