scholarly journals The R2R3-type MYB transcription factor MdMYB90-like is responsible for the enhanced skin color of an apple bud sport mutant

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Chao Sun ◽  
Chunming Wang ◽  
Wang Zhang ◽  
Shuai Liu ◽  
Weiyao Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Skin Color ◽  
Anthocyanin Biosynthesis ◽  
Regulatory Gene ◽  
Gene Promoter ◽  
Luciferase Assay ◽  
Myb Transcription Factor ◽  
Anthocyanin Content ◽  
Mobility Shift ◽  
Mobility Shift Assay

AbstractThe anthocyanin content in apple skin determines its red coloration, as seen in a Fuji apple mutant. Comparative RNA-seq analysis was performed to determine differentially expressed genes at different fruit development stages between the wild-type and the skin color mutant. A novel R2R3-MYB transcription factor, MdMYB90-like, was uncovered as the key regulatory gene for enhanced coloration in the mutant. The expression of MdMYB90-like was 21.3 times higher in the mutant. MdMYB90-like regulates anthocyanin biosynthesis directly through the activation of anthocyanin biosynthesis genes and indirectly through the activation of other transcription factors that activate anthocyanin biosynthesis. MdMYB90-like bound to the promoters of both structural genes (MdCHS and MdUFGT) and other transcription factor genes (MdMYB1 and MdbHLH3) in the yeast one-hybrid system, electrophoretic mobility shift assay, and dual-luciferase assay. Transgenic analysis showed that MdMYB90-like was localized in the nucleus, and its overexpression induced the expression of other anthocyanin-related genes, including MdCHS, MdCHI, MdANS, MdUFGT, MdbHLH3, and MdMYB1. The mutant had reduced levels of DNA methylation in two regions (−1183 to −988 and −2018 to −1778) of the MdMYB90-like gene promoter, which might explain the enhanced expression of the gene and the increased anthocyanin content in the mutant apple skin.

scholarly journals PgMYB2, a MeJA-Responsive Transcription Factor, Positively Regulates the Dammarenediol Synthase Gene Expression in Panax Ginseng

2019 ◽  
Vol 20 (9) ◽  
pp. 2219 ◽  
Author(s):  
Tuo Liu ◽  
Tiao Luo ◽  
Xiangqian Guo ◽  
Xian Zou ◽  
Donghua Zhou ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Panax Ginseng ◽  
Growth Regulation ◽  
Ginseng Root ◽  
Myb Transcription Factor ◽  
Mobility Shift ◽  
Binding Interaction ◽  
Mobility Shift Assay ◽  
Dammarenediol Synthase

The MYB transcription factor family members have been reported to play different roles in plant growth regulation, defense response, and secondary metabolism. However, MYB gene expression has not been reported in Panax ginseng. In this study, we isolated a gene from ginseng adventitious root, PgMYB2, which encodes an R2R3-MYB protein. Subcellular localization revealed that PgMYB2 protein was exclusively detected in the nucleus of Allium cepa epidermis. The highest expression level of PgMYB2 was found in ginseng root and it was significantly induced by plant hormones methyl jasmonate (MeJA). Furthermore, the binding interaction between PgMYB2 protein and the promoter of dammarenediol synthase (DDS) was found in the yeast strain Y1H Gold. Moreover, the electrophoretic mobility shift assay (EMSA) identified the binding site of the interaction and the results of transiently overexpressing PgMYB2 in plants also illustrated that it may positively regulate the expression of PgDDS. Based on the key role of PgDDS gene in ginsenoside synthesis, it is reasonable to believe that this report will be helpful for the future studies on the MYB family in P. ginseng and ultimately improving the ginsenoside production through genetic and metabolic engineering.

scholarly journals MdMYB3 helps regulate anthocyanin accumulation in apple calli under moderately acidic conditions

2018 ◽  
Author(s):  
Yi-Cheng Wang ◽  
Jing-Jing Sun ◽  
Yan-Fen Qiu ◽  
Xiao-Jun Gong ◽  
Li Ma ◽  
...  
Keyword(s):  
Anthocyanin Biosynthesis ◽  
Myb Transcription Factor ◽  
Anthocyanin Content ◽  
Anthocyanin Accumulation ◽  
Mobility Shift ◽  
In The Wild ◽  
Acidic Conditions ◽  
Electrophoretic Mobility Shift Assays

AbstractAnthocyanins are the key factors controlling the coloration of plant tissues. However, the molecular mechanism underlying the effects of environmental pH on the synthesis of apple anthocyanins is unclear. In this study, we analyzed the anthocyanin contents of apple calli cultured in media at different pHs (5.5, 6.0, and 6.5). The highest anthocyanin content was observed at pH 6.0. Additionally, the moderately acidic conditions up-regulated the expression of MdMYB3 as well as specific anthocyanin biosynthesis structural genes (MdDFR and MdUFGT). Moreover, the anthocyanin content was higher in calli overexpressing MdMYB3 than in the wild-type controls at different pHs. Yeast one-hybrid assay results indicated that MdMYB3 binds to the MdDFR and MdUFGT promoters in vivo. An analysis of the MdDFR and MdUFGT promoters revealed multiple MYB-binding sites. Meanwhile, electrophoretic mobility shift assays confirmed that MdMYB3 binds to the MdDFR and MdUFGT promoters in vitro. Furthermore, GUS promoter activity assays suggested that the MdDFR and MdUFGT promoter activities are enhanced by acidic conditions, and the binding of MdMYB3 may further enhance activity. These results implied that an acid-induced apple MYB transcription factor (MdMYB3) promotes anthocyanin accumulation by up-regulating the expression of MdDFR and MdUFGT under moderately acidic conditions.

scholarly journals CmMYB#7, an R3 MYB transcription factor, acts as a negative regulator of anthocyanin biosynthesis in chrysanthemum

2019 ◽  
Vol 70 (12) ◽  
pp. 3111-3123 ◽  
Author(s):  
Lili Xiang ◽  
Xiaofen Liu ◽  
Heng Li ◽  
Xueren Yin ◽  
Donald Grierson ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Binding Site ◽  
Transient Expression ◽  
Regulatory Mechanism ◽  
Anthocyanin Biosynthesis ◽  
Expression Patterns ◽  
Negative Regulator ◽  
Myb Transcription Factor ◽  
Anthocyanin Content

Abstract ‘Jimba’, a well-known white flowered chrysanthemum cultivar, occasionally and spontaneously produces red colored petals under natural cultivation, but there is little information about the molecular regulatory mechanism underlying this process. We analysed the expression patterns of 91 MYB transcription factors in ‘Jimba’ and ‘Turning red Jimba’ and identified an R3 MYB, CmMYB#7, whose expression was significantly decreased in ‘Turning red Jimba’ compared with ‘Jimba’, and confirmed it is a passive repressor of anthocyanin biosynthesis. CmMYB#7 competed with CmMYB6, which together with CmbHLH2 is an essential component of the anthocyanin activation complex, for interaction with CmbHLH2 through the bHLH binding site in the R3 MYB domain. This reduced binding of the CmMYB6–CmbHLH2 complex and inhibited its ability to activate CmDFR and CmUFGT promoters. Moreover, using transient expression assays we demonstrated that changes in the expression of CmMYB#7 accounted for alterations in anthocyanin content. Taken together, our findings illustrate that CmMYB#7 is a negative regulator of anthocyanin biosynthesis in chrysanthemum.

scholarly journals A Novel R2R3-MYB Transcription Factor PqMYB4 Inhibited Anthocyanin Biosynthesis in Paeonia qiui

2020 ◽  
Vol 21 (16) ◽  
pp. 5878
Author(s):  
Dan Huo ◽  
Xiaokun Liu ◽  
Yue Zhang ◽  
Jingjing Duan ◽  
Yanlong Zhang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Coat Color ◽  
Anthocyanin Biosynthesis ◽  
Myb Transcription Factor ◽  
Anthocyanin Content ◽  
Wild Type ◽  
Tree Peony ◽  
Anthocyanin Pathway ◽  
Red Color ◽  
R2r3 Myb

Paeonia qiui is a wild tree peony native to China. Its leaves show a clear purple-red color from the germination to the flowering stage, and it has high leaf-viewing value. A MYB transcription factor gene, designated as PqMYB4, was isolated from leaves of P. qiui based on transcriptome datas. The full-length cDNA of PqMYB4 was 693 bp, encoding 230 amino acids. Sequence alignment and phylogenetic analysis revealed that PqMYB4 was a R2R3-MYB transcription factor clustered with AtMYB4 in Arabidopsis thaliana. Moreover, it contained a C1 motif, an EAR repression motif and a TLLLFR motif in the C-terminal domains, which were unique in transcription repression MYB. Subcellular location analysis showed that PqMYB4 was located in the cell nucleus. PqMYB4 was highly expressed in the late stage of leaf development, and was negatively correlated with the anthocyanin content. The petiole of wild-type Arabidopsis seedlings was deeper in color than the transgenic lines of PqMYB4 and showed a little purple-red color. The seed coat color of Arabidopsis seeds that overexpressed PqMYB4 gene was significantly lighter than that of wild-type seeds. In transgenic Arabidopsis, the expression level of AtCHS, AtCHI, AtDFR and AtANS were down-regulated significantly. These results showed that PqMYB4 was involved in the negative regulation of anthocyanin biosynthesis in tree peony leaves, which can control the anthocyanin pathway genes. Together, these findings provide a valuable resource with which to further study the regulatory mechanism of anthocyanin biosynthesis in the leaf of P. qiui. They also benefit the molecular breeding of tree peony cultivars with colored leaf.

scholarly journals Comprehensive Influences of Overexpression of a MYB Transcriptor Regulating Anthocyanin Biosynthesis on Transcriptome and Metabolome of Tobacco Leaves

2019 ◽  
Vol 20 (20) ◽  
pp. 5123 ◽  
Author(s):  
Yuan Zong ◽  
Shiming Li ◽  
Xinyuan Xi ◽  
Dong Cao ◽  
Zhong Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Anthocyanin Biosynthesis ◽  
Chemical Compounds ◽  
Phenylpropanoid Pathway ◽  
Myb Transcription Factor ◽  
Regulation Mechanism ◽  
Anthocyanin Content ◽  
Biosynthesis Pathway ◽  
Structural Genes ◽  
Transgenic Lines

Overexpression of R2R3-MYB transcriptor can induce up-expression of anthocyanin biosynthesis structural genes, and improve the anthocyanin content in plant tissues, but it is not clear whether the MYB transcription factor overexpression does effect on other genes transcript and chemical compounds accumulation. In this manuscript, RNA-sequencing and the stepwise multiple ion monitoring-enhanced product ions (stepwise MIM-EPI) strategy were employed to evaluate the comprehensive effect of the MYB transcription factor LrAN2 in tobacco. Overexpression of LrAN2 could promote anthocyanin accumulation in a lot of tissues of tobacco cultivar Samsun. Only 185 unigenes express differently in a total of 160,965 unigenes in leaves, and 224 chemical compounds were differently accumulated. Three anthocyanins, apigeninidin chloride, pelargonidin 3-O-beta-D-glucoside and cyanidin 3,5-O-diglucoside, were detected only in transgenic lines, which could explain the phenotype of purple leaves. Except for anthocyanins, the phenylpropanoid, polyphenol (catechin), flavonoid, flavone and flavonol, belong to the same subgroups of flavonoids biosynthesis pathway with anthocyanin and were also up-accumulated. Overexpression of LrAN2 activated the bHLH (basic helix-loop-helix protein) transcription factor AN1b, relative to anthocyanin biosynthesis and the MYB transcription factor MYB3, relative to proanthocyanin biosynthesis. Then, the structural genes, relative to the phenylpropanoid pathway, were activated, which led to the up-accumulation of phenylpropanoid, polyphenol (catechin), flavonoid, flavone, flavonol and anthocyanin. The MYB transcription factor CPC, negative to anthocyanin biosynthesis, also induced up-expression in transgenic lines, which implied that a negative regulation mechanism existed in the anthocyanin biosynthesis pathway. The relative contents of all 19 differently accumulated amino and derivers were decreased in transgenic lines, which meant the phenylalanine biosynthesis pathway completed the same substrates with other amino acids. Interestingly, the acetylalkylglycerol acetylhydrolase was down-expressed in transgenic lines, which caused 19 lyso-phosphatidylcholine and derivatives of lipids to be up-accumulated, and 8 octodecane and derivatives were down-accumulated. This research will give more information about the function of MYB transcription factors on the anthocyanin biosynthesis and other chemical compounds and be of benefit to obtaining new plant cultivars with high anthocyanin content by biotechnology.

scholarly journals Article Functional MYB transcription factor gene HtMYB2 is associated with anthocyanin biosynthesis in Helianthus tuberosus L.

2020 ◽  
Author(s):  
Jieming Gao ◽  
Xuemei Sun ◽  
Yuan Zong ◽  
Shipeng Yang ◽  
Lihui Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Promoter Region ◽  
Anthocyanin Biosynthesis ◽  
Jerusalem Artichoke ◽  
Myb Transcription Factor ◽  
Anthocyanin Content ◽  
Helianthus Tuberosus ◽  
Biosynthesis Pathway ◽  
Tuber Skin ◽  
Indel Mutation

Abstract Background: Tuber color is an important trait for Helianthus tuberosus L. (Jerusalem artichoke). Usually, purple tubers with high anthocyanin content are more nutritious than white tuber. But, the molecular mechanism underlying it is unknown. Results: In the current study, high-throughput RNA-sequencing was used to compare the transcriptomes between plants with tubers with red or white epidermis. Anthocyanin biosynthesis structural genes had greater expression in the red-skinned tubers of cultivar QY1, indicating that the anthocyanin biosynthesis pathway was activated in ‘QY1’; quantitative PCR confirmed this difference in expression. HtMYB2 (Unigene44371_All) was the only MYB transcription factor, homologous to the MYB transcription factor regulating anthocyanin biosynthesis, expressed in the red tuber epidermis of ‘QY1’. The anthocyanin concentration in the root, stem, leaf, flower, and tuber epidermis of ‘QY1’ was higher than in ‘QY3’, especially tuber epidermis. Correspondingly, HtMYB2 had greater expression in these tissues of ‘QY1’ than in ‘QY3’. The expression of HtMYB2 was associated with anthocyanin accumulation in the different tissues. Overexpression of HtMYB2 activated the anthocyanin biosynthesis pathway, accumulating the pigment in leaves of transgenic tobacco, supporting the model that HtMYB2 regulated anthocyanin biosynthesis. Further experiments found that HtMYB2 had the same coding sequence and genomic sequence in ‘QY1’ and ‘QY3’, but that there were several single nucleotide polymorphisms and one insertion–deletion (indel) mutation of 21 nucleotides in the promoter region between the two alleles. The deletion of three nucleotides “AAA” made the promoter of ‘QY1’ predicted to contain one more possible promoter region. A specific primer, based on the indel, could differentiate between cultivars with red or white tuber epidermis. The genetic variation in HtMYB2 was associated with the tuber skin color in a natural population. Conclusions: RNA-seq can successfully isolate the candidate gene ( HTMYB2 ) controlling anthocyanin biosynthesis in purple epidermis of Jerusalem artichoke tuber. HTMYB2 can regulate anthocyanin biosynthesis in plants and is closely related to the formation of purple phenotype in tubers. This study should be useful in understanding the genetic mechanism underlying different tuber skin colors and in breeding new H. tuberosus cultivars with different tuber skin colors.

scholarly journals Article Functional MYB transcription factor gene HtMYB2 is associated with anthocyanin biosynthesis in Helianthus tuberosus L.

2020 ◽  
Author(s):  
Jieming Gao ◽  
Xuemei Sun ◽  
Yuan Zong ◽  
Shipeng Yang ◽  
Lihui Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Promoter Region ◽  
Anthocyanin Biosynthesis ◽  
Jerusalem Artichoke ◽  
Myb Transcription Factor ◽  
Anthocyanin Content ◽  
Helianthus Tuberosus ◽  
Biosynthesis Pathway ◽  
Tuber Skin ◽  
Indel Mutation

Abstract Background: Tuber color is an important trait for Helianthus tuberosus L. (Jerusalem artichoke). Usually, purple tubers with high anthocyanin content are more nutritious than white tuber. But, the molecular mechanism underlying it is unknown. Results: In the current study, high-throughput RNA-sequencing was used to compare the transcriptomes between plants with tubers with red or white epidermis. Compared with the white-skinned tubers of cultivar QY3, anthocyanin biosynthesis structural genes had greater expression in the red-skinned tubers of cultivar QY1, indicating that the anthocyanin biosynthesis pathway was activated in ‘QY1’; quantitative PCR confirmed this difference in expression. HtMYB2 (Unigene44371_All) was the only MYB transcription factor，homologous to the MYB transcription factor regulating anthocyanin biosynthesis, expressed in the red tuber epidermis of ‘QY1’. The anthocyanin concentration in the root, stem, leaf, flower, and tuber epidermis of ‘QY1’ was higher than in ‘QY3’, especially tuber epidermis. Correspondingly, HtMYB2 had greater expression in these tissues of ‘QY1’ than in ‘QY3’. The expression of HtMYB2 was associated with anthocyanin accumulation in the different tissues. Overexpression of HtMYB2 activated the anthocyanin biosynthesis pathway, accumulating the pigment in leaves of transgenic tobacco, supporting the model that HtMYB2 regulated anthocyanin biosynthesis. Further experiments found that HtMYB2 had the same coding sequence and genomic sequence in ‘QY1’ and ‘QY3’, but that there were several single nucleotide polymorphisms and one insertion–deletion (indel) mutation of 21 nucleotides in the promoter region between the two alleles. The deletion of three nucleotides “AAA” made the promoter of ‘QY1’ predicted to contain one more possible promoter region. A specific primer, based on the indel, could differentiate between cultivars with red or white tuber epidermis. The genetic variation in HtMYB2 was associated with the tuber skin color in a natural population.Conclusions: RNA-seq can successfully isolate the candidate gene (HTMYB2) controlling anthocyanin biosynthesis in purple epidermis of Jerusalem artichoke tuber. HTMYB2 can regulate anthocyanin biosynthesis in plants and is closely related to the formation of purple phenotype in tubers. This study should be useful in understanding the genetic mechanism underlying different tuber skin colors and in breeding new H. tuberosus cultivars with different tuber skin colors.

scholarly journals Integrated Metabolomic and Transcriptomic Analysis Reveals the Flavonoid Regulatory Network by Eutrema EsMYB90

2021 ◽  
Vol 22 (16) ◽  
pp. 8751
Author(s):  
Yuting Qi ◽  
Chuanshun Li ◽  
Chonghao Duan ◽  
Caihong Gu ◽  
Quan Zhang
Keyword(s):  
Transgenic Tobacco ◽  
Anthocyanin Biosynthesis ◽  
Ectopic Expression ◽  
Flavonoid Biosynthesis ◽  
Luciferase Assay ◽  
Myb Transcription Factor ◽  
Integrated Analysis ◽  
Anthocyanin Content ◽  
Metabolome Analysis ◽  
Tobacco Leaves

Flavonoids are representative secondary metabolites with different metabolic functions in plants. Previous study found that ectopic expression of EsMYB90 from Eutrema salsugineum could strongly increase anthocyanin content in transgenic tobacco via regulating the expression of anthocyanin biosynthesis genes. In the present research, metabolome analysis showed that there existed 130 significantly differential metabolites, of which 23 metabolites enhanced more than 1000 times in EsMYB90 transgenic tobacco leaves relative to the control, and the top 10 of the increased metabolites included caffeic acid, cyanidin O-syringic acid, myricetin and naringin. A total of 50 markedly differential flavonoids including flavones (14), flavonols (13), flavone C-glycosides (9), flavanones (7), catechin derivatives (5), anthocyanins (1) and isoflavone (1) were identified, of which 46 metabolites were at a significantly enhanced level. Integrated analysis of metabolome and transcriptome revealed that ectopic expression of EsMYB90 in transgenic tobacco leaves is highly associated with the prominent up-regulation of 16 flavonoid metabolites and the corresponding 42 flavonoid biosynthesis structure genes in phenylpropanoid/flavonoid pathways. Dual luciferase assay documented that EsMYB90 strongly activated the transcription of NtANS and NtDFR genes via improving their promoter activity in transiently expressed tobacco leaves, suggesting that EsMYB90 functions as a key regulator on anthocyanin and flavonoid biosynthesis. Taken together, the crucial regulatory role of EsMYB90 on enhancing many flavonoid metabolite levels is clearly demonstrated via modulating flavonoid biosynthesis gene expression in the leaves of transgenic tobacco, which extends our understanding of the regulating mechanism of MYB transcription factor in the phenylpropanoid/flavonoid pathways and provides a new clue and tool for further investigation and genetic engineering of flavonoid metabolism in plants.

scholarly journals Article Functional MYB transcription factor gene HtMYB2 is associated with anthocyanin biosynthesis in Helianthus tuberosus L.

2020 ◽  
Author(s):  
Jieming Gao ◽  
Xuemei Sun ◽  
Yuan Zong ◽  
Shipeng Yang ◽  
Lihui Wang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Promoter Region ◽  
Anthocyanin Biosynthesis ◽  
Jerusalem Artichoke ◽  
Myb Transcription Factor ◽  
Anthocyanin Content ◽  
Helianthus Tuberosus ◽  
Biosynthesis Pathway ◽  
Tuber Skin ◽  
Indel Mutation

Abstract Background: Tuber color is an important trait for Helianthus tuberosus L. (Jerusalem artichoke). Usually, purple tubers with high anthocyanin content are more nutritious than white tuber. But, the molecular mechanism underlying it is unknown. Results: In the current study, high-throughput RNA-sequencing was used to compare the transcriptomes between plants with tubers with red or white epidermis. Anthocyanin biosynthesis structural genes had greater expression in the red-skinned tubers of cultivar QY1, indicating that the anthocyanin biosynthesis pathway was activated in ‘QY1’; quantitative PCR confirmed this difference in expression. HtMYB2 (Unigene44371_All) was the only MYB transcription factor, homologous to the MYB transcription factor regulating anthocyanin biosynthesis, expressed in the red tuber epidermis of ‘QY1’. The anthocyanin concentration in the root, stem, leaf, flower, and tuber epidermis of ‘QY1’ was higher than in ‘QY3’, especially tuber epidermis. Correspondingly, HtMYB2 had greater expression in these tissues of ‘QY1’ than in ‘QY3’. The expression of HtMYB2 was associated with anthocyanin accumulation in the different tissues. Overexpression of HtMYB2 activated the anthocyanin biosynthesis pathway, accumulating the pigment in leaves of transgenic tobacco, supporting the model that HtMYB2 regulated anthocyanin biosynthesis. Further experiments found that HtMYB2 had the same coding sequence and genomic sequence in ‘QY1’ and ‘QY3’, but that there were several single nucleotide polymorphisms and one insertion–deletion (indel) mutation of 21 nucleotides in the promoter region between the two alleles. The deletion of three nucleotides “AAA” made the promoter of ‘QY1’ predicted to contain one more possible promoter region. A specific primer, based on the indel, could differentiate between cultivars with red or white tuber epidermis. The genetic variation in HtMYB2 was associated with the tuber skin color in a natural population. Conclusions: RNA-seq can successfully isolate the candidate gene ( HTMYB2 ) controlling anthocyanin biosynthesis in purple epidermis of Jerusalem artichoke tuber. HTMYB2 can regulate anthocyanin biosynthesis in plants and is closely related to the formation of purple phenotype in tubers. This study should be useful in understanding the genetic mechanism underlying different tuber skin colors and in breeding new H. tuberosus cultivars with different tuber skin colors.

scholarly journals A MYB transcription factor, PlMYB308, plays an essential role in flower senescence of herbaceous peony

2021 ◽  
Author(s):  
Xiaotong Ji ◽  
Zhuangzhuang Xu ◽  
Meiling Wang ◽  
Xuyang Zhong ◽  
Lingling Zeng ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Anthocyanin Biosynthesis ◽  
Bimolecular Fluorescence Complementation ◽  
Luciferase Assay ◽  
Flower Senescence ◽  
Myb Transcription Factor ◽  
Vase Life ◽  
Herbaceous Peony ◽  
Expression Levels ◽  
Variable Expression

AbstractHerbaceous peony is an important cut-flower plant cultivated across the world, but its short vase life substantially restricts the economic value of this crop. It is well established that endogenous hormones regulate the senescing process, but the molecular mechanism of them in flower senescence is still unclear. Here, we isolated a MYB transcription factor gene PlMYB308 from herbaceous peony flowers. Transcript abundance of PlMYB308 was strongly up-regulated in senescing petals. Silencing of PlMYB308 resulted in delayed peony flower senescence, and dramatically increased gibberellin (GA) but reduced ethylene and abscisic acid (ABA) levels in petals. Ectopic overexpression of PlMYB308 in tobacco accelerated flower senescence, and reduced GA but increased ethylene and ABA accumulation. Correspondingly, biosynthetic genes of ethylene, ABA, and GA showed variable expression levels in petals after silencing or overexpression of PlMYB308. A dual-luciferase assay showed that PlMYB308 specifically bound to the PlACO1 promoter. High expression levels of PlMYB308 were accompanied by low petal anthocyanin accumulation in senescing petals. A further bimolecular fluorescence complementation assay revealed an interaction between PlMYB308 and PlbHLH33, which was supposed to inhibit the anthocyanin biosynthesis. Taken together, our results suggest that the PlMYB308-PlACO1 and PlMYB308-PlbHLH33 regulatory checkpoints perhaps positively and negatively operate the production of ethylene and anthocyanin, respectively, and thus contribute to the senescence with impaired pigmentation in herbaceous peony flowers.

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