A model for potato storage organ differentiation from the cambial meristem
Plant species forming storage organs like bulbs, tubers, or tuberous roots are cultivated as staple food and feed crops because of their high starch caloric content, and elevated yields per hectare. These organs can differentiate from the petioles, stems or the roots, in a secondary growth program whose control is little understood. Tubers and bulbs serve as propagation organs to the plant and remain dormant in soil during winter, to be reactivated the following spring and generate a new plant that is genetically identical to the mother plant. Plants sense short days and cool nights as an indicator of the approaching winter. In potato, these external cues activate expression of a member of the FLOWERING LOCUS T (FT) gene family acting as a main tuberigen signal, on be transported to the underground stolons. In this proposal I aim at characterizing the genes acting downstream of FT, and to identify the cells that respond to this mobile signal, thereby serving as tuber initials. As storage organs can initiate from different tissues, my working hypothesis is that this secondary growth process relies on the cambium meristem, which is induced to divide and differentiate into storage parenchyma instead of its default pathway to xylem vessels. Outcomes of this work will not only contribute to a better comprehension of cambium function, but unveil key regulators for storage organ identity which will imply a major breakthrough in our understanding on how these highly economical relevant plant organs are differentiated.