Evolution Of Flowering Plants Research Articles

Genome-Wide Analysis of MADS-Box Gene Family Reveals CjSTK as a Key Regulator of Seed Abortion in Camellia japonica.

The plant MADS-box transcription factor family is a major regulator of plant flower development and reproduction, and the AGAMOUS-LIKE11/SEEDSTICK (AGL11/STK) subfamily plays conserved functions in the seed development of flowering plants. Camellia japonica is a world-famous ornamental flower, and its seed kernels are rich in highly valuable fatty acids. Seed abortion has been found to be common in C. japonica, but little is known about how it is regulated during seed development. In this study, we performed a genome-wide analysis of the MADS-box gene the in C. japonica genome and identified 126 MADS-box genes. Through gene expression profiling in various tissue types, we revealed the C/D-class MADS-box genes were preferentially expressed in seed-related tissues. We identified the AGL11/STK-like gene, CjSTK, and showed that it contained a typical STK motif and exclusively expressed during seed development. We found a significant increase in the CjSTK expression level in aborted seeds compared with normally developing seeds. Furthermore, overexpression of CjSTK in Arabidopsis thaliana caused shorter pods and smaller seeds. Taken together, we concluded that the fine regulation of the CjSTK expression at different stages of seed development is critical for ovule formation and seed abortion in C. japonica. The present study provides evidence revealing the regulation of seed development in Camellia.

Flowering and Flower Development in Plants

In the life cycle of a plant, flowering marks the transition from vegetative growth to reproductive development [...]

The Association between BZIP Transcription Factors and Flower Development in Litsea cubeba

The basic leucine zipper (bZIP) family is one of the largest families of transcription factors among eukaryotic organisms. Members of the bZIP family play various roles in regulating the intricate process of flower development in plants. Litsea cubeba (Lour.) (family: Lauraceae) is an aromatic, dioecious plant used in China for a wide range of applications. However, no study to date has undertaken a comprehensive analysis of the bZIP gene family in L. cubeba. In this work, we identified 68 members of the bZIP gene family in L. cubeba and classified them into 12 subfamilies based on previous studies on Arabidopsis thaliana. Transcriptome data analysis revealed that multiple LcbZIP genes exhibit significantly high expression levels in the flowers of L. cubeba, while some also demonstrate distinct temporal specificity during L. cubeba flower development. In particular, some LcbZIP genes displayed specific and high expression levels during the stamen and pistil degradation process. Using differential gene expression analysis, weighted gene co-expression network analysis, and Gene Ontology enrichment analysis, we identified six candidate LcbZIP genes that potentially regulate stamen or pistil degradation during flower development. In summary, our findings provide a framework for future functional analysis of the LcbZIP gene family in L. cubeba and offer novel insights for investigating the mechanism underlying pistil and stamen degeneration in this plant.

Evaluating the influences of floral traits and pollinator generalism on α and β diversity of heterospecific pollen on stigmas

Abstract Pollinator sharing often leads to receipt of heterospecific pollen (HP) along with conspecific pollen. As a result, flowering plants can accumulate diverse communities of HP on stigmas. While variation in HP diversity is an important selective force contributing to flowering plant fitness, evolution and community assembly, our understanding of the extent and drivers of heterogeneity of HP diversity is limited. In this study, we examined the species compositions and abundances of ~1000 HP communities across 59 co‐flowering plant species in three serpentine seep communities in California, USA. We evaluated the variation in HP diversity (γ diversity) across plant species in each seep and asked whether the variation in HP γ diversity was caused by variation in HP diversity within stigmas (α diversity) or HP compositional variation among stigmas (β diversity) due to the replacement of HP species (turnover) or their loss (nestedness) from one stigma to another. We further evaluated the potential drivers of variation in HP α and β diversity using phylogenetic structural equation models. We found that variation in HP γ diversity across plant species was driven strongly by differences among species in HP α diversity and to a lesser extent by HP β diversity. HP community turnover contributed more to HP β diversity than nestedness consistently across plant species and seeps, suggesting a general pattern of HP compositional heterogeneity from stigma to stigma. The phylogenetic structural equation models further revealed that floral traits (e.g., stigma area, stigma‐anther distance, stigma exposure) and floral abundance were key in determining HP α diversity by influencing HP abundance (load size), while floral traits and abundance showed variable impact on HP β diversity (turnover and nestedness). Pollination generalism contributed relatively less to HP‐α and β diversity. These findings disentangle the heterogeneity in HP diversity at different levels, which is essential for understanding the process underlying patterns of HP receipt in plant communities. That floral traits drive the heterogeneity in HP diversity points to additional avenues by which HP receipt may contribute to plant evolution. Read the free Plain Language Summary for this article on the Journal blog.

Holomorphology, Space, and Time to Shed Light on the Evolution and Distributional Pattern of the Endemic Flowering Plants of Brazil

Holomorphology, Space, and Time to Shed Light on the Evolution and Distributional Pattern of the Endemic Flowering Plants of Brazil

Species-specific regulatory pathways of small RNAs play sophisticated roles in flower development in Dimocarpus longan Lour.

Flower development plays vital role in horticultural plants. Post-transcriptional regulation via small RNAs is important for plant flower development. To uncover post-transcriptional regulatory networks during the flower development in Dimocarpus longan Lour. ‘Shixia’, an economically important fruit crop in subtropical regions, we collected and analyzed sRNA deep-sequencing datasets and degradome libraries Apart from identifying miRNAs and phased siRNA generating loci (PHAS loci), 120 hairpin loci, producing abundant sRNAs, were identified by in-house protocols. Our results suggested that 56 miRNA-target pairs, 22 21-nt-PHAS loci, and 111 hairpin loci are involved in post-transcriptional gene silencing during longan reproductive development. Lineage-specific or species-specific post-transcriptional regulatory modules have been unveiled, including miR482-PHAS and miRN15. miR482-PHAS might be involved in longan flower development beyond their conserved roles in plant defense, and miRN15 is a novel miRNA likely associated with a hairpin locus (HPL-056) to regulate strigolactone receptor gene DWARF14 (D14) and the biogenesis of phasiRNAs from D14. These small RNAs are enriched in flower buds, suggesting they are likely involved in post-transcriptional regulatory networks essential for longan flower development via the strigolactone signaling pathway.

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.

The tomato CONSTANS-LIKE protein SlCOL1 regulates fruit yield by repressing SFT gene expression

BackgroundCONSTANS (CO) and CONSTANS-LIKE (COL) transcription factors have been known to regulate a series of cellular processes including the transition from the vegetative growth to flower development in plants. However, their role in regulating fruit yield in tomato is poorly understood.ResultIn this study, the tomato ortholog of Arabidopsis CONSTANS, SlCOL1, was shown to play key roles in the control of flower development and fruit yield. Suppression of SlCOL1 expression in tomato was found to lead to promotion of flower and fruit development, resulting in increased tomato fruit yield. On the contrary, overexpression of SlCOL1 disturbed flower and fruit development, and significantly reduced tomato fruit yield. Genetic and biochemical evidence indicated that SlCOL1 controls inflorescence development by directly binding to the promoter region of tomato inflorescence-associated gene SINGLE-FLOWER TRUSS (SFT) and negatively regulating its expression. Additionally, we found that SlCOL1 can also negatively regulate fruit size in tomato.ConclusionsTomato SlCOL1 binds to the promoter of the SFT gene, down-regulates its expression, and plays a key role in reducing the fruit size.

The role of NAC transcription factors in flower development in plants

Transcription factors, the proteins with special structures, can bind to specific sites and regulate specific expression of target genes. NAC (NAM, ATAF1/2, CUC1/2) transcription factors, unique to plants, are composed of a conserved N-terminal domain and a highly variable C-terminal transcriptional activation domain. NAC transcription factors are involved in plant growth and development, responses to biotic and abiotic stresses and other processes, playing a regulatory role in flower development. In this paper, we reviewed the studies about NAC transcription factors in terms of discovery, structure, and regulatory roles in anther development, other floral organ development and flowering time. This review will provide a theoretical basis for deciphering the regulatory mechanism and improving the regulatory network of NAC transcription factors in flower development.

Sex Determination in Plants and its Contribution to Genetic Variability

Sex determination is a process that leads to the physical separation of male and female gamete-producing structures to different individuals of a species. Sexual reproduction is an ancient feature of eukaryote life, yet the sexes as we currently recognize them are relative late comers in the evolution of sex. Sex determination systems in plants have evolved many times from hermaphroditic ancestors (including monoecious plants with separate male and female flowers on the same individual),and sex chromosome systems have arisen several times in flowering plant evolution. Sex chromosome evolution is intimately connected with Y chromosome degeneration. Most current understanding of how the distinctive properties of Y chromosomes evolved comes from theoretical work on the evolution of genomic regions with low recombination. The identification of sex chromosomes in plants is problematic because most of them do not differ morphologically from autosomes or from one another. For example in some species, such as Actinidia deliciosa var. deliciosa, X and Y chromosomes are too small to support observations of their distinguishing characteristics.) In the majority of plants, male and female organs are formed and developed simultaneously, but only up to a point when the growth of either set of sex organs is inhibited. Inhibition of sexual development can vary in character so that in most cases, sexual development is inhibited by the absence of cell division. In many species of bryophytes, heterothallism (unisexuality) has been correlated with the presence of sex chromosomes. Although the extent of heterothallism and sex chromosomes in the bryophytes has not been assessed systematically, this is the only known group of homosporous plants that uses sex chromosomes in sex determination. To date, studies of bryophyte sex determination have focused on the heterothallic liverwort Marchantia polymorpha. Many dioecious species, including those with well-developed sex chromosomes, ........

Comprehensive Analyses of Four PtoNF-YC Genes from Populus tomentosa and Impacts on Flowering Timing.

Flowering is an important link in the life process of angiosperms, and it is also an important sign of the transformation of plants from vegetative to reproductive growth. Although the flowering regulation network of Arabidopsis is well-understood, there has been little research on the molecular mechanisms of perennial woody plant flower development regulation. Populus tomentosa is a unique Chinese poplar species with fast growth, strong ecological adaptability, and a long lifecycle. However, it has a long juvenile phase, which seriously affects its breeding process. Nuclear factor-Y (NF-Y) is an important type of transcription factor involved in the regulation of plant flowering. However, there are few reports on PtoNF-Y gene flowering regulation, and the members of the PtNF-YC subfamily are unknown. In this study, four key genes were cloned and analyzed for sequence characteristics, gene structure, genetic evolution, expression patterns, and subcellular localization. The plant expression vector was further constructed, and transgenic Arabidopsis and P. tomentosa plants were obtained through genetic transformation and a series of molecular tests. The flowering time and other growth characteristics were analyzed. Finally, the expression level of flowering genes was detected by quantitative PCR, the interaction between PtoNF-YC and PtoCOL proteins was measured using the yeast two-hybrid system to further explain the flowering regulation mechanism, and the molecular mechanisms by which PtNF-YC6 and PtNF-YC8 regulate poplar flowering were discussed. These results lay the foundation for elucidating the molecular regulation mechanism of PtoNF-YC in flowering and furthering the molecular design and breeding of poplar, while providing a reference for other flowering woody plants.

Fire-prone Rhamnaceae with South African affinities in Cretaceous Myanmar amber.

The rapid Cretaceous diversification of flowering plants remains Darwin's 'abominable mystery' despite numerous fossil flowers discovered in recent years. Wildfires were frequent in the Cretaceous and many such early flower fossils are represented by charcoalified fragments, lacking complete delicate structures and surface textures, making their similarity to living forms difficult to discern. Furthermore, scarcity of information about the ecology of early angiosperms makes it difficult to test hypotheses about the drivers of their diversification, including the role of fire in shaping flowering plant evolution. We report the discovery of two exquisitely preserved fossil flower species, one identical to the inflorescences of the extant crown-eudicot genus Phylica and the other recovered as a sister group to Phylica, both preserved as inclusions together with burned plant remains in Cretaceous amber from northern Myanmar (~99 million years ago). These specialized flower species, named Phylica piloburmensis sp. nov. and Eophylica priscastellata gen. et sp. nov., exhibit traits identical to those of modern taxa in fire-prone ecosystems such as the fynbos of South Africa, and provide evidence of fire adaptation in angiosperms.

The role of salicylic acid in plant flower development

Salicylic acid (SA), belonging to a family of naturally occurring phenolic compounds, is a crucial plant hormone involved in many biological processes, such as plant immunity, seed germination, root initiation, stomatal closure, and biotic/abiotic stress response. SA playing central roles in many metabolic processes have been extensively characterized. However, the function of SA in plant flower development has rarely been investigated. This paper reviews recent research advances on the roles of SA in flower development, including regulation of stamen development, flowering time, and ovarian development. This study provides multiple lines and levels of evidence substantiating that SA plays important roles in flower development, and suggests a pressing need to study the flower development-related functions of SA in both annual and perennial plants.

Analyses of MADS-box Genes Suggest HvMADS56 to Regulate Lateral Spikelet Development in Barley.

MADS-box transcription factors are crucial regulators of inflorescence and flower development in plants. Therefore, the recent interest in this family has received much attention in plant breeding programs due to their impact on plant development and inflorescence architecture. The aim of this study was to investigate the role of HvMADS-box genes in lateral spikelet development in barley (Hordeum vulgare L.). A set of 30 spike-contrasting barley lines were phenotypically and genotypically investigated under controlled conditions. We detected clear variations in the spike and spikelet development during the developmental stages among the tested lines. The lateral florets in the deficiens and semi-deficiens lines were more reduced than in two-rowed cultivars except cv. Kristina. Interestingly, cv. Kristina, int-h.43 and int-i.39 exhibited the same behavior as def.5, def.6, semi-def.1, semi-def.8 regarding development and showed reduced lateral florets size. In HOR1555, HOR7191 and HOR7041, the lateral florets continued their development, eventually setting seeds. In contrast, lateral florets in two-rowed barley stopped differentiating after the awn primordia stage giving rise to lateral floret sterility. At harvest, the lines tested showed large variation for all central and lateral spikelet-related traits. Phylogenetic analysis showed that more than half of the 108 MADS-box genes identified are highly conserved and are expressed in different barley tissues. Re-sequence analysis of a subset of these genes showed clear polymorphism in either SNPs or in/del. Variation in HvMADS56 correlated with altered lateral spikelet morphology. This suggests that HvMADS56 plays an important role in lateral spikelet development in barley.

Complete Plastid and Mitochondrial Genomes of Aeginetia indica Reveal Intracellular Gene Transfer (IGT), Horizontal Gene Transfer (HGT), and Cytoplasmic Male Sterility (CMS).

Orobanchaceae have become a model group for studies on the evolution of parasitic flowering plants, and Aeginetia indica, a holoparasitic plant, is a member of this family. In this study, we assembled the complete chloroplast and mitochondrial genomes of A. indica. The chloroplast and mitochondrial genomes were 56,381 bp and 401,628 bp long, respectively. The chloroplast genome of A. indica shows massive plastid genes and the loss of one IR (inverted repeat). A comparison of the A. indica chloroplast genome sequence with that of a previous study demonstrated that the two chloroplast genomes encode a similar number of proteins (except atpH) but differ greatly in length. The A. indica mitochondrial genome has 53 genes, including 35 protein-coding genes (34 native mitochondrial genes and one chloroplast gene), 15 tRNA (11 native mitochondrial genes and four chloroplast genes) genes, and three rRNA genes. Evidence for intracellular gene transfer (IGT) and horizontal gene transfer (HGT) was obtained for plastid and mitochondrial genomes. ψndhB and ψcemA in the A. indica mitogenome were transferred from the plastid genome of A. indica. The atpH gene in the plastid of A. indica was transferred from another plastid angiosperm plastid and the atpI gene in mitogenome A. indica was transferred from a host plant like Miscanthus siensis. Cox2 (orf43) encodes proteins containing a membrane domain, making ORF (Open Reading Frame) the most likely candidate gene for CMS development in A. indica.

IL PUNTO DI VISTA DI UN REGOLATORE EPIGENETICO DELL'ESPRESSIONE GENICA, COMUNE A UOMO E PIANTE

The regulation of gene expression is at the heart of all the fundamental processes of living organisms. It is controlled by Transcriptional Factors which, by binding to specific DNA sequences of genomes, recruit protein machineries that modify the organization of chromatin (epigenetics). Our studies are focused on the NF-Y trimeric transcription factor, a crucial activator of gene expression in all eukaryotes. Two subunits have a structure similar to histones, the basic elements of chromatin, the third -NF-YA- confers specificity to the CCAAT box. I will illustrate how regulation of NF-Y complexes is important for two completely different gene expression systems: the neoplastic transformation of human cells, and the development of flowers in plants.

Cloning and Sequence Analysis of <i>GBM5</i> Gene from <i>Ginkgo biloba</i>

AGAMOUS (AG), a member of MADS-box gene family, is a key gene related to regulation of flower development in plants. The AG homologous gene GBM5 (Accession No.: AY114304.1) was obtained from the transcriptome of Ginkgo biloba . Primers were designed according to the obtained GBM5 gene sequence, and the full-length cDNA sequence of GBM5 gene with 732 bp in size and 243 amino acids in coding product can be synthetized by designing primers. The comparative analysis of evolutionary tree and amino acid sequence showed that ginkgo GBM5 was closely related to cycads AG and black spruce AG . qPCR analysis showed that the expression of GBM5 in different tissues of Ginkgo biloba was different at different periods, the expression levels of different tissues are as follows: Female flower>Male flower>Primordia>Foliage; Its expression is high in the undifferentiated stage of flower bud, the expression patterns were: April leaf>May leaf>September leaf, April primordia>May primordia>September primordia.

Rice transcription factor MADS32 regulates floral patterning through interactions with multiple floral homeotic genes.

Floral patterning is regulated by intricate networks of floral identity genes. The peculiar MADS32 subfamily genes, absent in eudicots but prevalent in monocots, control floral organ identity. However, how the MADS32 family genes interact with other floral homeotic genes during flower development is mostly unknown. We show here that the rice homeotic transcription factor OsMADS32 regulates floral patterning by interacting synergistically with E class protein OsMADS6 in a dosage-dependent manner. Furthermore, our results indicate important roles for OsMADS32 in defining stamen, pistil, and ovule development through physical and genetic interactions with OsMADS1, OsMADS58, and OsMADS13, and in specifying floral meristem identity with OsMADS6, OsMADS3, and OsMADS58, respectively. Our findings suggest that OsMADS32 is an important factor for floral meristem identity maintenance and that it integrates the action of other MADS-box homeotic proteins to sustain floral organ specification and development in rice. Given that OsMADS32 is an orphan gene and absent in eudicots, our data substantially expand our understanding of flower development in plants.

Effect of the suppression of BpAP1 on the expression of lignin related genes in birch

Lignin is an integral part of secondary cell walls in plants and plays important roles in maintaining the strength of stems, enhancing transport ability of stems, and providing resistance to multiple stresses. Lignin biosynthesis has become one of the hotspots in molecular forest biology research. The AP1 transcription factor plays important roles in plant flower development. However, in this study, suppression of BpAP1 altered the transcription profiles of white birch and RNA-seq was used to find that suppression of BpAP1 changed the expression of lignin pathway-related genes; C4H/CYP73A, POD were down-regulated and HCT, CCoAOMT, REF1 and CAD were up-regulated. Cell walls of the suppressed transgenic birch were significantly thinner than the wild type of birch, and BpAP1- repressed birch contained less lignin. In addition to regulation of floral development, BpAP1 might play a role in regulating the expression of genes in lignin biosynthesis of birch. This study could provide a new insight into the function of AP1 genes in woody species.

Gibberellin Metabolism in Flowering Plants: An Update and Perspectives.

In plants, gibberellins (GAs) play important roles in regulating growth and development. Early studies revealed the large chemodiversity of gibberellins in plants, but only GA1, GA3, GA4, and GA7 show biological activity that controls plant development. However, the elucidation of the GA metabolic network at the molecular level has lagged far behind the chemical discovery of GAs. Recent advances in downstream GA biosynthesis (after GA12 formation) suggest that species-specific gibberellin modifications were acquired during flowering plant evolution. Here, we summarize the current knowledge of GA metabolism in flowering plants and the physiological functions of GA deactivation, with a focus on GA 13 hydroxylation. The potential applications of GA synthetic biology for plant development are also discussed.