Dynamic 13 C/ 1 H NMR imaging uncovers sugar allocation in the living seed

摘要

Seed growth and accumulation of storage products relies on the delivery of sucrose from the maternal to the filial tissues. The transport route is hidden inside the seed and has never been visualized in vivo . Our approach, based on high?￠????field nuclear magnetic resonance and a custom made 13 C/ 1 H double resonant coil, allows the non?￠????invasive imaging and monitoring of sucrose allocation within the seed. The new technique visualizes the main stream of sucrose and determines its velocity during the grain filling in barley ( Hordeum vulgare L.). Quantifiable dynamic images are provided, which allow observing movement of 13 C?￠????sucrose at a sub?￠????millimetre level of resolution. The analysis of genetically modified barley grains ( Jekyll transgenic lines, seg8 and Ris????13 mutants) demonstrated that sucrose release via the nucellar projection towards the endosperm provides an essential mean for the control of seed growth by maternal organism. The sucrose allocation was further determined by structural and metabolic features of endosperm. Sucrose monitoring was integrated with an in silico flux balance analysis, representing a powerful platform for non?￠????invasive study of seed filling in crops.