Project description:The plant height is an important trait in fruit tree. However, the molecular mechanism on dwarfism is still poorly understood. We found that colchicine-induced autotetraploid apple plants (Malus × domestica) exhibited a dwarf phenotype. The vertical length of cortical parenchyma cells was shorter in autotetraploids than in diploids, by observing paraffin sections. Hormone levels of indoleacetic acid (IAA) and brassinosteroid (BR) were significantly decreased in 3- and 5-year-old autotetraploid plants. Digital gene expression (DGE) analysis showed that the differentially expressed genes were mainly involved in IAA and BR pathways. microRNA390 was significantly upregulated according to microarray analysis. Exogenous application of IAA and BR promoted stem elongation of both apple plants grown in medium. The results show that dwarfing in autotetraploid apple plants is most likely regulated by IAA and BR. The dwarf phenotype of autotetraploid apple plants could be due to accumulation of miR390 after genome doubling, leading to upregulation of apple trans-acting short-interfering RNA 3 (MdTAS3) expression, which in turn downregulates the expression of MdARF3. Overall, this leads to partial interruption of the IAA and BR signal transduction pathway. Our study provides important insights into the molecular mechanisms underlying dwarfism in autopolyploid apple plants.
Project description:Bud dormancy is a critical developmental process for perennial plant survival, and also an important physiological phase that affects the next season’s growth of temperate fruit trees. Bud dormancy is regulated by multiple genetic factors, and affected by various environmental factors, tree age and vigor. To understand molecular mechanism of bud dormancy in Japanese apricot (Prunus mume Sieb. et Zucc.), we constructed a custom oligo DNA microarray covering the Japanese apricot dormant bud ESTs referring to peach (P. persica) genome sequence. Because endodormancy release is a chilling temperature-dependent physiological event, genes showing chilling-mediated differential expression patterns are candidates to control endodormancy release. Using the microarray constructed in this study, we monitored gene expression changes of dormant vegetative buds of Japanese apricot during prolonged artificial chilling exposure. In addition, we analyzed seasonal gene expression changes. ‘Nanko’ vegetative buds collected in November, and those exposed to chilling for 40 or 60 days were used as microarray samples. Among the 58539 different unigene probes, 2345 and 1059 genes were identified as being more than two-fold up-regulated and down-regulated, respectively, following chilling exposure for 60 days (P value < 0.05). The down-regulated genes included P. mume DORMANCY-ASSOCIATED MADS-box genes, which supported the previous quantitative RT-PCR and EST analyses showing that these genes are repressed by prolonged chilling treatments. The genes encoding lipoxygenase were remarkably up-regulated by prolonged chilling. Cluster analysis suggested that the expression of the genes showing expression changes by artificial chilling exposure were coordinately regulated by seasonal changes. Our parametric analysis of gene set enrichment suggested that genes related to jasmonic acid (JA) and oxylipin biosynthesis and metabolic processes were significantly up-regulated by prolonged chilling, whereas genes related to circadian rhythm were significantly down-regulated. The results obtained from the microarray analyses were verified by quantitative RT-PCR analysis of selected genes. Taken together, this study raised the possibility that the microarray platform constructed in this study is applicable for deeper understanding of molecular network related to agronomically important bud phisiologies including dormancy release.
Project description:Plant form is shaped by a complex network of intrinsic and extrinsic signals. Light-directed growth of seedlings (photomorphogenesis) depends on the coordination of several hormone signals, including brassinosteroids (BRs) and auxin. Although the close relationship between BRs and auxin has been widely reported, the molecular mechanism for combinatorial control of shared target genes has remained elusive. Here we demonstrate that BRs synergistically increase seedling sensitivity to auxin and show that combined treatment with both hormones can increase the magnitude and duration of gene expression. Moreover, we describe a direct connection between the BR-regulated BIN2 kinase and ARF2, a member of the Auxin Response Factor family of transcriptional regulators. Phosphorylation by BIN2 results in loss of ARF2 DNA binding and repression activities. arf2 mutants are less sensitive to changes in endogenous BR levels, whereas a large proportion of genes affected in an arf2 background are returned to near wild-type levels by altering BR biosynthesis. Together, these data suggest a model where BIN2 increases expression of auxin-induced genes by directly inactivating repressor ARFs, leading to synergistic increases in transcription.
Project description:Bud dormancy is a critical developmental process for perennial plant survival, and also an important physiological phase that affects the next seasonM-bM-^@M-^Ys growth of temperate fruit trees. Bud dormancy is regulated by multiple genetic factors, and affected by various environmental factors, tree age and vigor. To understand molecular mechanism of bud dormancy in Japanese apricot (Prunus mume Sieb. et Zucc.), we constructed a custom oligo DNA microarray covering the Japanese apricot dormant bud ESTs referring to peach (P. persica) genome sequence. Because endodormancy release is a chilling temperature-dependent physiological event, genes showing chilling-mediated differential expression patterns are candidates to control endodormancy release. Using the microarray constructed in this study, we monitored gene expression changes of dormant vegetative buds of Japanese apricot during prolonged artificial chilling exposure. In addition, we analyzed seasonal gene expression changes. M-bM-^@M-^XNankoM-bM-^@M-^Y vegetative buds collected in November, and those exposed to chilling for 40 or 60 days were used as microarray samples. Among the 58539 different unigene probes, 2345 and 1059 genes were identified as being more than two-fold up-regulated and down-regulated, respectively, following chilling exposure for 60 days (P value < 0.05). The down-regulated genes included P. mume DORMANCY-ASSOCIATED MADS-box genes, which supported the previous quantitative RT-PCR and EST analyses showing that these genes are repressed by prolonged chilling treatments. The genes encoding lipoxygenase were remarkably up-regulated by prolonged chilling. Cluster analysis suggested that the expression of the genes showing expression changes by artificial chilling exposure were coordinately regulated by seasonal changes. Our parametric analysis of gene set enrichment suggested that genes related to jasmonic acid (JA) and oxylipin biosynthesis and metabolic processes were significantly up-regulated by prolonged chilling, whereas genes related to circadian rhythm were significantly down-regulated. The results obtained from the microarray analyses were verified by quantitative RT-PCR analysis of selected genes. Taken together, this study raised the possibility that the microarray platform constructed in this study is applicable for deeper understanding of molecular network related to agronomically important bud phisiologies including dormancy release. In this study, we used chilling exposed bud samples (0, 40, 60 days starting at November) and seasonal monthly bud samples (June to March). For the samples in dataset 1 (three different time points during chilling treatment), three technical replicates (60K M-CM-^W 3 per sample) with three biological replicates were averaged, whereas three technical replicates were averaged for the samples in dataset 2 (10 different seasonal time points)
Project description:Prunus mume (mei), which was domesticated in China more than 3,000 years ago as ornamental plant and fruit, is one of the first genomes among Prunus subfamilies of Rosaceae been sequenced. Here, we assemble a 280M genome by combining 101-fold next-generation sequencing and optical mapping data. We further anchor 83.9% of scaffolds to eight chromosomes with genetic map constructed by restriction-site-associated DNA sequencing. Combining P. mume genome with available data, we succeed in reconstructing nine ancestral chromosomes of Rosaceae family, as well as depicting chromosome fusion, fission and duplication history in three major subfamilies. We sequence the transcriptome of various tissues and perform genome-wide analysis to reveal the characteristics of P. mume, including its regulation of early blooming in endodormancy, immune response against bacterial infection and biosynthesis of flower scent. The P. mume genome sequence adds to our understanding of Rosaceae evolution and provides important data for improvement of fruit trees.
Project description:Brassinosteroids (BRs) regulate plant growth and stress responses via the BES1/BZR1 family of transcription factors, which regulate the expression of thousands of downstream genes. BRs are involved in the response to drought, however the mechanistic understanding of interactions between BR signalling and drought response remains to be established. Here we show that transcription factor RD26 mediates crosstalk between drought and BR signalling. When overexpressed, BES1 target gene RD26 can inhibit BR-regulated growth. Global gene expression studies suggest that RD26 can act antagonistically to BR to regulate the expression of a subset of BES1-regulated genes, thereby inhibiting BR function. We show that RD26 can interact with BES1 protein and antagonize BES1 transcriptional activity on BR-regulated genes and that BR signalling can also repress expression of RD26 and its homologues and inhibit drought responses. Our results thus reveal a mechanism coordinating plant growth and drought tolerance.
Project description:We have sequenced a wild Prunus mume and constructed a reference sequence for this genome. In order to improve quality of gene models, RNA samples of five tissues (bud, leaf, root, stem, fruit) were extracted from the Prunus mume. To investigate tissue specific expression using the reference genome assembly and annotated genes, we extracted RNA samples of different tissues and conducted transcriptome sequencing and DEG analysis.