Transcriptome dynamics during adventitious root formation in cuttings of Cryptomeria japonica D.Don
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ABSTRACT: To reveal transcriptome dynamics during adventitious root formation in a coniferous tree, C. japonica, we conducted custom microarry experiments. Three parts from cuttings of easy-to-root clone of C. japonica were collected at eight time points during adventitious root formation. The results revealed major turning points on transcriptome toward adventitious root formation and the expression behavior of genes related to carbohydrate, plant hormone and others suggested the important biological changes for adventitious root formation.
Project description:In order to identify genes specifically induced during various developmental stages of Adventitious Root (AR) formation (described in Ahkami et al. 2009) in leafy cuttings of Petunia hybrida (line W115) and to describe the series of physiological processes during adventitious rooting, a microarray-based transcriptome analysis in the stem base of the cuttings was conducted. The microarray was described by Breuillin et al. (2010) and included a normalized cDNA library from different time points after taking the cuttings from mother plant. Because physiological processes and molecular changes specifically involved in AR formation were considered as of major interest, rather than those associated with wound responses, a filtration approach was chosen to eliminate primarily wound-responsive genes. This study is mainly focused on changes in transcript abundances of genes related to specific metabolic pathways or cellular events including primary metabolism, membrane transport, cell division or signalling during various phases of AR formation.
Project description:We analysed the expression profile of genes involved in adventitious root formation in carnation cuttings in response to exogenous auxin.
Project description:In order to identify genes specifically induced during various developmental stages of Adventitious Root (AR) formation (described in Ahkami et al. 2009) in leafy cuttings of Petunia hybrida (line W115) and to describe the series of physiological processes during adventitious rooting, a microarray-based transcriptome analysis in the stem base of the cuttings was conducted. The microarray was described by Breuillin et al. (2010) and included a normalized cDNA library from different time points after taking the cuttings from mother plant. Because physiological processes and molecular changes specifically involved in AR formation were considered as of major interest, rather than those associated with wound responses, a filtration approach was chosen to eliminate primarily wound-responsive genes. This study is mainly focused on changes in transcript abundances of genes related to specific metabolic pathways or cellular events including primary metabolism, membrane transport, cell division or signalling during various phases of AR formation. The overall design of the custom microarray used in this study is described in Breuillin et al. (2010). In brief, a database of 24,816 unigene sequences (including 4,700 ESTs from P. hybrida cutting base and all public available P. hybrida and P. axillaris sequences) was used for construction of a custom microarray.
Project description:Cell totipotency and pluripotency are the cellular basis for root regeneration in Platycladus orientalis cuttings, and the regeneration of adventitious roots is a key determinant for improving stem-cutting. However, the cellular basis and physiological regulation of adventitious root formation are still ambiguous. In this work, root primordia initiation and organogenesis were histologically observed, dynamic alterations in soluble proteins were monitored, and Tandem Mass Tag protein profiling during adventitious root development was carried out.
Project description:We investigated root associated fungi in young Norway spruce (Picea abies) cuttings rooted from slow- and fast-growing trees showing variable growth rate in long-term field experiments and compared their roots’ gene expression patterns five and 18 months after adventitious root initiation. Gene expression patterns of adventitious roots could not be systematically linked with the growth phenotype at the initiation of root formation, and thus fundamental differences in the receptiveness of fungal symbionts could not be assumed.
Project description:The loss of rooting capability following the transition from the juvenile to the mature phase is a known phenomenon in woody plant development. Eucalyptus grandis was used here as a model system to study the differences in gene expression between juvenile and mature cuttings. RNA was prepared from the base of the two types of cuttings before root induction and hybridized to a DNA microarray of E. grandis. In juvenile cuttings, 363 transcripts were specifically upregulated, enriched in enzymes of oxidation/reduction processes. In contrast, in mature cuttings, 245 transcripts were specifically upregulated, enriched in transcription factors involved in the regulation of secondary metabolites. A gene encoding for nitrate reductase (NIA), an enzyme that is known to be involved in nitric oxide (NO) production, was among the genes that were upregulated in juvenile cuttings. Concomitantly, a transient burst of NO upon excision was higher in juvenile cuttings than in mature ones. Treatment with a NO donor improved rooting of both juvenile and mature cuttings. A single NIA gene was found in the newly released E. grandis genome sequence, the cDNA of which was isolated, overexpressed in Arabidopsis plants and shown to increase NO production. Therefore, higher levels of NIA in E. grandis juvenile cuttings might lead to their better ability to produce NO and form adventitious roots. The Arabidopsis transgenic plants did not exhibit significantly increased lateral or adventitious roots, suggesting that spatial and temporal rather than a constitutive increase in NO is favorable for root formation.
Project description:The loss of rooting capability following the transition from the juvenile to the mature phase is a known phenomenon in woody plant development. Eucalyptus grandis was used here as a model system to study the differences in gene expression between juvenile and mature cuttings. RNA was prepared from the base of the two types of cuttings before root induction and hybridized to a DNA microarray of E. grandis. In juvenile cuttings, 363 transcripts were specifically upregulated, enriched in enzymes of oxidation/reduction processes. In contrast, in mature cuttings, 245 transcripts were specifically upregulated, enriched in transcription factors involved in the regulation of secondary metabolites. A gene encoding for nitrate reductase (NIA), an enzyme that is known to be involved in nitric oxide (NO) production, was among the genes that were upregulated in juvenile cuttings. Concomitantly, a transient burst of NO upon excision was higher in juvenile cuttings than in mature ones. Treatment with a NO donor improved rooting of both juvenile and mature cuttings. A single NIA gene was found in the newly released E. grandis genome sequence, the cDNA of which was isolated, overexpressed in Arabidopsis plants and shown to increase NO production. Therefore, higher levels of NIA in E. grandis juvenile cuttings might lead to their better ability to produce NO and form adventitious roots. The Arabidopsis transgenic plants did not exhibit significantly increased lateral or adventitious roots, suggesting that spatial and temporal rather than a constitutive increase in NO is favorable for root formation. E. grandis seedlings were grown from seeds to the age of 6-7 months. The seedlings were pruned either at 10-15 cm or at 150-200 cm above the ground. The newly developed shoots were used as cuttings. To induce rooting, auxin (6000 ppm of K-IBA), was applied by quick dipping (20 sec). Stem cuttings taken from low-pruned seedlings were found to be easy-to root, exhibiting 45% rooting after 14 days and 60% after 35 days. These cuttings were defined as juvenile (RNA from two biological replicates was extracted). In contrast, stem cuttings taken from high pruned seedlings, barely rooted (5%) after 35 days, and were defined as mature (RNA from two biological replicates was extracted). The two biological replicates was used to dye swap experimental design.
Project description:Adventitious root formation at the base of plant cuttings is an innate de novo organogenesis process that allows massive vegetative propagation of many economically and ecologically important species. The early molecular events following shoot excision are not well understood. Using whole-genome microarrays, we detected significant transcriptome remodeling during 48 hours following shoot removal in Populus softwood cuttings in the absence of exogenous auxin, with 27% and 36% of the gene models showing differential abundance between 0 and 6 hours, and 6 and 24 hours, respectively. During these two time intervals, gene networks involved in protein turnover, protein phosphorylation, molecular transport and translation were among the most significantly regulated. Transgenic lines expressing a constitutively active form of the Populus type-B response regulator PtRR13 (ΔDDKPtRR13) have a delayed rooting phenotype and cause misregulation of COV1, a negative regulator of vascularization; PDR9, an auxin efflux transporter; two AP2/ERF genes with sequence similarity to TINY1. Cytokinin action appeared to disrupt root development 24 hours after shoot excision, when root founder cells are hypothesized to be sensitive to the negative effects of cytokinin. Our results suggest that PtRR13 acts downstream of cytokinin to repress adventitious root formation in intact plants, and that reduced cytokinin signaling after shoot excision enables coordinated expression of ethylene, auxin and vascularization pathways leading to adventitious root development.