INDUCTION OF WILTING BY MANNOSE IN SPINACH BEET LEAVES

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Abstract
SUMMARY: Mannose, but not glucose, induces loss of turgor in whole plants, detached leaves and leaf discs of spinach beet. There is no comparable effect in leaves of tobacco and geranium. Supply of mannose to spinach beet discs causes an enhanced conductivity in the bathing medium after 8–10 h and this is associated with increased leakage of potassium ions over controls. After 24–36 h, water‐soaking is evidence of intercellular accumulation of water in the tissue. Previous work has established that mannose sequesters orthophosphate as mannose phosphate in leaves of spinach beet but not in those of tobacco and geranium, and the implied changes in cell membrane permeability are probably due to limited availability of Pi for ATP synthesis and turnover of phospholipid membrane components. The rate of cuticular transpiration may also be increased.