Figure 6.

Examples of positron imaging of carbon transportation and allocation dynamics. A) PETIS was used to model phloem transport of [¹¹C]photoassimilates within a broad bean plant.⁷¹ Results indicated phloem transport speeds increased in farther internodes from the dosed leaf and were also greater using enriched CO₂. B) Salinity-induced stress reduced transportation of [¹¹C]CO₂ photoassimilates to the basal stem and roots of a tomato plant, resulting in accumulation in the leaves.⁷⁶ C) A combination of magnetic resonance imaging (MRI) and PET was used to quantify sectorial source-sink photoassimilate partitioning in maize.²² Uptake of [¹¹C]CO₂ by specific leaves was linked with correspondingly specific regions of accumulation in maize roots. D) PET was used in conjunction with amino acid, sugar, and hormone quantification to characterize the effects of rootworm herbivory on maize roots.⁷⁴ Browsed maize plants had increased transport despite reduced allocation of [¹¹C]photoassimilates to damaged roots.