In vivo transport of three radioactive [18F]-fluorinated deoxysucrose analogs by the maize sucrose transporter ZmSUT1

Abstract

Sucrose transporter (SUT) proteins translocate sucrose across cell membranes; however, mechanistic aspects of sucrose binding by SUTs are not well resolved. Specific hydroxyl groups in sucrose participate in hydrogen bonding with SUT proteins. We previously reported that substituting a radioactive fluorine-18 [F] at the C-6' position within the fructosyl moiety of sucrose did not affect sucrose transport by the maize (Zea mays) ZmSUT1 protein. To determine how F substitution of hydroxyl groups at two other positions within sucrose, the C-1' in the fructosyl moiety or the C-6 in the glucosyl moiety, impact sucrose transport, we synthesized 1'-[F]fluoro-1'-deoxysucrose and 6-[F]fluoro-6-deoxysucrose ([F]FDS) analogs. Each [F]FDS derivative was independently introduced into wild-type or sut1 mutant plants, which are defective in sucrose phloem loading. All three (1'-, 6'-, and 6-) [F]FDS derivatives were efficiently and equally translocated, similarly to carbon-14 [C]-labeled sucrose. Hence, individually replacing the hydroxyl groups at these positions within sucrose does not interfere with substrate recognition, binding, or membrane transport processes, and hydroxyl groups at these three positions are not essential for hydrogen bonding between sucrose and ZmSUT1. [F]FDS imaging afforded several advantages compared to [C]-sucrose detection. We calculated that 1'-[F]FDS was transported at approximately a rate of 0.90 ± 0.15 m.h-1 in wild-type leaves, and at 0.68 ± 0.25 m.h-1 in sut1 mutant leaves. Collectively, our data indicated that [F]FDS analogs are valuable tools to probe sucrose-SUT interactions and to monitor sucrose transport in plants.

From the Outside in: An Overview of Positron Imaging of Plant and Soil Processes

“…For example, in a recent study, the disaccharide sucrose was labelled with 18 F in different positions (1 0 and 6 0 substitutions in fructosyl and 6 in glucosyl moieties) by substituting hydroxyl groups and was then applied to wild and mutant maize leaf tips. 87 Radiography showed that the labelled analogues were transported similarly within respective wild and mutant maize plants, suggesting the hydroxyl groups removed from the sucrose did not bind with the ZmSUT1 transporter protein. Differences in transport rate were observed between wild and mutant type maize, with the mutant variety showing a greater transport rate relative to the wild.…”

“…The application of positron imaging to plant studies has increased significantly since the initial water transport analyses by McKay et al 2 While dynamics of water movement with PET in plants has been widely studied, [25][26][27][28][29][30][31][32][33][34][35] other topics related to PET have increasingly been investigated, including uptake and translocation of nutrients, [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]98,99 photoassimilate fixation/allocation, 15,22,23, sugar transport, 21,[82][83][84][85][86][87] and heavy metal contaminant uptake and transport 25,[88][89][90][91][92][93]…”

An Inexpensive, Easy‐to‐Use, and Highly Customizable Growth Chamber Optimized for Growing Large Plants

“…When the growth chamber is inside an air‐conditioned room (e.g., a laboratory or classroom), the temperature of the growth chamber reaches room temperature (21°–22°C) at night time. This is the optimum temperature for growing many warm‐season plant species, such as maize and soybean (Cheesbrough, ; Tran et al., ).…”

Quantitative monitoring of paramagnetic contrast agents and their allocation in plant tissues via DCE-MRI

“…Another powerful tool to assess in vivo assimilate allocation is 11 C- and 14 C-autoradiography and positron emission tomography (PET) [ 14 , 29 ]. Also [18F]- and [19F]-fluorinated compounds (like 2-deoxy-2-fluoro- d -glucose or 6-[F18] fluoro-6-deoxysucrose) are used for real time monitoring of translocation as well as for analyzing solute transport, root uptake, photoassimilate tracing, carbon allocation, and glycoside biosynthesis [ 18 , 56 , 57 ]. However, using ionizing radiation raised numerous concerns and appears challenging in practical use.…”