Flower development and a functional analysis of related genes in Impatiens uliginosa.

Impatiens uliginosa is a plant of the Impatiens, with peculiar flowers. In this study, we combined morphogenesis and molecular biology to explore its development of flowers. An analysis of basic observational data and paraffin sectioning showed that it took approximately 13 d for the floral organs to differentiate. An analysis of the development of inflorescences and floral organs by scanning electron microscopy showed that the inflorescence of I. uliginosa is a spiral raceme. The floral organs differentiated in the following order: lateral sepals (Ls), posterior sepal (Ps), anterior sepals (As), anterior petal (Ap), lateral petals (Lp), stamens (St) and gynoecium (Gy). I. uliginosa was found to have four sepals, and the connate stamens are caused by the fusion and growth of filament appendages. The results of fluorescence quantification and virus-induced gene silencing showed that I. uliginosa had its own unique model for flower development, and there was functional diversity of IuAP1 and IuDEF. Among them, IuAP1 controls the formation of bract s (Br), regulates the morphogenesis of posterior sepal, controls the anthocyanin precipitation of the anterior petals and the formation of lateral petals. IuDEF regulates the morphogenesis of lateral sepals, the length of development of the spur, and controls the size of yellow flower color plaques of the lateral petals. In this study, the process of flower development and the function of flower development genes of I. uliginosa were preliminarily verified. This study provides basic guidance and new concepts that can be used to study the development of Impatiens flowers.

De novo transcriptome sequencing of Impatiens uliginosa and the analysis of candidate genes related to spur development.

BACKGROUND: Spur, a structure capable of producing and storing nectar, not only plays a vital role in the pollination process but also promotes the rapid diversification of some plant lineages, which is considered a key innovation in plants. Spur is the focus of many studies, such as evolution and ecological hypothesis, but the current understanding of spur development is limited. High-throughput sequencing of Impatiens uliginosa was carried out to study the molecular mechanism of its spur development, which is believed to provide some insights into the spur development of Impatiens. RESULTS: Transcriptomic sequencing and analysis were performed on spurs and limbs of I. uliginosa at three developmental stages. A total of 47.83 Gb of clean data were obtained, and 49,716 unigene genes were assembled. After comparison with NR, Swiss-Prot, Pfam, COG, GO and KEGG databases, a total of 27,686 genes were annotated successfully. Through comparative analysis, 19,356 differentially expressed genes were found and enriched into 208 GO terms and 146 KEGG pathways, among which plant hormone signal transduction was the most significantly enriched pathway. One thousand thirty-two transcription factors were identified, which belonged to 33 TF families such as MYB, bHLH and TCP. Twenty candidate genes that may be involved in spur development were screened and verified by qPCR, such as SBP, IAA and ABP. CONCLUSIONS: Transcriptome data of different developmental stages of spurs were obtained, and a series of candidate genes related to spur development were identified. The importance of genes related to cell cycle, cell division, cell elongation and hormones in spur development was clarified. This study provided valuable information and resources for understanding the molecular mechanism of spur development in Impatiens.

An Aux/IAA Family Member, RhIAA14, Involved in Ethylene-Inhibited Petal Expansion in Rose (Rosa hybrida).

Flower size, a primary agronomic trait in breeding of ornamental plants, is largely determined by petal expansion. Generally, ethylene acts as an inhibitor of petal expansion, but its effect is restricted by unknown developmental cues. In this study, we found that the critical node of ethylene-inhibited petal expansion is between stages 1 and 2 of rose flower opening. To uncover the underlying regulatory mechanism, we carried out a comparative RNA-seq analysis. Differentially expressed genes (DEGs) involved in auxin-signaling pathways were enriched. Therefore, we identified an auxin/indole-3-acetic acid (Aux/IAA) family gene, RhIAA14, whose expression was development-specifically repressed by ethylene. The silencing of RhIAA14 reduced cell expansion, resulting in diminished petal expansion and flower size. In addition, the expressions of cell-expansion-related genes, including RhXTH6, RhCesA2, RhPIP2;1, and RhEXPA8, were significantly downregulated following RhIAA14 silencing. Our results reveal an Aux/IAA that serves as a key player in orchestrating petal expansion and ultimately contributes to flower size, which provides new insights into ethylene-modulated flower opening and the function of the Aux/IAA transcription regulator.

Basic Characteristics of Flower Transcriptome Data and Derived Novel EST-SSR Markers of Luculia yunnanensis, an Endangered Species Endemic to Yunnan, Southwestern China.

Luculia yunnanensis (Rubiaceae), an evergreen shrub or small tree, is endemic to China and confined to Nujiang Prefecture, Yunnan Province. This plant is of high ornamental value owing to its attractive pink flowers, sweet fragrance, and long flowering period. Due to the influence of climate change and human factors, the distribution range of L. yunnanensis has exhibited a significant shrinking trend, and it has become a vulnerable species that is in urgent need of conservation and rational utilization research. In this study, the flower transcriptome sequencing of L. yunnanensis was conducted using an Illumina HiSeq platform. We designed and developed a series of EST-SSR primers based on the flower transcriptome data of L. yunnanensis. The results showed that 98,389 unigenes were obtained from the L. yunnanensis flower transcriptome, all of which were aligned with sequences in public databases. Nr, Nt, Pfam, KOG/COG, Swiss-Prot, KEGG, and GO annotated 31,859, 13,853, 22,684, 10,947, 21,416, 9722, and 23,390 unigenes, respectively. The MISA (Microsatellite) tool was used to identify SSR loci from all unigenes, and a total of 15,384 SSRs were identified. Repeat motifs were given priority with mononucleotides, dinucleotides, and trinucleotides. The 81 primer pairs were synthesized randomly, of which 44 pairs showed effective amplification. A total of 17 primers showed stable amplification, and rich polymorphism was observed in 6 populations. We concluded via genetic diversity analysis that the average effective number of alleles (Ne), Shannon's information index (I), and polymorphism information content (PIC) were 1.925, 0.837, and 0.403, respectively. In conclusion, 17 EST-SSR primers can be used for subsequent population genetic diversity analysis and molecular-marker-assisted breeding, which is of great significance for formulating resource conservation and utilization strategies for L. yunnanensis.

Magneto-optic rotation detection scheme for miniaturized coherent population trapping atomic clock.

In order to suppress the effects of carrier and high-order sidebands on the coherent population trapping (CPT) signal, a scheme of interaction between an elliptically polarized beam and alkali atoms using the magneto-optic rotation detection is examined. By canceling the spin-polarized dark state in the CPT state preparation, a CPT resonance signal with a contrast of 32.5% is obtained. Our scheme requires minor modifications of the optical path in the prevalent scheme, and the short-term frequency stability of our scheme is five times better than that of the prevalent scheme, making it ideal for miniaturized CPT atomic clock applications.

Interference-enhanced and power-reduced CPT atomic realization approach with an external cavity.

A scheme is studied for a coherent population trapping (CPT) atomic clock with counterpropagating left and right circularly polarized lasers, wherein the vertical-cavity surface-emitting laser and the partially reflecting mirror form an external cavity of an established length. With cancellation of spin-polarized dark states and interaction repeated with atoms, a CPT signal is obtained that is eight times larger than that of the conventional scheme. For the improvement of modulation efficiency, CPT resonance still can be excited with a lower microwave power compared with the conventional scheme. The experimental results suggest that it is an alternative for low-power atomic clocks.

The complete chloroplast genome sequence of sugar beet (Beta vulgaris ssp. vulgaris).

The complete nucleotide sequence of the sugar beet (Beta vulgaris ssp. vulgaris) chloroplast genome (cpDNA) was determined in this study. The cpDNA was 149,637 bp in length, containing a pair of 24,439 bp inverted repeat regions (IR), which were separated by small and large single copy regions (SSC and LSC) of 17,701 and 83,057 bp, respectively. 53.4% of the sugar beet cpDNA consisted of gene coding regions (protein coding and RNA genes). The gene content and relative positions of 113 individual genes (79 protein encoding genes, 30 tRNA genes, 4 rRNA genes) were almost identical to those of tobacco cpDNA. The overall AT contents of the sugar beet cpDNA were 63.6% and in the LSC, SSC and IR regions were 65.9%, 70.8% and 57.8%, respectively. Fifteen genes contained one intron, while three genes had two introns.

Mesenchymal stem cells attenuate vascular remodeling in monocrotaline-induced pulmonary hypertension rats.

Intravenous and intratracheal implantation of mesenchymal stem cells (MSCs) may offer ameliorating effects on pulmonary hypertension (PH) induced by monocrotaline (MCT) in rats. The aim of this study was to examine the anti-remodeling effect of intravenous MSCs (VMSCs) and intratracheal MSCs (TMSCs) in rats with PH, and the underlying mechanisms. MSCs were isolated from rat bone marrow and cultured. PH was induced in rats by intraperitoneal injection of MCT. One week after MCT administration, the rats were divided into 3 groups in terms of different treatments: VMSCs group (intravenous injection of MSCs), TMSCs group (intratracheal injection of MSCs), PH group (no treatment given). Those receiving saline instead of MCT served as negative control (control group). Pulmonary arterial structure was pathologically observed, pulmonary arterial dynamics measured, and remodeling-associated cytokines Smad2 and Smad3 detected in the lungs, three weeks after MCT injection. The results showed that PH group versus control group had higher pulmonary arterial pressure (PAP) and wall thickness index (WTI) 21 days after MCT treatment. The expression of phosphorylated (p)-Smad2 and the ratio of p-Smad2/Smad2 were much higher in PH group than in control group. Fluorescence-labeled MSCs were extensively distributed in rats' lungs in VMSCs and TMSCs groups 3 and 14 days after transplantation, but not found in the media of the pulmonary artery. WTI and PAP were significantly lower in both VMSCs and TMSCs groups than in PH group three weeks after MCT injection. The p-Smad2 expression and the ratio of p-Smad2/Smad2 were obviously reduced in VMSCs and TMSCs groups as compared with those in PH group. In conclusion, both intravenous and intratracheal transplantation of MSCs can attenuate PAP and pulmonary artery remodeling in MCT-induced PH rats, which may be associated with the early suppression of Smad2 phosphorylation via paracrine pathways.

Spin-polarized dark state free CPT state preparation with co-propagating left and right circularly polarized lasers.

We have developed and experimentally studied a coherent population trapping (CPT) state preparation scheme for atomic clock application with co-propagating left and right circularly polarized lasers. With realization of constructive interference and spin-polarized dark state free in CPT state preparation, we have obtained CPT resonance signal 3 times larger than that of the conventional scheme used in atomic clock. Polarization fluctuations and CPT signal sensitivity to laser power behaviors are both improved with the scheme. Our study reveals that it is a promising candidate for both normal-size and chip-scale CPT atomic clocks.