Auxin and carbohydrate control flower bud development in Anthurium andraeanum during early stage of sexual reproduction.

BACKGROUND: Flower buds of Anthurium andraeanum frequently cease to grow and abort during the early flowering stage, resulting in prolonged planting times and increased commercialization costs. Nevertheless, limited knowledge exists of the mechanism of flower development after initiation in A. andraeanum. RESULTS: In this study, the measurement of carbohydrate flow and intensity between leaves and flowers during different growth stages showed that tender leaves are strong sinks and their concomitant flowers are weak ones. This suggested that the tender leaves compete with their concomitant flower buds for carbohydrates during the early growth stages, potentially causing the abortion of the flower buds. The analysis of transcriptomic differentially expressed genes suggested that genes related to sucrose metabolism and auxin response play an important role during flower bud development. Particularly, co-expression network analysis found that AaSPL12 is a hub gene engaged in flower development by collaborating carbohydrate and auxin signals. Yeast Two Hybrid assays revealed that AaSPL12 can interact with AaARP, a protein that serves as an indicator of dormancy. Additionally, the application of exogenous IAA and sucrose can suppress the expression of AaARP, augment the transcriptional abundance of AaSPL12, and consequently expedite flower development in Anthurium andraeanum. CONCLUSIONS: Collectively, our findings indicated that the combination of auxin and sugar signals could potentially suppress the repression of AaARP protein to AaSPL12, thus advancing the development of flower buds in Anthurium andraeanum.

Genome-Wide Analysis of TCP Transcription Factors and Their Expression Pattern Analysis of Rose Plants (Rosa chinensis).

The plant-specific transcription factor TEOSINTE BRANCHED, CYCLOIDEA, AND PROLIFERATING CELL FACTOR (TCP) gene family plays vital roles in various biological processes, including growth and development, hormone signaling, and stress responses. However, there is a limited amount of information regarding the TCP gene family in roses (Rosa sp.). In this study, we identified 18 TCP genes in the rose genome, which were further classified into two subgroups (Group A and Group B) via phylogenetic analysis. Comprehensive characterization of these TCP genes was performed, including gene structure, motif composition, chromosomal location, and expression profiles. Synteny analysis revealed that a few TCP genes are involved in segmental duplication events, indicating that these genes played an important role in the expansion of the TCP gene family in roses. This suggests that segmental duplication events have caused the evolution of the TCP gene family and may have generated new functions. Our study provides an insight into the evolutionary and functional characteristics of the TCP gene family in roses and lays a foundation for the future exploration of the regulatory mechanisms of TCP genes in plant growth and development.

Bioinformatics Analysis of WRKY Family Genes in Flax (Linum usitatissimum).

WRKY gene family is one of the largest transcription factor families involved in various physiological processes of plants. Flax (Linum usitatissimum) is an important stem fiber crop, and it is also an economically important crop in natural fiber and textile industries around the world. In this study, 105 WRKY genes were obtained by screening the whole genome of flax. There were 26 in group I, 68 in group II, 8 in group III and 3 in group UN. The characteristics of the WRKY motif and gene structure in each group are similar. The promoter sequence of WRKY genes includes photoresponsive elements, core regulatory elements and 12 cis-acting elements under abiotic stress. Similar to A. thaliana and Compositae plants, WRKY genes are evenly distributed on each chromosome, with segmental and tandem repeated events, which play a major role in the evolution of WRKY genes. The flax WRKY gene family is mainly concentrated in group I and group II. This study is mainly based on genome-wide information to classify and analyze the flax WRKY gene family, laying a foundation for further understanding the role of WRKY transcription factors in species evolution and functional analysis.

The complete chloroplast genome sequence of Anthurium andraeanum Linden (Araceae; Pothoideae).

The chloroplast genome of Anthurium andraeanum Linden 1877 was assembled and analyzed in this study. The genome size is 162,560 bp, of which contains a large single-copy (LSC) region with 88,814 bp, a small single-copy (SSC) region with 22,856 bp, and two inverted repeat regions (IRA and IRB) with 25,445 bp, respectively. The plastome contains 124 genes, including 80 protein-coding genes, 37 tRNAs, six rRNAs and one pseudogene. Phylogenetic analysis indicated that A. andraeanum is a member of Pothoideae and sister to A. huixtlense.

The Chromosome-Scale Assembly of the Curcuma alismatifolia Genome Provides Insight Into Anthocyanin and Terpenoid Biosynthesis.

Curcuma alismatifolia, a bulbous flower known for its showy bracts, is widely used around the world as a cut flower, potted, and garden plant. Besides its ornamental value, this species is rich in terpenoid metabolites and could serve as a resource for essential oils. Here, we report a chromosome-level genome assembly of C. alismatifolia and describe its biosynthetic pathways for anthocyanins and terpenoids. This high-quality, assembled genome size is 991.3 Mb with a scaffold N50 value of 56.7 Mb. Evolutionary analysis of the genome suggests that C. alismatifolia diverged from Zingiber officinale about 9.7 million years ago, after it underwent a whole-genome duplication. Transcriptome analysis was performed on bracts at five developmental stages. Nine highly expressed genes were identified, encoding for six enzymes downstream of the anthocyanin biosynthetic pathway. Of these, one gene encoding F3'5'H might be a key node in the regulation of bract color formation. Co-expression network analysis showed that MYB, bHLH, NAC, and ERF transcription factors collectively regulated color formation in the bracts. Characterization of terpenoid biosynthesis genes revealed their dispersal and tandem duplications, both of which contributed greatly to the increase in the number of terpene synthase genes in C. alismatifolia, especially to species-specific expansion of sesquiterpene synthase genes. This work facilitates understanding of genetic basis of anthocyanin and terpenoid biosynthesis and could accelerate the selective breeding of C. alismatifolia varieties with higher ornamental and medicinal value.

The chloroplast genome of the moss Haplocladium microphyllum, first in family Thuidiaceae.

Bryophytes are a highly diverse group containing more than 12,800 species. Haplocladium microphyllum is in a large moss belonging to the family Thuidiaceae. We report the complete chloroplast (124,478 bp) genome sequence of H. microphyllum, it includes a pair of inverted repeat regions (IRs, 9727 bp), one large single-copy (LSC, 86,528 bp) region, and one small single-copy (SSC, 18,496 bp) region. Besides, the complete chloroplast genome contains 134 genes in total, including 88 protein-coding genes, 38 tRNA genes, and eight rRNA genes. Phylogenetic analysis showed that H. microphyllum has the closest relationship with Sanionia uncinata in Amblystegiaceae. Our study lays a foundation for further research like speciation of this species and the phylogeny of the Thuidiaceae family.

Piriformospora indica-induced phytohormone changes and root colonization strategies are highly host-specific.

Piriformospora indica, an endophytic fungus of Sebacinales, has a wide host range and promotes the performance of mono- and eudicot plants. Here, we compare the interaction of P. indica with the roots of seven host plants (Anthurium andraeanum, Arabidopsis thaliana, Brassica campestris, Lycopersicon esculentum, Oncidium orchid, Oryza sativa, and Zea mays). Microscopical analyses showed that the colonization time and the mode of hyphal invasion into the roots differ in the symbiotic interactions. Substantial differences between the species were also observed for the levels and accumulation of jasmonate (JA) and gibberellin (GA) and the transcript levels for genes involved in their syntheses. No obvious correlation could be detected between the endogenous JA and/or GA levels and the time point of root colonization in a given plant species. Our results suggest that root colonization strategies and changes in the two phytohormone levels are highly host-specific.

Ectopic expression of the AaFUL1 gene identified in Anthurium andraeanum affected floral organ development and seed fertility in tobacco.

Anthurium andraeanum is a high-grade potted flower that enjoys global popularity. Its floral organs have been substantially modified, and its ornamental value is based on its petaloid bracts. MADS-box gene products are important transcription factors that control plant development. In particular, the APETALA1 (AP1)/FRUITFULL (FUL) family of MADS-box genes plays a key role in flowering transitions and out-whorl floral organ identity specification. In this report, one FUL-like gene was cloned from Anthurium andraeanum and named AaFUL1 after bioinformatics identification. Subsequent subcellular localization experiments confirmed that the AaFUL1 protein was located in the nucleus, and data obtained from an expression analysis indicated that the relative expression level of AaFUL1 was the highest in bracts and inflorescences, while its expression was relatively low in stems and roots. Next, an AaFUL1 overexpression vector was constructed and ectopically expressed in tobacco. The transformants did not show any early flowering phenotype, but the average internode length of the inflorescence branch was significantly higher than that observed in the control, and its petal color had substantially faded. The morphology of the petal and pistil was clearly changed, the fruit was deformed, and the seed was largely aborted. These data indicate that even though the sequence of AaFUL1 is relatively conserved, its function differs from that of other orthologs, and the FUL subfamily of MADS-box transcription factors may have taken on new functions during the evolution processes. The results of this experiment enrich our knowledge of FUL transcription factors in monocotyledon plants.

iTRAQ-based quantitative proteomic analysis reveals dynamic changes during daylily flower senescence.

MAIN CONCLUSION: Sugar-related metabolic biological processes and metabolic pathways as well as invertase, protease, and ribosomal proteins may be critical regulators controlling the circadian rhythm and ephemeral properties of daylily flowers. Daylily is a familiar perennial flower. The daylily flower opens at dawn and withers away at night. Flower longevity in almost all daylily varieties from opening to fading is less than 24 h. In the past decades, the physiological changes and genetic responses to senescence in daylily flowers have been reported. However, the main metabolic pathways and biological processes involved in daylily flower senescence and the proteins involved in premature senility of daylily flowers are poorly understood. Herein, we identified differences between the proteomes of four developmental stages (s1-s4) of daylily flowers using iTRAQ-based quantitative proteomic methods. A total of 445 proteins (containing at least two unique peptides) were identified, and differentially expressed proteins (upregulation ≥ 1.5 or downregulation ≤ 0.67, P value ≤ 0.05) were detected between these stages in the following numbers: 58 (s2/s1), 59 (s3/s1), 31 (s3/s2), 64 (s4/s1), 52 (s4/s2), and 29 (s4/s3). Protein functions and classifications were analyzed based on GO, KEGG, and COG, and expressive hierarchical cluster analysis and functional enrichment analysis for differentially expressed proteins were carried out. A comparison of the late stages (s3 and s4) with the early stage (s1) revealed that the sugar (hexose, monosaccharide, and glucose) metabolic process GO category was the most enriched, and sugar (galactose, pentose, starch, and sucrose) metabolism pathways constituted the most enriched KEGG category. Finally, the potential research value of invertase, protease, and ribosomal proteins for revealing the mechanism underlying the circadian rhythm and ephemeral properties of daylily flowers are discussed. These data and analyses provide new insight into the senescence mechanism of daylily flowers.

Cloning and functional analysis of a novel ascorbate peroxidase (APX) gene from Anthurium andraeanum.

An 888-bp full-length ascorbate peroxidase (APX) complementary DNA (cDNA) gene was cloned from Anthurium andraeanum, and designated as AnAPX. It contains a 110-bp 5'-noncoding region, a 28-bp 3'-noncoding region, and a 750-bp open reading frame (ORF). This protein is hydrophilic with an aliphatic index of 81.64 and its structure consisting of α-helixes, ß-turns, and random coils. The AnAPX protein showed 93%, 87%, 87%, 87%, and 86% similarities to the APX homologs from Zantedeschia aethiopica, Vitis pseudoreticulata, Gossypium hirsutum, Elaeis guineensis, and Zea mays, respectively. AnAPX gene transcript was measured non-significantly in roots, stems, leaves, spathes, and spadices by real-time polymerase chain reaction (RT-PCR) analysis. Interestingly, this gene expression was remarkably up-regulated in response to a cold stress under 6 °C, implying that AnAPX might play an important role in A. andraeanum tolerance to cold stress. To confirm this function we overexpressed AnAPX in tobacco plants by transformation with an AnAPX expression construct driven by CaMV 35S promoter. The transformed tobacco seedlings under 4 °C showed less electrolyte leakage (EL) and malondialdehyde (MDA) content than the control. The content of MDA was correlated with chilling tolerance in these transgenic plants. These results show that AnAPX can prevent the chilling challenged plant from cell membrane damage and ultimately enhance the plant cold tolerance.

De novo characterization of the Anthurium transcriptome and analysis of its digital gene expression under cold stress.

BACKGROUND: Anthurium andraeanum is one of the most popular tropical flowers. In temperate and cold zones, a much greater risk of cold stress occurs in the supply of Anthurium plants. Unlike the freeze-tolerant model plants, Anthurium plants are particularly sensitive to low temperatures. Improvement of chilling tolerance in Anthurium may significantly increase its production and extend its shelf-life. To date, no previous genomic information has been reported in Anthurium plants. RESULTS: Using Illumina sequencing technology, we generated over two billion base of high-quality sequence in Anthurium, and demonstrated de novo assembly and annotation of genes without prior genome information. These reads were assembled into 44,382 unigenes (mean length = 560 bp). Based on similarity search with known protein in the non-redundant (nr) protein database, 27396 unigenes (62%) were functionally annotated with a cut-off E-value of 10-5. Further, DGE tags were mapped to the assembled transcriptome for gene expression analysis under cold stress. In total, 4363 differentially expressed genes were identified. Among these genes, 292, 805 and 708 genes were up-regulated after 1-h, 5-h and 24-h cold treatment, respectively. Then we mapped these cold-induced genes to the KEGG database. Specific enrichment was observed in photosynthesis pathway, metabolic pathways and oxidative phosphorylation pathway in 1-h cold-treated plants. After a 5-h cold treatment, the metabolic pathways and oxidative phosphorylation pathway were significantly identified as the top two pathways. After 24-h cold treatment, mRNA surveillance pathway, RNA transport pathway and plant-pathogen interaction pathway were significantly enriched. Together, a total of 39 cold-inducible transcription factors were identified, including subsets of AP2/ERF, Zinc figure, NAC, MYB and bZIP family members. CONCLUSION: Our study is the first to provide the transcriptome sequence resource for Anthurium plants, and demonstrate its digital gene expression profiling under cold conditions using the assembled transcriptome data for reference. These data provides a valuable resource for genetic and genomic studies under abiotic conditions for Anthurium plants.

Molecular characterization of cultivated bromeliad accessions with Inter-Simple Sequence Repeat (ISSR) Markers.

Bromeliads are of great economic importance in flower production; however little information is available with respect to genetic characterization of cultivated bromeliads thus far. In the present study, a selection of cultivated bromeliads was characterized via inter-simple sequence repeat (ISSR) markers with an emphasis on genetic diversity and population structure. Twelve ISSR primers produced 342 bands, of which 287 (~84%) were polymorphic, with polymorphic bands per primer ranging from 17 to 34. The Jaccard's similarity ranged from 0.08 to 0.89 and averaged ~0.30 for the investigated bromeliads. The Bayesian-based approach, together with the un-weighted paired group method with arithmetic average (UPGMA)-based clustering and the principal coordinate analysis (PCoA), distinctly grouped the bromeliads from Neoregelia, Guzmania, and Vriesea into three separately clusters, well corresponding with their botanical classifications; whereas the bromeliads of Aechmea other than the recently selected hybrids were not well assigned to a cluster. Additionally, ISSR marker was proven efficient for the identification of hybrids and bud sports of cultivated bromeliads. The findings achieved herein will further our knowledge about the genetic variability within cultivated bromeliads and therefore facilitate breeding for new varieties of cultivated bromeliads in future as well.