Plant Diversity ›› 2018, Vol. 40 ›› Issue (01): 19-27.DOI: 10.1016/j.pld.2017.12.005

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Physiological and biochemical analysis of mechanisms underlying cadmium tolerance and accumulation in turnip

Xiong Lia,b, Xiaoming Zhanga,b,c, Yuansheng Wud, Boqun Lia,b, Yongping Yanga,b   

  1. a Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China;
    b China Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China;
    c University of Chinese Academy of Sciences, Beijing, China;
    d College of Plant Protection, Yunnan Agricultural University, Kunming, China
  • Received:2017-06-04 Revised:2017-12-27 Online:2018-02-25 Published:2021-11-05
  • Contact: Yongping Yang
  • Supported by:
    This work was financially supported by the Western Youth Project B of the "Light of West China" Program of Chinese Academy of Sciences (Y7260411W1) and the National Natural Science Foundation of China (31590823).

Abstract: The capacity of plants to accumulate cadmium (Cd) is significant for phytoremediation of Cd-polluted soils. Turnips cultivated in China include species featuring high Cd accumulation and some of these plants act as Cd hyperaccumulator landraces. These plants can accumulate over 100 mg Cd kg-1 dry weight in leaves without injury. Hence, studies that explore mechanisms underlying Cd detoxification and transport in turnip plants are essential. In the present study, we compared physiological and biochemical changes in turnip leaves treated with two Cd concentrations to controls. We discovered that Cd stress significantly increased the enzymatic activities or compound contents in the antioxidant system, including members of the glutathione-ascorbic acid cycle, whereas oxidation of reactive oxygen species (ROS) remained stable. Cd treatments also increased the contents of phytochelatins as well as a number of amino acids. Based on these results, we conclude that turnips initiate a series of response processes to manage Cd treatment. First, the antioxidant system maintaining ROS homeostasis and osmotic adjustment is excited to maintain stability of cell osmotic potential. Cd is chelated into its stable form to reduce its toxicity. Cd is possibly transported to vacuoles or non-protoplasts for isolation. Amino acid synthesis may directly and indirectly play an important role in these processes. This study partly revealed physiological and biochemical mechanisms underlying turnip response to Cd stress and provides information on artificially increasing or decreasing Cd accumulation in turnips and other plants.

Key words: Turnip, Cadmium, Detoxification, Antioxidant system, Phytochelatin