Volatile Growth Inhibitors Produced by Salvia Leucophylla: Effects on Seedling Root Tip Ultrastructure

Volatile monoterpenes emanating from leaves of Salvia leucophylla (Labiatae) are responsible for anatomical and physiological changes occurring in herb seedlings which were exposed to the vapors. Examination of treated root tip cells from Cucumis sativus by electron microscopy revealed widespread systemic disturbances. These included the accumulation of globules which appear to be lipid in nature in the cytoplasm, a drastic reduction in the number of a variety of intact organelles including mitochondria, and a disruption of membranes surrounding nuclei, mitochondria, and dictyosomes. These effects, coupled with the effects of environmental stress, may account for the failure of herb seedlings to survive in the areas adjacent to Salvia thickets.