Chenopodium murale L. hairy root exudates induce ultrastructural changes in wheat (Triticum aestivum L) seedlings

Abstract

Hairy root exudates of allelopathic weed Chenopodium murale L. have been previously shown to exert allelopathic activity against test plant species lettuce, wheat and Arabidopsis, inhibiting germination and seedling development of these plants. In the present study we used transmission electron microscopy (TEM) to investigate the effect of different concentrations of Chenopodium murale hairy root exudates, applied as phytotoxic media (PM), on ultrastructural changes of meristematic cells in Triticum aestivum L. roots and leaves. TEM studies of root cells treated with lower concetration of PM, showed irregular shaped cell walls, numerous distributed organelles in cytoplasm, prominent nucleus and distinct nucleolus. Exposure to higer concentration of PM showed that the mitochondria and chloroplasts were removed with the plasmalemma into the cell interior. TEM observation of treated leaves cells showed undulating cell walls, dense cytoplasm with numerous organelles and large nucleus with three nucleolus. In some cells the chloroplasts were removed and grouped near the cell wall, while in some other cells the increased number of mitochondria were presented. In conclusion, ultrastructural analysis of treated seedlings showed significant ultrastructural changes. Removing of organelles with the plasmalemma into the cell interior and reorganization of the vacuolar compartment was probably occurred in order to protect the cell if the tonoplast was damaged by toxicity of C. murale root exudate. The increased number of mitochondria could be connected with increased ATP generation as an adaptation process against C. murale allelochemicals.