Abstracts:Phytoremediation of lead (Pb) polluted soil by Brassica napushas been evaluated as a promising strategy considering the higher extraction efficiency and higher economical value. However, it urgently demand to develop hyper-tolerant B. napuscultivars. In this study, the variation of Pb tolerance was investigated among 472 worldwide-collected B.napusaccessions, firstly. Results showed revealed that the B. napusnatural population exhibited a broad variation of Pb tolerance, as the relative radicle length (RRL) were range from 12.17 to 123.65. And then six Pb-tolerant genotypes were selected for potential phytoremediation based on the criterion of RRL >85% in the population.

In order to identify genetic factors of Pb tolerance in B. napuswhich could be efficiently used in molecular breeding, the genome wide association study (GWAS) were employed in present study. In these way, nine candidate genes including GSTUs, BCATs, UBP13, TBRand HIPP01, located in four QTLs were identified to be associated with Pb tolerance. Furthermore, most of these genes were expressed significantly higher in Pb-tolerant genotypes than in Pb-sensitive genotypes and it were mostly induced by Pb stress in Pb-tolerant accessions. Theae nine candidate genes which might contribute to Pb tolerance by regulating glutathione metabolism, amino acid metabolism, ubiquitination, and cell wall development were identified in B. napus.

In conclusion, these findings of Pb-tolerant accessions and candidate genes would provide valuable genetic resources for developing hyper-tolerant B. napuscultivar and accelerate the progress of remediating heavy metal polluted field.

Keywords:lead (Pb) tolerance; phytoremediation; SNP markers; GWAS; rapeseed.