Regulation Of Flower Development Research Articles

BnAP2-12 overexpression delays ramie flowering: evidence from AP2/ERF gene expression.

The APETALA2/ethylene response factor (AP2/ERF) superfamily plays a significant role in regulating plant gene expression in response to growth and development. To date, there have been no studies into whether the ramie AP2/ERF genes are involved in the regulation of flower development. Here, 84 BnAP2/ERF members were identified from the ramie genome database, and various bioinformatics data on the AP2/ERF gene family, structure, replication, promoters and regulatory networks were analysed. BnAP2-12 was transferred into Arabidopsis through the flower-dipping method. Phylogenetic analysis classified the 84 BnAP2/ERF members into four subfamilies: AP2 (18), RAV (3), ERF (42), and DREB (21). The functional domain analysis of genes revealed 10 conserved motifs. Genetic mapping localised the 84 members on 14 chromosomes, among which chromosomes 1, 3, 5, and 8 had more members. Collinearity analysis revealed that 43.37% possibly resulted from replication events during the evolution of the ramie genome. Promoter sequence analysis identified classified cis-acting elements associated with plant growth and development, and responses to stress, hormones, and light. Transcriptomic comparison identified 3,635 differentially expressed genes (DEGs) between male and female flowers (1,803 and 1,832 upregulated and downregulated genes, respectively). Kyoto Encyclopaedia of Genes and Genomes pathway analysis categorised DEGs involved in metabolic pathways and biosynthesis of secondary metabolites. Gene Ontology enrichment analysis further identified enriched genes associated with pollen and female gamete formations. Of the 84 BnAP2/ERFs genes, 22 and 8 upregulated and downregulated genes, respectively, were present in female flowers. Co-expression network analysis identified AP2/ERF members associated with flower development, including BnAP2-12. Subcellular localisation analysis showed that the BnAP2-12 protein is localised in the nucleus and cell membrane. Overexpression BnAP2-12 delayed the flowering time of Arabidopsis thaliana. These findings provide insights into the mechanism of ramie flower development.

The SEPALLATA-like CaSEP5 gene regulates flower sepal, pedicel, and fruit development in pepper (Capsicum annuum L.)

Flowers are reproductive plant organs that determine final fruit or seed yield. SEPALLATA-like MADS-box genes participate in floral determination and/or flower organ specification. Nevertheless, their molecular mechanisms in bell pepper have not yet been elucidated. In this study, we identified CaSEP5, which encodes a duplicated SEPALLATA-like MADS-box protein grouped in the FBP9/23-subclade. CaSEP5 genes were detected in all whorls of floral organs, and were relatively highly expressed in the sepals and petals. Subcellular localization revealed that CaSEP5 was in the nucleus. This finding aligns with transcription factor characteristics. The physical interactions of CaSEP5 with B-, C-, and other CaSEPs indicated that CaSEP5 act as glue to form protein complexes to regulate flower development by altering the hormones level and distribution. CaSEP5-silenced plants had elongated, leaf-like sepals, rigid, straight pedicels, reduced fruit size, altered expression patterns of other floral homeotic genes, and varied hormone levels. We proposed that CaSEP5 plays an important role in pepper flower and fruit development by means of a complex hormone and genetic network.

Characterization of the MIKCC-type MADS-box gene family in blueberry and its possible mechanism for regulating flowering in response to the chilling requirement.

The expression peak of VcAP1.4, VcAP1.6, VcAP3.1, VcAP3.2, VcAG3, VcFLC2, and VcSVP9 coincided with the endo-dormancy release of flower buds. Additionally, GA4+7 not only increased the expression of these genes but also promoted flower bud endo-dormancy release. The MIKCC-type MADS-box gene family is involved in the regulation of flower development. A total of 109 members of the MIKCC-type MADS-box gene family were identified in blueberry. According to the phylogenetic tree, these 109 MIKCC-type MADS-box proteins were divided into 13 subfamilies, which were distributed across 40 Scaffolds. The results of the conserved motif analysis showed that among 20 motifs, motifs 1, 3, and 9 formed the MADS-box structural domain, while motifs 2, 4, and 6 formed the K-box structural domain. The presence of 66 pairs of fragment duplication events in blueberry suggested that gene duplication events contributed to gene expansion and functional differentiation. Additionally, the presence of cis-acting elements revealed that VcFLC2, VcAG3, and VcSVP9 might have significant roles in the endo-dormancy release of flower buds. Meanwhile, under chilling conditions, VcAP3.1 and VcAG7 might facilitate flower bud dormancy release. VcSEP11 might promote flowering following the release of endo-dormancy, while the elevated expression of VcAP1.7 (DAM) could impede the endo-dormancy release of flower buds. The effect of gibberellin (GA4+7) treatment on the expression pattern of MIKCC-type MADS-box genes revealed that VcAP1.4, VcAP1.6, VcAP3.1, VcAG3, and VcFLC2 might promote flower bud endo-dormancy release, while VcAP3.2, VcSEP11, and VcSVP9 might inhibit its endo-dormancy release. These results indicated that VcAP1.4, VcAP1.6, VcAP1.7 (DAM), VcAP3.1, VcAG3, VcAG7, VcFLC2, and VcSVP9 could be selected as key regulatory promoting genes for controlling the endo-dormancy of blueberry flower buds.

Insights into the functional role of tomato TM6 as a transcriptional regulator of flower development.

Flower development is a crucial step towards the completion of the plant life cycle. Physiological processes and gene regulatory mechanisms underlying flower formation have been extensively characterized, and the implication of MADS-box transcription factors as primary regulators of flower morphology has been widely described, mainly due to the analysis of loss-of-function mutants in model species. Nevertheless, detailed characterization of allele variation in several MADS-box homologous genes from crop species remains undescribed. Here, we have characterized a tomato mutant with aberrant flower development. Mutant plants exhibit changes in petal cell identity, as well as homeotic transformations of stamens into carpelloid structures, which in most cases result in succulent organs. Molecular analysis proved that a loss-of-function mutation in the TOMATO MADS-BOX 6 (TM6) gene is responsible for this mutant phenotype. Furthermore, as a result of the loss of function of TM6, misregulation of the transcription and mRNA processing of other MADS-box genes involved in reproductive development has been detected. Our findings demonstrate that TM6 is a key player in the complex regulatory network of MADS-box genes controlling flower development and also provide a novel mutant that may be useful for generating male sterile lines in tomatoes.

Genome-Wide Identification of PEBP Gene Family in Two Dendrobium Species and Expression Patterns in Dendrobium chrysotoxum.

The PEBP gene family plays a significant role in regulating flower development and formation. To understand its function in Dendrobium chrysotoxum and D. nobile flowering, we identified 22 PEBP genes (11 DchPEBPs and 11 DnoPEBPs) from both species. We conducted analyses on their conserved domains and motifs, phylogenetic relationships, chromosome distribution, collinear correlation, and cis elements. The classification results showed that the 22 PEBPs were mainly divided into three clades, as follows: FT, MFT, and TFL1. A sequence analysis showed that most PEBP proteins contained five conserved domains, while a gene structure analysis revealed that 77% of the total PEBP genes contained four exons and three introns. The promoter regions of the 22 PEBPs contained several cis elements related to hormone induction and light response. This suggests these PEBPs could play a role in regulating flower development by controlling photoperiod and hormone levels. Additionally, a collinearity analysis revealed three pairs of duplicate genes in the genomes of both D. chrysotoxum and D. nobile. Furthermore, RT-qPCR has found to influence the regulatory effect of DchPEBPs on the development of flower organs (sepals, petals, lip, ovary, and gynostemium) during the flowering process (bud, transparent stage, and initial bloom). The results obtained imply that DchPEBP8 and DchPEBP9 play a role in the initial bloom and that DchPEBP7 may inhibit flowering processes. Moreover, DchPEBP9 may potentially be involved in the development of reproductive functionality. PEBPs have regulatory functions that modulate flowering. FT initiates plant flowering by mediating photoperiod and temperature signals, while TFL1 inhibits flowering processes. These findings provide clues for future studies on flower development in Dendrobium.

The BnTFL1–BnGF14nu–BnFD module regulates flower development and plant architecture in Brassica napus

Flower development and plant architecture determine the efficiency of mechanized harvest and seed yield in Brassica napus. Although TERMINAL FLOWER 1 (AtTFL1) is a regulator of flower development in Arabidopsis thaliana, the function and regulatory mechanism of TFL1 orthologs in B. napus remains unclear. Six BnTFL1 paralogs in the genome of the B. napus inbred line ‘K407’ showed steadily increasing expression during vernalization. CRISPR/Cas-induced mutagenesis of up to four BnTFL1 paralogs resulted in early flowering and alteration of plant architecture, whereas seed yield was not altered in BnTFL1 single, double, or triple mutants. Six BnTFL1 paralogs, but not BnaA02.TFL1, showed an additive and conserved effect on regulating flowering time, total and terminal flower number, and plant architecture. BnaA10.TFL1 regulates flower development by interacting with BnaA08.FD through the protein BnaA05.GF14nu, resulting in the transcriptional repression of floral integrator and floral meristem identity genes. These findings about the regulatory network controlling flower development and plant architecture present a promising route to modifying these traits in B. napus.

Variation in antioxidant capacity, antioxidant activity and mineral composition during flower development of oil-bearing rose (Rosa damascena Mill.)

Oil-bearing rose is an economically important rose species with a wide range of uses such as cosmetics, perfumery, food and health, but the changes in antioxidant capacity and antioxidant activity during flower development are not well understood. The antioxidant content and free radical scavenging properties of oil-bearing rose flowers are used in the cosmetic industry to modulate skin damage, and in the food industry as a source of antioxidants and sweeteners. The present investigation was carried out to explore the antioxidant capacity, antioxidant enzyme activity, and the composition and distribution of minerals in petals of oil-bearing rose at five flower development stages. The total antioxidant capacity of petals was determined using CUPRAC, DPPH, FRAP, FIC and ABTS methods. The antioxidant capacity of petals decreased during the flower development, suggesting that flowers in stage I and II are valuable sources of antioxidants. CUPRAC, DPPH, FRAP, FIC and ABTS scavenging activity of the petals at various developmental stages are strongly and positively correlated with each other. The activity of the antioxidant enzymes; superoxide dismutase, catalase, glutathione reductase, ascorbate peroxidase was highest at the bud stage (stage I), whereas the fully opened flowers (stage V) exhibited the lowest activity in oil-bearing rose petals. During the development of flower, malondialdehyde (MDA) content increased significantly from stage I to stage III and decreased at stage IV. Here we detected the contents of 15 elements in petals, some of them, especially calcium, magnesium, potassium and phosphorus showed significant changes during rose flowering. Generally, the highest mineral content was observed in stage I while the lowest content observed in stage V of flower development. These results showed a close link between flower development, antioxidant capacity, enzymatic antioxidant activity and mineral content, with stage I exhibiting the best antioxidant activity, mineral content and free radical scavenging potential. This work will serve as a baseline for understanding the possible roles of antioxidant capacity, antioxidant enzymes, mineral content and their interactions in the regulation of flower development.

Thinking outside the F-box: how UFO controls angiosperm development.

The formation of inflorescences and flowers is essential for the successful reproduction of angiosperms. In the past few decades, genetic studies have identified the LEAFY transcription factor and the UNUSUAL FLORAL ORGANS (UFO) F-box protein as two major regulators of flower development in a broad range of angiosperm species. Recent research has revealed that UFO acts as a transcriptional cofactor, redirecting the LEAFY floral regulator to novel cis-elements. In this review, we summarize the various roles of UFO across species, analyze past results in light of new discoveries and highlight the key questions that remain to be solved.

Verification of gene function and interaction protein of PhPIF4

In order to investigate the molecular mechanism of PhPIF4 in response to gibberellin-regulated floral transition of Phalaenopsis, qRT-PCR and functional verification experiment of transgenic Arabidopsis thaliana was carried out, and the results showed that PhPIF4 expression was significantly increased in flower buds, leaves and roots after spraying with growth regulator GA3. In PhPIF4 overexpressed Arabidopsis thaliana, hypocotyl elongation, early flowering and increased flowering amount were observed, especially after exogenous GA3 treatment. The content of the endogenous hormone GA3 in the transgenic Arabidopsis thaliana was higher. The interaction between PhDELLA and PhPIF4 was verified by Y2H experiment. The Y1H test demonstrated that PhDELLA could not interact with the PhPIF4 promoter but PhMYB which plays an important role in the regulation of flower development and flowering time could interacte with the PhPIF4 promoter. These findings indicated PhPIF4 participated in the flowering transition and might be directly regulated by GA and the PhPIF4 protein interacts with PhDELLA to go through the GA signaling pathway and the PhPIF4 gene was regulated by PhMYB.

An integrated transcriptome and metabolome analysis reveals the gene network regulating flower development in Pogostemon cablin.

Pogostemon cablin is a well-known protected species widely used in medicine and spices, however the underlying molecular mechanisms and metabolite dynamics of P. cablin flower development remain unclear due to the difficulty in achieving flowering in this species. A comparison of the transcriptome and widely targeted metabolome during P. cablin flower development was first performed in this study. Results showed that a total of 13,469 differentially expressed unigenes (DEGs) and 371 differentially accumulated metabolites (DAMs) were identified. Transcriptomic analysis revealed that the DEGs were associated with starch and sucrose metabolism, terpenoid biosynthesis and phenylpropanoid biosynthesis. Among these DEGs, 75 MIKC-MADS unigenes were associated with the development of floral organs. Gibberellins (GAs), auxin, and aging signaling might form a cross-regulatory network to regulate flower development in P. cablin. According to the metabolic profile, the predominant DAMs were amino acids, flavonoids, terpenes, phenols, and their derivatives. The accumulation patterns of these predominant DAMs were closely associated with the flower developmental stage. The integration analysis of DEGs and DAMs indicated that phenylpropanoids, flavonoids, and amino acids might be accumulated due to the activation of starch and sucrose metabolism. Our results provide some important insights for elucidating the reproductive process, floral organ, and color formation of P. cablin flowers at the molecular level. These results will improve our understanding of the molecular and genetic mechanisms involved in the floral development of P. cablin.

Cloning and Functional Analysis of the VfRR17 Gene from tung tree (Vernicia fordii).

Tung tree (Vernicia fordii) is one of the four major woody oilseed species in China. However, its fruit yield is severely hampered by the low number of female flowers and the imbalanced male-to-female flower ratio, which is a problem that restricts the development of the oilseed industry. Previous research has demonstrated that the exogenous application of cytokinins can significantly augment the number of female flowers, although the underlying regulatory mechanism remains elusive. To elucidate the involvement of VfRR17, a member of the A-type ARRs family, in the exogenous cytokinin regulation of flower sexual differentiation in tung tree, this study conducted a comprehensive bioinformatic analysis of the physicochemical properties, structural characteristics, and evolutionary relationships of the protein encoded by VfRR17. Additionally, gene function analysis was performed using subcellular localization, qRT-PCR, and genetic transformation techniques. The findings revealed that the VfRR17 gene's coding region spanned 471 bp, encoding an unstable protein of 156 amino acids with a relative molecular mass of 17.4 kDa. Phylogenetic analysis demonstrated a higher similarity between VfRR17 of the tung tree and the RR17 gene of Jatropha curcas, Ricinus communis, Hevea brasiliensis, and other species within the Euphorbiaceae family compared to other species, with the greatest similarity of 86% observed with the RR17 gene of Jatropha curcas. The qRT-PCR analysis indicated that VfRR17 exhibited high expression levels during the early stage of tung tree inflorescence buds following 6-BA treatment, peaking at 24 h and displaying a 3.47-fold increase compared to that at 0 h. In female and male flowers of the tung tree, the expression in female flowers during the 1 DBF period was significantly higher than in male flowers, exhibiting a difference of approximately 47.91-fold. Furthermore, notable differential expression was observed in the root, leaf, and petiole segments of the tung tree under low-temperature stress at the 12-h time point. In transgenic Arabidopsis, the VfRR17 lines and wild-type lines exhibited significantly different flowering times under an exogenous 6-BA treatment at a concentration of 2 mg/L, with the VfRR17 lines experiencing an 11-day delay compared to the wild-type lines. Additionally, the number of fruit pods in VfRR17 transgenic Arabidopsis lines was significantly reduced by 28 compared to the wild-type lines at a 6-BA concentration of 3 mg/L. These findings suggest that VfRR17 likely plays a critical role in regulating flower development in response to exogenous 6-BA, providing valuable insights into the mechanisms underlying exogenous 6-BA-mediated regulation of female flower development in the tung tree.

GmUFO1 Regulates Floral Organ Number and Shape in Soybean.

The UNUSUAL FLORAL ORGANS (UFO) gene is an essential regulatory factor of class B genes and plays a vital role in the process of inflorescence primordial and flower primordial development. The role of UFO genes in soybean was investigated to better understand the development of floral organs through gene cloning, expression analysis, and gene knockout. There are two copies of UFO genes in soybean and in situ hybridization, which have demonstrated similar expression patterns of the GmUFO1 and GmUFO2 genes in the flower primordium. The phenotypic observation of GmUFO1 knockout mutant lines (Gmufo1) showed an obvious alteration in the floral organ number and shape and mosaic organ formation. By contrast, GmUFO2 knockout mutant lines (Gmufo2) showed no obvious difference in the floral organs. However, the GmUFO1 and GmUFO2 double knockout lines (Gmufo1ufo2) showed more mosaic organs than the Gmufo1 lines, in addition to the alteration in the organ number and shape. Gene expression analysis also showed differences in the expression of major ABC function genes in the knockout lines. Based on the phenotypic and expression analysis, our results suggest the major role of GmUFO1 in the regulation of flower organ formation in soybeans and that GmUFO2 does not have any direct effect but might have an interaction role with GmUFO1 in the regulation of flower development. In conclusion, the present study identified UFO genes in soybean and improved our understanding of floral development, which could be useful for flower designs in hybrid soybean breeding.

Overexpression of the mango MiGF6A and MiGF6B genes promotes early flowering in transgenic Arabidopsis plants

14-3-3 genes are universal regulators that play important roles in regulating flower development and stress responses. In this study, two homologous 14-3-3 genes, MiGF6A and MiGF6B, were obtained from the genome of SiJiMi mango. Sequence analysis showed that both MiGF6A and MiGF6B have a fully conserved 14-3-3 superfamily domain. MiGF6A and MiGF6B were expressed in tissues at all stages of development, especially in the flowers and buds. Both MiGF6A and MiGF6B were expressed in response to low temperature, NaCl and polyethylene glycol (PEG) treatments. Subcellular localization analysis showed that MiGF6A and MiGF6B were located in the nucleus. Overexpression of MiGF6A and MiGF6B in Arabidopsis thaliana resulted in an early-flowering phenotype and significant upregulation of the flowering-related genes FLOWERING LOCUS T (AtFT), AtFD1, and LEAFY (AtLFY). Yeast two-hybrid and bimolecular fluorescence complementation (BiFC) analyses showed that MiGF6A and MiGF6B interact with the MiFD1, MiFD2 and MiSVP3 proteins. These results suggest that MiGF6A and MiGF6B may play positive roles in the mango flowering process.

[Mining and identification of members of MYB transcription factor family in Lonicera macranthoides].

As a large family of transcription factors, the MYB family plays a vital role in regulating flower development. We studied the MYB family members in Lonicera macranthoides for the first time and identified three sequences of 1R-MYB, 47 sequences of R2R3-MYB, two sequences of 3R-MYB, and one sequence of 4R-MYB from the transcriptome data. Further, their physicochemical properties, conserved domains, phylogenetic relationship, protein structure, functional information, and expression were analyzed. The results show that the 53 MYB transcription factors had different conserved motifs, physicochemical properties, structures, and functions in wild type and 'Xianglei' cultivar of L. macranthoides, indicating their conservation and diversity in evolution. The transcript level of LmMYB was significantly different between the wild type and 'Xianglei' cultivar as well as between flowers and leaves, and some genes were specifically expressed. Forty-three out of 53 LmMYB sequences were expressed in both flowers and leaves, and 9 of the LmMYB members showed significantly different transcript levels between the wild type and 'Xianglei' cultivar, which were up-regulated in the wild type. The results provide a theoretical basis for further studying the specific functional mechanism of the MYB family.

Comparative analysis of the chrysanthemum transcriptome with DNA methylation inhibitors treatment and silencing MET1 lines

BackgroundAs one of the ten most famous flowers in China, the chrysanthemum has rich germplasm with a variety of flowering induction pathways, most of which are photoperiod-induced. After treatment with DNA methylation inhibitors, it was found that DNA methylation plays an important role in flowering regulation, but the mechanism of action remains unclear. Therefore, in this study, curcumin, 5-azaC, their mixed treatment, and MET1-RNAi lines were used for transcriptome sequencing to find out how different treatments affected gene expression in chrysanthemums at different stages of flowering.ResultsGenomic DNA methylation levels were measured using HPLC technology. The methylation level of the whole genome in the vegetative growth stage was higher than that in the flowering stage. The methylation level of DNA in the vegetative growth stage was the lowest in the curcumin and mixed treatment, and the methylation level of DNA in the transgenic line, mixed treatment, and curcumin treatment was the lowest in the flowering stage. The flowering rate of mixed treatment and curcumin treatment was the lowest. Analysis of differentially expressed genes in transcriptomes showed that 5-azaC treatment had the most differentially expressed genes, followed by curcumin and transgenic lines, and mixed treatment had the fewest. In addition, 5-azaC treatment resulted in the differential expression of multiple DNA methylation transferases, which led to the differential expression of many genes. Analysis of differentially expressed genes in different treatments revealed that different treatments had gene specificity. However, the down-regulated GO pathway in all 4 treatments was involved in the negative regulation of the reproductive process, and post-embryonic development, and regulation of flower development. Several genes associated with DNA methylation and flowering regulation showed differential expression in response to various treatments.ConclusionsBoth DNA methylase reagent treatment and targeted silencing of the MET1 gene can cause differential expression of the genes. The operation of the exogenous application is simple, but the affected genes are exceedingly diverse and untargeted. Therefore, it is possible to construct populations with DNA methylation phenotypic diversity and to screen genes for DNA methylation regulation.

Molecular characterization of SPL gene family during flower morphogenesis and regulation in blueberry

The SPL gene is a plant-specific transcription factor involved in the regulation of plant growth and development, which have been identified in woody plants. The process of floral bud differentiation affects the timing of flowering and fruit set and regulates plant growth, however, the mechanism of regulation of flower development by SPL genes is less studied. In this study, 56 VcSPL genes were identified in the tetraploid blueberry. The VcSPL gene family was classified into six subfamilies, and analysis of cis-elements showed that VcSPL genes were regulated by light, phytohormones (abscisic acid, MeJA), and low temperature. In the evolutionary analysis, segmental replication may play an important role in VcSPL gene amplification. Interestingly, we also studied diploid blueberry (Bilberry), in which 24 SPL genes were identified, and 36 homologous pairs were found, suggesting a high degree of convergence in the syntenic relationship between blueberry (Vaccinium corymbosum L) and bilberry (Vaccinium darrowii). Based on the expression profile, VcSPL genes were expressed at high levels in flowers, shoots, and roots, indicating a diversity of gene functions. Then we selected 20 differentially-expressed SPL genes to further investigate the role of VcSPL in floral induction and initiation. It showed that the genes VcSPL40, VcSPL35, VcSPL45, and VcSPL53 may play a crucial role in the blueberry floral transition phase (from vegetative growth to flower initiation). These results provided important information for understanding and exploring the role of VcSPLs in flower morphogenesis and plant growth. 

Integrated cytological and transcriptomic analysis reveals insights into pollen fertility in newly synthetic Brassica allohexaploids.

Trigenomic Brassica allohexaploids (AABBCC, 2n = 6x = 54) have great potential in oilseed breeding and genetic diversity. However, Brassica allohexaploids do not exist naturally, and the underlying mechanism regulating pollen fertility in artificially synthesized Brassica allohexaploids is still unclear. In this study, synthetic Brassica allohexaploids were produced by crossing allotetraploid B. carinata (BBCC, 2n = 4x = 34) and diploid B. rapa (AA, 2n = 2x = 20), followed by chromosome doubling. The results showed that the pollen fertility was significantly reduced and the pollen structures were mostly distorted, but the nursing anther tapetum developed normally in the synthetic Brassica allohexaploids. Furthermore, the data showed that the meiotic events occurred irregularly with uneven chromosome segregation and microspore development appeared mostly abnormal. Transcription analysis showed that the upregulation of genes related to the negative regulation of flower development and the downregulation of genes related to chromosome segregation might play an essential role in reduction of pollen fertility in the Brassica allohexaploids. In conclusion, this study elucidated the related mechanisms affecting pollen fertility during male gametophytic development at the cytological and transcriptomic levels in the newly synthesized Brassica allohexaploids.

B Class Floral Homeotic Genes are Involved in the Petal Identity and Flower Meristem Determinations in Chrysanthemum morifolium

Chrysanthemum morifolium, an ornamental crop with diverse forms of inflorescence, is a good model for studying flower development in Asteraceae. However, the genetic background is complex and the mechanisms of regulating flower development are still unclear. Here, we identified two natural mutant lines of chrysanthemum and named them M1 and M2 according to the severity of the phenotype. Both lines showed defects in petal identity, and the petals of the M1 line had a mild phenotype: partially loss of petal identity and conversion of petals into green, leaf-like organs. The M2 line had severe phenotypes: in addition to severe petal defects, secondary inflorescences were produced in the capitulum to replace the normal ray and disc florets, which indicated a transformation of a flower meristem into an inflorescence meristem. Transcriptome sequencing of WT and M2 inflorescences was performed and found altered expression of floral organ development A, B and E class genes, where B and E class genes were significantly down-regulated. qRT-PCR analysis in both M1 and M2 lines revealed that the expression of three chrysanthemum class B genes CmAP3.1, CmAP3.2 and CmPI, was negatively correlated with phenotypic severity. This suggests that class B genes in chrysanthemum not only have conserved functions in determining petal identity but also were involved in the determinacy of the flower meristem. This study provides insights into the functions of class B genes in flower development, and is informative for dissecting the molecular mechanisms of flower development in chrysanthemum.

The role of CDPKs in plant development, nutrient and stress signaling.

The second messenger calcium (Ca2+) is a ubiquitous intracellular signaling molecule found in eukaryotic cells. In plants, the multigene family of calcium-dependent protein kinases (CDPKs) plays an important role in regulating plant growth, development, and stress tolerance. CDPKs sense changes in intracellular Ca2+ concentration and translate them into phosphorylation events that initiate downstream signaling processes. Several functional and expression studies on different CDPKs and their encoding genes have confirmed their multifunctional role in stress. Here, we provide an overview of the signal transduction mechanisms and functional roles of CDPKs. This review includes details on the regulation of secondary metabolites, nutrient uptake, regulation of flower development, hormonal regulation, and biotic and abiotic stress responses.

Genome-wide identification and characterization of AP2/ERF gene superfamily during flower development in Actinidia eriantha

BackgroundAs one of the largest transcription factor families in plants, AP2/ERF gene superfamily plays important roles in plant growth, development, fruit ripening and biotic and abiotic stress responses. Despite the great progress has been made in kiwifruit genomic studies, little research has been conducted on the AP2/ERF genes of kiwifruit. The increasing kiwifruit genome resources allowed us to reveal the tissue expression profiles of AP2/ERF genes in kiwifruit on a genome-wide basis.ResultsIn present study, a total of 158 AP2/ERF genes in A. eriantha were identified. All genes can be mapped on the 29 chromosomes. Phylogenetic analysis divided them into four main subfamilies based on the complete protein sequences. Additionally, our results revealed that the same subfamilies contained similar gene structures and conserved motifs. Ka/Ks calculation indicated that AP2/ERF gene family was undergoing a strong purifying selection and the evolutionary rates were slow. RNA-seq showed that the AP2/ERF genes were expressed differently in different flower development stages and 56 genes were considered as DEGs among three contrasts. Moreover, qRT-PCR suggested partial genes showed significant expressions as well, suggesting they could be key regulators in flower development in A. eriantha. In addition, two genes (AeAP2/ERF061, AeAP2/ERF067) had abundant transcription level based on transcriptomes, implying that they may play a crucial role in plant flower development regulation and flower tissue forming.ConclusionsWe identified AP2/ERF genes and demonstrated their gene structures, conserved motifs, and phylogeny relationships of AP2/ERF genes in two related species of kiwifruit, A. eriantha and A. chinensis, and their potential roles in flower development in A. eriantha. Such information would lay the foundation for further functional identification of AP2/ERF genes involved in kiwifruit flower development.