Abstracto

Subcellular distribution of lead in different rice cultivars and its relation with lead translocation and grain accumulation

Jianguo Liu, Wen Zhang, Jiakuan Xu, Mingxin Wang

To test the hypothesis that lead (Pb) content of rice grain may be related to its transport and subcellular distribution in rice plant, the present study was conducted with six rice cultivars of different types under different soil Pb levels. The results showed that grain Pb concentrations were correlated positively and significantly (P<0.05 or 0.01) with distribution ratios (DR) of Pb from shoots to ears/grains, but insignificantly (P>0.05) with the DR from roots to shoots. The DR from shoots to ears/grains were correlated positively and significantly (P<0.05, or 0.01) with subcellular distribution ratios (SDR) of Pb in soluble fraction of shoots, but negatively and significantly (P<0.05, or 0.01) with the SDR in cell wall fraction of shoots. In conclusion, Pb transportation from shoot to grain was the key factor in determining Pb content of rice grain. The Pb distributed in soluble fraction of shoot tissue was the key source of Pb for transferring into the grain. The Pb precipitated in cell wall fraction was the key sink of Pb in shoot tissue for restricting the transport of Pb from shoot to the grain