Impact of aluminium, NaCl and growth retardant tetcyclacis on growth and protein composition of maize roots

Alterations of protein composition were examined in cell wall, microsomal and cytoplasmic fractions of maize roots exposed to stress conditions induced by Al (metal and acidity stress), NaCl (salinity stress) or by growth retardant tetcyclacis (TET). Impact of each of the stress factors was demonstrated by some specific and some common characteristics at the level of growth and protein composition of maize roots. Aluminium and NaCl-induced stress seriously inhibited root growth in contrast to TET which in opposite, significantly stimulated root growth. Analysis of cytoplasmic proteins revealed that Al and NaCl treatment induced accumulation of one polypeptide with molecular mass of 28 kDa while TET did not. The most pronounced changes were found in protein composition isolated from the cell wall compartment. In the cell wall fraction Al induced accumulation of four polypeptides (45.5, 35, 22.5, and 18 kDa) similarly as TET (63, 52, 45.5, and 35 kDa) while NaCl induced only two polypeptides (22.5 and 18 kDa). Qualitative differences were also found in the fraction of peripheral membrane proteins where Al induced accumulation of three polypeptides (61, 51, and 39 kDa) similarly as TET (58, 51, and 39 kDa). NaCl induced accumulation of four polypeptides with molecular mass of 61, 51, 39 and 29 kDa. Analysis of polypeptide profile of integral membrane proteins revealed that composition of this fraction of membrane proteins was resistant to Al, TET or NaCl, and remains unaffected even during five day lasting exposure of roots to these stress factors.