Recent Advances in Radioisotope Imaging Technology for Plant Science Research in Japan

Abstract

Soil provides most of the essential elements required for the growth of plants. These elements are absorbed by the roots and then transported to the leaves via the xylem. Photoassimilates and other nutrients are translocated from the leaves to the maturing organs via the phloem. Non-essential elements are also transported via the same route. Therefore, an accurate understanding of the movement of these elements across the plant body is of paramount importance in plant science research. Radioisotope imaging is often utilized to understand element kinetics in the plant body. Live plant imaging is one of the recent advancements in this field. In this article, we recapitulate the developments in radioisotope imaging technology for plant science research in Japanese research groups. This collation provides useful insights into the application of radioisotope imaging technology in wide domains including plant science.

Simulation evaluation on a compact monitor for gamma-emitting tracers in plant stems

“…Recently, imaging systems for positron annihilation gamma rays, such as positron emission tomography and planar positron imaging systems (PPIS), have been vigorously applied to plant research. [1][2][3] Although positron imaging experiments have the advantage of visualizing the dynamics of nutrient and toxic elements by using positron-emitting radioisotopes such as 11 C (T 1/2 : 20.36 min), 4-7) 1 3 N (9.97 min), [8][9][10] 64 Cu (12.70 h), 11) 74 As (17.77 d) 12) and 107 Cd (6.50 h) [13][14][15][16][17][18][19][20][21] produced by using cyclotrons, they have the disadvantage of not being able to visualize commercially or non-commercially available radioisotopes emitting single gamma rays such as 42 K (T 1/2 : 12,36 d, main gamma-ray energy: 1525 keV, main gamma-ray intensity: 18.1%) 43 K (22.30 d, 373 keV, 86.8%), 54 Mn (312.05 d, 835 keV, 100%), 59 Fe (44.50 d, 1099 keV, 56.5%), and 137 Cs (30.08 y, 662 keV, 85.1%). This disadvantage causes a limitation in facilitating the research on elemental dynamics in plants.…”

Autoradiography system with phosphor powder (ZnS:Ag) for imaging radioisotope dynamics in a living plant

“…Imaging techniques using radioisotopes (RIs) as tracers are effective for this purpose. 1) Autoradiography, an RI imaging technique, has been widely used in the field of plant science. [2][3][4] Although this technique can yield high-resolution RI distribution images, it is invasive and cannot enable observation of the dynamics of elements.…”

Visualization and quantification of 2-deoxy-2-fluoro[18F]-D-glucose in plant tissues by a commercial PET system

“…If we aspire to explain plant growth or to increase the productivity of agriculture or forestry, it is crucial to understand the dynamics and the controls of water and sugar flow, as well as their interactions. Therefore, an accurate understanding of the movement of metabolites and elements across the plant body is of paramount importance in plant science research (Suzui et al 2019). It is also essential to unravel how transport in plants affects their functioning and their ability to withstand stress, and also which conditions determine whether a plant thrives or dies (Hubeau and Steppe 2015).…”

“…Research focused on the distribution and dynamics of photoassimilates in plants is important for increasing food production. Imaging methods based on radioisotopes application represent unique technics to understand the kinetics of elements and bioorganic compounds in the plant body (Suzui et al 2019). Furthermore, non-invasive radioisotopes imaging techniques, which can image the temporal changes in radioisotopes distributions, are effective for investigating the dynamics and distributions of elements and molecules under in vivo conditions.…”