Solute Leakage Resulting from Leaf Desiccation

Abstract

The leakage of solutes from foliar tissue is utilized as a dynamic measure of apparent changes in membrane integrity in response to desiccation. It is found that rehydrating leaf discs of cowpea (Vigna sixensis IL.l Endi.) show increasing leakiness in proportion to the extent of prior desiccation, whereas SelgineUa kpidophyla Spring., a resurrection plant, does not. RESULTS Using the A at 280 nm as a measure of the leakage of solutes from the leaf tissues immersed in water, one can compare the apparent relative leakiness from tissues that have been desiccated to various levels. Such an experiment for leaf discs of cowpea (a plant which is relatively susceptible to desiccation) and for frond pieces ofSelaginella (a plant with notable resistance to desiccation) is shown in Figure 1. When cowpea leaf discs had been dried to various degrees (90, 76, or 52% of original fresh weight), the subsequent leakage characteristics obtained from the discs in water show a period of relatively rapid loss of solutes lasting for about 4 or 5 min, and after that a relatively steady rate of leakage (Fig. IA). Both the slope of that leakage curve and the total amounts of solutes leaked out over a 20-min period indicate that, after greater amounts of desiccation, there is an increased amount of leakage. On the other hand, Selaginella was found to suffer no perceptable increase in leakage even when desiccation had advanced to 40o of initial fresh weight (Fig. IB).The relation of the extent of leakage and the extent of desiccation damage is further illustrated in Figure 2. When the total amount of leakage after 20 min is plotted against the extent of prior desiccation, it is evident that the cowpea leaf discs lose increasing amounts of solutes with greater extents of desiccation, whereas the Selaginella tissue does not.In the course of these experiments, it was found that differences in leakage rates were obtained as leaves of differing ages were used. A comparison of leaf discs desiccated to 55% of fresh weight and undesiccated discs of three different leaf ages are shown in Figure 3. In this case, the leakage is expressed as a percentage of total content of A28o-absorbing materials, since the total A2ws content increases with the age of the leaf. It can be seen that the extent of leakage increases with leaf age, and that the desiccation experience results in substantially greater solute leakage from

Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade

“…S6): When desiccated membranes are rehydrated, they become transiently leaky, making the uptake of large macromolecules possible (29), which has been exploited previously to introduce large nucleic acids and drugs into the cytoplasm of rehydrating anhydrobiotic cells (30)(31)(32). In addition, when tardigrades, rotifers, and other anhydrobionts desiccate, genomic double-stranded breakages and other damage are induced (19,33,34), and there appear to be robust mechanisms for repairing this damage (19,34).…”

Internal CO2 Measured Directly in Leaves

“…However, the stomatal closure at high ABA was similar to that at low 'K, perhaps because leaves develop high ABA concentrations at low 'K (14,23). In addition, however, the low 'I', treatment had a low leaf water content (12), shrunken mesophyll cells ( 12), collapsed intercellular spaces ( 12), and probably some cell lysis (12,16). Concentrations of nonmetabolizable cell constituents would have increased in the viable cells because of the water loss (24).…”

A Zinc Finger Protein Regulates Flowering Time and Abiotic Stress Tolerance in Chrysanthemum by Modulating Gibberellin Biosynthesis

“…Chrysanthemum plants were grown at 23°C under LD and then sprayed three times with 100 mM GA 4+7 , once every 3 d. Plants with/without GA treatment were then transferred to 22°C chamber for 48 h. Leaves were harvested from the middle of the stem, and electrolyte leakage was determined according to the method of Leopold et al (1981).…”