title: Xylem transport and gene expression play decisive roles in cadmium accumulation in shoots of two oilseed rape cultivars (Brassica napus).
abstract: Cadmium (Cd) is a toxic metal which harms human health through food chains. The mechanisms underlying Cd accumulation in oilseed rape are still poorly understood. Here, we investigated the physiological and genetic processes involved in Cd uptake and transport of two oilseed rape cultivars (Brassica napus). L351 accumulates more Cd in shoots but less in roots than L338. A scanning ion-selective electrode technique (SIET) and uptake kinetics of Cd showed that roots were not responsible for the different Cd accumulation in shoots since L351 showed a lower Cd uptake ability. However, concentration-dependent and time-dependent dynamics of Cd transport by xylem showed L351 exhibited a superordinate capacity of Cd translocation to shoots. Additionally, the Cd concentrations of shoots and xylem sap showed a great correlation in both cultivars. Furthermore, gene expression levels related to Cd uptake by roots (IRT1) and Cd transport by xylem (HMA2 and HMA4) were consistent with the tendencies of Cd absorption and transport at the physiological level respectively. In other words, L351 had stronger gene expression for Cd transport but lower for Cd uptake. Overall, results revealed that the process of Cd translocation to shoots is a determinative factor for Cd accumulation in shoots, both at physiological and genetic levels.
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Sun
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Qiling
authors.initials: Q
authors.lastname: Tan
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Yafang
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Nie
authors.affiliation: Research Center of Trace Elements, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: hucx@mail.hzau.edu.cn.
authors.forename: Chengxiao
authors.initials: C
authors.lastname: Hu
mesh_terms: D001692:Biological Transport / Q000235:genetics; D018533:Biomass; D029688:Brassica napus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D015870:Gene Expression; D006801:Humans; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity; D013045:Species Specificity; D052584:Xylem / Q000235:genetics / Q000378:metabolism
chemical_list: D012989:Soil Pollutants; D002104:Cadmium
keywords: Cadmium; Oilseed rape cultivar; Transport; Uptake