Fig. 3

PdTT8 enhances the transcriptional activation activity of PdMYB118. a Transient expression of PdMYB118 or PdTT8 in poplar mesophyll protoplasts. The constructs of pGreenII62-SK-PdMYB118, pGreenII62-SK-PdTT8 or pGreenII62-SK-PdMYB118 + pGreenII62-SK-PdTT8 were transfected into the poplar leaf protoplasts, respectively. The empty vector was used as a negative control. RNA was extracted from the transfected protoplasts for qRT-PCR analyses of ABGs, PdTT8 and PdMYB118. PtrCHS1, PtrCHI1, PtrF3H, PtrF3’H, PtrF3’5’H, PtrDFR2 and PtrANS1 are the ABG genes respectively encoding chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, flavanone 3′-hydroxylase, flavonoid 3′5’-hydroxylase, dihydroflavonol 4-reductase and anthocyanidin synthase in Populus. C, protoplasts transfected with pGreenII62-SK (control); M, protoplasts transfected with pGreenII62-SK-PdMYB118; T, protoplasts transfected with pGreenII62-SK-PdTT8; M + T; protoplasts transfected with pGreenII62-SK-PdMYB118 and pGreenII62-SK-PdTT8. b BiFC assays to detect the interaction of PdTT8 and PdMYB118. PdMYB118 or PdTT8 was respectively fused with N-terminal and C-terminal fragments of YFP. Construct pairs indicated on the left were co-expressed in the leaf protoplasts of WT poplar plants. Gene expression level in the control sample was set to 1. Values are means and standard deviations of three biological replicates (n = 3). ***, significant difference in comparison to C and T at P < 0.001, respectively (Student’s t-test)