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| Subcellular distribution and chemical forms of cadmium in cucumber seedlings |
| Received:April 10, 2019 |
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| KeyWord:cadmium (Cd);cucumber seedlings;accumulation;subcellular distribution;chemical form |
| Author Name | Affiliation | E-mail | | YAN Lei | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | ZHU Yuan-chen | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | CHEN Chen | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | ZHANG Si-jia | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | DING Gong-yao | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | LA Yue-peng | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | | | QU Juan-juan | School of Resources and Environment, Northeast Agricultural University, Harbin 150030, China | juanjuanqu@126.com |
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| Abstract: |
| To investigate the characteristics of cadmium uptake and accumulation in cucumber seedlings, cucumber seedlings were cultured in nutrient solution at different cadmium concentrations (0, 10, 50, 100, 200, 300 mol·L-1) for 17 d. The cadmium contents in shoot and root of cucumber seedlings and the subcellular and chemical morphological distribution of cadmium in leaves were determined. The results showed that with the increase of cadmium concentration, the transfer coefficient decreased gradually, and the cadmium transport capacity from root to shoot of cucumber decreased. The cadmium contents of different subcellular components in cucumber leaves increased significantly with time or concentration. The trend of cadmium accumulation was in the order of soluble part > cell wall > organelle, and cadmium contents of soluble fraction (44.88%~84.94%) were much higher than those of organelle (3.10%~17.05%) and cell wall (11.20%~39.66%). When cadmium concentration was increased under the same cultivation time, the proportion of cadmium in cell wall increased first and then decreased, and that of soluble cadmium decreased initially and increased afterwards. With the prolongation of cultivation time, the proportion of Cd in cell wall decreased, while the proportion of Cd in soluble fraction increased. The highest proportion of NaCl-extracted cadmium was found in cucumber leaves (33.69%~54.23%), but with the increase of cadmium concentration, the proportion of ethanol-extracted cadmium and hydrogen peroxide-extracted cadmium increased. When cadmium concentration reached 300 mmol·L-1, the cadmium in cucumber leaves existed mainly in ethanol-extracted, hydrogen peroxide-extracted and NaCl-extracted speciation. At the organ level, cucumber reduces cadmium toxicity to shoots by limiting cadmium transport from root to shoot. At the subcellular level, cell wall binding and vacuolar compartmentalization are very important for the Cd detoxification in cucumber leaves, while the former is dominant. At the chemical morphological distribution, the chemical transformation of cadmium is also an important strategy for cucumber to deal with cadmium stress. |
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