Project description:Auxin and cytokinin can regulate callus formation from developed plant organs and shoot regeneration from callus. The regulation of dedifferentiation and regeneration of plant cells by auxin and cytokinin stimulation was considered to be caused by the regulation of reprograming of callus cells, but the hypothesis had been argued still in now. Although elucidation of the regulatory mechanisms of callus formation and shoot regeneration has helped advance plant biotechnology research, many plant species are intractable to transformation because of difficulties with callus regulation. In this study, we identified the compound Fipexide (FPX) as a useful regulatory compound through chemical biology-based screening. Compared with the activity of auxin and cytokinin, FPX showed higher efficiency as a chemical inducer in callus formation, shoot regeneration, and Agrobacterium infection. In regards to morphology, the cellular organization of FPX-induced callus differed from that produced under auxin/cytokinin conditions. According to a microarray analysis, the expressions of approximately 971 genes were two-fold up-regulated by FPX treatment for 2 days. Among these genes, 598 genes were also induced by auxin/cytokinin, while 373 genes, including metabolic regulation-related genes, were specifically expressed only under FPX treatment. FPX can promote callus formations in rice, poplar, and several vegetables. FPX should be a useful tool to reveal unknown mechanisms of plant development and to increase the number of transgenic plant species.
Project description:Auxin and cytokinin can regulate callus formation from developed plant organs and shoot regeneration from callus. The regulation of dedifferentiation and regeneration of plant cells by auxin and cytokinin stimulation was considered to be caused by the regulation of reprograming of callus cells, but the hypothesis had been argued still in now. Although elucidation of the regulatory mechanisms of callus formation and shoot regeneration has helped advance plant biotechnology research, many plant species are intractable to transformation because of difficulties with callus regulation. In this study, we identified the compound Fipexide (FPX) as a useful regulatory compound through chemical biology-based screening. Compared with the activity of auxin and cytokinin, FPX showed higher efficiency as a chemical inducer in callus formation, shoot regeneration, and Agrobacterium infection. In regards to morphology, the cellular organization of FPX-induced callus differed from that produced under auxin/cytokinin conditions. According to a microarray analysis, the expressions of approximately 971 genes were two-fold up-regulated by FPX treatment for 2 days. Among these genes, 598 genes were also induced by auxin/cytokinin, while 373 genes, including metabolic regulation-related genes, were specifically expressed only under FPX treatment. FPX can promote callus formations in rice, poplar, and several vegetables. FPX should be a useful tool to reveal unknown mechanisms of plant development and to increase the number of transgenic plant species.
Project description:The applications of plant callus regeneration has been widely spreaded in agricultural improvement. By using immature sorghum embryos as explants, progress in successful genetic transformation has been made in sorghum. However, the underlying mechanism of callus differentiation is still largely unknown in sorghum. Here, we described three types of callus with different abilities of redifferentiation (Callus I-III), undergoing distinct induction from immature embryo in the variety of Hiro-1. In comparison to the non-embryonic Callus III who lost the ability of regeneration, the Callus I produced only some characterized adventitious roots and the embryonic Callus II is sufficient to regenerate whole plants. Genome-wide transcriptome profiles were performed to reveal the underlying mechenisms. The numbers of differentially expressed genes for the three types of callus vary from 5906 to 8029. Principal component analysis analysis demonstrated that gene expression patterns of Callus I and II were totally different from that of Callus III and differential leaves from Callus II, indicating that the compassions of Callus I and II provide clues for revealing regulations of regeneration in sorghum callus. Notably, KEGG and GO analysis showed that plant ribosome, lignin metabolic process, and metabolism of starch and sucrose are main processes that are associated with callus differentiation. Taken together, the results contributed the elucidation of molecular regulation in three types of callus with several regeneration abilities in sorghum.
Project description:Purpose: Maize somatic embryogenesis is usually required to achieve genetic transformation and represents an important alternative in plant development. Although many embryogenesis-related genes have been studied in this model, the molecular mechanisms underlying cell dedifferentiation and further plant regeneration are not completely understood. Methods: Immature embryos smRNA profiles of 15-day-after-pollination (IE) and Embryogenic Callus from one (C1), four (C4), and ten months (C10) were generated by deep sequencing, using Illumina GAIIx. The sequence reads that passed quality filters were analyzed with two methods: Bowtie 1.1.2 and ShortStack 3.4. qRT–PCR validation for selected miRNAs was performed using SYBR Green assays. Results: We used high throughput sequencing to explore the sRNA populations during maize embryogenic callus induction and established subcultures from the Mexican cultivar VS-535, Tuxpeño landrace. We detected readjustments in 24 nt and 21-22 nt sRNA populations during the embryogenic callus establishment and maintenance. miRNAs related to stress response substantially increased upon callus proliferation establishment, correlating with a reduction in some of their target levels. On the other hand, while 24 nt-long hc-siRNAs derived from transposable retroelements transiently decreased in abundance during the embryogenic callus establishment, a population of 22 nt- hc-siRNAs increased. This was accompanied by reduction in transposon expression in the established callus subcultures. Conclusions: Stress- and development-related miRNAs are highly expressed upon maize EC callus induction and during maintenance subcultures, while miRNAs involved in hormone response only transiently increase during induction. The establishment of proliferative maize embryogenic callus is accompanied by important readjustments in the length of hc-siRNAs mapping to LTR retrotransposons, and their expression regulation.
Project description:Plant regeneration could be achieved via formation of a pluripotent cell mass termed callus, nature of which is a group of fast-dividing root primordium cells. However, mechanisms that strictly control the stem cell fate transition in regeneration of callus remain elusive. Here we show that the Arabidopsis ISWI type chromatin remodelers specifically promote the second-step cell fate transition from root founder cells to root primordium cells in the leaf-to-callus transition.
Project description:The formation of vascular tissue occurs when cellulose, hemicellulose, lignin and other wall components are deposited within the primary cell wall. These secondary thickened cells then undergo programmed cell death producing a network of empty cells with which water and ions can be transported throughout the plant. The hormones auxin and cytokinin are the principle signals for vascular tissue initiation. As a consequence cells cultured in-vitro can be converted into vascular tissue with the addition of exogenous auxin and cytokinin. We have created an in-vitro cell system, using callus produced from leaves that can be induced to form vascular tissue. Leaves are callused on induction media for two weeks. The callus is then transferred to liquid media and incubated under optimum conditions resulting in an increase in vascular tissue formation. Approximately 20% of cells will differentiate during the incubation period. The alteration of cytokinin concentration affects the ability of the cultured cells to undergo differentiation. Consequently callus incubated in liquid media, containing lower cytokinin concentrations, will undertake relatively little differentiation. Samples have been isolated from cell cultures at different time points and different hormone concentrations during incubation. Quantitative PCR using the marker AtCesA7, which encodes a cellulose synthase subunit specific to secondary wall deposition, was used as a guide to determine periods of high and low vascular differentiation. This system provides an opportunity to compare gene expression between differentiating and non differentiating cells and allow the identification of genes up regulated during vascular tissue formation.
Project description:Arabidopsis thaliana plant expressing 35S:WIND1 shows callus-like morphology without hormone treatment. Transcriptomes of the callus-like cell expressing 35S:WIND1, callus of T87 cultured cell, 2,4-D-induced callus and control seedling plant were compared by Agilent microarray.