Identification of Agrostis tenuis leaf proteins in response to As(V) and As(III) induced stress using a proteomics approach

Agrostis tenuis is known to be able to metabolise arsenate (As(V)) and arsenite (As(III)) which are toxic salts for most plants. A proteomic approach was developed to identify proteins expressed in response to treatments with these salts. A. tenuis plants were grown hydroponically in the presence of 134 and 668 μM As(V) or As(III) for 8 days at pH 7. During arsenic treatments, leaves showed chlorotic symptoms but fresh and dry leaf weights were not reduced, except in the presence of 668 μM As(III). On the contrary, a slight increase in biomass was observed with high As(V) concentrations. Thus, A. tenuis was more sensitive to As(III) than to As(V) and biomass was affected. Proteomic analysis enabled identification of a set of A. tenuis leaf proteins differentially expressed in response to arsenic exposure including a major functionally homogeneous group of enzymes such as oxygen-evolving enhancer protein, RuBisCO small and large subunits, RuBisCO activase and ATP synthase involved in the Calvin or Krebs cycle. The adaptative response to treatments resulted in partial disruption of the photosynthetic processes with prominent fragmentation of the RubisCO. Other proteins expressed differently from controls were identified and are possibly involved in the tolerance mechanisms of A. tenuis to arsenic treatments.