Gibberellic Acid Signaling Research Articles

The novel transcription factor TRP interacts with ZFP5, a trichome initiation-related transcription factor, and negatively regulates trichome initiation through gibberellic acid signaling.

The trichome-related protein (TRP) is a novel transcription factor (TF) that negatively regulates trichome initiation-related TFs through gibberellin (GA) signaling. Trichomes, which are outgrowths of leaf epidermal cells, provide the plant with a first line of defense against damage from herbivores and reduce transpiration. The initiation and development of trichomes are regulated by a network of positively or negatively regulating transcription factors (TFs). However, little information is currently available on transcriptional regulation related to trichome formation. Here, we report a novel TF Trichome-Related Protein (TRP) that was observed to negatively regulate the trichome initiation-related TFs through gibberellic acid (GA) signaling. ProTRP:GUS revealed that TRP was only expressed in the trichome. The TRP loss-of-function mutant (trp) had an increased number of trichomes on the flower, cauline leaves, and main inflorescence stems compared to the wild-type. In contrast, TRP overexpression lines (TRP-Ox) exhibited a decreased number of trichomes on cauline leaves and main inflorescence stem following treatment with exogenous GA. Moreover, the expressions of trichome initiation regulators (GIS, GIS2, ZFP8, GL1, and GL3) increased in trp plants but decreased in TRP-Ox lines after GA treatment. TRP was observed to physically interact with ZFP5, a C2H2 TF that controls trichome cell development through GA signaling, both in vivo and in vitro. Based on these results, we suggest that TRP functions upstream of the trichome initiation regulators and represses the binding of ZFP5 to the ZFP8 promoter.

Transcriptome assembly in Suaeda aralocaspica to reveal the distinct temporal gene/miRNA alterations between the dimorphic seeds during germination

BackgroundDimorphic seeds from Suaeda aralocaspica exhibit different germination behaviors that are thought to be a bet-hedging strategy advantageous in harsh and unpredictable environments. To understand the molecular mechanisms of Suaeda aralocaspica dimorphic seed germination, we applied RNA sequencing and small RNA sequencing for samples collected at three germination stages.ResultsA total of 79,414 transcripts were assembled using Trinity, of which 57.67% were functionally annotated. KEGG enrichment unveiled that photosynthesis and flavonol biosynthesis pathways were activated earlier in brown seed compared with black seed. Gene expression analysis revealed that nine candidate unigenes in gibberellic acid and abscisic acid signal transduction and 23 unigenes in circadian rhythm-plant pathway showed distinct expression profiles to promote dimorphic seed germination. 194 conserved miRNAs comprising 40 families and 21 novel miRNAs belonging to 20 families in Suaeda aralocaspica were identified using miRDeep-P and Mfold. The expression of miRNAs in black seed was suppressed at imbibition stage. Among the identified miRNAs, 59 conserved and 13 novel miRNAs differentially expressed during seed germination. Of which, 43 conserved and nine novel miRNAs showed distinct expression patterns between black and brown seed. Using TAPIR, 208 unigenes were predicted as putative targets of 35 conserved miRNA families and 17 novel miRNA families. Among functionally annotated targets, genes participated in transcription regulation constituted the dominant category, followed by genes involved in signaling and stress response. Seven of the predicted targets were validated using 5′ rapid amplification of cDNA ends or real-time quantitative reverse transcription-PCR.ConclusionsOur results indicate that specific genes and miRNAs are regulated differently between black and brown seed during germination, which may contribute to the different germination behaviors of Suaeda aralocaspica dimorphic seeds in unpredictable variable environments. Our results lay a solid foundation for further studying the roles of candidate genes and miRNAs in Suaeda aralocaspica dimorphic seed germination.

Stunted Growth Caused by Blast Disease in Rice Seedlings Is Associated with Changes in Phytohormone Signaling Pathways.

In response to pathogen attack, plants prioritize defense reactions generally at the expense of plant growth. In this work, we report that changes in phytohormone signaling pathways are associated with the stunted plant growth caused by blast disease in rice seedlings. Infection of rice seedlings with blast fungus Magnaporthe oryzae (race 007.0) at the four-leaf stage (three true leaves) resulted in considerable inhibition of the growth of the upper uninfected distal leaves; the length of leaf blade and leaf sheath of the sixth and seventh leaf was reduced by 27 and 82%, and 88 and 72%, respectively, compared to that in the uninoculated plant control. Interestingly, cutting off the blast-infected fourth leaf blade within 2 days post inoculation (dpi) significantly rescued the inhibition of leaf growth, implying that an inhibitory substance(s) and/or signal was generated in the blast-infected leaves (fourth leaf) and transmitted to the upper distal leaves (sixth and seventh) during the 2-dpi period that induced growth inhibition. Expression analysis of marker genes for phytohormone pathways revealed acute activation of the jasmonate (JA) and abscisic acid (ABA) signaling pathways, and repression of auxin, gibberellic acid (GA) and salicylic acid (SA) signaling pathways, in the sixth leaf. The genes related to cell wall expansion were also significantly downregulated. In the blast-infected fourth leaf, JA pathway was activated within 2 dpi, followed by activation of ABA pathway 3 dpi. Further, leaf inhibition caused by blast infection was partially rescued in the rice mutant line coleoptile photomorphogenesis 2 (cpm2), which is defective in the gene encoding allene oxide cyclase (OsAOC). These results indicate that the JA signaling pathway is at least partly involved in the growth inhibition processes. Collectively, our data suggest that, upon pathogen attack, rice seedlings prioritize defense reactions against the infecting pathogen by temporarily ceasing plant growth through the systemic control of phytohormone pathways.

Rice inositol polyphosphate kinase gene (OsIPK2), a putative new player of gibberellic acid signaling, involves in modulation of shoot elongation and fertility

Gibberellic acid (GA) is an important plant hormone mediating plant growth and development throughout the life span. Although many GA biosynthesis genes and signaling components have been revealed, the signal transduction mechanisms from GA perception to physiological actions are still largely unclear. In this study, we investigated the functions of a rice (Oryza sativa) inositol polyphosphate kinase gene (OsIPK2) in rice growth and development, showing that OsIPK2 is a putative new player in GA signaling. OsIPK2 is widely expressed in rice with high accumulation in tender and rapidly dividing tissues. The OsIPK2 protein is mainly localized in the nucleus and plasma membrane. To study the biological roles of OsIPK2 in rice, RNA interference and overexpression transgenic plants were generated. OsIPK2 antisense plants exhibited taller seedling height and lower fertility rate than the wild type, while overexpression lines showed reduced plant height. Microarray and qRT-PCR assays showed that expression levels of several GA-related genes were altered in transgenic plants. Besides, down-regulation of OsIPK2 resulted in hypersensitivity to paclobutrazol (PAC), a GA biosynthesis inhibitor. We also described that the expression of OsIPK2 could be either induced by GA or repressed by PAC. Taken together, these findings suggested that OsIPK2 is likely a negative regulator of GA signaling and involves in modulating shoot elongation and fertility.

Low genetic diversity and functional constraint of miRNA genes participating pollen-pistil interaction in rice.

In this study, we sequenced and analyzed the expression and evolution of rice miRNA genes participating pollen-pistil interaction that is crucial to rice yield. Pollen-pistil interaction is an essential reproductive process for all flowering plants. While microRNAs (miRNAs) are important noncoding small RNAs that regulate mRNA levels in eukaryotic cells, there is little knowledge about which miRNAs involved in the early stages of pollen-pistil interaction in rice and how they evolve under this conserved process. In this study, we sequenced the small RNAs in rice from unpollinated pistil (R0), pistil from 5min and 15min after pollination, respectively, to identify known and novel miRNAs that are involved in this process. By comparing the corresponding mRNA-seq dataset, we identified a group of miRNAs with strong negative expression pattern with their target genes. Further investigation of all miRNA loci (MIRNAs) across 1083 public rice accessions revealed significantly reduced genetic diversity in MIRNAs with strong negative expression of their targets when comparing to those with little or no impact on targets during pollen-pistil interaction. Annotation of targets suggested that those MIRNAs with strong impact on targets were pronounced in cell wall related processes such as xylan metabolism. Additionally, plant conserved miRNAs, such as those with functions in gibberellic acid, auxin and nitrate signaling, were also with strong negative expression of their targets. Overall, our analyses identified key miRNAs participating pollen-pistil interaction and their evolutionary patterns in rice, which can facilitate the understanding of molecular mechanisms associated with seed setting.

The Synergistic Priming Effect of Exogenous Salicylic Acid and H2O2 on Chilling Tolerance Enhancement during Maize (Zea mays L.) Seed Germination.

Chilling stress is an important constraint for maize seedling establishment in the field. To examine the role of salicylic acid (SA) and hydrogen peroxide (H2O2) in response to chilling stress, we investigated the effects of seed priming with SA, H2O2, and SA+H2O2 combination on maize resistance under chilling stress (13°C). Priming with SA, H2O2, and especially SA+H2O2 shortened seed germination time and enhanced seed vigor and seedling growth as compared with hydropriming and non-priming treatments under low temperature. Meanwhile, SA+H2O2 priming notably increased the endogenous H2O2 and SA content, antioxidant enzymes activities and their corresponding genes ZmPAL, ZmSOD4, ZmAPX2, ZmCAT2, and ZmGR expression levels. The α-amylase activity was enhanced to mobilize starch to supply metabolites such as soluble sugar and energy for seed germination under chilling stress. In addition, the SA+H2O2 combination positively up-regulated expressions of gibberellic acid (GA) biosynthesis genes ZmGA20ox1 and ZmGA3ox2, and down-regulated GA catabolism gene ZmGA2ox1 expression; while it promoted GA signaling transduction genes expressions of ZmGID1 and ZmGID2 and decreased the level of seed germination inhibitor gene ZmRGL2. The abscisic acid (ABA) catabolism gene ZmCYP707A2 and the expressions of ZmCPK11 and ZmSnRK2.1 encoding response receptors in ABA signaling pathway were all up-regulated. These results strongly suggested that priming with SA and H2O2 synergistically promoted hormones metabolism and signal transduction, and enhanced energy supply and antioxidant enzymes activities under chilling stress, which were closely relevant with chilling injury alleviation and chilling-tolerance improvement in maize seed.Highlights:Seed germination and seedling growth were significantly improved under chilling stress by priming with SA+H2O2 combination, which was closely relevant with the change of reactive oxygen species, metabolites and energy supply, hormones metabolism and regulation.

Gibberellic Acid Signaling Is Required to Induce Flowering of Chrysanthemums Grown under Both Short and Long Days.

Flower bud formation and flowering in chrysanthemums occur under short day conditions (SD), but the molecular basis for the switch to reproductive growth is less well understood than in model plants. Here, a spontaneous mutant able to flower under long days is described. In an attempt to reveal the pathway(s) involved in the formation of flower buds under contrasting daylengths, transcriptome sequencing was carried out in plants grown both under SD and long day conditions (LD). A number of differentially transcribed genes involved in the various known flowering pathways were identified. Both circadian clock genes and Chrysanthemum FLOWERING LOCUS T Like3 (CmFTL3) were up-regulated under SD, thereby inducing floral bud formation and flowering. The gibberellin (GA) signaling pathway-related genes Gibberellin 20-oxidase (GA20ox) and Gibberellin receptor (GID1) were up-regulated in the mutant under LD, while the catabolic genes Gibberellin 2-oxidase (GA2ox) and GA-INSENSITIVE (GAI) were down-regulated, thereby inducing the transcription of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) and LEAFY (LFY). The GA content of the leaf was higher in the mutant than in the wild type (WT) under LD and SD, and the mutant has more branching than WT plants under LD or SD. When treated with GA, the mutant flowered earlier under both SD and LD relative to WT, but there was no detectable phenotype difference between the two lines. The indication was that the photoperiod pathway majorly regulates flower bud formation and flowering time in chrysanthemums under SD. The GA signaling pathway only plays a subsidiary role for flowering. However, the GA signaling pathway predominated for flowering under LD.

CKB1 is involved in abscisic acid and gibberellic acid signaling to regulate stress responses in Arabidopsis thaliana

Casein kinase II (CK2), an evolutionarily well-conserved Ser/Thr kinase, plays critical roles in all higher organisms including plants. CKB1 is a regulatory subunit beta of CK2. In this study, homozygous T-DNA mutants (ckb1-1 and ckb1-2) and over-expression plants (35S:CKB1-1, 35S:CKB1-2) of Arabidopsis thaliana were studied to understand the role of CKB1 in abiotic stress and gibberellic acid (GA) signaling. Histochemical staining showed that although CKB1 was expressed in all organs, it had a relatively higher expression in conducting tissues. The ckb1 mutants showed reduced sensitivity to abscisic acid (ABA) during seed germination and seedling growth. The increased stomatal aperture, leaf water loss and proline accumulation were observed in ckb1 mutants. In contrast, the ckb1 mutant had increased sensitivity to polyaluminum chloride during seed germination and hypocotyl elongation. We obtained opposite results in over-expression plants. The expression levels of a number of genes in the ABA and GA regulatory network had changed. This study demonstrates that CKB1 is an ABA signaling-related gene, which subsequently influences GA metabolism, and may play a positive role in ABA signaling.

Characterization of miR061 and its target genes in grapevine responding to exogenous gibberellic acid.

MicroRNAs (miRNAs), as an important growth regulator, are also involved in gibberellic acid (GA) signaling, revealing much relationship between miRNAs and GA in various plant responses. Grape is highly sensitive to GA3, which plays a significant regulatory role in regulation of flower development, berry expansion, berry set, berry ripening, and seedlessness induction; further, it was found that grapevine miR061 (VvmiR061) is a GA3 responsive miRNA. In this study, grapevine REV (VvREV) and HOX32 (VvHOX32), two target genes of VvmiR061, were predicted, verified, and cloned; homologous conservation was analyzed in various plants. The expression profiles of both VvmiR061 and its target genes (VvREV and VvHOX32) under GA3 treatment were detected by qRT-PCR during grapevine flower and berry development. Results revealed that GA3 treatment has upregulated the transcription of VvREV and VvHOX32, while it downregulated the expression of VvmiR061. The function of VvmiR061 in cleaving target genes VvREV and VvHOX32 was diminished by GA3 treatment during flower developmental process. The results of this study exhibited the importance of VvmiR061 in regulating flower development and GA3 signaling pathway and also contributed some to the knowledge of small RNA-mediated regulation in grape.

Fackel interacts with gibberellic acid signaling and vernalization to mediate flowering in Arabidopsis.

Fackel (FK) is involved in the flowering of Arabidopsis mainly via the gibberellin pathway and vernalization pathway. This new function of FK is partially dependent on the FLOWERING LOCUS C ( FLC ). A common transitional process from vegetative stage to reproductive stage exists in higher plants during their life cycle. The initiation of flower bud differentiation, which plays a key role in the reproductive phase, is affected by both external environmental and internal regulatory factors. In this study, we showed that the Arabidopsis weak mutant allele fk-J3158, impaired in the FACKEL (FK) gene, which encodes a C-14 reductase involved in sterol biosynthesis, had a long life cycle and delayed flowering time in different photoperiods. In addition, FK overexpression lines displayed an earlier flowering phenotype than that of the wild type. These processes might be independent of the downstream brassinosteroid (BR) pathway and the autonomous pathway. However, the fk-J3158 plants were more sensitive than wild type in reducing the bolting days and total leaf number under gibberellic acid (GA) treatment. Further studies suggested that FK mutation led to an absence of endogenous GAs in fk-J3158 and FK gene expression was also affected under GA and paclobutrazol (PAC) treatment. Moreover, the delayed flowering time of fk-J3158 could be rescued by a 3-week vernalization treatment, and the expression of FLOWERING LOCUS C (FLC) was accordingly down-regulated in fk-J3158. We also demonstrated that flowering time of fk-J3158 flc double mutant was significantly earlier than that of fk-J3158 under the long-day (LD) conditions. All these results indicated that FK may affect the flowering in Arabidopsis mainly via GA pathway and vernalization pathway. And these effects are partially dependent on the FLOWERING LOCUS C (FLC).

Single nucleotide polymorphisms in two GID1 orthologs associate with growth and wood property traits in Populus tomentosa

Gibberellic acids (GAs) have multiple functions in various stages of plant growth and wood development, and GA receptor GIBBERELLIN INSENSITIVE DWARF 1 (GID1) is a key player in GA signaling. Here, we used association studies to examine the allelic variation within PtoGID1a and PtoGID1b associated with growth and wood properties in a natural population of Populus tomentosa. We isolated two full-length PtoGID1a and PtoGID1b cDNA by reverse transcription PCR, and both of these two genes had an open reading frame with the same length (1035 bp) and encoded a protein of 344 amino acids. Analysis of tissue-specific expression profiles indicated that these two genes had similar transcription patterns, being expressed predominantly in leaves. Nucleotide diversity and linkage disequilibrium (LD) analysis showed that PtoGID1a and PtoGID1b harbor high single nucleotide polymorphism (SNP) diversity (π Τ = 0.08237 and 0.00921, respectively) and low LD (r 2 > 0.1, within 350 and 1000 bp, respectively). SNP- and haplotype-based association tests identified that six single SNPs (Q < 0.05) and six haplotypes (P < 0.05, Q < 0.10) were significantly associated with growth and wood properties, explaining 0.99–10.28 and 3.10–5.39 % of the phenotypic variance, respectively. Therefore, isolation of PtoGID1a and PtoGID1b and dissection of their allelic polymorphisms open an avenue to understand the regulation of PtoGID1 in the growth and wood formation in trees.

Identification and Functional Analysis of microRNAs Involved in the Anther Development in Cotton Genic Male Sterile Line Yu98-8A.

Hybrid vigor contributes in a large way to the yield and quality of cotton (Gossypium hirsutum) fiber. Although microRNAs play essential regulatory roles in flower induction and development, it is still unclear if microRNAs are involved in male sterility, as the regulatory molecular mechanisms of male sterility in cotton need to be better defined. In this study, two independent small RNA libraries were constructed and sequenced from the young buds collected from the sporogenous cell formation to the meiosis stage of the male sterile line Yu98-8A and the near-isogenic line. Sequencing revealed 1588 and 1536 known microRNAs and 347 and 351 novel miRNAs from male sterile and male fertile libraries, respectively. MicroRNA expression profiles revealed that 49 conserved and 51 novel miRNAs were differentially expressed. Bioinformatic and degradome analysis indicated the regulatory complexity of microRNAs during flower induction and development. Further RT-qPCR and physiological analysis indicated that, among the different Kyoto Encyclopedia Gene and Genomes pathways, indole-3-acetic acid and gibberellic acid signaling transduction pathways may play pivotal regulatory functions in male sterility.

The NF-YC-RGL2 module integrates GA and ABA signalling to regulate seed germination in Arabidopsis.

The antagonistic crosstalk between gibberellic acid (GA) and abscisic acid (ABA) plays a pivotal role in the modulation of seed germination. However, the molecular mechanism of such phytohormone interaction remains largely elusive. Here we show that three Arabidopsis NUCLEAR FACTOR-Y C (NF-YC) homologues NF-YC3, NF-YC4 and NF-YC9 redundantly modulate GA- and ABA-mediated seed germination. These NF-YCs interact with the DELLA protein RGL2, a key repressor of GA signalling. The NF-YC–RGL2 module targets ABI5, a gene encoding a core component of ABA signalling, via specific CCAAT elements and collectively regulates a set of GA- and ABA-responsive genes, thus controlling germination. These results suggest that the NF-YC–RGL2–ABI5 module integrates GA and ABA signalling pathways during seed germination.

Gibberellin Induces Diploid Pollen Formation by Interfering with Meiotic Cytokinesis.

The plant hormone gibberellic acid (GA) controls many physiological processes, including cell differentiation, cell elongation, seed germination, and response to abiotic stress. In this study, we report that exogenous treatment of flowering Arabidopsis (Arabidopsis thaliana) plants with GA specifically affects the process of male meiotic cytokinesis leading to meiotic restitution and the production of diploid (2n) pollen grains. Similar defects in meiotic cell division and reproductive ploidy stability occur in Arabidopsis plants depleted of RGA and GAI, two members of the DELLA family that function as suppressor of GA signaling. Cytological analysis of the double rga-24 gai-t6 mutant revealed that defects in male meiotic cytokinesis are not caused by alterations in meiosis I (MI or meiosis II (MII) chromosome dynamics, but instead result from aberrations in the spatial organization of the phragmoplast-like radial microtubule arrays (RMAs) at the end of meiosis II. In line with a role for GA in the genetic regulation of the male reproductive system, we additionally show that DELLA downstream targets MYB33 and MYB65 are redundantly required for functional RMA biosynthesis and male meiotic cytokinesis. By analyzing the expression of pRGA::GFP-RGA in the wild-type Landsberg erecta background, we demonstrate that the GFP-RGA protein is specifically expressed in the anther cell layers surrounding the meiocytes and microspores, suggesting that appropriate GA signaling in the somatic anther tissue is critical for male meiotic cell wall formation and thus plays an important role in consolidating the male gametophytic ploidy consistency.

DELLA proteins are common components of symbiotic rhizobial and mycorrhizal signalling pathways.

Legumes form symbiotic associations with either nitrogen-fixing bacteria or arbuscular mycorrhizal fungi. Formation of these two symbioses is regulated by a common set of signalling components that act downstream of recognition of rhizobia or mycorrhizae by host plants. Central to these pathways is the calcium and calmodulin-dependent protein kinase (CCaMK)–IPD3 complex which initiates nodule organogenesis following calcium oscillations in the host nucleus. However, downstream signalling events are not fully understood. Here we show that Medicago truncatula DELLA proteins, which are the central regulators of gibberellic acid signalling, positively regulate rhizobial symbiosis. Rhizobia colonization is impaired in della mutants and we provide evidence that DELLAs can promote CCaMK–IPD3 complex formation and increase the phosphorylation state of IPD3. DELLAs can also interact with NSP2–NSP1 and enhance the expression of Nod-factor-inducible genes in protoplasts. We show that DELLA is able to bridge a protein complex containing IPD3 and NSP2. Our results suggest a transcriptional framework for regulation of root nodule symbiosis.

Molecular cloning, expression analysis and subcellular localization of four DELLA genes from hybrid poplar.

Gibberellic acid (GA) signaling regulates diverse aspects of plant growth and developmental processes. The DELLA repressors of GA signaling are named for an N-terminal conserved DELLA domain. In this study, four genes encoding DELLA proteins, PeRGA1, PeRGA2, PeGAI1 and PeGAI2, were isolated and characterized in poplar. A gene structural analysis revealed that the DELLA genes were all intron-free. Multiple protein sequence alignments revealed that these proteins contained seven highly conserved domains: the DELLA domain, the TVHYNP domain, leucine heptad repeat I (LHR I), the VHIID domain, leucine heptad repeat II (LHR II), the PFYRE domain, and the SAM domain. Temporal expression patterns of these genes were profiled during the adventitious root development of poplar. The four DELLA genes were expressed in root, stem and leaf in a dynamic manner. The subcellular localization demonstrated that these DELLA genes were mainly localized to the nucleus. These results suggest that the four DELLA genes may play diverse regulatory roles in the adventitious root, stem and leaf development of poplar, and contribute to improving our understanding of conserved and divergent aspects of DELLA proteins that restrain GA signaling in various species.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2728-x) contains supplementary material, which is available to authorized users.

RNA-Seq Analysis of the Arabidopsis Transcriptome in Pluripotent Calli.

Plant cells have a remarkable ability to induce pluripotent cell masses and regenerate whole plant organs under the appropriate culture conditions. Although the in vitro regeneration system is widely applied to manipulate agronomic traits, an understanding of the molecular mechanisms underlying callus formation is starting to emerge. Here, we performed genome-wide transcriptome profiling of wild-type leaves and leaf explant-derived calli for comparison and identified 10,405 differentially expressed genes (> two-fold change). In addition to the well-defined signaling pathways involved in callus formation, we uncovered additional biological processes that may contribute to robust cellular dedifferentiation. Particular emphasis is placed on molecular components involved in leaf development, circadian clock, stress and hormone signaling, carbohydrate metabolism, and chromatin organization. Genetic and pharmacological analyses further supported that homeostasis of clock activity and stress signaling is crucial for proper callus induction. In addition, gibberellic acid (GA) and brassinosteroid (BR) signaling also participates in intricate cellular reprogramming. Collectively, our findings indicate that multiple signaling pathways are intertwined to allow reversible transition of cellular differentiation and dedifferentiation.

Gibberellic Acid: A Key Phytohormone for Spikelet Fertility in Rice Grain Production.

The phytohormone gibberellic acid (GA) has essential signaling functions in multiple processes during plant development. In the “Green Revolution”, breeders developed high-yield rice cultivars that exhibited both semi-dwarfism and altered GA responses, thus improving grain production. Most studies of GA have concentrated on germination and cell elongation, but GA also has a pivotal role in floral organ development, particularly in stamen/anther formation. In rice, GA signaling plays an important role in spikelet fertility; however, the molecular genetic and biochemical mechanisms of GA in male fertility remain largely unknown. Here, we review recent progress in understanding the network of GA signaling and its connection with spikelet fertility, which is tightly associated with grain productivity in cereal crops.

Strawberry MOTHER OF FT AND TFL1 regulates seed germination and post-germination growth through integrating GA and ABA signaling in Arabidopsis

The phytohormones gibberellic acid (GA) and abscisic acid (ABA) are known to play antagonistic roles in the control of seed germination and seedling establishment. Here, the regulatory roles of woodland strawberry MOTHER OF FT AND TFL1 (FvMFT) involved in GA and ABA signaling were investigated. FvMFT, which encodes a phosphatidylethanolamine-binding protein, was predominantly expressed in young strawberry fruits. Transient over-expression of FvMFT repressed the expression of several DELLA genes in strawberry fruits. Ectopic over-expression of FvMFT in Arabidopsis thaliana markedly altered the expression levels of ABA-INSENSITIVE (ABI) and DELLA genes, which is accompanied by partially restoring the impaired post-germination growth when the seeds were germinated on sugar-free medium. The same transgenic Arabidopsis plants also exhibited hypersensitivity to GA3 and ABA treatments during seed germination and post-germination growth. In addition, the fluorescence-tagged FvMFT proteins exhibited intriguing subcellular localizations in integument cells and endosperm cells of transgenic Arabidopsis. Taken together, our results support the notion that FvMFT could act as a dual regulator of seed germination and post-germination growth in response to GA and ABA signaling in plants.

A Machine Learning Approach for Prediction of Domains of DELLA Proteins, a Key Component of Gibberellic Acid Signaling in Plants

Background/Objective: For the annotation of large scale proteins, generally computational methods or tools are used. One of the drawbacks of these annotation tools is that they are not specific protein prediction programs. Methods/Analysis: In this study, we implement a machine-learning algorithm for fast and accurate prediction of DELLA proteins. Findings: We developed various modules by using conserved protein domains in DELLA proteins. To evaluate the modules classifiers like sequential minimum optimization, J48 decision tree, AD tree and logistic algorithms were used. By analyzing the results obtained from independent data set and cross-validation tests, maximum accuracy was achieved by logistic algorithm. The developed tool was tested with various inputs and it's showed that the algorithm developed in the study would be helpful in predicting plant DELLA domains. Applications: This tool will significantly contribute to deep level functional genome annotation and development of predictors.