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A Comparative Study of Leaf Ultrastructure and Physiological Changes of Cucumber Seedlings Grown Under Stress of Di-2-ethylhexyl Phthalate(DEHP)
  
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KeyWord:cucumber; DEHP; ultrastructure; chlorophyll; H2O2
Author NameAffiliation
ZHANG Ying College of Resources & Environment, Northeast Agricultural University, Harbin 150030, China 
DUAN Shu-wei College of Resources & Environment, Northeast Agricultural University, Harbin 150030, China 
WANG Lei College of Resources & Environment, Northeast Agricultural University, Harbin 150030, China 
ZHANG Hui College of Resources & Environment, Northeast Agricultural University, Harbin 150030, China 
DU Na College of Resources & Environment, Northeast Agricultural University, Harbin 150030, China 
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Abstract:
      Due to its wide uses, di-2-ethylhexyl phthalate(DEHP) is everywhere in the environment. It has been detected in most agricultural soils in China. It may affect the growth and development of plants. A comparative analysis of the influence of different concentrations of DEHP(0, 6, 10, 20, 40 mg·kg-1) on ultrastructure of cucumber seedling leaves at the early growth stages was performed in a pot experiment. Transmission electron microscope(TEM) was employed to examine the effects of DEHP on the ultrastructure of the leaves. Increasing DEHP concentrations led to expanded vacuoles and collapsed structure of cell membrane. At 10 mg·kg-1 of DEHP, mitochondria became vacuolized, and the number of mitochondrial cristae decreased. Meanwhile, thylakoids of chloroplast swelled gradually, chloroplast envelopes were destroyed, and the quantity and volume of starch grains in the chloroplast increased. At 20 mg·kg-1 DEHP, the nucleolus became integrated, the chromatin of nucleus was agglutinated, and the nuclear membrane was disrupted. Consistent with the ultrastructure results, the contents of chlorophyll a, chlorophyll b and total chlorophyll decreased while the content of hydrogen peroxide(H2O2) increased with increasing concentrations of DEHP, indicating that DEHP stress caused damages to the ultrastructure of cucumber leaves by overproducing reactive oxygen species.