Abstract
Oxylipins, including jasmonic acid (JA) and volatiles, are important for signaling in plants, and these are formed by the lipoxygenase (LOX) enzyme family. There is a large gap in ...understanding of the underlying molecular basis of their roles in tea plants. Here, we identified 11 CsLOX genes from the tea plant (Camellia sinensis), and characterized their phylogeny, gene structure and protein features into three subclasses. We then examined their enzymatic activities, LOX expression and alternative splicing of transcripts during development and in response to abiotic or biotic stresses in tea plants. In vitro expressed protein assays showed that the CsLOX2, 3 and 9 enzymatically function to produce 9/13-HPOT, 13-HPOT and 9-HPOT, respectively. CsLOX2 and CsLOX9 green fluorescent protein (GFP) fusion proteins localized to chloroplasts and the cytoplasm, respectively. RNA sequencing, quantitative reverse transcription–PCR and Northern blot analysis suggested that CsLOX5, 6 and 9 were predominantly expressed in seeds, flowers and roots, respectively. CsLOX2, 3, 4, 6 and 7 were up-regulated after attack by the insect Ectropis oblique, while CsLOX1 was induced after infection with the pathogen Glomerella cingulata. CsLOX3, 7 and 10 were up-regulated by JA but not ABA or salicylic acid. Long-term cold stress down-regulated CsLOX expression while a short duration of cold induced the expression of CsLOX1, 6 and 7. Alternatively spliced transcripts of six CsLOX genes were dynamically regulated through time and varied in relative abundances under the investigated stresses; we propose a mechanism of competing or compensating regulation between isoforms. This study improves our understanding of evolution of LOXs and regulation of their diverse functions in plants.
Liquid and semi-solid stir casting processes were applied to fabricate B
4
C particles-reinforced aluminum-matrix composites. The effects of manufacturing processes on particle distribution, ...particle/matrix interface, and mechanical properties of the prepared composites were studied. The results show that particle distribution can be significantly improved by using K
2
TiF
6
-flux and Ti powders in the liquid stir casting process, whereas in the semi-solid stir casting process it could be improved by decreasing the temperature of the slurry. With additions of Ti, the decomposition of B
4
C was prevented, and the interfacial bonding strength was significantly improved due to the fact that a TiB
2
layer formed at the particle/matrix interface. Compared to the matrix, the hardness and tensile strength of the Al-B
4
C composite fabricated by the liquid stir casting process were increased by 89.6% and 128.8%, respectively; those of the A356-B
4
C composite fabricated by the semi-solid stir casting process had no significant improvement due to the weak particle/matrix interface and the presence of particle porosity clusters.
is a rare and precious relict plant in China. It is an important genetic resource for almond improvement and an indispensable material in ecological protection and landscaping. However, the research ...into molecular breeding and genetic evolution has been severely restricted due to the lack of genome information. In this investigation, we created a chromosome-level genomic pattern of
, 231 Mb in length with a contig N50 of 18.1 Mb by Hi-C techniques and high-accuracy PacBio HiFi sequencing. The present assembly predicted 32,088 protein-coding genes, and an examination of the genome assembly indicated that 94.7% among all assembled transcripts were alignable to the genome assembly; most (97.24%) were functionally annotated. By phylogenomic genome comparison, we found that
is an ancient group that diverged approximately 13.4 million years ago (mya) from 13 additional closely related species and about 6.5 Mya from the cultivated almond. Collinearity analysis revealed that
is highly syntenic and has high sequence conservation with almond and peach. However, this species also exhibits many presence/absence variants. Moreover, a large inversion at the 7588 kb position of chromosome 5 was observed, which may have a significant association with phenotypic traits. Lastly, population genetic structure analysis in eight different populations indicated a high genetic differentiation among the natural distribution of
. This high-quality genome assembly provides critical clues and comprehensive information for the systematic evolution, genetic characteristics, and functional gene research of
. Moreover, it provides a valuable genomic resource for in-depth study in protection, developing, and utilizing
germplasm resources.
Characteristic secondary metabolites, including flavonoids, theanine and caffeine, are important components of
, and their biosynthesis has attracted widespread interest. Previous studies on the ...biosynthesis of these major secondary metabolites using next-generation sequencing technologies limited the accurately prediction of full-length (FL) splice isoforms. Herein, we applied single-molecule sequencing to pooled tea plant tissues, to provide a more complete transcriptome of
. Moreover, we identified 94 FL transcripts and four alternative splicing events for enzyme-coding genes involved in the biosynthesis of flavonoids, theanine and caffeine. According to the comparison between long-read isoforms and assemble transcripts, we improved the quality and accuracy of genes sequenced by short-read next-generation sequencing technology. The resulting FL transcripts, together with the improved assembled transcripts and identified alternative splicing events, enhance our understanding of genes involved in the biosynthesis of characteristic secondary metabolites in
.
Accurate and stable positioning is significant for vehicle navigation systems, especially in complex urban environments. However, urban canyons and dynamic interference make vehicle sensors prone to ...disturbance, leading to vehicle positioning errors and even failures. To address these issues, an adaptive loosely coupled IMU/GNSS/LiDAR integrated navigation system based on factor graph optimization with sensor weight optimization and fault detection is proposed. First, the factor nodes and system framework are constructed based on error models of sensors, and the optimization method principle is derived. Second, the interactive multiple-model algorithm based on factor graph optimization (IMMFGO) is utilized to calculate and adjust sensor weights for global optimization, which will reduce the impact of disturbed sensors. Finally, a multi-stage fault detection, isolation, and recovery (MSFDIR) strategy is implemented based on the IMMFGO results and IMU pre-integration measurements, which can detect significant sensor faults and optimize the system structure. Vehicle experiments show that our IMMFGO method generally obtains better performance in positioning accuracy by 23.7% compared to adaptive factor graph optimization (AFGO) methods, and the MSFDIR strategy possesses the capability of fault sensor detection, which provides an essential reference for multi-source vehicle navigation systems in urban canyons.
Persimmon (
) fruit have significant variation between pollination-constant non-astringent (PCNA) and pollination-constant astringent (PCA) persimmons. The astringency type affects not only the ...soluble tannin concentration but also the accumulation of individual sugars. Thus, we comprehensively investigate the gene expression and metabolite profiles of individual sugars to resolve the formation of flavor differences in PCNA and PCA persimmon fruit. The results showed that soluble sugar, starch content, sucrose synthase, and sucrose invertase were significantly different between PCNA and PCA persimmon fruit. The sucrose and starch metabolism pathway was considerably enriched, and six sugar metabolites involving this pathway were significantly differentially accumulated. In addition, the expression patterns of diferentially expressed genes (such as
,
,
,
,
, and
genes) were significantly correlated with the content of deferentially accumulated metabolites (such as starch, sucrose, and trehalose) in the sucrose and starch metabolism pathway. These results indicated that the sucrose and starch metabolism pathway maintained a central position of sugar metabolism between PCNA and PCA persimmon fruit. Our results provide a theoretical basis for exploring functional genes related to sugar metabolism and provide useful resources for future studies on the flavor differences between PCNA and PCA persimmon fruit.
Chilling stress threatens the yield and distribution pattern of global crops, including the tea plant (
), one of the most important cash crops around the world. Circular RNA (circRNA) plays roles in ...regulating plant growth and biotic/abiotic stress responses. Understanding the evolutionary characteristics of circRNA and its feedbacks to chilling stress in the tea plant will help to elucidate the vital roles of circRNAs. In the current report, we systematically identified 2702 high-confidence circRNAs under chilling stress in the tea plant, and interestingly found that the generation of tea plant circRNAs was associated with the length of their flanking introns. Repetitive sequences annotation and DNA methylation analysis revealed that the longer flanking introns of circRNAs present more repetitive sequences and higher methylation levels, which suggested that repeat-elements-mediated DNA methylation might promote the circRNAs biogenesis in the tea plant. We further detected 250 differentially expressed circRNAs under chilling stress, which were functionally enriched in GO terms related to cold/stress responses. Constructing a circRNA-miRNA-mRNA interaction network discovered 139 differentially expressed circRNAs harboring potential miRNA binding sites, which further identified 14 circRNAs that might contribute to tea plant chilling responses. We further characterized a key circRNA,
, which was significantly induced under chilling stress. FISH and silencing experiments revealed that
was potentially involved in chilling tolerance of the tea plant. Our study emphasizes the importance of circRNA and its preliminary role against low-temperature stress, providing new insights for tea plant cold tolerance breeding.
•The stages in meiotic were related to the phenotypic development of male flowers.•The presence of lagging chromosomes, triads and dyads was discovered during meiosis.•42 °C for 4 h produced the ...greatest amount of 2n pollen (up to 22.04%).
Unreduced gametes (2n) are of significant value in plant polyploid breeding. Cross breeding using natural or artificially induced 2n pollen is one of the best procedures for generating persimmon nonaploids. Successful artificial induction of 2n pollen requires a comprehensive understanding of the microsporogenesis process and the timing of physicochemical treatment application. We observed the development of male flowers and the meiotic process in microspore mother cells of persimmon plants originating from the Hubei Mulan Grassland. Except for some abnormal phenomena, such as the lagging of chromosomes in metaphase I and the formation of triads and dyads, the meiotic process of microspore mother cells was normal. The stages in this process were related to the phenotypic development of male flowers, i.e., when the flower buds began to swell and the corolla and the calyx were flattened apically (April 8–12), the microspore mother cells began meiosis. This period was optimal for the physicochemical induction of 2n pollen. We also induced 2n pollen between zygotene and diplotene via high temperature exposure. The treatment combination of 42 °C for 4 h produced the greatest amount of diploid pollen (up to 22.04% of the total yield).
Our results will enable progress in procedures that use naturally occurring or artificially induced 2n pollen for nonaploid breeding of persimmon.
Dioecy, a sexual system of single-sexual (gynoecious/androecious) individuals, is rare in flowering plants. This rarity may be a result of the frequent transition from dioecy into systems with ...co-sexual individuals. In this study, co-sexual expression (monoecy and hermaphroditic development), previously thought to be polyploid-specific in Diospyros species, was identified in the diploid D. oleifeara historically. We characterized potential genetic mechanisms that underlie the dissolution of dioecy to monoecy and andro(gyno)monoecy, based on multiscale genome-wide investigations of 150 accessions of Diospyros oleifera. We found all co-sexual plants, including monoecious and andro(gyno)monoecious individuals, possessed the male determinant gene OGI, implying the presence of genetic factors controlling gynoecia development in genetically male D. oleifera. Importantly, discrepancies in the OGI/MeGI module were found in diploid monoecious D. oleifera compared with polyploid monoecious D. kaki, including no Kali insertion on the promoter of OGI, no different abundance of smRNAs targeting MeGI (a counterpart of OGI), and no different expression of MeGI between female and male floral buds. On the contrary, in both single- and co-sexual plants, female function was expressed in the presence of a genome-wide decrease in methylation levels, along with sexually distinct regulatory networks of smRNAs and their targets. Furthermore, a genome-wide association study (GWAS) identified a genomic region and a DUF247 gene cluster strongly associated with the monoecious phenotype and several regions that may contribute to andromonoecy. Collectively, our findings demonstrate stable breakdown of the dioecious system in D. oleifera, presumably also a result of genomic features of the Y-linked region.
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