Transcriptome profiling of the basal region of poplar stems during the early gravitropic response
ABSTRACT: Young poplar stems show a preponderantly primary growth in the top internodes and differential cambium activity in the basal internodes after inclination with some tension wood formed after 45 min. This study was conducted in order to characterize the early changes in gene expression during early stages of the gravitropic response in the poplar. Hybridizations were performed to compare gravistimulated poplar stems (basal region) after 45 min of inclination and untreated control stems. Two biological replicates were done. Two hybridizations with a dye swap for each tree pair were done, making a total of four hybridizations.
Project description:The Poplar transcriptome was analyzed in mycorrhizal root tips in contact with Laccaria bicolor for 2 weeks. During mycorrhization the roots were treated with either 250µm ACC, 10nM JA or 500µM SA and compared to untreated mycorrhiza or control roots without contact to L. bicolor. In addition the poplar mutants 35S::PttACO1 and 35S::Atetr1 were used We performed 27 hybridizations (NimbleGen) with samples derived from Populus tremula x Populus alba clone 717-1B4 control roots, untreated mycorrhiza, SA-treated mycorrhiza, ACC-treated mycorrhiza and JA-treated mycorrhiza (3 biological replicates each) as well as Populus tremula x Populus tremuloides T89 control roots, mycorrhiza, 35S::PttACO1 mycorrhiza and 35S::Atetr1-1 mycorrhiza (3 biological replicates). All samples were labeled with Cy3.
Project description:Populus euphratica is a natural population grown in semirid areas. The molecular response of the poplar to drought maintain to be elucided, especially at global genome level. We used Affymetrix poplar genome genechip microarrays to analyze the full transcript expression underlying different drought intensities and identified significantly differently expressed genes during this process. Uniformly developed seedlings of P. euphratica grown in gradually long-term drought throught water-withholding treatment. Affymetrix poplar genechip was hired to investigate the full transcripts changed of the poplar response to different drought intensity levels.
Project description:Transcriptional profile of leaves from poplar plants transformed with a pine GS1a gene under two different nitrate nutrition level (50mM and 10mM). Two conditions: nitrate nutrition (50mM and 10 mM) and genotype (GS1a transgenic poplar vs WT poplar)
Project description:Flavan-3-ols including the monomeric catechin and the polymeric proanthocyanidins (PAs) are abundant phenolic metabolites in poplar (Populus spp.) previously described to protect leaves against pathogen infection. However, it is not known whether stems are also defended in this way. Here we investigated flavan-3-ol accumulation, activity, and the regulation of formation in black poplar (P. nigra) stems after infection by a newly described fungal stem pathogen, Plectosphaerella populi, which forms canker-like lesions in stems. We showed that flavan-3-ol contents increased in P. populi-infected black poplar stems over the course of infection compared to non-infected controls. Transcripts of leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) genes involved in the last steps of flavan-3-ol biosynthesis were also upregulated upon fungal infection indicating de novo biosynthesis. Amending culture medium with catechin and PAs reduced the mycelial growth of P. populi, suggesting that these metabolites act as anti-pathogen defenses in poplar in vivo. Among the hormones, salicylic acid (SA) was higher in P. populi-infected tissues compared to the non-infected controls over the course of infection studied, while jasmonic acid (JA) and JA-isoleucine (JA-Ile) levels were higher than controls only at the early stages of infection. Interestingly, cytokinins (CKs) were also upregulated in P. populi-infected stems. Poplar saplings treated with CK showed decreased levels of flavan-3-ols and SA in stems suggesting a negative association between CK and flavan-3-ol accumulation. Taken together, the sustained upregulation of SA in correlation with catechin and PA accumulation suggests that this is the dominant hormone inducing the formation of antifungal flavan-3-ols during P. populi infection of poplar stems.
Project description:Sorghum bicolor is a drought-resilient C4 grass used for production of grain, forage, sugar, and biomass. Sorghum genotypes capable of accumulating high levels of stem sucrose have solid stems that contain low levels of aerenchyma. The D-locus on SBI06 modulates the extent of aerenchyma formation in sorghum stems and leaf midribs. A QTL aligned with this locus was identified and fine-mapped in populations derived from BTx623*IS320c, BTx623*R07007, and BTx623*Standard broomcorn. Analysis of coding polymorphisms in the fine-mapped D-locus showed that genotypes that accumulate low levels of aerenchyma encode a truncated NAC transcription factor (Sobic.006G147400, SbNAC_d1), whereas parental lines that accumulate higher levels of stem aerenchyma encode full-length NAC TFs (SbNAC-D). During vegetative stem development, aerenchyma levels are low in nonelongated stem internodes, internode growing zones, and nodes. Aerenchyma levels increase in recently elongated internodes starting at the top of the internode near the center of the stem. SbNAC_D was expressed at low levels in nonelongated internodes and internode growing zones and at higher levels in regions of stem internodes that form aerenchyma. SbXCP1, a gene encoding a cysteine protease involved in programmed cell death, was induced in SbNAC_D genotypes in parallel with aerenchyma formation in sorghum stems but not in SbNAC_d1 genotypes. Several sweet sorghum genotypes encode the recessive SbNAC_d1 allele and have low levels of stem aerenchyma. Based on these results, we propose that SbNAC_D is the D-gene identified by Hilton (1916) and that allelic variation in SbNAC_D modulates the extent of aerenchyma formation in sorghum stems.
Project description:The Poplar transcriptome was analyzed in Populus tremulaxPopulus alba clone 717-1B4 control roots and in two poplar lines overexpressing MiSSP7. We performed 9 hybridizations (NimbleGen) with samples derived from Populus tremulaxPopulus alba clone 717-1B4 control roots, as well as from roots of LINE1 and LINE2 MiSSP7 overexpressor poplars (3 biological replicates each). All samples were labeled with Cy3.
Project description:Illumina HiSeq technology was used to generate mRNA profiles of bark from MIR15 compared to wildtype plants. Wild type (WT) and transgenic poplars (Populus tremula x P. alba, clone INRA 717-1B4) were grown aseptically on Woody Plant Medium. Total RNA was extracted using Tri-Reagent according to the manufacturer’s instructions. Reads of 2X100bp were generated and aligned to Populus trichocarpa v3.0 reference transcripts (http://phytozome.jgi.doe.gov/pz/portal.html#!info?alias=Org_Ptrichocarpa; Ptrichocarpa_210_transcript_primaryTranscriptOnly) using CLC Genomics Workbench 7. mRNA profiles of bark from MIR15 compared to wildtype plants were generated by paired-end (2x100bp) Illumina HiSeq2000 sequencing. Two biological replicates were sequenced for MIR15 and WT samples.
Project description:Some of the most damaging tree pathogens can attack woody stems, causing lesions (cankers) that may be lethal. To identify the genomic determinants of wood colonization leading to canker formation, we sequenced the genomes of the poplar canker pathogen, Mycosphaerella populorum, and the closely related poplar leaf pathogen, M. populicola. A secondary metabolite cluster unique to M. populorum is fully activated following induction by poplar wood and leaves. In addition, genes encoding hemicellulose-degrading enzymes, peptidases, and metabolite transporters were more abundant and were up-regulated in M. populorum growing on poplar wood-chip medium compared with M. populicola. The secondary gene cluster and several of the carbohydrate degradation genes have the signature of horizontal transfer from ascomycete fungi associated with wood decay and from prokaryotes. Acquisition and maintenance of the gene battery necessary for growth in woody tissues and gene dosage resulting in gene expression reconfiguration appear to be responsible for the adaptation of M. populorum to infect, colonize, and cause mortality on poplar woody stems.
Project description:We analyzed the transcriptome in roots, young and mature leaves, nodes and internodes in the reference genotype Nisqually-1 and identified a core set of approximately 10,000 genes expressed in common among vegetative organs. Quantitative contrasts of transcript levels among organs identified expected patterns of expression associated with organ-specific physiological processes, although a surprisingly high number of defense-related genes were preferentially expressed in young leaves and nodes. Application of a novel runs test established an objective criterion for the identification of genomic regions in which adjacent genes were expressed more frequently than expected by chance, suggesting the presence of chromatin domains. Comparisons between P. trichocarpa Nisqually-1 and the P. tremula X P. alba hybrid INRA 717-1B4 revealed similar expression patterns, particularly in stems. Although a comparison to Arabidopsis thaliana revealed similar proportions of expressed genes in leaves and stems, there was very little conservation between rank correlations of expression patterns. Keywords: gene expression Overall design: Plant material. Branches from the P. trichocarpa reference genotype Nisqually-1 were placed in soil. After budbreak, shoots were rooted in a misthouse for two weeks. Rooted cuttings (cloned biological replicates) were planted in separate pots in a greenhouse equipped with an ebb-and-flow flood bench system with daily supply of Peters Professional 20-10-20 water-soluble fertilizer diluted to a final concentration of 4 mM nitrogen. After 45 days, whole-roots (R), young leaves (YL) - leaf plastochrone index (LPI) 0-5, mature leaves (ML) - LPI 6-9, nodes (N) and internodes (IN) were collected and immediately frozen in liquid nitrogen. RNA was extracted using standard methods (Chang et al. 1993), DNAse-treated and purified in RNAeasy Qiagen columns (Valencia, CA). The P. tremula × P. alba hybrid genotype INRA 717-1B4, used for a comparison of transcript abundance between poplar species was grown under the same conditions as those described above. Poplar whole-genome oligonucleotide microarrays. This study was based on hybridizations to whole-genome microarrays containing features representing 42,364 predicted transcriptional units from the P. trichocarpa nuclear genome. All transcriptional units were represented by three 60-mer probes, designed by NimbleGen (Madison, WI) in collaboration with Oak Ridge National Laboratory and were synthesized using maskless lithography. cRNA was synthesized from total RNA extracted from individual plants. Labeling, hybridization and scanning were carried out by NimbleGen (Madison, WI) using standard procedures.
Project description:In Populus, the transcripts of fasciclin-like arabinogalactan proteins (FLAs) are accumulated in tension wood (TW) xylem, however their biological functions in TW formation are largely unknown. In this work, we demonstrated that PtFLA6, one of poplar TW-associated PtFLAs, was abundantly expressed in TW, and mainly localized in differentiating G-fibers. The bended stems of PtFLA6 antisense transgenic poplar showed decreased transcripts of PtFLAs, including PtFLA6, and reduced PtFLA6 like proteins, leading to inhibited TW differentiation and formation. We also showed that gibberellin A3 (GA3) was enriched in the xylem of TW side, accompanied with a lowered level of PtRGA1, a poplar DELLA protein. When GA3 biosynthesis was restrained in the bended poplar stems by a GA biosynthesis inhibitor (daminozide), TW formation was obviously repressed, as a result of restricted PtRGA1 degradation, and reduced PtFLA6 like proteins and PtFLA expression. Further studies indicated that PtFLAs were negatively regulated by PtRGA1. This study suggests that PtFLAs play important roles in the poplar TW formation, possibly regulated by GA signaling.