Project description:In plants, juvenile to adult phase transition is regulated by the sequential activity of two microRNAs: miR156 and miR172. A decline in miR156 and increase in miR172 abundance is associated with phase transition. There is very limited information on phase transition in economically important horticultural tree crops, which have a significantly long vegetative phase affecting fruit bearing. Here we profiled various molecular cues known to be involved in phase transition and flowering, including the microRNAs miR156 and miR172, in three horticultural tree crops avocado (Persea americana), mango (Mangifera indica) and macadamia (Macadamia integrifolia). We observed that miR156 expression decreases as these trees age and can potentially be used as a juvenility marker. Consistent with findings in annual plants, we also observed conserved regulation of the miR156-SPL3/4/5 regulatory module in these genetically distant tree crops, suggesting that this pathway may play a highly conserved role in vegetative identity. Meanwhile, the abundance of miR172 and its target AP2-like genes, as well as the accumulation level of SPL9 transcripts, were not related with plant age in these crops except in avocado where miR172 expression increased steadily. Finally, we demonstrate that various floral genes, including AP1 and SOC1 were upregulated in the reproductive phase and can be used as potential markers for the reproductive phase transition. Overall, this study provides an insight into the molecular associations of juvenility and phase transition in horticultural trees where crop breeding and improvement is encumbered by long juvenile phases.
Project description:In plants, juvenile to adult phase transition is regulated by the sequential activity of two microRNAs: miR156 and miR172. A decline in miR156 and increase in miR172 abundance is associated with phase transition. There is very limited information on phase transition in economically important horticultural tree crops, which have a significantly long vegetative phase affecting fruit bearing. Here, we profiled various molecular cues known to be involved in phase transition and flowering, including the microRNAs miR156 and miR172, in three horticultural tree crops: avocado (Persea americana), mango (Mangifera indica), and macadamia (Macadamia integrifolia). We observed that miR156 expression decreases as these trees age and can potentially be used as a juvenility marker. Consistent with findings in annual plants, we also observed conserved regulation of the miR156-SPL3/4/5 regulatory module in these genetically distant tree crops, suggesting that this pathway may play a highly conserved role in vegetative identity. Meanwhile, the abundance of miR172 and its target AP2-like genes as well as the accumulation level of SPL9 transcripts were not related with plant age in these crops except in avocado where miR172 expression increased steadily. Finally, we demonstrate that various floral genes, including AP1 and SOC1 were upregulated in the reproductive phase and can be used as potential markers for the reproductive phase transition. Overall, this study provides an insight into the molecular associations of juvenility and phase transition in horticultural trees where crop breeding and improvement are encumbered by long juvenile phases.
Project description:Genome-wide transcriptome analysis was performed to understand the expression pattern of transcriptomes in tolerant and susceptible subtropical maize genotypes under water deficit stress condition.<br><br>
Project description:SVP is a key MADS-box transcription factor for Arabidopsis development since it acts both during vegetative and reproductive phases where it plays different roles probably by interacting with different partners to regulate specific sets of target genes. In fact, whereas SVP functions as a repressor of floral transition during the vegetative phase, it works as floral meristem gene during reproductive phase. We studied the behavior of SVP during two distinct developmental phases: the vegetative and reproductive phase. The aim of these studies is to identify subsets of genes that are regulated by SVP by means of Arabidopsis Tiling 1.0R Arrays (Affymetrix) during the two distinct phases of development.
Project description:Background and aimsVegetative storage proteins (VSPs) are commonly bioactive in herbaceous plants but few VSPs with bioactivity have been identified in trees. In addition, information on the characterization of VSPs in evergreen trees is limited. The objective of this study was to characterize the VSPs with bioactivity in evergreen trees. Methods The VSP in lychee (Litchi chinensis), an evergreen fruit tree, was characterized by a combination of cytological, biochemical and molecular biological techniques.Key resultsThe VSP in lychee was a 22-kDa protein. It accumulated in the large central vacuoles of protein-storing cells (PSCs) in two distinguishable forms, granular and floccular. The PSCs were of a novel type. The 22-kDa protein is distributed in mature leaves, bark tissues of branches, trunk and large roots, paralleling the distribution of PSCs. Its homologues were present in mature seed. During young shoot development and fruiting, the 22-kDa protein decreased apparently, suggesting a nitrogen-storage function. The 22-kDa protein had several isoforms encoded by a small multigene family. One gene member, LcVSP1, was cloned. The LcVSP1 had no intron and contained a 675 bp open reading frame encoding a putative protein of 225 amino acids. LcVSP1 was homologous to Kunitz trypsin inhibitors. The 22-kDa protein inhibited trypsin and chymotrypsin, but had no inhibitory effect on subtilisin.ConclusionsLychee is rich in a 22-kDa VSP with trypsin inhibitor activity. The VSP plays an important role in nitrogen storage while its possible defensive function remains to be elucidated.
Project description:Vegetative phase change is the developmental transition from the juvenile phase to the adult phase during which a plant becomes competent for sexual reproduction. Gain of ability to flower is often accompanied by changes in patterns of differentiation in newly forming vegetative organs. In maize, juvenile leaves differ from adult leaves in morphology, anatomy, and cell wall composition. Whereas the normal sequence of juvenile followed by adult is repeated with every sexual generation, this sequence can be altered in maize by the isolation and culture of the shoot apex from an adult phase plant; an “adult” meristem so treated reverts to forming juvenile vegetative organs. To investigate the molecular differences between the juvenile and adult phases in maize comparisons among two juvenile samples, leaf 4 and culture-derived leaf 3 or 4, and an adult sample (leaf 9) were made using cDNA microarrays. All samples were leaf primordia at plastochron 6. A gene was scored as “phase specific” if it was up- (or down-) regulated in both juvenile samples compared to the adult sample with at least a twofold-change in gene expression at P-value less than or equal to 0.005. Some 221 ESTs up-regulated in juvenile and 28 ESTs up-regulated in adult were identified. Altered patterns of expression of selected ESTs in the phase change mutants Tp2, d1 and gl15 further confirmed these genes as being phase-specific and allowed us to position these genes in the known genetic hierarchy regulating phase change. Keywords: Transcript profiling among seed-derived juvenile leaf 4 and adult leaf 9 and culture-rejuvenated leaf 3 or 4 in maize