Element-Specific Distribution in a Plant

Abstract

For the first stage of the study of the elements, the distribution of the element within the plant tissue was presented employing neutron activation analysis (NAA). Since NAA allows nondestructive analysis of the elements in the sample, this is the only method to measure the absolute amount of elements in the sample.The results showed that the element-specific profile varied throughout the whole plant, and this distribution tendency remained similar throughout development. There were many junctions of element-specific concentrations between the tissues, suggesting barriers to the movement of the elements. Generally, heavy elements tended to accumulate in roots, except for Mn and Cr. Of the elements measured, Ca and Mg showed changes in concentration with the circadian rhythm. Since the amount of the element in a plant reflects the features of the soil where the plant grows, multielement analysis of the plant could specify the site of the agricultural products produced.Before addressing the development of a real-time RI imaging system (RRIS), the production of RIs for essential elements for plant nutrition, 28Mg and 42K, is presented. The reason why concentrating on RIs is because when we examine the history of plant research, physiological research on the elements without available radioisotopes has not been well developed. For example, the boron (B) transporter was recently found and the study of B in plants is far behind compared to the other elements.Therefore, we developed a preparation method for elements whose available RIs were not previously employed in plant research, 28Mg and 42K. They are the radioisotopes we prepared and a root absorption study using 28Mg as a tracer is presented as an example. It was found that the orientation of Mg transfer was different according to the site of the root where Mg was absorbed. The specific role of Mg has not yet been clarified by florescent imaging because the overwhelming amount of Ca makes it difficult to distinguish Mg and Ca.