GbMYBR1 from Ginkgo biloba represses phenylpropanoid biosynthesis and trichome development in Arabidopsis

Abstract

Main Conclusion GbMYBR1, a new type of R2R3-MYB repressor from Ginkgo biloba, displayed pleiotropic effects on plant growth, phenylpropanoid accumulation, by regulating multiple related genes at different levels. Abstract Ginkgo biloba is a typical gymnosperm that has been thriving on earth for millions of years. MYB transcription factors (TFs) play important roles in diverse processes in plants. However, the role of MYBs remains largely unknown in Ginkgo. Here, an MYB TF gene from Ginkgo, designated as GbMYBR1, was found to act as a repressor in multiple processes. GbMYBR1 was mainly expressed in the leaves of Ginkgo. Over-expression of GbMYBR1 in Arabidopsis thaliana led to growth retardation, decreases in lignin content, reduced trichome density, and remarkable reduction in anthocyanin and flavonol contents in leaves. Proanthocyanidin content was decreased in the seeds of transgenic Arabidopsis, which led to light-brown seed color. Both qPCR and transcriptome sequencing analyses demonstrated that the transcript levels of multiple genes related to phenylpropanoid biosynthesis, trichome formation, and pathogen resistance were down-regulated in the transgenic Arabidopsis. In particular, we found that GbMYBR1 directly interacts with the bHLH cofactor GL3 as revealed by yeast two-hybrid assays. Our work indicated that GbMYBR1 has pleiotropic effects on plant growth, phenylpropanoid accumulation, and trichome development, mediated by interaction with GL3 or direct suppression of key pathway genes. Thus, GbMYBR1 represents a novel type of R2R3 MYB repressor.

Structure, synthesis, biosynthesis, and activity of the characteristic compounds fromGinkgo bilobaL.

“…Five cDNA fragments of the putative R2R3-MYB gene were isolated and identified in G. biloba , namely, GbMYBF10 , GbMYBF2 , GbMYBFL , and two GbMYBF1s . 254–256 The expression level of GbMYBF2 had a significant negative correlation with flavonoid content and the transcript levels of GbPAL , GbFLS , GbANS , and GbCHI , whereas the opposite was seen for GbMYBF1 and GbMYBF10 . The overexpression of GbMYBF2 in Arabidopsis significantly inhibited flavonoid accumulation, which reflected the repression of a large number of genes associated with flavonoid biosynthesis, including CHS , F3H , FLS , and ANS .…”

“…All identified genes involved in ginkgo flavonoid biosynthesis are listed in Table 3. 235,241–245,248,250,252,254–256…”

“…The overexpression of GbMYBR1 in A. thaliana led to growth retardation, lower lignin content, lower trichome density, a marked reduction in anthocyanin and flavonol contents in the leaves, and a decrease in proanthocyanidin content in the seeds. 256…”

Genome-wide identification and expression pattern analysis of the TCP transcription factor family in Ginkgo biloba

“… 36 For instance, GbMYBF2 and GbMYBR2 were reported to negatively regulate biosynthesis of flavonoid in G. biloba . 80 , 81 GbbHLH, GbTrihelix , and three GbERFs contributed to flavonoid biosynthesis by regulating the expression of structural genes in the flavonoid biosynthesis pathway. 82 In recent years, some studies found that TCPs may also be involved in flavonoid biosynthesis.…”

Identification of Transcription Factor Genes and Functional Characterization of PlMYB1 From Pueraria lobata

“…U39568) was used as an internal reference gene for the calculation of relative transcript levels. Primers used for genes from kudzu were listed in Supplementary Table 6, and primers for genes from Arabidopsis were the same as in our previous study (Su et al, 2020). Each reaction (20 µl) contained 1 µM each primer, 1 µl cDNA (1:10 diluted), 7 µl RNase-free H 2 O, and 10 µl PCR buffer of SYBR Real Master Mix.…”