Genome-wide identification and transcription factor regulation of monolignol biosynthetic genes in Ginkgo biloba L.

Background Ginkgo biloba L. is a widely cultivated Mesozoic relict gymnosperm, and the wood is resource-rich. As a main component of plant cell walls, lignin serves for plant water transport and mechanical support, as well as directly defining the properties of wood-based products. The lignin biosynthesis pathway in gymnosperms is simpler than that in angiosperms, but has been poorly studied due to the lack of model plants. Results In the present study, we systematically identified a total of 157 monolignol biosynthetic genes from 10 families in G. biloba, including 12 Gb4CLs, 34 GbC3Hs, 7 GbC4Hs, 34 GbCADs, 8 GbCCoAOMTs, 19 GbCCRs, 13 GbCOMTs, 14 GbCSEs, 11 GbHCTs and 5 GbPALs. The chromosome localization, gene structure, gene promoter and other analyses were also conducted. We established a regulatory network between the identified monolignol biosynthetic genes and TFs generated by TGMI algorithm using 133 public RNA-seq datasets of various G. biloba tissues. We then examined 2 gene pairs from the network of their regulatory relationship via yeast one-hybrid and dual-luciferase reporter assay, and the results were positive confirming interactions existing between the GbMYB-025 protein and GbCAD31 promoter, GbERF-174 protein and GbCSE13 promoter in vivo. Conclusions Our results provided a new effective approach to find transcriptional regulatory relationships and established an important foundation for molecular mechanisms and genetic regulation of monolignol biosynthesis in G. biloba.