APPLICATION OF VERTICAL-BEAM IN-AIR PIXE TO SURFACE ANALYSIS OF PLANT ROOT EXPOSED TO ALUMINUM STRESS

Abstract

Elemental composition of living cells and tissues reflects their physiological function and status. However, it has been difficult to know in-situ elemental distribution by conventional analytical methods. In-air PIXE seems suitable for surface analysis of living cells and tissues because any treatment (e.g. freeze drying, digestion) is not required before and during measurement. We applied Via (vertical-beam in-air) PIXE to surface analysis of plant roots exposed to aluminum ( Al ). Aluminum stress is a major factor that limits elongation of plant roots in acid soils. We previously reported decrease in atomic ratio of potassium to phosphorus (K/P ratio) of dried root-tip of alfalfa (Medicago sativa L.) under Al stress using in-vacuum PIXE. In Via PIXE, 5 to 7-minute irradiation by 3 MeV proton beams of 200 pA was sufficient to obtain X-ray spectra without drying root samples. Decrease in K/P ratio in surface cells of root-tips was observed by short-term (6-8 h) exposure of root to Al . Via PIXE is recognized as a powerful tool for in-situ surface analysis of plant material.