Cloning and functional analysis of NtNramp1 from two Nicotiana varieties with different Cd accumulating pattern

[Objective] The present study was conducted to investigate the molecule mechanism of different cadmium accumulation ability among tobacco varieties.[Method] Based on AtNramp1 sequence of Arabidopsis thaliana, the NtNramp1 gene from Jinying and Komotini Basma, which the two varieties has different cadmium accumulation ability, were coloned and the sequence was analyzed by bioinformatics methods. The yeast heterologous expression system was used to analyses the different cadmium transport activity of NtNramp1 form different varieties. [Result]Jinying and Komotini Basma were two tobacco varieties (Nicotiana tabacum L.) that had significant difference of cadmium accumulation ability. The NtNramp1 cloned from Jinying and Komotini Basma were named as NtNramp1a and NtNramp1b respectively. There were 57 single nucleotide polymorphisms (SNP) in the coding region between NtNramp1a and NtNramp1b. The SNP in 1305 bp of NtNramp1a lead to premature termination of protein translation, which resulted in missing two transmembrane structure in the C-terminal compared with NtNramp1b. Heterologous expression of NtNramp1a and NtNramp1b in yeast showed that the yeast strain expressing NtNramp1b was more sensitive to cadmium than the yeast strain expressing NtNramp1a, suggesting that the cadmium transport activity of NtNramp1b was significantly more strong than that of NtNramp1a.[Conclusion] The different cadmium transport activity of NtNramp1 between Jinying and Komotini Basma resulted in significant cadmium accumulation difference between the two tobacco varieties.