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The main objective of this study was to evaluate the quality and select the best varieties from 85 olive varieties in the Liangshan region, China, from the perspective of oil content, fatty acid, and triacylglycerol compositions. Although 85 varieties of olive oil showed no difference in the type of fatty acid composition and the distribution of triglycerides, they varied greatly in the oil content, the relative proportion of fatty acids, and triglycerides. Principal component analysis (PCA) and cluster and heatmap analysis clearly divided the 85 samples into three groups. Group A included 36 varieties and was characterized by high oleic acid, mono-unsaturated fatty acids (MUFA), eicosenoic acid, OOO (glyceryl trioleate), and OOL (1-oleic acid-2-oleic acid-3-linoleic acid glycerides) contents, but rare palmitoleic acid, SFA (saturated fatty acid), and POP (1-palmitic acid-2-oleic acid-3-palmitic acid glycerides) levels. Group B contained 9 varieties of olive, with the main characteristics of high oleic acid, linolenic acid, MUFA, MUFA/PUFA, SFA, and OLnO (1-oleic acid-2-linolenic acid-3-oleic acid glycerides) content, but low in linoleic acid, PUFA (polyunsaturated fatty acid), PLL levels and ratio of omega-6 to omega-3 polyunsaturated fatty acids. Group C comprised 40 varieties, identified by high linoleic acid and PUFA levels but low ratios of oleic acid, MUFA, OOO, MUFA/PUFA, and the ratio of omega-6 to omega-3 polyunsaturated fatty acids. Combined with the oil content (FW) (%) of 85 varieties, we suggested four distinguished varieties in Group A, namely Lechín, Coratina, Koroneiki, and Arbosana; three distinguished varieties in Group B, namely Picual, Ezhi, Cornicabra; two distinguished varieties in Group C namely Frantoio and Arbequina as the objects of large-scale cultivation by Chinese cultivators. More importantly, the obtained data also demonstrated that some locally bred specific varieties, such as Zhongze-3 and Yuntai, had interesting unsaturated fatty acids and had cultivation and popularization value in China. [ABSTRACT FROM AUTHOR]

The plant B3 gene superfamily contains a large number of transcription factors playing a vital role in both vegetative growth and reproductive development in plants. Although several B3 genes have been well studied, molecular functions of the B3 genes in olive are largely unknown. In our study, a total of 200 B3 genes were identified in olive genome based on RNA-seq and comparative genomic analyses and further classified into five groups (i.e., REM, RAV, LAV, HSI, and ARF) based on phylogenetic analysis. Results of gene structure and motif composition analyses revealed diversified functions among these five groups of B3 genes. Results of genomic duplication and syntenic analyses indicated the gene expansion in the B3 genes. Results of gene expression based on both transcriptomics and relative expression revealed the tissue-biased expression patterns in B3 genes. The results of the comparative expression analysis of B3 genes between two olive cultivars with high and low oil contents identified several potential REM genes which may be involved in oil biosynthesis in olive. Based on the comprehensive characterization of the molecular structures and functions of B3 genes in olive genome, our study provided novel insights into the potential roles of B3 transcription factors in oil biosynthesis in olive and lays the groundwork for the functional explorations into this research field. [ABSTRACT FROM AUTHOR]

As one of the most important crops for oil, olive (Olea europaea L.) is well-known worldwide for its commercial product "virgin olive oil" containing high-content fatty acids and many secondary metabolites. The molecular mechanisms underlying the enhanced oil content in olive remain unclear. To further investigate the molecular mechanisms of olive oil biosynthesis, we selected two olive cultivars, i.e., Kalinjot (JZ) and Coratina (KLD), at three maturity stages (MI-1, MI-3, and MI-6) for transcriptomic analysis based on Nanopore sequencing. Significant differences were observed in oil content between JZ and KLD during three maturity stages. Enrichment analysis revealed significant enrichment of differentially expressed genes (DEGs) in metabolic pathways of photosynthesis, amino acid biosynthesis, response to stress, and energy metabolism, in particular, fatty acid metabolism. A total of 170 (31.54% of 539 genes involved in oil synthesis) DEGs were further investigated based on expression analysis to identify their molecular functions in oil biosynthesis in olive. A co-expression network based on 714 transcription factors and their targeted genes in oil biosynthesis was constructed. Our study provided novel experimental evidence to investigate the molecular mechanisms of olive oil biosynthesis and to improve the breeding of olive varieties with enhanced oil contents. [ABSTRACT FROM AUTHOR]

Fiber-loop ring-down spectroscopy (FLRDS) is a recently developed absorption spectroscopic technique suitable for very small liquid samples. It is based on measurements of the optical decay constant of laser intensity in a loop made of optical waveguide material. This decay constant changes as small liquid samples containing absorbing species are introduced into the loop. In this report, it is demonstrated that one can also obtain the optical decay constant using a continuous wave laser beam that is intensity modulated and then coupled into an optical fiber loop. The inherent exponential decay in the fiber loop introduces a phase shift of the light emitted from the loop with respect to the pumping beam. By measuring rids phase shift, one can readily determine the concentration of the analyte introduced between the two fiber ends and a model is established to describe the relationship. It is demonstrated that this technique, dubbed phase-shift fiber-loop ring-down spectroscopy (PS-FLRDS), is well suited as an absorption detector for any flow system in which the optical absorption path is limited by the instrument architecture. By measuring the phase angle as a function of concentration of 1, 1'-diethyl-4,4'-dicarbocyanine iodide in dimethyl sulfoxide, the detection limit was determined as ~6 [micro]M for a 30-40-[micro]m absorption path. A temporal resolution of ~100 ms was demonstrated by a rapid displacement of the solutions between the two fiber ends. Proof-of-principle use of the PS-FLRDS detection in capillary flow systems using a commercial four-way microcross established that the alignment of the fiber and the capillary can be made simple and effective, while retaining both a low detection limit and a fast response.

Cavity ring-down (CRD) spectrometers used for analytical applications frequently have design requirements different from spectrometers used for gas-phase spectroscopic applications. A formalism that allows for maximization of the relative sensitivity by adapting the cavity length and absorption path through the sample is presented. These experimental configurations may not reduce the detection limit but do allow for a high sensitivity of the ring-down time measurement in the concentration range of interest. The formalism is applied to two common CRDS experimental configurations and to a fiber-loop ring-down experiment. Key words: cavity ring-down (CRD), absorption, detector, fiber-loop, sensitivity, detection limit.

The aim of this study was to explore the regional characteristics of soluble sugars, organic acids, and stable isotopes (δ2H, δ18O, and δ13C) in Fuji apple and the viability of tracing the geographical origin. Totally, 181 Fuji apple samples from 2017 and 2018 from three main apple production regions in China, Bohai Bay (BHB), Loess Plateau (LP), and Northwest region (NW) were collected. The parameters of soluble sugars, organic acids, and stable isotopes in samples were analyzed with HPLC, IC, and IRMS, respectively. The results of regional difference analysis, multiway variance analysis, and correlation analysis indicated that sorbitol (Sor), glucose (Glu), fructose (Fru), sucrose (Sucr), δ2H, and δ13C can be used to distinguish the samples from the three regions. Stepwise linear discriminant analysis (SLDA) showed that the correct discriminant rate of samples from the advantageous production areas of apples in China (BHB and LP) was 82.2%, and the most effective indexes were Glu, Fru, Sucr, and δ2H. Moreover, satisfactory classification can be achieved in samples from BHB and NW, with a correct classification rate of 90.0%, and Sor, Glu, and Fru were included in the discrimination model. Furthermore, the validity of the discriminant model was verified by the prediction set. The study also found that organic acids were not suitable to distinguish the apple samples from the three regions. In addition, soluble sugars and stable isotopes could not effectively distinguish LP and NW samples, which was also the reason that the samples from the three main apple production regions could not be distinguished well. [ABSTRACT FROM AUTHOR]

Pulsed, visible and near-infrared laser light is coupled into an optical fiber, which is wound into a loop using a fiber splice connector. The light pulses traveling through the fiber-loop are detected using a photomultiplier detector. It is found that once the light is coupled into the fiber it experiences very little loss and the light pulses do a large number of round trips before their intensity is below the detection threshold. Measurements of the loss-per-pass and of the ring-down time allow for characterization of the different loss mechanisms of the light pulses in the fiber and splice connector. This method resembles "cavity ring-down absorption spectroscopy" and is well suited to characterize low-loss processes in fiber optic transmission independent from power fluctuations of the light source. It is demonstrated that by measuring the ring-down times one can accurately determine the absolute transmission of an optical fiber and of the fiber connector. In addition it is demonstrated that the technique is useful as an absorption spectroscopic technique of very small sample volumes. A solution of an organic dye was placed between the fiber ends instead of the usual index matching fluid, and an absorption spectrum of 7 × 10[sup -15] mol of the dye 1,1'-diethyl4,4'-dicarbocyanine iodide in 7 × 10[sup -12] L of dimethylsulfoxide was recorded. [ABSTRACT FROM AUTHOR]

Cavity ring-down spectroscopy has proven to be a very sensitive gas-phase spectroscopic technique, suitable to record either very weak transitions of abundant gases or stronger transitions of trace gases. Here, an adaptation of the ring-down measurement principle to optical waveguides is presented. Fiber-loop ring-down spectroscopy (FLRDS) allows for the measurement of absorption spectra of minute quantities of liquid solutions. An optical fiber is wound into a loop using a fiber splice connector. A nanosecond laser light pulse (λ∼810 nm) is coupled into the loop and the light pulses are detected using a photomultiplier detector. It is found that once the light is coupled into the fiber it experiences very little loss and the light pulses do a large number of round trips before their intensity is below the detection threshold. The characteristic ring-down time is obtained by exponential fitting of the envelope of the wave form. This method is well suited to characterize low-loss processes in fiber optic transmission independent from power fluctuations of the light source. The strengths of the technique are demonstrated by characterization of a variety of loss processes—in particular by the measurement of the absolute loss of the optical fiber and of the fiber connector, losses due to macrobending of a section of the fiber loop, as well as losses due to lateral and longitudinal displacement in the fiber–fiber connection. Furthermore, it is shown that FLRDS is useful as an absorption spectroscopic technique for very small sample volumes and may be applied as an absorption detection method in analytical chemistry devices. A crude 47 μm channel in polydimethylsiloxane polymer was fabricated between the fiber end facets and the dye 1,1[sup ′]-diethyl-4,4[sup ′]-dicarbocyanine iodide (DDCI) was introduced into the channel. From the concentration dependence of ring-down time the sample volume was determined as 700 pL and the detection limit as about 10[sup -10] mol, or 7×10[sup -8] g of DDCI. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Double-flower ornamental crabapples display eye-catching morphologies in comparison to single flower, but the genetic basis of double-flower development is not yet well known in apples. In order to comprehensively understand the differential expression of genes (DEGs) between single and double flower, the transcriptome of double flower crabapples Malus Kelsey, Malus micromalus, Malus Royalty, and a single flower cultivar Malus Dolgo were compared by RNA-sequencing. The results showed that there were 1854 genes in overlapped DEGs among all sample comparisons in apple single and double flower varieties. A large number of development and hormone related DEGs were also recognized on the basis of GO and KEGG annotations, and most of the genes were found to be down-regulated in double flowers. Particularly, an AGL24-MADS-box gene (MD08G1196900) and an auxin responsive gene (MD13G1137000) were putatively key candidate genes in the development of double flower by weighted gene co-expression network analysis (WGCNA). The study provides insights into the complex molecular mechanism underlying the development of the double flower in apple. [ABSTRACT FROM AUTHOR]

Background: RT-qPCR is a preferred method for rapid and reliable quantification of gene expression studies. Appropriate application of RT-qPCR in such studies requires the use of reference gene(s) as an internal control to normalize mRNA levels between different samples for an exact comparison of gene expression level. However, recent studies have shown that no single reference gene is universal for all experiments. Thus, the identification of high quality reference gene(s) is of paramount importance for the interpretation of data generated by RT-qPCR. Only a few studies on reference genes have been done in plants and none in peach (Prunus persica L. Batsch). Therefore, the present study was conducted to identify suitable reference gene(s) for normalization of gene expression in peach., Results: In this work, eleven reference genes were investigated in different peach samples using RT-qPCR with SYBR green. These genes are: actin 2/7 (ACT), cyclophilin (CYP2), RNA polymerase II (RP II), phospholipase A2 (PLA2), ribosomal protein L13 (RPL13), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 18S ribosomal RNA (18S rRNA), tubblin beta (TUB), tubblin alpha (TUA), translation elongation factor 2 (TEF2) and ubiquitin 10 (UBQ10). All eleven reference genes displayed a wide range of Cq values in all samples, indicating that they expressed variably. The stability of these genes except for RPL13 was determined by three different descriptive statistics, geNorm, NormFinder and BestKeeper, which produced highly comparable results., Conclusion: Our study demonstrates that expression stability varied greatly between genes studied in peach. Based on the results from geNorm, NormFinder and BestKeeper analyses, for all the sample pools analyzed, TEF2, UBQ10 and RP II were found to be the most suitable reference genes with a very high statistical reliability, and TEF2 and RP II for the other sample series, while 18S rRNA, RPL13 and PLA2 were unsuitable as internal controls. GAPDH and ACT also performed poorly and were less stable in our analysis. To achieve accurate comparison of levels of gene expression, two or more reference genes must be used for data normalization. The combinations of TEF2/UBQ10/RP II and TEF2/RP II were suggested for use in all samples and subsets, respectively.