Protein profiles in roots of aluminium sensitive and resistant barley cultivars after aluminium treatment

Alterations of protein composition in Al-sensitive and resistant barley cul tivars were examined in extracellular and intracellular compartments of the roots after Al stress. The greatest changes in protein composition were fo und in cell wall fraction of the roots. Exposure of roots to 100 mu mmol L- 1 Al resulted in a reduction of several proteins in both Al-sensitive and A l-resistant plants. However, at the same time the synthesis of six differen t proteins was stimulated. Two of them with molecular mass of 14 and 16 kDa accumulated only in the resistant cultivar, while the other four proteins which were accumulated in both Al-sensitive and Al-resistant cultivars. Wit hin the peripheral membrane proteins Al-induced reduction of small polypept ides was observed. Content of only two proteins increased in both cultivars following Al exposure, while accumulation of four proteins was specific fo r the Al-sensitive cultivar. In the fraction of integral membrane proteins, Al stress induced accumulation of four proteins, three of which were accum ulated both in sensitive and resistant cultivars. The 40 kDa polypeptide, o bserved after Al treatment in both cultivars, has also been presented in co ntrol plants of resistant cultivar. Analysis of cytoplasmic proteins reveal ed a very intensive Al induced accumulation of 28 kDa polypeptide in roots of both Al-sensitive and Al-resistant barley cultivars. The observed differences in polypeptide pattern between control and Al-trea ted roots indicate the role of proteins in the response of barley plants to aluminium stress.