SMA1, a homolog of the splicing factor Prp28, has a multifaceted role in miRNA biogenesis in Arabidopsis

MicroRNAs (miRNAs) are a class of small non-coding RNAs that repress gene expression. In plants, the RNase III enzyme Dicer-like (DCL1) processes primary miRNAs (pri-miRNAs) into miRNAs. Here, we show that SMALL1 (SMA1), a homolog of the DEADbox pre-mRNA splicing factor Prp28, plays essential roles in miRNA biogenesis in Arabidopsis. A hypomorphic sma1-1 mutation causes growth defects and reduces miRNA accumulation correlated with increased target transcript levels. SMA1 interacts with the DCL1 complex and positively influences primiRNA processing. Moreover, SMA1 binds the promoter region of genes encoding pri-miRNAs (MIRs) and is required for MIR transcription. Furthermore, SMA1 also enhances the abundance of the DCL1 protein levels through promoting the splicing of the DCL1 pre-mRNAs. Collectively, our data provide new insights into the function of SMA1/Prp28 in regulating miRNA abundance in plants

Characterization of Non-heading Mutation in Heading Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

Heading is a key agronomic trait of Chinese cabbage. A non-heading mutant with flat growth of heading leaves (fg-1) was isolated from an EMS-induced mutant population of the heading Chinese cabbage inbred line A03. In fg-1 mutant plants, the heading leaves are flat similar to rosette leaves. The epidermal cells on the adaxial surface of these leaves are significantly smaller, while those on the abaxial surface are much larger than in A03 plants. The segregation of the heading phenotype in the F2 and BC1 population suggests that the mutant trait is controlled by a pair of recessive alleles. Phytohormone analysis at the early heading stage showed significant decreases in IAA, ABA, JA and SA, with increases in methyl IAA and trans-Zeatin levels, suggesting they may coordinate leaf adaxial-abaxial polarity, development and morphology in fg-1. RNA-sequencing analysis at the early heading stage showed a decrease in expression levels of several auxin transport (BrAUX1, BrLAXs, and BrPINs) and responsive genes. Transcript levels of important ABA responsive genes, including BrABF3, were up-regulated in mid-leaf sections suggesting that both auxin and ABA signaling pathways play important roles in regulating leaf heading. In addition, a significant reduction in BrIAMT1 transcripts in fg-1 might contribute to leaf epinastic growth. The expression profiles of 19 genes with known roles in leaf polarity were significantly different in fg-1 leaves compared to wild type, suggesting that these genes might also regulate leaf heading in Chinese cabbage. In conclusion, leaf heading in Chinese cabbage is controlled through a complex network of hormone signaling and abaxial-adaxial patterning pathways. These findings increase our understanding of the molecular basis of head formation in Chinese cabbage

Underlying Biochemical and Molecular Mechanisms for Seed Germination

With the burgeoning population of the world, the successful germination of seeds to achieve maximum crop production is very important. Seed germination is a precise balance of phytohormones, light, and temperature that induces endosperm decay. Abscisic acid and gibberellins—mainly with auxins, ethylene, and jasmonic and salicylic acid through interdependent molecular pathways—lead to the rupture of the seed testa, after which the radicle protrudes out and the endosperm provides nutrients according to its growing energy demand. The incident light wavelength and low and supra-optimal temperature modulates phytohormone signaling pathways that induce the synthesis of ROS, which results in the maintenance of seed dormancy and germination. In this review, we have summarized in detail the biochemical and molecular processes occurring in the seed that lead to the germination of the seed. Moreover, an accurate explanation in chronological order of how phytohormones inside the seed act in accordance with the temperature and light signals from outside to degenerate the seed testa for the thriving seed’s germination has also been discussed

Expression Analyses of ABCDE Model Genes and Changes in Levels of Endogenous Hormones in Chinese Cabbage Exhibiting Petal-Loss

Abnormal formation of floral organs affects plant reproduction and can directly interfere with the progress of breeding programs. Using PCR amplification, ABCDE model genes BraAP2, BraAP3, BraPI, BraAG, BraSHP, and BraSEP were isolated from Chinese cabbage (Brassica rapa L. ssp. pekinensis). We examined six development stages of floral buds collected from Chinese cabbage and compared between a line demonstrating normal flowering (A-8) and two mutated lines that exhibited plants having petal-loss (A-16 and A-17). The expression of ABCDE model genes has been analyzed by qRT-PCR. Compared with flower buds of petal-loss plants and normal plants, the expression of A-class gene BraAP2 was significantly decreased during the first to fourth stages, C-class gene BraAG expression was significantly decreased during the first to fifth stages, and D-class gene BraSHP expression was significantly decreased during the first to third stages. Furthermore, B-class gene BraAP3 and BraPI and E-class gene BraSEP expressions were significantly decreased during all six stages of petal-loss plants compared with normal plants. Enzyme-linked immunosorbent assays detected nine endogenous phytohormones during all stages examined here. Except for the second-stage and third-stage buds, levels of the auxin IAA and cytokinin dhZR were always higher in the petal-loss plants than the normal plants at corresponding time points. Meanwhile, concentrations of GA1+3 at the first, fourth, and fifth stages were higher in the petal-loss plants than in the normal plants. Our results provide a theoretical basis for future exploration of the molecular mechanism that determines petal loss and the effects that hormones have on such development in Chinese cabbage plants

Glucosinolates in Self-crossed Progenies of Monosomic Cabbage Alien Addition Lines in Chinese Cabbage

Brassica species have been reported to possess cancer preventive activity due to glucosinolates (GLS) and their derived properties. Many studies on GLS have focused on Brassica oleracea and Brassica rapa. However, information on GLS in progeny between Chinese cabbage (B. rapa ssp. pekinensis) and cabbage (B. oleracea var. capitata) remains limited. In this study, eight GLS were detected in the self-crossed progenies of monosomic cabbage alien addition lines in Chinese cabbage (Chinese cabbage – cabbage MAALs) and parental Chinese cabbage, and nine GLS were detected in the parental cabbage. The variation of GLS content ranges was greater in the progeny than in the parental Chinese cabbage. The nine GLS identified were subjected to PCA to evaluate the differences among progeny and parents. Eight progeny samples had a comprehensive principal component score closer to or greater than that of cabbage, and four of them exhibited glucoraphanin (GRA) and total GLS contents greater than that of Chinese cabbage with the relative content of total indolic GLS was greater than 50%. These results offered new opportunity to improve GLS-containing of Chinese cabbage using genes from cabbage

Characterization of atmospheric organic carbon and element

ABSTRACT Concentrations of organic carbon (OC) and elemental carbon (EC) in atmospheric particles were measured in Tianjin during January, April, July and October in 2008. The 24-h PM 2.5 (particles with aerodynamic diameters less than 2.5 micrometer [ m]) and PM 10 (particles with aerodynamic diameters less than 10 micrometer [ m]) samples were simultaneously collected every day during sampling periods. These samples were analyzed for OC/EC by thermal/optical reflectance (TOR) following the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. The annual average concentration was 109.8 ± 48.5 g/m 3 in PM 2.5 , and 196.2 ± 86.1 g/m 3 in PM 10 , respectively. The average ratio of PM 2.5 /PM 10 was 57.9%, indicating the PM 2.5 had been one of the main contaminations affecting urban atmospheric environmental quality in Tianjin. The concentrations of OC and EC in PM 2.5 and PM 10 were all relatively higher in winter and fall and lower in summer and spring. This seasonal variation could be attributed to the cooperative effects of changes in emission rates and seasonal meteorological conditions. The annual average concentration of the estimated secondary organic carbon (SOC) was 14.9 g/m 3 and occupied 61.7% of the total OC in PM 2.5 , while those in PM 10 were 23.4 g/m 3 and 61.2%, respectively, indicating SOC had been an important contributor to organic aerosol in Tianjin. The distribution of eight carbon fractions (OC1, OC2, OC3, OC4, EC1, EC2, EC3 and OP) was also reported and found that the biomass burning, coal-combustion and motor-vehicle exhaust were all contributed to the carbonaceous particles in Tianjin

SMA1, a homolog of the splicing factor Prp28, has a multifaceted role in miRNA biogenesis in Arabidopsis

MicroRNAs (miRNAs) are a class of small non-coding RNAs that repress gene expression. In plants, the RNase III enzyme Dicer-like (DCL1) processes primary miRNAs (pri-miRNAs) into miRNAs. Here, we show that SMALL1 (SMA1), a homolog of the DEADbox pre-mRNA splicing factor Prp28, plays essential roles in miRNA biogenesis in Arabidopsis. A hypomorphic sma1-1 mutation causes growth defects and reduces miRNA accumulation correlated with increased target transcript levels. SMA1 interacts with the DCL1 complex and positively influences primiRNA processing. Moreover, SMA1 binds the promoter region of genes encoding pri-miRNAs (MIRs) and is required for MIR transcription. Furthermore, SMA1 also enhances the abundance of the DCL1 protein levels through promoting the splicing of the DCL1 pre-mRNAs. Collectively, our data provide new insights into the function of SMA1/Prp28 in regulating miRNA abundance in plants

Propagation characteristics of Doppler ultrasonic wave in gas–liquid two-phase flow in an offshore deepwater riser

During offshore deepwater drilling, the strata with abnormal pressure are often encountered and gas invasion and overflow occur easily. If they cannot be detected and controlled in time, blowout may happen and even get out of control, which will cause considerable economic loss and irreparable casualties and may even damage the marine ecologic environment seriously. How to monitor overflow early during deepwater drilling is a global research hot, focus and difficulty at present. In order to provide theoretical guidance for the early monitoring of overflow in the riser during offshore deepwater drilling, this paper designed an experimental device for the early monitoring of gas invasion based on the propagation principle of Doppler ultrasonic wave. Then, the installation mode and angle of Doppler probe were optimized. Finally, the propagation of Doppler ultrasonic wave in the gas–liquid two-phase flow with a void fraction of 0–46% and a liquid flow velocity of 0–0.7 m/s was experimentally studied, and the change laws of Doppler ultrasonic wave with void fraction were revealed. And the following research results are obtained. First, when the void fraction changes, the signal voltage will jump up and down at different amplitudes and frequencies on the basis of initial curve. The signal voltage amplitude increases firstly and then decreases with the increase of void fraction. Second, when the increase amplitude of mean signal voltage caused by multiple reflection is greater than the attenuation degree of ultrasonic wave, the mean signal voltage increases. Otherwise, the signal voltage decreases. Third, the fitting curve of mean signal voltage scatters and void fraction under different flow velocities and void fractions during pump stopping and starting present a change law of quadratic function. In conclusion, void fraction can be quantitatively predicted based on the measured signal voltage, so as to provide guidance for the early monitoring of riser overflow and well kill operation during offshore deepwater drilling