Fig. 2

The full-length SVBV SP1 promoter showed potential for transient expression of exogenous genes in plants. A Transient expression of GFP in N. benthamiana stems. Agrobacterium cells harboring the pCHF-SP1 (1), pCHF-SP2 (2), pCHF-SP3 (3), pCHF-SP4 (4), pCHF-FLt-US (5), pCHF3 (6), or pCHF3-35SΔ (7) vector were injected into the stems of N. benthamiana plants. Freehand sections were cut from the injected stems at 64 hpi, and GFP signals were detected under a fluorescent microscope. Bar = 50 µM. B Analysis of GUS gene expression in N. benthamiana stems. Agrobacterium cells harboring the pINT-SP1 (1), pINT-SP2 (2), pINT-SP3 (3), pINT-SP4 (4), pINT-FLt-US (5), pINT121 (6), or pINT-35SΔ (7) vector were injected into the stems of N. benthamiana plants. The injected stems were harvested at 64 hpi and stained overnight in a 1 mM X-Gluc staining solution prior to paraffin embedding. Sections prepared from the embedded tissues were examined under a microscope for GUS staining results. Blue staining indicates positive expression of the GUS gene in stems. Bar = 50 µM. C Analysis of GUS activity in N. benthamiana leaves. Agrobacterium cells harboring the pINT-SP1, pINT-SP2, pINT-SP3, pINT-SP4, pINT-FLt-US, pINT121, or pINT-35SΔ (negative control) vector were inoculated into leaves of N. benthamiana plants. The inoculated leaves were harvested at 64 hpi and used for GUS activity fluorometric assays. Each treatment had five biological replicates, and the experiment was repeated three times. Standard errors were determined using the LSD method. The biochemical expression assay in leaves was repeated thrice and average readings are represented. Statistical analysis showed a P value of < 0.05, indicating high significance