Project description:Petunia floral scent production and emission is highly regulated, with a major role for the transcription factor ODORANT1 (ODO1) in directing activation of volatile biosynthesis. Using ChIP-seq of tagged ODO1 protein from petunia flowers, and RNA-seq of wild-type and odo1i RNAi flowers, the ODORANT1-regulated gene network of petunia is described, which extends to branches involved in phenylpropanoid intermediate production and S-adenosyl-methionine biosynthesis to potentiate production and emission of volatiles. Analysis of direct targets of regulation has also enabled the identification of an ODO1 binding motif.
Project description:Shoot branching of flowering plants exhibits phenotypic plasticity and variability. This plasticity is determined by the activity of axillary meristems, which in turn is influenced by endogenous and exogenous cues such as nutrients and light. In many species, not all buds on the main shoot develop into branches despite favorable growing conditions. In petunia, basal buds (buds 1-3) typically do not grow out to form branches, while more apical buds (buds 6 and 7) are competent to grow. The genetic regulation of buds was explored using transcriptome analyses of petunia axillary buds at different positions on the main stem. To suppress or promote bud outgrowth, we grew the plants in media with differing phosphate (P) levels. Using RNA-seq, we found many (>5000) differentially expressed genes between bud 6 or 7, and bud 2. In addition, more genes were differentially expressed when we transferred the plants from low P to high P medium, compared with shifting from high P to low P medium. Buds 6 and 7 had increased transcript abundance of cytokinin and auxin-related genes, whereas the basal non-growing buds (bud 2 and to a lesser extent bud 3) had higher expression of strigolactone, abscisic acid, and dormancy-related genes, suggesting the outgrowth of these basal buds was actively suppressed. Consistent with this, the expression of ABA associated genes decreased significantly in apical buds after stimulating growth by switching the medium from low P to high P. Furthermore, comparisons between our data and transcriptome data from other species suggest that the suppression of outgrowth of bud 2 was correlated with a limited supply of carbon to these axillary buds. Candidate genes that might repress bud outgrowth were identified by co-expression analysis.
Project description:N1-methyladenosine is a unique base methylation because it blocks Watson-Crick base paring and introduces a positive charge. Previous studies showed that m1A is prevalent in yeast and mammals mRNA and has a functional role in promoting translation of methylated mRNA. However, little is known about its abundance, topology and dynamics in plant mRNA. In this study, dot blotting and LC–MS/MS analyses reveal a dynamic pattern of m1A mRNA modification in various tissues and at different developmental stages in petunia (Petunia hybrida). Transcriptome-wide profiling of mRNA m1A in petunia was reported by applying m1A mRNA immunoprecipitation followed by a deep-sequencing approach (m1A-seq). m1A-seq analysis identified 4993 m1A peaks in 3231 expressed genes in petunia corollas. Each methylated gene averagely carries 1.55 peaks. Among the identified m1A peaks, there are 251 m1A peaks in which the adenines was partly replaced by thymine (T) and/or the reverse transcription stops happened in adenine site, in 199 expressed genes. We found that m1A is enriched in coding sequences with one peaks located immediately after start codons, and a slight negative correlation between methylated genes and gene expression was observed. Totally, ethylene treatment reduced the m1A level of mRNA in petunia corollas. We show that a RNA m1A-methyltransferase, tRNA specific methyltransferase 61A (PhTRMT61A), is an m1A mRNA methyltransferase. PhTRMT61A silencing results in decreased m1A peaks in mRNA in leaves and abnormal leaf development. PhTRMT61A is located to the nucleus. Our results suggest that m1A in mRNA is an important epitranscriptome marker and plays a role in plant development.
Project description:Petunia is an excellent model system, especially for genetic, physiological and molecular studies. Thus far, however, genome-wide expression analysis has been rarely applied because of the lack of sequence information. We applied next-generation sequencing to generate, through de novo read assembly, a large catalogue of transcripts for Petunia axillaris and Petunia inflata. On the basis of the transcriptome of each species, comprehensive microarray chips for gene expression analysis were established and used for the analysis of global- and organ-specific gene expression in both species. In addition, microarray analysis was applied to explore the molecular basis of the seed coat defects in Petunia hybrida mutants, homozygous for a null allele of the AN11 gene, encoding a WDR transcription regulator. Among the transcripts differentially expressed in an11 seeds compared to wild type, many expected targets of AN11 were found but also several interesting new candidates that might play a role in morphogenesis of the seed coat. Our results validate the combination of next-generation sequencing with microarray analyses strategies to identify the transcriptome of two petunia species without previous knowledge of their genome, and to develop comprehensive chips as useful tools for the analysis of gene expression in P. axillaris, P. inflata and P. hybrida.
Project description:Petunia is an excellent model system, especially for genetic, physiological and molecular studies. Thus far, however, genome-wide expression analysis has been rarely applied because of the lack of sequence information. We applied next-generation sequencing to generate, through de novo read assembly, a large catalogue of transcripts for Petunia axillaris and Petunia inflata. On the basis of the transcriptome of each species, comprehensive microarray chips for gene expression analysis were established and used for the analysis of global- and organ-specific gene expression in both species. In addition, microarray analysis was applied to explore the molecular basis of the seed coat defects in Petunia hybrida mutants, homozygous for a null allele of the AN11 gene, encoding a WDR transcription regulator. Among the transcripts differentially expressed in an11 seeds compared to wild type, many expected targets of AN11 were found but also several interesting new candidates that might play a role in morphogenesis of the seed coat. Our results validate the combination of next-generation sequencing with microarray analyses strategies to identify the transcriptome of two petunia species without previous knowledge of their genome, and to develop comprehensive chips as useful tools for the analysis of gene expression in P. axillaris, P. inflata and P. hybrida. The manuscript describes the creation by next generation sequencing of a large catalogue of the transcriptome of the two Petunia species, that are considered to represent the natural material from which the breeders selected their varieties. This submission represents the transcriptome component of study. The high throughput sequencing data were submitted to SRA (accession numbers: SRA027293, SRP004866.1, SRX036999.2, SRX036998.2).
Project description:To better understand how diurnal transcriptional regulation contributes to day/night cycles of volatile emission from the petunia flower, RNA extracted from corolla in the morning (7AM) and evening (7PM) was sequenced to determine genes differentially expressed at the two time points.
Project description:We report the application of sequencing-by-synthesis technology for high-throughput profiling of small RNAs involved in Chalcone synthase A (CHS-A) sense cosuppression in petunia. Sense cosuppression is a classical form of eukaryotic post-transcriptional gene silencing. It was first reported in transgenic petunia, where a transgene overexpressing the host Chalcone Synthase-A (CHS-A) gene caused the degradation of the homologous transcripts and the loss of flower pigmentation. Though sense cosuppression is recognized as an RNA silencing mechanism, little evidence has been yet provided demonstrating its association with the generation of individual small interfering RNAs (siRNAs) that are the assumed determinants. In this work, the deep sequencing of small RNAs in cosuppressed transgenic petunia and WT petunia respectively allowed for the identication of siRNAs that vastly predominate in the silenced flower and guide prominent cleavage events in CHS-A mRNA.