Inclusions And Morphological Changes In Two Duckweeds During Dehydration Stress

Based on the dehydration stress of aquatic vascular plants Lemna minor and Spirodela by different concentrations of PEG6000,we studied the change of mortality rate, not damaged rate, and its contents. Then we studied the morphology of the duckweeds during the treatment. The result proved that the two duckweeds had strong ability to resisting dehydration.Through the study,we found:(1) Under the same degree of dehydration treatment, the mortality rate and damaged degree of Spirodela was lower than Lemna minor.(2) Water content of them trended nearly, Lemna minor slightly higher than Spirodela. (3) When stressed by 500g/kg of PEG6000, chlorophyll and lutein of two duckweed, showed no significant change but duckweed had high mortality rates. When stressed by 400g/kg, the chlorophyll content declined significantly, lutein content did not change significantly. (4) When stressed by 500g/kg of PEG6000, two duckweeds soluble protein hydrolyses seriously. When stressed by 400g/kg, the change was not obvious, and Spirodela tolerance was better. Non-soluble protein had similar trends with soluble protein, but slightly better. (5) Under the stress of 400g/kg PEG, the genomic DNA of two duckweeds occurred varying degrees of degradation, the trends of DNA degradation matched the damaged rate. (6) We found that stressing caused fronds cells damaged and death by Evans blue dying, Lemna minor were more vulnerable. (7) The result of SEM observation of the upper and lower epidermis and the cross-section of duckweeds proved:under the same stress conditions, Spirodela shrinking, collapsing was seriously than Lemna minor, both of them had strong ability of against the deformation and extrusion.