Az Eszterházy Károly Tanárképző Főiskola Tudományos Közleményei. 2004. Sectio Biologiae. (Acta Academiae Paedagogicae Agriensis : Nova series ; Tom. 25)
Zsoldos, F., Vashegyi, Á., Pécsváradi, A. and Bóna, L.: Aluminium toxicity in roots: correlation between root elongation and potassium fluxes in aluminium-sensitive and aluminium-tolerant cereal species
164 Zsoldos, F. et al. 140 120 100 GK Betadur 0,1 P 1,0 P • Root Jub. 50 3 0,1 P 1 • Shoot GK Marco -P 0,1 P 1,0 P GK Wibro 0,1 P 1,0 P (mM) Figure 4. Post-effects of Al- and P-treatments on the K^ t 6 Rb) uptake of the roots and translocation toward the shoots of different cereal seedlings. Plants were grown for 4 days in 0.5 mM CaS0 4 solution at pH 6.5. After the 4th day the seedlings were treatedfor 3 days with 0.5 mM CaS0 4 solution in presence and absence of Al and P as indicated on the graph, pH value was 4.1. After the Al- and P-pretreatments the seedlings were testedfor 6h with 1 mMK f 6Rb)Cl + 0.5 mM CaCl 2 , pH value was 6.5. The effects of Al and P (phosphate) pretreatments on the short-term (6h) K( 8 6Rb) uptake (influx) of roots of different cereal seedlings are presented in Figure 4. The data clearly indicate that the P-treatments significantly influence (decrease) the toxic effect of Al on K +( 8 6Rb) transport in seedlings. Discussion Formerly we reported that in short-term (6-24h) experiments the influx of K7( 8 6Rb) in roots of wheat was positively correlated with Al concentration of the outer medium (Zsoldos et al. 2000). The mechanism(s) whereby the Al enhances the influx of K +( 8 6Rb) is not known. In our experiments with different cereal seedlings (Fig. 2) no phosphate was used in the growth solution supplied simultaneously with Al, therefore in low salt condition (0.5 mM CaS0 4) precipitation of P-complexes in culture solution or on the surface of roots can be excluded. Considering the dry weight data and visual observations, Al inhibits root growth in accordance with Al tolerance of cereal species (Fig. 1). Inhibition of root elongation at pH values below 5 is a common feature in many plant species and is caused by various factors such as impairment of FT efflux and related processes (Marschner 1995). In soil-grown plants inhibition of root
