Abstract: | Root tips of the wilty pepper mutant scarbrous diminutive accumulateless rubidium than those of the normal genotype. This phenomenonwas evident in root tips excised from plants maintained for2 d in CaSO4 solution (low salt plants), especially in the lowerexternal concentration range (0.1 1.0 mM) of RbCl. Theefflux rate of Rb+ from mutant root tips was twice as high asin normal root tips. These results indicate that the ability of the mutant rootsto absorb and accumulate Rb+ and K+ is impaired. This defectcould be a consequence of either an impaired Na+/K+ carriersystem, or increased leakiness of mutant membranes, or both. The fact that the normal roots can accumulate Rb+ much fasterthan mutant roots supports the first alternative, i.e. thatthe high affinity carrier system was impaired in the mutantroots. However, the higher efflux rate of Rb+ from the mutantroots suggests that membrane leakiness was also affected. |