Fruit characteristics of sweet watermelon are largely the result of human selection. Here we report an improved watermelon reference genome and whole-genome resequencing of 414 accessions ...representing all extant species in the Citrullus genus. Population genomic analyses reveal the evolutionary history of Citrullus, suggesting independent evolutions in Citrullus amarus and the lineage containing Citrullus lanatus and Citrullus mucosospermus. Our findings indicate that different loci affecting watermelon fruit size have been under selection during speciation, domestication and improvement. A non-bitter allele, arising in the progenitor of sweet watermelon, is largely fixed in C. lanatus. Selection for flesh sweetness started in the progenitor of C. lanatus and continues through modern breeding on loci controlling raffinose catabolism and sugar transport. Fruit flesh coloration and sugar accumulation might have co-evolved through shared genetic components including a sugar transporter gene. This study provides valuable genomic resources and sheds light on watermelon speciation and breeding history.
•Ag–Cu–3.5Ti active filler is used to braze W and Fe–Ni–Co alloy.•The effect of Ti on W/Ag–Cu–3.5Ti/4J33 joint is analyzed and its mechanism is proposed.•The addition of active element Ti in Ag–28Cu ...greatly improves its wettability to W.•The addition of Ti in Ag–28Cu greatly improves the shear strength of the joints.
W/Fe–Ni–Co joints are achieved using Ag–28Cu at 850°C for 5min and Ag–27Cu–3.5Ti at 880°C for 5min. The effect of active element Ti in Ag–28Cu on microstructures and shear strength of the joints are investigated. The results show that the wetting angles of Ag–28Cu and Ag–27Cu–3.5Ti on the W matrixes are 147±2deg and 21±4deg, respectively. Due to the poor wettability of Ag–28Cu on W matrix, voids and cracks are observed in W/Ag–28Cu interface. The fracture of W/Ag–28Cu/Fe–Ni–Co alloy joint occurs at W/Ag–28Cu interface and the shear strength of the joint is 72.3±30MPa. In contrast, the addition of active element Ti in the filler promotes the wettability of Ag–27Cu–3.5Ti on W matrix and chemical reactions, so an interfacial microstructure of Fe–Ni–Co alloy/a diffusion layer/Ag–Cu eutectic/Ag-rich+CuTi2/W is obtained. The shear strength test results of the joints brazing with Ag–27Cu–3.5Ti show that the fracture occurs in the W matrix near the joint and the shear strength is higher than 317.7±20MPa.
The flesh color of watermelon (
) is an important fruit quality trait that helps to determine fruit attractiveness and is potentially beneficial to human health. Previous inheritance analyses ...determined that a single dominant gene,
, produces the scarlet red flesh color rather than the coral red flesh color in watermelon. However, no genomic region or gene-based molecular markers for the locus
have been reported thus far. In the present study, two high-density genetic maps and whole-genome variation detection aided by genome resequencing were first map the flesh color locus
to a small region on chromosome 6 based on two independent populations derived from two scarlet red-fleshed lines and two coral red-fleshed lines. Two major quantitative trait loci located in the same genomic regions were identified in the F
and BC
P
populations and explained 90.36% and 75.1% of the phenotypic variation in flesh color, respectively. Based on the genetic variation in the two parental lines, newly developed PCR-based markers narrowed the
region to 40 Kb. Of the five putative genes in this region, four encoded glycine-rich cell wall structural proteins, which implied that a new regulatory mechanism might occur between scarlet red- and coral red-fleshed in watermelon. Moreover, the genotypes of two newly developed InDel markers (InDel27_fc6 and InDel28_fc6) were completely consistent with the phenotypes in the F
and BC
P
populations and all 56 scarlet red-fleshed watermelon accessions. The results presented here provide valuable information for marker-assisted selection of flesh color breeding and the functional validation of candidate genes in watermelon.
•The high-density genetic map presented herein is the densest map based on two elite watermelon cultivars.•The genetic map and markers will facilitate the mapping of quantitative trait loci, ...map-based cloning, molecular breeding and marker-assisted selection in cultivated watermelon breeding programs.•Several unassembled scaffolds were anchored to different linkage groups, which considerably improved the assembly of the watermelon genome.
Watermelon (Citrullus lanatus L.) is an important vegetable crop worldwide, but a high-density genetic map of elite watermelon cultivars has not yet been reported. The present study reported the large-scale discovery of single nucleotide polymorphisms (SNPs) by specific length amplified fragment sequencing (SLAF-seq) for high-density genetic map construction using two elite watermelon cultivars. The map contained 2634 SNPs distributed on 11 linkage groups (LGs) corresponding to the number of chromosome pairs in watermelon. The total length of the linkage map was 1,906.31cM, with an average distance of 0.72cM between adjacent markers. Notably, 35 unmapped scaffolds, which contained 91 SNPs and covered 4.56Mb, were dispersedly anchored to LG1, LG2, LG4, LG7, LG8, LG9 and LG11. Although disagreements were observed on LG1 and LG11, the local collinearity between the genetic and physical distances, haplotype map and heat map indicated that the genetic map herein is of high quality. The present study reports the first high-density linkage map of two watermelon elite parents.
Egusi watermelon has a unique egusi seed type, which could be useful for breeding both edible seeds and edible flesh in watermelon. However, the genetic basis of the unique egusi seed type is not ...clear. In the present study, we first reported that at least two genes with inhibitory epistasis were responsible for the thin seed coat (unique egusi seed type) in watermelon. Inheritance analysis of five populations, including F
, BC, and BCF
, suggested that the thin seed coat trait was controlled by a suppressor gene together with the egusi seed locus (
) in egusi watermelon. Based on high-throughput sequencing technology, two quantitative trait loci located on chromosome 1 and chromosome 6 were identified for the thin seed coat trait in watermelon. One of the loci, the
locus on chromosome 6, was finely mapped to a genomic region of 15.7 kb, which contained only one candidate gene. Comparative transcriptome analysis highlighted differentially expressed genes involved in cellulose and lignin synthesis between watermelon genotypes varying in the thickness of the seed coat and provided several potential candidate genes for the thin seed coat trait. Taken together, our data suggest that at least two genes are complementarily involved in the thin seed coat trait and will be useful for cloning novel genes. The results presented here provide a new reference for uncovering egusi seed genetic mechanisms and valuable information for marker-assisted selection in seed coat breeding.
To account for the internal thermal effects of solid-state lasers, a method using a back propagation (BP) neural network integrated with a particle swarm optimization (PSO) algorithm is developed, ...which is a new wavefront distortion correction technique. In particular, by using a slab laser model, a series of fiber pumped sources are employed to form a controlled array to pump the gain medium, allowing the internal temperature field of the gain medium to be designed by altering the power of each pump source. Furthermore, the BP artificial neural network is employed to construct a nonlinear mapping relationship between the power matrix of the pump array and the thermally induced wavefront aberration. Lastly, the suppression of thermally induced wavefront distortion can be achieved by changing the power matrix of the pump array and obtaining the optimal pump light intensity distribution combined using the PSO algorithm. The minimal beam quality β can be obtained by optimally distributing the pumping light. Compared with the method of designing uniform pumping light into the gain medium, the theoretically computed single pass beam quality β value is optimized from 5.34 to 1.28. In this numerical analysis, experiments are conducted to validate the relationship between the thermally generated wavefront and certain pumping light distributions.
Although crop domestication has greatly aided human civilization, the sequential domestication and regulation of most quality traits remain poorly understood. Here, we report the stepwise selection ...and regulation of major fruit quality traits that occurred during watermelon evolution. The levels of fruit cucurbitacins and flavonoids were negatively selected during speciation, whereas sugar and carotenoid contents were positively selected during domestication. Interestingly, fruit malic acid and citric acid showed the opposite selection trends during the improvement. We identified a novel gene cluster (CGC1, cucurbitacin gene cluster on chromosome 1) containing both regulatory and structural genes involved in cucurbitacin biosynthesis, which revealed a cascade of transcriptional regulation operating mechanisms. In the CGC1, an allele caused a single nucleotide change in ClERF1 binding sites (GCC-box) in the promoter of ClBh1, which resulted in reduced expression of ClBh1 and inhibition of cucurbitacin synthesis in cultivated watermelon. Functional analysis revealed that a rare insertion of 244 amino acids, which arose in C. amarus and became fixed in sweet watermelon, in ClOSC (oxidosqualene cyclase) was critical for the negative selection of cucurbitacins during watermelon evolution. This research provides an important resource for metabolomics-assisted breeding in watermelon and for exploring metabolic pathway regulation mechanisms.
By using the more effective IRES (internal ribosome entry site) element, an innovative cap‐independent protein expression system mediated by RNA polymerase I, which only transcribes rRNA normally, ...was established in Saccharomyces cerevisiae. Such system made the reporter gene yEGFP3 express variation especially after mutagenesis. Combined with flow cytometry, cells with high fluorescence intensity were sorted from 200,000 cells and the strain with 58% RNA content higher than the parental strain was obtained. So the model for large‐scale screening of high‐nucleic‐acid content yeasts was set up.
Summary
Saccharomyces cerevisiae is the preferred source of RNA derivatives, which are widely used as supplements for foods and pharmaceuticals. As the most abundant RNAs, the ribosomal RNAs (rRNAs) transcribed by RNA polymerase I (Pol I) have no 5′ caps, thus cannot be translated to proteins. To screen high‐nucleic‐acid content yeasts more efficiently, a cap‐independent protein expression system mediated by Pol I has been designed and established to monitor the regulatory changes of rRNA synthesis by observing the variation in the reporter genes expression. The elements including Pol I‐recognized rDNA promoter, the internal ribosome entry site from cricket paralytic virus which can recruit ribosomes internally, reporter genes (URA3 and yEGFP3), oligo‐dT and an rDNA terminator were ligated to a yeast episomal plasmid. This system based on the URA3 gene worked well by observing the growth phenotype and did not require the disruption of cap‐dependent initiation factors. The fluorescence intensity of strains expressing the yEGFP3 gene increased and drifted after mutagenesis. Combined with flow cytometry, cells with higher GFP level were sorted out. A strain showed 58% improvement in RNA content and exhibited no sequence alteration in the whole expression cassette introduced. This study provides a novel strategy for breeding high‐nucleic‐acid content yeasts.
Background
The human lip vermilion, also known as the red lip, is important to the quality of life and has long attracted the attention of cosmetic researchers. However, there is limited existing ...literature on the physiological characteristics and age‐related alterations in the human vermilion.
Objective
We aim to provide an overview of the physiological characteristics and age‐related alterations in the human vermilion.
Methods
This article is a result of previous research. We conducted a literature search using various academic databases such as Google Scholar, Web of Science, and PubMed. Our findings provided a comprehensive understanding of the physiological characteristics and age‐related changes of the human lip vermilion.
Results
The human lip vermilion has a unique structure and physiological characteristics, and during the aging process, a few changes may occur in the human lip vermilion.
Conclusion
Understanding the human lip vermilion's physiological characteristics and age‐related changes can provide key information for the future innovation of lip vermilion care products. Further investigations are necessary to reach a consensus on the physiological characteristics and age‐related alterations in the human vermilion.
Melon is an economically important fruit crop that has been cultivated for thousands of years; however, the genetic basis and history of its domestication still remain largely unknown. Here we report ...a comprehensive map of the genomic variation in melon derived from the resequencing of 1,175 accessions, which represent the global diversity of the species. Our results suggest that three independent domestication events occurred in melon, two in India and one in Africa. We detected two independent sets of domestication sweeps, resulting in diverse characteristics of the two subspecies melo and agrestis during melon breeding. Genome-wide association studies for 16 agronomic traits identified 208 loci significantly associated with fruit mass, quality and morphological characters. This study sheds light on the domestication history of melon and provides a valuable resource for genomics-assisted breeding of this important crop.
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