| Abstract: | The expression ofArabidopsis PDF1.2 gene is regulated by jasmonic acid (JA) and ethylene (ET). It also has been well documented that GCC box is an element responsive
to ET, however, the responsive mechanism of JA in such plant defense gene expression is unclear. In this paper, the authors
define the essential cis-acting element inPDF1.2 promoter responsive to methyl jasmonate (MeJA) through fragment deletions and site-directed mutageneses combiningAgrobacterium-mediated transient reporter gene expression in tobacco leaves. Firstly, the MeJA inducible expression ofPDF1.2 was confirmed by using the upstream −1.86 kb fragment ofPDF1.2 gene. Secondly, the upstream −300–−243 bp fragment of the promoter was evidenced to respond to MeJA. To further characterize
this promoter region, three point mutations were introduced into the −300–−243 bp fragment of the promoter. This result showed
that the mutation of GCC box abolished MeJA induction, whereas the mutations of the G box-like and the imperfect palindrome
sequence did not significantly decrease MeJA inducible effect, indicating that GCC box inPDF1.2 is essential for MeJA induction. The sufficient responsiveness to MeJA of this GCC box was further investigated by 4×GCC
fused upstream to the CaMV 35S minimal promoter. This result suggested that the fused promoter was able to activate reporter
gene expression in response to MeJA. Thus these results indicate that the GCC box inPDF1.2 is an essential and sufficient element to confer MeJA induction. |
