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| Bioaccumulation, Subcellular Distribution and Chemical Forms of Strontium in Brassica juncea L. |
| Received:May 29, 2015 |
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| KeyWord:strontium;bioaccumulation;subcellular distribution;chemical form;Brassica juncea L. |
| Author Name | Affiliation | E-mail | | LAI Jin-long | Life Science College, Sichuan Normal University, Chengdu 610101, China | | | YANG Lei-yan | Life Science College, Sichuan Normal University, Chengdu 610101, China | | | FU Qian | Life Science College, Sichuan Normal University, Chengdu 610101, China | | | HE Jiao | Life Science College, Sichuan Normal University, Chengdu 610101, China | | | TAO Zong-ya | Life Science College, Sichuan Normal University, Chengdu 610101, China | t89807596@163.com | | LUO Xue-gang | Engineering Research Center of Biomass Materials(SWUST), Ministry of Education, Mianyang 621010, China | |
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| Abstract: |
| This study examined the characteristics of uptake, accumulation, subcellular distribution, and chemical forms of Sr2+ in Brassica juncea seedlings at the two-leaf stage exposed to varying doses of Sr2+[ρ(Sr2+)167(CK)~350 mg·L-1] for 7 days. The accumulation of Sr2+ in plant organs displayed the following sequence:leaves > stems > roots. Between 84.93%~90.46% of Sr2+ in the plant was accumulated in the aboveground parts(leaves and stems). Translocation factor(TF) and bioaccumulation factor(BCF) of Sr2+ were 5.63~9.48 and 8.21~12.34, respectively. Subcellular distribution showed that 95.62%~100% of plant Sr2+ was localized in the cell walls and soluble fractions, with 2.92% of Sr2+ accumulated in organelles(including nucleus, chloroplast/proplastid and mitochondrion). Plant Sr2+ existed in different chemical forms. In roots, the greatest amount of Sr2+ was found in 1 mol·L-1 NaCl-extractable fraction, while most of the Sr2+ was extracted by dH2O in leaves and stems. For Sr2+ uptake by Brassica juncea, Sr2+ was first crossed through root plasma membrane mediated by plasma membrane transporters, combined with pectates and proteins in the roots, and then transported in solution to the leaves. In leaves, most of Sr2+ was adsorbed on the cell wall, and Sr2+ in the cytosol was transported into vacuoles for provisional or permanent storage. As a result, Sr2+ content in organelles was effectively reduced, which may greatly alleviate the damage of Sr2+ to organelles. Therefore, Sr2+ location in the cell walls and vacuoles may contribute jointly to the accumulation and tolerance of Sr2+ in Brassica juncea. |
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