Abstract: An indoor hydroponic experiment was carried out cultivating Pogonatherum crinitum under Pb stress for 15 days and then the plants were sampled for analysis of chemical forms and cellular compartmentation of Pb,using the sequential chemical extraction method and electron microscopy.It was found that Pb existed in the roots and shoots mainly in the form of HCl-extractable Pb,which accounted on average for >30% of the total Pb present in the plant,and peaked up to 46.84% and 61.49%,respectively.HAc-and NaCl-extractable Pb were the next most abundant forms of Pb and residual and water extractable Pb the least abundant.The findings suggest that among the chemical forms of Pb in the plant,apart from HCl-extractable Pb,there were mainly phosphate-bonded Pb,protein-bonded Pb or adsorbed Pb,which,being rather weak in mobility and reducing Pb toxication of the plant.Observation by electron microscope found that most of the Pb in roots and leaves of the plant was bound to the cell walls,which is consistent with the findings about Pb chemical forms in Pogonatherum crinitum.However,the plant is still highly capable of transporting Pb from roots to shoots.

Key words: Pb, hyperaccumulator, Pogonatherum crinitum, chemical form, cellular compartmentation