Arabidopsis thaliana
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Project description:The model plant Arabidopsis thaliana has five double-stranded RNA-binding proteins (DRB1-DRB5), two of which, DRB1 and DRB4, are well characterized. In contrast, the functions of DRB2, DRB3 and DRB5 have yet to be elucidated. In this study, we tried to uncover their functions using drb mutants and DRB-over-expressed lines. In over-expressed lines of all five DRB genes, the over-expression of DRB2 or DRB3 (DRB2ox or DRB3ox) conferred a downward-curled leaf phenotype, but the expression profiles of 10 small RNAs were similar to that of the wild-type (WT) plant. Phenotypes were examined in response to abiotic stresses. Both DRB2ox and DRB3ox plants exhibited salt-tolerance. When these plants were exposed to cold stress, drb2 and drb3 over-accumulated anthocyanin but DRB2ox and DRB3ox did not. Therefore, the over-expression of DRB2 or DRB3 had pleiotropic effects on host plants. Microarray and deep-sequencing analyses indicated that several genes encoding key enzymes for anthocyanin biosynthesis, including chalcone synthase (CHS), dihydroflavonol reductase (DFR) and anthocyanidin synthase (ANS), were down-regulated in DRB3ox plants. When DRB3ox was crossed with the pap1-D line, which is an activation-tagged transgenic line that over-expresses the key transcription factor PAP1 (Production of anthocyanin pigmentation1) for anthocyanin biosynthesis, over-expression of DRB3 suppressed the expression of PAP1, CHS, DFR and ANS genes. DRB3 negatively regulates anthocyanin biosynthesis by modulating the level of PAP1 transcript. Since two different small RNAs regulate PAP1 gene expression, a possible function of DRB3 for small RNA biogenesis is discussed.
2016-11-30 | GSE87780 | GEO
Project description:The notion that plants use specialized metabolism to protect against environmental stresses needs to be experimentally proven by addressing the question of whether stress tolerance by specialized metabolism is directly due to metabolites such as flavonoids. We report that flavonoids with radical scavenging activity mitigate against oxidative and drought stress in Arabidopsis thaliana. Metabolome and transcriptome profiling and experiments with oxidative and drought stress in wild-type, single overexpressors of MYB12/PFG1 (PRODUCTION OF FLAVONOL GLYCOSIDES1) or MYB75/PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT1), double overexpressors of MYB12 and PAP1, transparent testa4 (tt4) as a flavonoid-deficient mutant, and flavonoid-deficient MYB12 or PAP1 overexpressing lines (obtained by crossing tt4 and the individual MYB overexpressor) demonstrated that flavonoid overaccumulation was key to enhanced tolerance to such stresses. Antioxidative activity assays using 2,2-diphenyl-1-picrylhydrazyl, methyl viologen, and 3,3'-diaminobenzidine clearly showed that anthocyanin overaccumulation with strong in vitro antioxidative activity mitigated the accumulation of reactive oxygen species in vivo under oxidative and drought stress. These data confirm the usefulness of flavonoids for enhancing both biotic and abiotic stress tolerance in crops.
2013-12-06 | MTBLS57 | MetaboLights
Project description:Nitrogen (N) and nitrate (NO3-) per se regulate many aspects of plant metabolism, growth and development. N/NO3- also suppresses parts of secondary metabolism including anthocyanin synthesis. Molecular components for this repression are unknown. We report that three N/NO3--induced members of the LATERAL ORGAN BOUNDARY DOMAIN (LBD) gene family of transcription factors (LBD37, LBD38 and LBD39) act as negative regulators of anthocyanin biosynthesis in Arabidopsis (Arabidopsis thaliana). Over-expression of each of the three genes in the absence of N/NO3- strongly suppresses the key regulators of anthocyanin synthesis PAP1 and PAP2, genes in the anthocyanin-specific part of flavonoid synthesis, as well as cyanidin- but not quercetin- or kaempferol-glycoside production. Conversely, lbd37, lbd38 or lbd39 T-DNA insertion mutants accumulate anthocyanins when grown in N/NO3--sufficient conditions and show constitutive expression of anthocyanin biosynthetic genes. The LBD genes also repress many other known N-responsive genes including key genes required for NO3- uptake and assimilation, resulting in altered NO3- content, nitrate reductase activity/activation, protein, amino acid and starch levels, and N-related growth phenotypes. The results identify LBD37 and its two close homologs as novel repressers of anthocyanin biosynthesis and N-availability signals in general. They also show that besides being developmental regulators LBD genes fulfill roles in metabolic regulation. We used microarrays to test whether LBD37 and LBD38 have a more widespread role in NO3-/N-regulation.
2009-11-24 | GSE18818 | GEO
Project description:Nitrogen (N) and nitrate (NO3-) per se regulate many aspects of plant metabolism, growth and development. N/NO3- also suppresses parts of secondary metabolism including anthocyanin synthesis. Molecular components for this repression are unknown. We report that three N/NO3--induced members of the LATERAL ORGAN BOUNDARY DOMAIN (LBD) gene family of transcription factors (LBD37, LBD38 and LBD39) act as negative regulators of anthocyanin biosynthesis in Arabidopsis (Arabidopsis thaliana). Over-expression of each of the three genes in the absence of N/NO3- strongly suppresses the key regulators of anthocyanin synthesis PAP1 and PAP2, genes in the anthocyanin-specific part of flavonoid synthesis, as well as cyanidin- but not quercetin- or kaempferol-glycoside production. Conversely, lbd37, lbd38 or lbd39 T-DNA insertion mutants accumulate anthocyanins when grown in N/NO3--sufficient conditions and show constitutive expression of anthocyanin biosynthetic genes. The LBD genes also repress many other known N-responsive genes including key genes required for NO3- uptake and assimilation, resulting in altered NO3- content, nitrate reductase activity/activation, protein, amino acid and starch levels, and N-related growth phenotypes. The results identify LBD37 and its two close homologs as novel repressers of anthocyanin biosynthesis and N-availability signals in general. They also show that besides being developmental regulators LBD genes fulfill roles in metabolic regulation. We used microarrays to test whether LBD37 and LBD38 have a more widespread role in NO3-/N-regulation. Experiment Overall Design: 9-day old Arabidopsis seedlings were harvested for RNA extraction and hybridization on Affymetrix microarrays. Total RNA was prepared separately from three biological replicates of N-limited LBD37OX, LBD38OX and WT seedlings, and N-replete lbd37-1 mutant, lbd38 mutant and WT seedlings (18 samples).
2009-11-28 | E-GEOD-18818 | biostudies-arrayexpress
Project description:MicroRNA172 (miR172) plays a role in regulating a diverse range of plant developmental processes. However, its role in regulating anthocyanin biosynthesis is unclear. In this study, we show that transgenic apple plants over-expressing miR172 show a reduction in red colouration and anthocyanin accumulation in multiple tissue types. This reduction was consistent with decreased expression of APETALA2 homolog MdAP2_1a (a miR172 target gene), MdMYB10, and targets of MdMYB10, as demonstrated by both RNA-seq and RT-PCR analyses. During the onset of anthocyanin biosynthesis in apple fruit skin, miR172 transcript abundance was negatively correlated and MdAP2_1a mRNA concentration was positively correlated with fruit skin red-colouration. The positive role of MdAP2_1a in regulating anthocyanin biosynthesis was supported by the enhanced petal anthocyanin accumulation in transgenic tobacco plants overexpressing MdAP2_1a, and by the reduction in anthocyanin accumulation in apple and cherry fruits transfected with an MdAP2_1a virus-induced-gene-silencing construct. We demonstrated that MdAP2_1a could bind directly to the promoter and protein sequences of MdMYB10 in yeast and tobacco, and enhance MdMYB10 promotor activity. In Arabidopsis, over-expression of miR172 reduced anthocyanin concentration and RNA transcript abundance of anthocyanin genes in plantlets cultured on medium containing 7% sucrose. The anthocyanin content and RNA abundance of anthocyanin genes could be partially restored by using a synonymous mutant of MdAP2_1a, which had lost the miR172 target sequences at mRNA level, but not restored by using a WT MdAP2_1a. These results indicate that miR172 inhibits anthocyanin biosynthesis through suppressing the expression of an AP2 transcription factor that positively regulates MdMYB10.
2022-12-24 | GSE173297 | GEO
Project description:Jasmonate (JA) is a plant hormone that controls trade-offs between plant growth and responses to biotic and abiotic stresses. Although recent studies uncover core mechanism for JA-induced responses in Arabidopsis thaliana, it remains elusive how plants attenuate those responses. We report here that a basic-helix-loop-helix type transcription factor named JA-INDUCIBLE MYC2-LIKE1 (JAM1) acts as a transcriptional repressor and negatively regulates JA signaling. Arabidopsis plants expressing the chimeric repressor for JAM1 exhibited a substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by Spodoptera exigua. Conversely, jam1-4 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to the insect attack. Competitive binding of JAM1 and MYC2 to the target sequence of MYC2 suggested negative regulation of JA signaling by JAM1 and suppression of MYC2 function. These results indicate that JAM1 plays a pivotal role in fine-tuning of JA-mediated stress responses and plant growth by negatively regulating JA signaling. Transcriptomes of ProJAM1:JAM1-SRDX, ProMYC2:MYC2-SRDX and wild-type Arabidopsis seedlings with or without jasmonic acid were compared.
2013-07-03 | E-GEOD-42552 | biostudies-arrayexpress
Project description:Plastid Encoded RNA Polymerase (PEP) is a bacterial type multisubunit RNA polymerase responsible for the bulk of transcription in chloroplasts. It contains four core subunits, which are orthologs of their cyanobacterial counterparts. In Arabidopsis thaliana PEP associates with 12 PEP-associated proteins (PAPs), which serve as peripheral subunits of the RNA polymerase. The exact contributions of PAPs to PEP function remain poorly understood. We show that a peripheral subunit of PEP, PAP1 (pTAC3), binds the same genomic loci as RpoB, a core subunit of PEP. PAP1 (pTAC3) and another peripheral PEP subunit, PAP7 (pTAC14), are required for RpoB binding to DNA. RpoB and another core PEP subunit, RpoC1, are expressed in pap1 (ptac3) and pap7 (ptac14) mutants. We propose that the peripheral subunits of PEP are required for the recruitment of core PEP subunits to DNA. pTAC3, binds the same genomic loci as RpoB, a core subunit of PEP. PAP1 pTAC3 and another peripheral PEP subunit, PAP7
2024-03-05 | GSE259283 | GEO
Project description:Oilseed rape is both an important oleaginous crop and agriculture sightseeing crop whereas has relatively scanty flower color. As natural flavonoids, Anthocyanin are responsible for the attractive red, purple, and blue colors of various tissues in higher plants, especially for the ornamental plants flower. One Brassica napus-Orychophragmus violaceus disomic addition line (M4) obtained previously exhibits red petals whichresult from anthocyanin biosynthesis. Transcriptome analysis of M4, B. napus (H3), natural individuals of O. violaceus with purple petals (OvP) and white petals (OvW) revealed that most of structural genes for the anthocyanin synthesis were up-regulated in both M4 and OvP, especially key gene ANS in the last step. Reads assembling and sequence alignment showed that the regulatory DEG PAP2 in M4 was from the transcript of O. violaceus. OvPAP2 was transformed into Arabidopsis thaliana and B. napus driven by the CaMV35S promoter and the rape petal-specific prompter XY355. Transgenic A. thaliana plants showed different levels of purple pigments in most of the organs, including the petals, and transgenic B. napus flowers exhibited restricted accumulation of anthocyanins in stamens when driven by CaMV35S promoter, but generated both red petals and anthers driven by the XY355 promoter. These results provided a platform for expounding the anthocyanin biosynthesis pathway in B. napus petals and give a successful case for flower color modification of the agriculture sightseeing rape.
2017-12-30 | GSE93089 | GEO
Project description:Jasmonate (JA) is a plant hormone that controls trade-offs between plant growth and responses to biotic and abiotic stresses. Although recent studies uncover core mechanism for JA-induced responses in Arabidopsis thaliana, it remains elusive how plants attenuate those responses. We report here that a basic-helix-loop-helix type transcription factor named JA-INDUCIBLE MYC2-LIKE1 (JAM1) acts as a transcriptional repressor and negatively regulates JA signaling. Arabidopsis plants expressing the chimeric repressor for JAM1 exhibited a substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by Spodoptera exigua. Conversely, jam1-4 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to the insect attack. Competitive binding of JAM1 and MYC2 to the target sequence of MYC2 suggested negative regulation of JA signaling by JAM1 and suppression of MYC2 function. These results indicate that JAM1 plays a pivotal role in fine-tuning of JA-mediated stress responses and plant growth by negatively regulating JA signaling.
2013-07-03 | GSE42552 | GEO