Ion Imbalance in Capsicum annum scarbrous diminutive a Wilty Mutant of pepper: II.RUBIDIUM FLUX

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.     

Ion Imbalance in Capsicum annuum, scabrous diminutive, a Wilty Mutant of Pepper I. SODIUM FLUXES

Leaves of the wilty pepper mutant, scabrous diminutive, accumulatemore Na+ than those of the normal genotype, when both grow inmedium containing N⁺. It seems that the regulation of Na⁺ fluxin the mutant root was modified. Net uptake of Na⁺ was muchhigher and efflux of ²²Na⁺ was lower in the mutant roots thanin the normal ones. Two possible explanations for these differencesbetween mutant and normal plants are discussed, namely (a) achange in membrane permeability and (b) a change in the mechanismof Na⁺ extrusion.     

Short- and Long-term Effects of High Temperatures (47–49°C) on Tobacco Leaves. II. O2 Uptake and Amylolytic Activity

Detached tobacco (Nicotiana rustiest L.) leaves were exposed for 2 min to a temperature range of 24° to 47.5°C. The heat treatment enbanced O₂ uptake by 30 Vs. Likewise, amylolytic activity in chloroplast extracts was intensified; this activity being observed also in situ. The enhancements can be reversed either by short-term cold treatment (7°C for 10 min), or by application of kinetin.     

Preconditioning of Tobacco and Bean Leaves to Heat Shock by High Temperature or NaCl

The present paper examines whether leaves subjected to heat or salt pretreatment are better adapted to heat shock than untreated leaves. Such adaptation could result from either acquired thermo-stability and/or better recovery. The rates of metabolic processes such as ¹⁴CO₂ fixation, ¹⁴C-leucine incorporation into the TCA insoluble fraction, ³²P incorporation into phospholipids and ³⁶Cl efflux were used as indicators of adaptability. It was found that pretreatments (heat or salt) protect leaves only slightly against the short-term effects of a heat treatment, but have a pronounced effect on recovery. Cytokinin level was reduced by heat shock, and as in the case of metabolic response, pretreatment had no effect on this reduction.     

Short- and Long-term Effects of High Temperatures (47–49 °C) on Tobacco Leaves, in. Efflux and 32P Incorporation into Phospholipids

The efflux of ³⁶C and ¹⁴C metabolites from heat-treated tissue was studied. A two-minute heat treatment at 47.5°C increased the leakiness of the membranes. The heat effect may be reversed either by treatment with kinetin or may occur spontaneously with time. The spontaneous reversal is tem—perature dependent and resembles the recovery of CO₂ fixa—tion after heat treatment. The loss of membrane integrity is reflected in the rate of incorporation of ³²P into phospho—lipids.