Determinating zinc accumulation, sub-cellular distribution and chemical forms of Thalia dealbata Fraser

In this study, 6 zinc concentrations were used in Thalia dealbata Fraser aquaculture to determine the enrichment, and root sub-cellular fraction distribution and chemical forms of zinc of T. dealbata. The zinc concentrations were 0 (CK), 0.075 mmol·L^-1, 0.250 mmol·L^-1, 0.500 mmol·L^-1, 1.000 mmol·L^-1 and 2.000 mmol·L^-1. The results showed the zinc was not effectively transportable to the above-ground part of T. dealbata and was mainly accumulated in roots.T. dealbata was not a hyper-accumulator as all the transfer coefficients were less than 1 under different zinc concentrations. On that basis, differential centrifugation technique and sequential chemical extraction method were used to study sub-cellular distribution and chemical forms of zinc in roots of T. dealbata. The results showed that under low znic concentrations (CK, 0.075 mmol·L^-1 and 0.250 mmol·L^-1), zinc was mainly bounded to cell walls, cell nucli and chloroplasts. Ethanol extractable zinc was in a dominant extractable state and accounted for over 50%, followed by NaCl extractable zinc in T. dealbata roots. With increasing zinc concentrations (0.500 mmol·L^-1, 1.000 mmol·L^-1 and 2.000 mmol·L^-1), cytosol became the main zinc distribution site in T. dealbata roots, followed by cell walls. Zinc in cytosol respectively accounted for 31.15%, 45.12% and 56.44%. The proportion of ethanol extractable zinc dropped while NaCl and water extractable zinc increased with increasing zinc concentration, accounting for over 30% of extracted zinc. Ethanol, NaCl and water extractable zinc were the three main zinc chemical forms.