Project description:Genetic changes involved in the juvenile-to-adult transition in the shoot apex of Olea europaea L. occurs years before the first flowering.
Project description:Flowering of several plant species is induced by exposure to specific photoperiods that promote the expression of florigenic proteins in the leaves and their subsequent translocation to the shoot apex, where they commit the meristem to a reproductive fate. Transition to reproductive growth at the apex is often accompanied by stem elongation, to expose flowers above the leaves and facilitate fertilization. However, how growth and inflorescence formation are coupled and how photoperiodic signals coordinate these processes at the apex is still unclear. We studied these mechanisms in rice, a short day plant. Here, we show that HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1), encoding components of the rice florigenic signal, are sufficient to repress expression of PREMATURE INTERNODE ELONGATION 1 (PINE1) at the shoot apex during the transition to flowering, thus promoting culm elongation. PINE1 encodes a nuclear C2H2 zinc finger transcriptional repressor that controls the mRNA abundance of GA3ox2, a gibberellin (GA) biosynthetic gene. These data uncover the existence of a regulatory network coordinating multiple aspects of phase transition, and indicate that GA-induced growth and activity of florigenic proteins at the shoot apex need to be strictly coupled.
Project description:Plants grow continuously and undergo numerous changes in their vegetative morphology and physiology during their life span. The molecular basis of these changes is largely unknown. To provide a more comprehensive picture of shoot development in Arabidopsis, microarray analysis was used to profile the mRNA content of shoot apices of different ages, as well as leaf primordia and fully-expanded leaves from 6 different positions on the shoot, in early-flowering and late-flowering genotypes. This extensive dataset provides a new and unexpectedly complex picture of shoot development in Arabidopsis. At any given time, the pattern of gene expression is different in every leaf on the shoot, and reflects the activity at least 6 developmental programs. Three of these are specific to individual leaves (leaf maturation, leaf aging, leaf senescence), two occur at the level of the shoot apex (vegetative phase change, floral induction), and one involves the entire shoot (shoot aging). Our results demonstrate that vegetative development is a much more dynamic process that previously imagined, and provide new insights into the underlying mechanism of this process.
Project description:We take the two year old plant for sampling.Use the Affymetrix poplar gene chip to elucidate the gene functions and mechanisms in Populus tomentosa shoot apex and mature xylem. We used microarrays to detail the global programme of gene expression in shoot apex and mature xylem. Populus tomentosa shoot apex and mature xylem were taken for RNA extraction and hybridization on Affymetrix microarrays.CB2009304-C and CB2009304-D from shoot apex, CB2009304-G and CB2009304-H from mature xylem.
Project description:We take the two year old plant for sampling.Use the Affymetrix poplar gene chip to elucidate the gene functions and mechanisms in Populus tomentosa shoot apex and mature xylem. We used microarrays to detail the global programme of gene expression in shoot apex and mature xylem.
Project description:The timing of reproductive development determines spike architecture and thus yield in temperate grasses such as barley (Hordeum vulgare L.). Reproductive development in barley is controlled by the photoperiod response gene Ppd-H1 which accelerates flowering time under long-day (LD) conditions. A natural mutation in Ppd-H1 prevalent in spring barley causes a reduced photoperiod response, and thus, late flowering under LD. However, it is not very well understood how LD and Ppd-H1 control pre-anthesis development, and thus spike architecture and yield in barley. We performed a detailed morphological analysis of the pre-anthesis development in the spring barley cultivar Scarlett and its wild barley derived introgression line S42-IL107, carrying the photoperiod responsive Ppd-H1 allele. Characterization of shoot apex development in these genotypes indicated that floral transition and initiation of floral primordia occurred under LD (16h light/ 8h dark) and short day (SD, 8h light/ 16h dark) conditions, while inflorescence and seed development strictly required LDs. Additionally, a fast photoperiod response in the presence of the dominant Ppd-H1 allele promoted floret fertility under LDs. To characterize the effects of the photoperiod and allelic variation at Ppd-H1 on gene expression during pre-anthesis development we performed RNA sequencing of leaves and developing main shoot apices during the vegetative phase and early stages of inflorescence development in Scarlett and S42-IL107 grown under SD and LD conditions. Main shoot apices of both genotypes were sampled at defined developmental stages, i.e. Waddington stage W0.5, W1.0, W2.0 and W3.5, respectively. Leaf samples were harvested from plants before (W1.0) and after floral transition (W2.0). We identified genes that were specifically regulated at floral transition independent of day-length and Ppd-H1 and thus may serve as markers for the staging of floral transition. Furthermore, we identified transcripts differentially expressed between photoperiods and between genotypes in leaves and in shoot apices. This set of transcripts might act as candidates downstream of Ppd-H1 and are correlated with the promotion of shoot apex development and higher floret fertility under LD and in the presence of the photoperiod responsive Ppd-H1 allele.
Project description:HB21 is a homeodomain leucine zipper transcription factor involved in the establishment of bud axillary dormancy. In this work we have characterized the role of HB21 in the control of the inflorescence arrest at the end of flowering. HB21, together with HB40 and HB53, are upregulated in the inflorescence apex at the end of the flowering phase promoting the floral bud arrest associated with the process. We also show that ABA accumulation occurs in the inflorescence apex at the end of flowering in physiological conditions, and that this accumulation depends on HB genes. Our work has allowed us to propose a physiological role of ABA in the control of floral bud arrest at the end of flowering