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SUMMARY: Erianin, crepidatin, and chrysotobibenzyl are typical medicinal polymethoxylated bibenzyls (PMBs) that are commercially produced in Dendrobium species. PMBs' chemo‐diversity is mediated by the manifold combinations of O‐methylation and hydroxylation in a definite order, which remains unsolved. To unequivocally elucidate the methylation mechanism of PMBs, 15 possible intermediates in the biosynthetic pathway of PMBs were chemically synthesized. DcOMT1–5 were highly expressed in tissues where PMBs were biosynthesized, and their expression patterns were well‐correlated with the accumulation profiles of PMBs. Moreover, cell‐free orthogonal tests based on the synthesized intermediates further confirmed that DcOMT1‐5 exhibited distinct substrate preferences and displayed hydroxyl‐group regiospecificity during the sequential methylation process. The stepwise methylation of PMBs was discovered from SAM to dihydro‐piceatannol (P) in the following order: P → 3‐MeP → 4‐OH‐3‐MeP → 4‐OH‐3,5‐diMeP → 3,3'(4′),5‐triMeP → 3,4,4′,5‐tetraMeP (erianin) or 3,3′,4,5‐tetraMeP (crepidatin) → 3,3′,4,4′,5‐pentaMeP (chrysotobibenzyl). Furthermore, the regioselectivities of DcOMTs were investigated by ligand docking analyses which corresponded precisely with the catalytic activities. In summary, the findings shed light on the sequential catalytic mechanisms of PMB biosynthesis and provide a comprehensive PMB biosynthetic network in D. catenatum. The knowledge gained from this study may also contribute to the development of plant‐based medicinal applications and the production of high‐value PMBs. [ABSTRACT FROM AUTHOR]

Seven grain quality traits were tested in the panel of 188 winter wheat accessions from Xinjiang. Twelve co-associated genetic loci were detected in four different environments via GWAS, explaining 6.021%-31.467% phenotypic variation. Two pleiotropism loci, located on chromosomes 6A and 2B, associated with protein content and settlement value, protein content and bulk density of wheat. Five pleiotropism loci, located on 3A, 1B, 6B, 7B, and 7D, shared by protein content and wet gluten content. One pleiotropism locus, located on 5B chromosome, associated with settlement value, bulk density of wheat and grain hardness. Three pleiotropism loci located on 7A, 3B, and 2D, respectively, which shared by protein content, settlement value, and wet gluten content, while one pleiotropism locus with unknown site was also associated with protein content, settlement value, and wet gluten content. These associated loci or genes might be employed to select favorite wheat genotypes, and cultivate elite wheat genotypes via marker-assisted selection in wheat quality breeding. Candidate genes at stable loci associated with multiple traits were searched, and 11 candidate genes that might be related to wheat grain quality with multiple traits and environments were screened. Among them, TraesCS6B01G347500 encoded a storage and transportation protein, TraesCS1B01G395400 encoded a carbohydrate transport protein/sugar transport protein, and TraesCS2D01G246500 gene encoded a protein ESKIMO1 related to cold tolerance, salt tolerance, and water conservation. These genes can be used as candidate genes for allelic variation analysis and marker development, provide molecular tools for wheat marker assisted selection breeding. [ABSTRACT FROM AUTHOR]

In order to clarify the influence of key cultivation measures on rapeseed oil quality, a single factor field experiments of sowing date, planting density, and nitrogen rate were carried out in Wuhan and Lanzhou with "Xiangzayou 518 (XZY518)" and "Dadi 199 (DD199)" as the experimental materials. The rapeseed was harvested at maturity stage, followed by cold pressing and oil content, oil extraction efficiency, color of rapeseed oil, peroxide value, total polar phenols, and phytosterol content were assessed, and rapeseed oil quality was evaluated comprehensively under each treatment. The results showed that sowing date, density, and nitrogen rate all significantly affected the key quality indexes of rapeseed oil, and the pattern of change of each index was not the same between the two varieties from two sites. Two varieties from two sites had higher oleic acid content in rapeseed oil under early sowing conditions, and as the sowing date was delayed, rapeseed oil color deepened, chlorophyll content increased, and the comprehensive quality decreased. The XZY518 from two sites at D2 density (4.5x105 hm-2) had a lower acid value, higher total polar phenol, total phytosterol, and total tocopherol contents, and better comprehensive quality. The DD 199 from two sites with increasing density, the chlorophyll content of rapeseed oil increased, the color deepened, the linoleic acid content decreased, and the comprehensive quality also decreased. Two varieties from two sites had higher oil content and oil extraction efficiency under low nitrogen (120 kg hm-2). With the increase of nitrogen rate, rapeseed oil color deepened, comprehensive quality declined. Principal component analysis showed that the effect of sowing date on the comprehensive quality of rapeseed oil was greater than that of planting density and nitrogen rate treatments, and that acid value, chlorophyll, total polar phenols, antioxidant power and total phytosterols were key quality indicators affecting rapeseed oils. Correlation analysis showed that seed oil content was significantly positively correlated with oil extraction efficiency, chlorophyll, carotenoids, and rapeseed oil color were all significantly positively correlated, and total polar phenols were significantly positively correlated with antioxidant power. In summary, early sowing at an appropriate date, reducing nitrogen fertilizer rate, and lowering planting density in production can improve the quality of pressed rapeseed oil. The findings of this study offer technical assistance to produce high-quality rapeseed oil raw materials. [ABSTRACT FROM AUTHOR]

In order to finely characterize the physical properties and seepage characteristics of underwater distributary channel sand bodies in a braided river delta, the particle size distribution, mercury injection, and withdrawal of low, medium, high, and extra-high permeability core samples from the TIII reservoir from 15 core wells in the Sangtamu Oilfield were compared. The pore-throat characteristics of the rocks with different deposition modes and their effects on the fluid seepage were analyzed from the perspective of the deposition processes. The statistical results revealed that the rocks formed in a continuous and stable strong hydrodynamic environment were coarse grained. The seepage capacities of the rock increased as the maximum throat radius connecting with the pores increased. The mercury withdrawal efficiency decreased as the difference between the throat radius and pore radius increased. The percentage of the throat volume without effective seepage to the total volume of the pore-throat system increased as the permeability of the samples increased. Therefore, when characterizing reservoirs based on the porosity and permeability, it is important to differentiate the energy of the hydrodynamic depositional environment of a monogenic sand body in order to improve the accuracy of the understanding of the reservoirs.