Metabolic control and sugar-signalling

Seeds determine the reproductive capacity of plants and are vital to their existence. To ensure seed survival and germination, the embryo enters the maturation phase in late development, which encompasses the accumulation of reserve compounds and the acquisition of desiccation tolerance. Trehalose 6‐phosphate (T6P), which functions as a signal for sugar availability in plants, is believed to regulate storage processes in seeds, since disruption of T6P synthesis in Arabidopsis thaliana causes embryo abortion at the onset of seed filling phase. To investigate the role of T6P during seed development, we modulated the T6P content in pea embryos by ectopic expression of T6P synthase (OtsA) or T6P phosphatase (OtsB) genes from E. coli. We already showed that T6P promotes cotyledon growth and starch accumulation in maturing seeds, and that this requires transcriptional induction of auxin biosynthesis. Our data indicate that T6P integrates auxin signalling with sugar availability to facilitate seed filling (Dissertation T. Meitzel 2018; McAdam et al., New Phytologist 2017). Yet, many aspects of this process are still not understood. To fill these gaps, we plan to characterize the phenotypic and metabolic changes in our transgenic plant models via NMR imaging, metabolite profiling and metabolic flux analysis. Furthermore, special emphasis will be put on the role of T6P during seed germination and lipid reserve accumulation in the oil crop Brassica napus.