鎘處理大豆 (Glycine max) 幼苗會明顯抑制根的生長，增加過氧化氫含量以及PODs和laccases活性。PODs (pI 8.8, pI 7.7, pI 5.2, pI 4.5, pI 4.4 and pI 3.7) 和laccases (pI 9.2, pI 8.9 and pI 8.3, pI 5.4, pI 4.2 and pI 3.7) 活性的增加伴隨著鎘處理組織內木質素含量的增加。在我們的結果中，推測laccases作用在鎘處理的早期，而當處理時間延長，laccases和PODs則共同作用在木質素的合成上。

The significant root inhibition of growth in Cd-treated soybean (Glycine max) seedling correlated with the increase of H2O2 levels, PODs and laccases activity. The increase of the activities of PODs (pI 8.8, pI 7.7, pI 5.2, pI 4.5, pI 4.4 and pI 3.7) and laccases (pI 9.2, pI 8.9 and pI 8.3, pI 5.4, pI 4.2 and pI 3.7) are accompanied by a rise of lignin contents in Cd-treated tissues. Our results suggested that laccases work during the early stage of Cd treatment. Laccases and peroxidases work cooperatively in lignin synthesis when the time of Cd treatment was prolonged.

TABLE OF CONTENTS

Abstract in Chinese ------------------------------2

Abstract in English ------------------------------ 3

Table of contents ------------------------------ 4

List of tables and figures --------------------- 5

Introduction ------------------------------------- 6

Materials and Methods ------------------------ 11

Results ------------------------------------------- 17

Discussion --------------------------------------- 21

References --------------------------------------- 25

Tables and figures ------------------------------ 29

List of Tables and Figures

Fig. 1. Effect of Cd on the growth of soybean roots ----------------------- 29

Fig. 2. Effect of Cd on the accumulation of H2O2 in soybean root tips -- 30

Fig. 3. Effect of Cd on the lignin content in soybean root tips ------------ 31

Fig. 4. Effect of Cd on the total peroxidase isozymes in soybean root tips ----------------------------------------------------------------------------- 32

Fig. 5. Effect of Cd on the activity of peroxidase isozymes in soybean root tips ------------------------------------------------------------------------ 33

Fig. 6. Quantification of peroxidase activity in soybean root tips of Cd- treated and control tissue ---------------------------------------------- 34

Fig. 7. Effect of Cd on the transcript accumulation of peroxidase isozymes in the soybean root tips------------------------------------------------- 35

Fig. 8. Quantification of peroxidase transcription level in soybean root tips of Cd-treated and control tissue---------------------------------------- 36

Fig. 9. Effect of Cd on the total laccase isozymes in soybean root tip ---- 37

Fig. 10. Effect of Cd on the activities of laccase isozymes in soybean root tips ----------------------------------------------------------------------- 38

Fig. 11. Quantification of laccase activity in soybean root tips of Cd-treated and control tissue ------------------------------------------------------ 39

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