The 26S proteasome, an essential protease complex of the ubiquitin-26S proteasome system (UPS), controls many cellular events by degrading short-lived regulatory proteins marked with polyubiquitin chains. The 20S proteolytic core protease (CP), the catalytic core of the 26S proteasome, is a central enzyme in the UPS. Its biogenesis proceeds in a multistep and orderly fashion assisted by a series of proteasome assembly chaperones. In this study, we identified a novel maize (Zea mays) kernel mutant named defective kernel40 (dek40), which produces small, collapsed kernels and exhibits delayed embryo and endosperm development. Dek40 was identified by map-based cloning and confirmed by transgenic functional complementation. Dek40 encodes a putative cytosol-localized proteasome biogenesis-associated chaperone4 (PBAC4) protein. DEK40 participates in the biogenesis of the 20S CP by interacting with PBAC3. Loss-of-function of DEK40 substantially affected 20S CP biogenesis, resulting in decreased activity of the 26S proteasome. Ubiquitylome analysis indicated that DEK40 influences the degradation of ubiquitinated proteins and plays an essential role in the maintenance of cellular protein homoeostasis. These results demonstrate that Dek40 encodes a PBAC4 chaperone that affects 20S CP biogenesis and is required for 26S proteasome function and seed development in maize.
Abstract Trichomes and fruit spines are important traits that directly affect the appearance quality and commercial value of cucumber (Cucumis sativus). Tril (Trichome-less), encodes a HD-Zip IV transcription factor that plays a crucial role in the initiation of trichomes and fruit spines, but little is known about the details of the regulatory mechanisms involved. In this study, analysis of tissue expression patterns indicated that Tril is expressed and functions in the early stages of organ initiation and development. Expression of Tril under the control of its own promoter (the TrilPro::Tril-3*flag fragment) could partly rescue the mutant phenotypes of tril, csgl3 (cucumber glabrous 3, an allelic mutant of tril), and fs1 (few spines 1, a fragment substitution in the Tril promoter region), providing further evidence that Tril is responsible for the initiation of trichomes and fruit spines. In lines with dense spine, fs1-type lines, and transgenic lines of different backgrounds containing the TrilPro::Tril-3*flag foreign fragment, spine density increased in conjunction with increases in Tril expression, indicating that Tril has a gene dosage effect on fruit spine density in cucumber. Numerous Spines (NS) is a negative regulatory factor of fruit spine density. Characterization of the molecular and genetic interaction between Tril and NS/ns demonstrated that Tril functions upstream of NS with respect to spine initiation. Overall, our results reveal a novel regulatory mechanism governing the effect of Tril on fruit spine development, and provide a reference for future work on breeding for physical quality in cucumber.
Zanthoxylum, belonging to the Rutaceae family, is widely distributed in tropical and subtropical regions. The genus has high economic value as spices, oils, medicinal plants, and culinary applications. Zanthoxylum has a long history of domestication and cultivation in China. However, the phylogenetic relationships and origin of wild and cultivated Zanthoxylum species in China remain largely unknown. Moreover, there is still no clear molecular phylogenetic system for Zanthoxylum species. Herein, 373 Zanthoxylum samples were collected from all presently known provenances of Zanthoxylum in China. In this study, four chloroplast DNA (cpDNA) markers (matK, ndhH, psbB, rbcL) were used to comprehensively analyze the genetic diversity, relatedness, and geographical origin of Chinese Zanthoxylum species. The results were as follows: (1) The aligned length of the four pairs of cpDNA sequences was 3836 bp, and 68 haplotypes were identified according to 219 variable polymorphic sites, including 90 singleton variable sites, 129 parsimony informative sites, 3 Indels (insertions and deletions). (2) Phylogenetic tree and haplotype network strongly supported the division of Zanthoxylum species consistent with the taxonomic recognition of five species: Z. bungeanum, Z. piasezkii, Z. piperitum, Z. armatum, and Z. micranthum. (3) Divergence time estimation suggested that Zanthoxylum genus originated from the Late Eocene, and most Zanthoxylum species diverged after the Middle Miocene. (4) Haplotype 16 (H16) was at the bottom of the phylogenetic tree, had higher haplotype diversity (Hd) and nucleotide polymorphism (Pi) than other haplotypes, and was located in the center of the network figure. Therefore, we deduced that the cultivated Zanthoxylum species may originate in Zhouqu County, Gansu Province, China. Meanwhile, our research provided a scientific basis for the identification and breeding programs of Chinese Zanthoxylum species.
Abstract Background Lectin receptor-like kinases (LecRLKs) are a class of membrane proteins found in plants that are involved in diverse functions, including plant development and stress responses. Although LecRLK families have been identified in a variety of plants, a comprehensive analysis has not yet been undertaken in cucumber ( Cucumis sativus L.).Results In this study, 46 putative LecRLK genes were identified in cucumber genome, including 23 G-type, 22 L-type and 1 C-type LecRLK genes. They unequally distributed on all 7 chromosomes with a clustering trendency. Most of the genes in the cucumber LecRLK (Cs LecRLK) gene family lacked introns. In addition, there were many regulatory elements associated with phytohormone and stress on these genes’ promoters. Transcriptome data demonstrated that distinct expression patterns of CsLecRLK genes in various tissues. Furthermore, we found that each member of the CsLecRLK family had its own unique expression pattern under hormone and stress treatment by the quantitative real time PCR (qRT-PCR) analysis.Conclusion This study provides a better understanding of the evolution and function of LecRLK gene family in cucumber, and opens the possibility to explore the roles that LecRLK s might play in the life cycle of cucumber.
Abstract NIR‐emitting CdSeTe/CdS/ZnS core/shell/shell QD‐encoded microbeads are combined with common flow cytometry with one laser for multiplexed detection of hepatitis B virus (HBV). A facile one‐pot synthetic route is developed to prepare CdSeTe/CdS/ZnS core/shell/shell QDs with high photoluminescence quantum yield and excellent stability in liquid paraffin, and a Shirasu porous glass (SPG) membrane emulsification technique is applied to incorporate the QDs into polystyrene–maleic anhydride (PSMA) microbeads to obtain highly fluorescent QD‐encoded microbeads. The relatively wide NIR photoluminescence full width half maximum of the CdSeTe/CdS/ZnS QDs is used to develop a ‘single wavelength’ encoding method to obtain different optical codes by changing the wavelengh and emission intensity of the QDs incorporated into the microbeads. Moreover, a detection platform combining NIR‐emitting CdSeTe/CdS/ZnS QD‐encoded microbeads and Beckman Coulter FC 500 flow cytometry with one laser of 488 nm is successfully used to conduct a 2‐plex hybridization assay for hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and a 3‐plex hybridization assay for hepatitis B surface antibody (HBsAb), hepatitis B e antibody (HBeAb), and hepatitis B core antibody (HBcAb), which suggests the promising application of NIR QD‐encoded microbeads for multiplex immunoassays.
Mitochondria are semi-autonomous organelles that are the powerhouse of the cells. Plant mitochondrial RNA editing guided by pentatricopeptide repeat (PPR) proteins is essential for energy production. We identify a maize defective kernel mutant dek36, which produces small and collapsed kernels, leading to embryos and/or seedlings lethality. Seed filling in dek36 is drastically impaired, in line with the defects observed in the organization of endosperm transfer tissue. Positional cloning reveals that DEK36, encoding a mitochondria-targeted E+ subgroup PPR protein, is required for mitochondrial RNA editing at atp4-59, nad7-383 and ccmFN -302, thus resulting in decreased activities of mitochondrial complex I, complex III and complex IV in dek36. Loss-of-function of its Arabidopsis ortholog At DEK36 causes arrested embryo and endosperm development, leading to embryo lethality. At_dek36 also has RNA editing defects in atp4, nad7, ccmFN1 and ccmFN2 , but at the nonconserved sites. Importantly, efficiency of all editing sites in ccmFN1 , ccmFN2 and rps12 is severely decreased in At_dek36, probably caused by the impairment of their RNA stabilization. These results suggest that the DEK36 orthologue pair are essential for embryo and endosperm development in both maize and Arabidopsis, but through divergent function in regulating RNA metabolism of their mitochondrial targets.
Abstract Trichomes that cover the epidermis of aerial plant organs play multiple roles in plant protection. Compared with a unicellular trichome in model plants, the development mechanism of the multicellular trichome is largely unclear. Notably, variations in trichome development are often accompanied by defects in the biosynthesis of cuticle and secondary metabolites; however, major questions about the interactions between developmental differences in trichomes and defects in metabolic pathways remain unanswered. Here, we characterized the glabrous mutant mict / csgl1/cstbh via combined metabolomic and transcriptomic analyses to extend our limited knowledge regarding multicellular trichome development and metabolism in cucumber. Mict was found to be explicitly expressed within trichome cells. Transcriptomic analysis indicated that genes involved in flavonoid and cuticle metabolism are significantly downregulated in mict mutants. Further metabolomic analysis confirmed that flavonoids, lipids, and cuticle compositions are dramatically altered in mict mutants. Additional studies revealed that Mict regulates flavonoid, lipid, and cuticle biosynthesis by likely directly binding to downstream functional genes, such as CsTT4 , CsFLS1 , CsCER26 , and CsMYB36 . These findings suggest that specific metabolic pathways (e.g., flavonoids and cuticle components) are co-regulated by Mict and provide insights into transcriptional regulation mechanisms of multicellular trichome development and its specific metabolism in cucumber.
Abstract Laccase exists widely in plants and fungi. It is a copper-containing polyphenol oxidase that can degrade lignin, oxidate, and phenolic substances, inhibit heterophytes, promote fruiting body formation, and improve the quality of mushrooms. In this study, 18 laccase genes were identified from the whole genome of a white strain (HM62) of Hypsizygus marmoreus , and the mapping, structure, and evolution of laccase genes were analyzed at the whole genome level, while the spatiotemporal expression was evaluated at different developmental stages. The laccase genes mainly distributed on chromosomes 1, 2, 3, 4, 6, 9, and 10, and 9 genes were clustered linearly on chromosome 6, indicating gene doubling. Phylogenetic tree analysis showed that the laccase gene family was divided into three subfamilies. The spatiotemporal expression analysis of the laccase gene family showed that HmLac09 and HmLac10 were highly expressed in different periods and might be involved in lignin degradation and fruit body formation, respectively. The expression levels of HmLac02, HmLac05, HmLac08 , and HmLac17 genes in gray or gray and white heterozygous strains were higher than those in white strains, which might be related to the difference in lignin decomposition in gray strains, and one of the factors leading to different growth rates. The present study investigated the characterization of the H. marmoreus laccase gene family, extending our understanding of laccase mediated fruiting body development and growth rate mechanisms in this fungi.
Summary Riboflavin is the precursor of essential cofactors for diverse metabolic processes. Unlike animals, plants can de novo produce riboflavin through an ancestrally conserved pathway, like bacteria and fungi. However, the mechanism by which riboflavin regulates seed development is poorly understood. Here, we report a novel maize ( Zea mays L.) opaque mutant o18 , which displays an increase in lysine accumulation, but impaired endosperm filling and embryo development. O18 encodes a rate‐limiting bifunctional enzyme ZmRIBA1, targeted to plastid where to initiate riboflavin biosynthesis. Loss of function of O18 specifically disrupts respiratory complexes I and II, but also decreases SDH1 flavinylation, and in turn shifts the mitochondrial tricarboxylic acid (TCA) cycle to glycolysis. The deprivation of cellular energy leads to cell‐cycle arrest at G1 and S phases in both mitosis and endoreduplication during endosperm development. The unexpected up‐regulation of cell‐cycle genes in o18 correlates with the increase of H3K4me3 levels, revealing a possible H3K4me‐mediated epigenetic back‐up mechanism for cell‐cycle progression under unfavourable circumstances. Overexpression of O18 increases riboflavin production and confers osmotic tolerance. Altogether, our results substantiate a key role of riboflavin in coordinating cellular energy and cell cycle to modulate maize endosperm development.
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