Research Projects

Plants forming the storage organs like tubers, or tuberous roots, bulbs are cultivated throughout the world as staple food and feed crops for their high starch caloric content, and high yields per hectare. Such organs are differentiated by very little understood pre-planned secondary growth patterns from the petioles, stems or the roots. 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. The advent of winter is sensed by plants by using short-days and cool nights as indicators. In potato, these external cues activate the expression of a member of the FLOWERING LOCUS T (FT) gene family, which acts as a main tuberigen signal upon its transport to the underground stolons. Despite the very high socio-economic importance of potato, the molecular mechanisms underlying its formation in the stolons are not very clear. In potato, the ortholog of FT is a mobile signal called SELF-PRUNNING 6A (SP6A). Under short-day conditions, potato SP6A (StSP6A) is produced in the leaves and transported to the stolons, where it interacts with 14-3-3 and some other transcription factors (TFs) to form a tuber-inducing complex called Tuberigen Activation Complex (TAC). Despite several recent attempts, the identity of the TFs involved in TAC formation is not clear. In this proposal we are going to address this key missing gap by using the preliminary proteomics data available in our laboratory. Through the Immunoprecipitation-Mass Spectrometry (IP-MS) experiment, we have identified several putative TFs, including some zinc finger (ZNF) domain containing INDETERMINATE DOMAIN (IDD) gene family members, as interacting partners of StSP6A, which could be a part of the TAC required for tuber initiation. In this proposal we are going to focus on two such IDD TFs, StIDD7 and StIDD9, selected from our IP-MS data. By using genetic, molecular, and biochemical approaches, we will validate whether they function as components of TAC and further elucidate their role in tuber formation in potato.