[Analysis of the salt-stress responsive element of the promoter of peanut small GTP binding protein gene AhRabG3f ].

To study the molecular mechanism of salt stress response of peanut small GTP binding protein gene , a 1 914 bp promoter fragment upstream of the start codon of gene (-P) from peanut was cloned. Subsequently, five truncated fragments (-P1--P5) with lengths of 1 729, 1 379, 666, 510 and 179 bp were obtained through deletion at the 5' end, respectively. Plant expression vectors where these six promoter fragments were fused with the gene were constructed and transformed into tobacco by -mediated method, respectively. GUS expression in transgenic tobacco and activity analysis were conducted. The gene expression can be detected in the transgenic tobacco harboring each promoter segment, among which the driving activity of the full-length promoter -P was the weakest, while the driving activity of the promoter segment -P3 was the strongest. Upon exposure of the transgenic tobacco to salt stress, the GUS activity driven by -P, -P1, -P2 and -P3 was 3.3, 1.2, 1.9 and 1.2 times compared to that of the transgenic plants without salt treatment. This suggests that the promoter was salt-inducible and there might be positive regulatory elements between -P and -P3 in response to salt stress. The results of GUS activity driven by promoter fragments after salt treatment showed that elements included MYB and GT1 between 1 930 bp and 1 745 bp. Moreover, a TC-rich repeat between 682 bp and 526 bp might be positive -elements responsible for salt stress, and an MYC element between 1 395 bp and 682 bp might be a negative -element responsible for salt stress. This study may facilitate using the induced promoter to regulate the salt resistance of peanut.