Cadmium Accumulation Characteristics in Turnip Landraces from China and Assessment of Their Phytoremediation Potential for Contaminated Soils

Abstract

Heavy metal (HM) pollution is a global environmental problem that threatens ecosystem and human health. Cadmium (Cd) pollution is the most prominent HM pollution type because of its high toxicity, strong migration, and the large polluted area globally. Phytoremediation of contaminated soil is frequently practiced because of its cost-effectiveness and operability and because it has no associated secondary pollution. High-accumulation plants, including those identified as hyperaccumulators, play an important role in phytoremediation. Therefore, screening of plants to identify hyperaccumulators is important for continued phytoremediation. In the present study, we investigated the Cd tolerance and accumulation capabilities of 18 turnip landraces from China under a soil experiment with known Cd level. The results indicated that turnip has a high capacity for Cd accumulation. Furthermore, significant differences in Cd tolerance and accumulation characteristics were found among different landraces when they grew at 50 mg kg-1 (dry weight) Cd concentration. Among the studied landraces, five turnip landraces met the requirements of Cd hyperaccumulators and three landraces were identified as potential candidates. However, the total Cd content accumulated by individual plant of different turnip landraces was dependent on both the Cd accumulation capacity and plant biomass. Compared with some reported Cd hyperaccumulators, turnip not only shows a high Cd-accumulation capacity but also has rapid growth and a wide distribution area. These advantages indicate that turnip may have considerable potential for phytoremediation of Cd-contaminated soil. Furthermore, the study also indicates that it is not advisable to consume turnip cultivated in an environment that exceeds safe Cd levels.

Genome-Wide Identification and Expression Analysis of the Cation Diffusion Facilitator Gene Family in Turnip Under Diverse Metal Ion Stresses

“…As MTP genes have been demonstrated to participate in tolerating and transporting various heavy metals, including plant trace elements and non-essential elements ( Kim et al, 2004 ; Delhaize et al, 2007 ; Xu et al, 2009 ; Lang et al, 2011 ), they might thus play significant roles in plant mineral nutrition maintenance and resistance to stresses caused by metals. Turnip has shown relatively high capacities toward absorbing trace elements and heavy metal Cd ( Li et al, 2016 ; Ma et al, 2016 ). Thus, exploring the functional characteristics of the metal ion transporters in turnip is of great interest.…”

“…Turnips from Xinjiang, China, reportedly contain abundant mineral elements ( Ma et al, 2016 ), indicating its eminent absorption ability for metal ions. Additionally, turnip has been classified as a high-Cd accumulation plant ( Arthur et al, 2000 ; Li et al, 2016 ). We found that turnip landraces from China have strong capacities for Cd accumulation, and several landraces were Cd hyperaccumulators ( Li et al, 2016 , Li X. et al, 2017 ).…”

“…Additionally, turnip has been classified as a high-Cd accumulation plant ( Arthur et al, 2000 ; Li et al, 2016 ). We found that turnip landraces from China have strong capacities for Cd accumulation, and several landraces were Cd hyperaccumulators ( Li et al, 2016 , Li X. et al, 2017 ). To explore the molecular mechanism of metal ion accumulation in turnip, we focused on several important ion transporters based on the sequencing results of turnip ( Cheng et al, 2016 ).…”

Selenium Accumulation Characteristics and Biofortification Potentiality in Turnip (Brassica rapa var. rapa) Supplied with Selenite or Selenate

“…Turnip seeds were collected from Ninglang County of China, from a population constituting a local landrace (NO. KTRG-B54) (Li et al, 2016 ). The seeds were germinated and grown outdoors in mid-April.…”

Effects of Foliar Selenite on the Nutrient Components of Turnip (Brassica rapa var. rapa Linn.)

“…Calcium (Ca), potassium (K), magnesium (Mg), and phosphorus (P) contents were determined in accordance with the method described by Li et al ( 2016 ) by using an inductively-coupled plasma spectrometer (ICP-OES Optima 8000, Perkin Elmer, USA). The contents of Se, copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) were determined in accordance with the method of Li et al ( 2017 ) by using an inductively-coupled plasma mass spectrometer (ICP-MS, Thermo Fisher Scientific, USA).…”