Minisci-Type Dehydrogenative Coupling of N-Heteroaromatic Rings with Inert C(sp3)-H Enabled by a Visible-Light-Catalyzed Intermolecular Hydrogen Atom Transfer Process.

The Minisci-type dehydrogenative coupling of N-heteroaromatic rings with inert C-H or Si-H partners via visible-light-catalyzed hydrogen atom transfer has been reported. This methodology allows the coupling reactions to be carried out in water as a solvent under air atmospheric conditions with visible-light illumination. A wide range of inert C-H and Si-H partners could be directly coupled with various N-aromatic heterocycles to deliver products in good to excellent yields.

GhTKPR1_8 functions to inhibit anther dehiscence and reduce pollen viability in cotton.

Sporopollenin, as the main component of the pollen exine, is a highly resistant polymer that provides structural integrity under unfavourable environmental conditions. Tetraketone α-pyrone reductase 1 (TKPR1) is essential for sporopollenin formation, catalyzing the reduction of tetraketone carbonyl to hydroxylated α-pyrone. The functional role of TKPR1 in male sterility has been reported in flowering plants such as maize, rice, and Arabidopsis. However, the molecular cloning and functional characterization of TKPR1 in cotton remain unaddressed. In this study, we identified 68 TKPR1s from four cotton species, categorized into three clades. Transcriptomics and RT-qPCR demonstrated that GhTKPR1_8 exhibited typical expression patterns in the tetrad stage of the anther. GhTKPR1_8 was localized to the endoplasmic reticulum. Moreover, ABORTED MICROSPORES (GhAMS) transcriptionally activated GhTKPR1_8 as indicated by luciferase complementation tests. GhTKPR1_8-knockdown inhibited anther dehiscence and reduced pollen viability in cotton. Additionally, overexpression of GhTKPR1_8 in the attkpr1 mutant restored its male sterile phenotype. This study offers novel insights into the investigation of TKPR1 in cotton while providing genetic resources for studying male sterility.

GhSTP18, a member of sugar transport proteins family, negatively regulates salt stress in cotton.

The sugar transporter protein (STP) family has been shown to play important roles in plant growth, development, and stress response. However, it has not been studied in cotton compared to other major crops. In this study, we identified 90 STP genes from four cotton species, performed bioinformatic analysis, and focused on the role of GhSTP18 in salt stress. According to our results, cotton STP proteins were divided into four subgroups according to the phylogenetic tree. A synteny analysis suggested that whole-genome duplication (WGD) and segmental duplication were key drivers in the expansion of the STP gene family. The transcriptomic data analysis showed that 29 GhSTP genes exhibited sink-specific expression. Quantitative real time-polymerase chain reaction (qRT-PCR) analyses revealed that expression of GhSTP18 was induced by salt treatment, heat treatment, cold treatment, and drought treatment, and continuously increased during a salt stress time course. Notably, GhSTP18 encodes a plasma membrane-localized galactose transporter. Suppression of GhSTP18 transcription by a virus-induced gene silencing (VIGS) assay reduced sensitivity to salt stress in cotton, indicating that GhSTP18 negatively regulates plant salt tolerance. These results provide an important reference and resource for further studying and deploying STP genes for cotton improvement.

Visible-light promoted photocatalyst-free aerobic α-oxidation of tertiary amines to amides.

A photocatalyst-free, visible-light-induced strategy for the α-oxygenation of tertiary amines by molecular oxygen (1 atm), enabled by electron-donor-acceptor (EDA) complexes, has been developed. This EDA-complex mediated process provides a facile access to amides and esters from readily accessible corresponding amines and ethers without the need for an external photoredox catalyst, and also features mild reaction conditions, broad substrate scope and excellent functional group compatibility. Mechanistic studies indicated a short radical chain reaction triggered by the decomposition of EDA complexes upon visible-light irradiation.

GhN/AINV13 positively regulates cotton stress tolerance by interacting with the 14-3-3 protein.

Neutral/alkaline invertases (N/AINVs) are sucrose hydrolases with important roles in plants. In this study, 15, 15, 15, 29, and 30 N/AINVs were identified in the Gossypium species, G. raimondii, G. herbaceum, G. arboreum, G. hirsutum, and G. barbadense, respectively. Along with two previously discovered branches, α and ß, a new clade γ was first discovered in our study. Investigation of gene collinearity showed that whole-genome duplication (WGD) and polyploidization were responsible for the expansion of the N/AINV gene family in allopolyploid Gossypium. Moreover, expression patterns revealed that GhN/AINV3/13/17/23/24/28 from the ß clade is highly expressed during the period of fiber initiation. The invertase activity of GhN/AINV13 and GhN/AINV23 were confirmed by restoring defects of invertase-deficient yeast mutant SEY2102. Treatments of abiotic stress showed that most GhN/AINVs were induced in response to polyethylene glycol (PEG) or salt stress. A virus-induced gene-silencing (VIGS) experiment and yeast two-hybrid assay demonstrated that GhN/AINV13 may interact with their positive regulators Gh14-3-3 proteins and participate in the fiber initiation or stress tolerance of cotton. Our results provided fundamental information regarding N/AINVs and highlight their potential functions in cotton stress tolerance.

GhTULP34, a member of tubby-like proteins, interacts with GhSKP1A to negatively regulate plant osmotic stress.

Tubby-like protein genes (TULPs), present in the form of large multigene families, play important roles in environmental stress. However, little is known regarding the TULP family genes in cotton. In this study, we systematically identified and analyzed the membership, characterization, and evolutionary relationship of TULPs in four species of cotton. Transcriptome analysis indicated that GhTULPs participate in environmental stress and cotton tissue development. At the same time, we also predicted and analyzed the potential molecular regulatory mechanisms and functions of TULPs. GhTULP34, as a candidate gene, significantly reduced the germination rate of transgenic Arabidopsis plants under salt stress, and inhibited root development and stomatal closure under mannitol stress. The yeast two-hybrid and luciferase (LUC) systems showed that GhTULP34 can interact with GhSKP1A, a subunit of the SCF-type (Skp1-Cullin-1-F-box) complex. This study will provide a basis and reference for future research on their roles in stress tolerance.

GhBOP1 as a Key Factor of Ribosomal Biogenesis: Development of Wrinkled Leaves in Upland Cotton.

Block of proliferation 1 (BOP1) is a key protein that helps in the maturation of ribosomes and promotes the progression of the cell cycle. However, its role in the leaf morphogenesis of cotton remains unknown. Herein, we report and study the function of GhBOP1 isolated from Gossypium hirsutum. The sequence alignment revealed that BOP1 protein was highly conserved among different species. The yeast two-hybrid experiments, bimolecular fluorescence complementation, and luciferase complementation techniques revealed that GhBOP1 interact with GhPES and GhWDR12. Subcellular localization experiments revealed that GhBOP1, GhPES and GhWDR12 were localized at the nucleolus. Suppression of GhBOP1 transcripts resulted in the uneven bending of leaf margins and the presence of young wrinkled leaves by virus-induced gene silencing assay. Abnormal palisade arrangements and the presence of large upper epidermal cells were observed in the paraffin sections of the wrinkled leaves. Meanwhile, a jasmonic acid-related gene, GhOPR3, expression was increased. In addition, a negative effect was exerted on the cell cycle and the downregulation of the auxin-related genes was also observed. These results suggest that GhBOP1 plays a critical role in the development of wrinkled cotton leaves, and the process is potentially modulated through phytohormone signaling.

Identification and characterization of the AINV genes in five Gossypium species with potential functions of GhAINVs under abiotic stress.

Acid invertase (AINV) is a kind of sucrose hydrolase with an important role in plants. Currently, the AINV genes have not been systematically studied in cotton. In this study, a total of 92 AINV genes were identified in five cotton species. The phylogenetic analysis revealed that the AINV proteins were divided into two subgroups in cotton: vacuolar invertase (VINV) and cell wall invertase (CWINV). The analysis of gene structures, conserved motifs, and three-dimensional protein structures suggested that GhAINVs were significantly conserved. The synteny analysis showed that whole-genome duplication was the main force promoting the expansion of the AINV gene family. The cis-element, transcriptome, and quantitative real time-polymerase chain reaction (qRT-PCR) showed that some GhAINVs were possibly associated with stress response. GhCWINV4, highly expressed in PEG treatment, was cloned, and subsequent virus-induced gene silencing assay confirmed that this gene was involved in the drought stress response. Overall, this study might be helpful for further analyzing the biological function of AINVs and provide clues for improving the resistance of cotton to stress.

Mitochondrial COI gene is valid to delimitate Tylenchidae (Nematoda: Tylenchomorpha) species.

Tylenchidae is a widely distributed soil-inhabiting nematode family. Regardless their abundance, molecular phylogeny based on rRNA genes is problematic, and the delimitation of taxa in this group remains poorly documented and highly uncertain. Mitochondrial Cytochrome Oxidase I (COI) gene is an important barcoding gene that has been widely used species identifications and phylogenetic analyses. However, currently COI data are only available for one species in Tylenchidae. In present study, we newly obtained 27 COI sequences from 12 species and 26 sequences from rRNA genes. The results suggest that the COI gene is valid to delimitate Tylenchidae species but fails to resolve phylogenetic relationships.Tylenchidae is a widely distributed soil-inhabiting nematode family. Regardless their abundance, molecular phylogeny based on rRNA genes is problematic, and the delimitation of taxa in this group remains poorly documented and highly uncertain. Mitochondrial Cytochrome Oxidase I (COI) gene is an important barcoding gene that has been widely used species identifications and phylogenetic analyses. However, currently COI data are only available for one species in Tylenchidae. In present study, we newly obtained 27 COI sequences from 12 species and 26 sequences from rRNA genes. The results suggest that the COI gene is valid to delimitate Tylenchidae species but fails to resolve phylogenetic relationships.

Identification of cotton PIP5K genes and role of GhPIP5K9a in primary root development.

Phosphatidylinositol 4 phosphate 5-kinase (PIP5K) is crucial for the phosphatidylinositol (PI) signaling pathway. It plays a significant role in plant growth and development, as well as stress response. However, its effects on cotton are unknown. This study identified PIP5K genes from four cotton species and conducted bioinformatic analyses, with a particular emphasis on the functions of GhPIP5K9a in primary roots. The results showed that cotton PIP5Ks were classified into four subgroups. Analysis of gene structure and motif composition showed obvious conservation within each subgroup. Synteny analysis suggested that the PIP5K gene family experienced significant expansion due to both whole-genome duplication (WGD) and segmental duplication. Transcriptomic data analysis revealed that the majority of GhPIP5K genes had the either low or undetectable levels of expression. Moreover, GhPIP5K9a is highly expressed in the root and was located in plasmalemma. Suppression of GhPIP5K9a transcripts resulted in longer primary roots, longer primary root cells and increased auxin polar transport-related genes expression, and decreased abscisic acid (ABA) content, indicating that GhPIP5K9a negatively regulates cotton primary root growth. This study lays the foundation for further exploration of the role of the PIP5K genes in cotton.

Minisci-Type Dehydrogenative Coupling of C(sp3)-H and N-Heteroaromatics Enabled by Photoelectrochemical Hydrogen Atom Transfer.

Minisci-type dehydrogenative coupling of C(sp3)-H and N-heteroaromatics was performed with N-hydroxysuccinimide as a hydrogen atom transfer catalyst in a photoelectrochemical cell composed of a mesoporous BiVO4 photoanode and a Pt electrode. In the absence of metal catalysts and chemical oxidants, a range of N-heteroarenes (e.g., quinolines, isoquinolines, and quinoxaline) can undergo coupling with various C(sp3)-H partners to form the corresponding products in excellent yields.

Exploring the role of GhN/AINV23: implications for plant growth, development, and drought tolerance.

BACKGROUND: Neutral/alkaline invertases (N/AINVs) play a crucial role in plant growth, development, and stress response, by irreversibly hydrolyzing sucrose into glucose and fructose. However, research on cotton in this area is limited. This study aims to investigate GhN/AINV23, a neutral/alkaline invertase in cotton, including its characteristics and biological functions. RESULTS: In our study, we analyzed the sequence information, three-dimensional (3D) model, phylogenetic tree, and cis-elements of GhN/AINV23. The localization of GhN/AINV23 was determined to be in the cytoplasm and cell membrane. Quantitative real-time polymerase chain reaction (qRT-PCR) results showed that GhN/AINV23 expression was induced by abscisic acid (ABA), exogenous sucrose and low exogenous glucose, and inhibited by high exogenous glucose. In Arabidopsis, overexpression of GhN/AINV23 promoted vegetative phase change, root development, and drought tolerance. Additionally, the virus-induced gene silencing (VIGS) assay indicated that the inhibition of GhN/AINV23 expression made cotton more susceptible to drought stress, suggesting that GhN/AINV23 positively regulates plant drought tolerance. CONCLUSION: Our research indicates that GhN/AINV23 plays a significant role in plant vegetative phase change, root development, and drought response. These findings provide a valuable foundation for utilizing GhN/AINV23 to improve cotton yield.

Visible-Light-Promoted Radical Cross-Dehydrogenative Coupling of C(sp3)-H/C(sp3)-H and C(sp3)-H/C(sp2)-H via Intermolecular HAT.

Cross-dehydrogenative coupling has emerged as a robust tool to construct C-C and C-heteroatom bonds. Herein, we reported an interesting visible-light-mediated radical CDC of C(sp3)-H/C(sp3)-H and C(sp3)-H/C(sp2)-H, enabled by a phenyl radical guided intermolecular HAT process. This strategy allowed the efficient coupling of a wide range of inert C(sp3)-H and C(sp2)-H with α-N C(sp3)-H of amines in good regioselectivities and yields. Mechanistic studies indicate that the EDA complex triggered an intermolecular HAT process.

Genome-wide analysis of JMJ-C histone demethylase family involved in salt-tolerance in Gossypium hirsutum L.

The jumonji C (JMJ-C) domain-containing protein is a histone demethylase and is involved in plant stress. However, the function of the JMJ-C gene family in cotton is still not confirmed. Herein, 25, 26, 52, and 53 members belonging to the JMJ-C gene family were identified in Gossypium raimondii, Gossypium arboreum, Gossypium hirsutum, and Gossypium barbadense, respectively. Based on phylogenetic relationships and conserved domains, the JMJ-C genes were categorized into five subfamilies, KDM3, KDM4, KDM5, JMJC, and JMJD6. The chromosomal location, gene structure, motif compositions, and cis-elements have been displayed. The collinear investigation showed that whole-genome duplication event is the mainly power to drive JMJ-C gene family expansion. Transcriptome and qRT-PCR analysis revealed that eight GhJMJs were induced by salt and PEG treatment. Further assays confirmed that GhJMJ34/40 greatly improved salt and osmotic tolerance in Saccharomyces cerevisiae. These results help clarify JMJ-C protein functions in preparation for further study.

Genome-Wide Analysis of the Phospholipase D Family in Five Cotton Species, and Potential Role of GhPLD2 in Fiber Development and Anther Dehiscence.

Phospholipase D (PLD) and its hydrolysis product phosphatidic acid play an important role in the regulation of several cellular processes, including root growth, pollen tube elongation, and microtubule reorganization. Here, we systematically identified and analyzed the membership, characterization, and evolutionary relationship of PLDs in five species of cotton. The results of the transcriptomic analysis suggested that the evaluated PLD genes showed high expression levels in anther tissue and during the fiber initiation and elongation periods. Quantitative real-time polymerase chain reaction showed differential expression of GhPLD genes in the anthers of photoperiod sensitive male sterility mutant 5 (psm5). Previous research on multiple stable quantitative trait loci also suggests the role of PLD genes in the fiber development. Further analyses showed that GhPLD2 protein is localized to the plasma membrane. The virus-induced gene silencing of GhPLD2 in cotton seedlings repressed its expression by 40-70%, which led to a reduction in reactive oxygen species (ROS) levels, 22% anther indehiscence, and disrupted fiber initiation and elongation. Thus, we inferred that GhPLD2 may promote ROS production, which, in turn, may regulate anther dehiscence and fiber development.

EMBRYONIC FLOWER2B, coming from a stable QTL, represses the floral transition in cotton.

The EMBRYONIC FLOWER 2 (EMF2) gene encodes a VEFS (VRN2-EMF2-FIS2-Su(z)12) domain protein involved in plant growth and development. Herein, genome-wide characterization of the VEFS-box gene family in Gossypium raimondii, G. arboreum, G. barbadense, and G. hirsutum was performed with a total of 3, 3, 6, and 6 homologous sequences respectively identified in the four species. The gene structure, protein motifs, and gene expression were further investigated. Based on our previous research on multiple stable quantitative trait loci for early maturity, GhEMF2B on chromosome D03 was selected as a candidate gene for further study. Quantitative real-time PCR analysis indicated that GhEMF2B was upregulated in the apical buds of late-maturing cultivars at the fourth and fifth true-leaf stages compared to that of early-maturing cultivars. Virus-induced gene silencing of GhEMF2B in cotton seedlings repressed expression by 50%-70%, which led to earlier floral bud development, young curled leaves, and abnormal petal formation. Further analysis demonstrated that the silencing of GhEMF2B enhanced the expression levels of the positive floral regulators AGAMOUS-LIKE 6 (GhAGL6), FLOWERING LOCUS T (GhFT), and APETALA 1 (GhAP1). Thus, it can be inferred that GhEMF2B plays important roles in the floral transition and development of cotton.

Comprehensive Genome-Wide Analysis of Thaumatin-Like Gene Family in Four Cotton Species and Functional Identification of GhTLP19 Involved in Regulating Tolerance to Verticillium dahlia and Drought.

Thaumatin-like proteins (TLPs) present in the form of large multigene families play important roles in biotic stress and abiotic stress. However, there has been no systematic analysis of the TLPs in cotton. In this study, comprehensive identification and evolutionary analysis of TLPs in four species of cotton were conducted. In total, 50, 48, 91, and 90 homologous sequences were identified in Gossypium raimondii, G. arboreum, G. barbadense, and G. hirsutum, respectively. Gene structure, protein motifs, and gene expression were further investigated. Transcriptome and quantitative real-time PCR analysis indicated that GhTLPs participate in abiotic, biotic stress and cotton fiber development. GhTLP19 on chromosome At05 was selected as a candidate gene for further study. When GhTLP19 was silenced by virus-induced gene silencing (VIGS) in cotton, with the increase of malondialdehyde (MDA) content and the decrease of catalase (CAT) content, and as the increase of disease index (DI) and hyphae accumulation, the plants were more sensitive to drought and Verticillium dahliae. Furthermore, the GhTLP19 overexpressing Arabidopsis transgenic lines exhibited higher proline content, thicker and longer trichomes and more tolerance to drought when compared to wild type. This study will provide a basis and reference for future research on their roles in stress tolerance and fiber development.