Mechanisms Regulating Adventitious Root Formation in Diospyros virginiana

Diospyros virginiana is a common rootstock in several countries growing commercial plantations of persimmon. This rootstock is exclusively propagated from seeds and therefore is not genetically uniform. As a result, trees grafted on D. virginiana vary in both vegetative and reproductive growth. In order to develop an efficient procedure for propagation of selected clones of D. virginiana rootstocks by cuttings, various factors affecting rooting capacity were studied. The rooting ability varied greatly between various selected clones, ranging from zero to close to 100%. These data suggest that clone genotype has a significant effect on the rooting ability. Cuttings collected at the early stage of the growing season displayed a relatively high rooting rate, which decreased as the growing season progressed. To further explore the mechanisms regulating adventitious root formation in D. virginiana cuttings, we performed anatomical studies, hormone profiling and comparative transcriptome analysis during adventitious root formation of easy and difficult-to-root clones at various collection dates. Our results suggest that auxin is the main hormone involved in adventitious root formation in D. virginiana and that auxin homeostasis plays an important role in the process. Further insights obtained regarding the mechanisms regulating adventitious root formation in D. virginiana will be presented and discussed.