Sugars transporters in fruit: role in carbon partitioning and in sugar signaling

Supervisor: Giannina Vizzotto

The partitioning of sugars in sink organs such as fruits or seeds is governed by several complex physiological processes, including phloem loading in the source leaf, long-distance translocation in the phloem, phloem unloading in sink organs, post-phloem transport and metabolism of imported sugars in sink cells. Elucidation of these pathways is essential, because the unloading path determines the key transport events responsible for assimilate movement from the sieve elements to the recipient sink cells. Several studies pointed out that the strategy adopted in phloem unloading (symplasmic or apoplasmic) depends on species, organ and developmental stage. A symplasmic phloem unloading pathway predominates in most vegetative storage sink and is also efficient in the maternal tissues of developing seeds, which represent a class of terminal reproductive storage sinks. The aim of this work is to characterize the mechanism of phloem unloading in developing peach fruit, particularly in two different tissues (mesocarp and seed) of the reference cultivar Redhaven, adopting different approaches. Firstly, a specific fluorescent marker of phloem transport, the carboxyfluorescein diacetate (CFDA), was utilized to trace fruit vascularization. Furthermore, the availability of the complete sequence of peach genome, allowed the identification of genes encoding proteins involved in sugar transport, and their transcriptional regulation during different stages of seed and fruit growth was analyzed by Real-Time PCR. Finally, in order to gain insight into the tissue- and cell-specific expression of genes of interest the technique of Laser Capture Microdissection (LCM) and in situ hybridization were adopted.

Biography and contacts
Laura Zanon was born in 1985. 2010: Degree cum laude in Plant Biotechnology at the University of Udine. From January 2011 PhD student in Plant Biotechnology at the University of Udine. Topic of PhD course: fruit tree physiology.

laura.zanon@uniud.it
[Phone: 0432-558646]