Research Progress in the Regulation of the ABA Signaling Pathway by E3 Ubiquitin Ligases in Plants.

E3 ubiquitin ligases (UBLs), as enzymes capable of specifically recognizing target proteins in the process of protein ubiquitination, play crucial roles in regulating responses to abiotic stresses such as drought, salt, and temperature. Abscisic acid (ABA), a plant endogenous hormone, is essential to regulating plant growth, development, disease resistance, and defense against abiotic stresses, and acts through a complex ABA signaling pathway. Hormone signaling transduction relies on protein regulation, and E3 ubiquitin ligases play important parts in regulating the ABA pathway. Therefore, this paper reviews the ubiquitin-proteasome-mediated protein degradation pathway, ABA-related signaling pathways, and the regulation of ABA-signaling-pathway-related genes by E3 ubiquitin ligases, aiming to provide references for further exploration of the relevant research on how plant E3 ubiquitin ligases regulate the ABA pathway.

Long-term conservation tillage increase cotton rhizosphere sequestration of soil organic carbon by changing specific microbial CO2 fixation pathways in coastal saline soil.

Coastal saline soil is an important reserve resource for arable land globally. Data from 10 years of continuous stubble return and subsoiling experiments have revealed that these two conservation tillage measures significantly improve cotton rhizosphere soil organic carbon sequestration in coastal saline soil. However, the contribution of microbial fixation of atmospheric carbon dioxide (CO2) has remained unclear. Here, metagenomics and metabolomics analyses were used to deeply explore the microbial CO2 fixation process in rhizosphere soil of coastal saline cotton fields under long-term stubble return and subsoiling. Metagenomics analysis showed that stubble return and subsoiling mainly optimized CO2 fixing microorganism (CFM) communities by increasing the abundance of Acidobacteria, Gemmatimonadetes, and Chloroflexi, and improving composition diversity. Conjoint metagenomics and metabolomics analyses investigated the effects of stubble return and subsoiling on the reverse tricarboxylic acid (rTCA) cycle. The conversion of citrate to oxaloacetate was inhibited in the citrate cleavage reaction of the rTCA cycle. More citrate was converted to acetyl-CoA, which enhanced the subsequent CO2 fixation process of acetyl-CoA conversion to pyruvate. In the rTCA cycle reductive carboxylation reaction from 2-oxoglutarate to isocitrate, synthesis of the oxalosuccinate intermediate product was inhibited, with strengthened CO2 fixation involving the direct conversion of 2-oxoglutarate to isocitrate. The collective results demonstrate that stubble return and subsoiling optimizes rhizosphere CFM communities by increasing microbial diversity, in turn increasing CO2 fixation by enhancing the utilization of rTCA and 3-hydroxypropionate/4-hydroxybutyrate cycles by CFMs. These events increase the microbial CO2 fixation in the cotton rhizosphere, thereby promoting the accumulation of microbial biomass, and ultimately improving rhizosphere soil organic carbon. This study clarifies the impact of conservation tillage measures on microbial CO2 fixation in cotton rhizosphere of coastal saline soil, and provides fundamental data for the improvement of carbon sequestration in saline soil in agricultural ecosystems.

Overexpression of GhABF3 increases cotton(Gossypium hirsutum L.) tolerance to salt and drought.

BACKGROUND: Plants suffer from various abiotic stresses during their lifetime, of which drought and salt stresses are two main factors limiting crop yield and quality. Previous studies have shown that abscisic acid (ABA) responsive element binding protein (AREB)/ ABRE binding factors (ABFs) in bZIP transcription factors are involved in plant stress response in an ABA-dependent manner. However, little is known about the properties and functions of AREB/ABFs, especially ABF3, in cotton. RESULTS: Here, we reported the cloning and characterization of GhABF3. Expression of GhABF3 was induced by drought,salt and ABA treatments. Silencing of GhABF3 sensitized cotton to drought and salt stress, which was manifested in decreased cellular antioxidant capacity and chlorophyll content. Overexpression of GhABF3 significantly improved the drought and salinity tolerance of Arabidopsis and cotton. Exogenous expression of GhABF3 resulted in longer root length and less leaf wilting under stress conditions in Arabidopsis thaliana. Overexpressing GhABF3 significantly improved salt tolerance of upland cotton by reducing the degree of cellular oxidation, and enhanced drought tolerance by decreasing leaf water loss rate. The increased expression of GhABF3 up-regulated the transcriptional abundance of downstream ABA-inducible genes under salt stress in Arabidopsis. CONCLUSION: In conclusion, our results demonstrated that GhABF3 plays an important role in plant drought and salt tolerance. Manipulation of GhABF3 by biotechnology might be an important strategy to alter the stress resistance of cotton.

Genome-wide identification and analysis of Oleosin gene family in four cotton species and its involvement in oil accumulation and germination.

BACKGROUND: Cotton is not only a major textile fiber crop but also a vital oilseed, industrial, and forage crop. Oleosins are the structural proteins of oil bodies, influencing their size and the oil content in seeds. In addition, the degradation of oleosins is involved in the mobilization of lipid and oil bodies during seed germination. However, comprehensive identification and the systematic analysis of the Oleosin gene (OLEOs) family have not been conducted in cotton. RESULTS: An in-depth analysis has enabled us to identify 25 and 24 OLEOs in tetraploid cotton species G. hirsutum and G. barbadense, respectively, while 12 and 13 OLEOs were identified in diploid species G. arboreum and G. raimondii, respectively. The 74 OLEOs were further clustered into three lineages according to the phylogenetic tree. Synteny analysis revealed that most of the OLEOs were conserved and that WGD or segmental duplications might drive their expansion. The transmembrane helices in GhOLEO proteins were predicted, and three transmembrane models were summarized, in which two were newly proposed. A total of 24 candidate miRNAs targeting GhOLEOs were predicted. Three highly expressed oil-related OLEOs, GH_A07G0501 (SL), GH_D10G0941 (SH), and GH_D01G1686 (U), were cloned, and their subcellular localization and function were analyzed. Their overexpression in Arabidopsis increased seed oil content and decreased seed germination rates. CONCLUSION: We identified OLEO gene family in four cotton species and performed comparative analyses of their relationships, conserved structure, synteny, and gene duplication. The subcellular localization and function of three highly expressed oil-related OLEOs were detected. These results lay the foundation for further functional characterization of OLEOs and improving seed oil content.

Leaf photosynthetic and anatomical insights into mechanisms of acclimation in rice in response to long-term fluctuating light.

Long-term fluctuating light (FL) conditions are very common in natural environments. The physiological and biochemical mechanisms for acclimation to FL differ between species. However, most of the current conclusions regarding acclimation to FL were made based on studies in algae or Arabidopsis thaliana. It is still unclear how rice (Oryza sativa L.) integrate multiple physiological changes to acclimate to long-term FL. In this study, we found that rice growth was repressed under long-term FL. By systematically measuring phenotypes and physiological parameters, we revealed that: (a) under short-term FL, photosystem I (PSI) was inhibited, while after 1-7 days of long-term FL, both PSI and PSII were inhibited. Higher acceptor-side limitation in electron transport and higher overall nonphotochemical quenching (NPQ) explained the lower efficiencies of PSI and PSII, respectively. (b) An increase in pH differences across the thylakoid membrane and a decrease in thylakoid proton conductivity revealed a reduction of ATP synthase activity. (c) Using electron microscopy, we showed a decrease in membrane stacking and stomatal opening after 7 days of FL treatment. Taken together, our results show that electron flow, ATP synthase activity and NPQ regulation are the major processes determining the growth performance of rice under long-term FL conditions.

Identification and characterization analysis of sulfotransferases (SOTs) gene family in cotton (Gossypium) and its involvement in fiber development.

BACKGROUND: Sulfotransferases (SOTs) (EC 2.8.2.-) play a crucial role in the sulphate conjugation reaction involved in plant growth, vigor, stress resistance and pathogen infection. SOTs in Arabidopsis have been carried out and divided into 8 groups. However, the systematic analysis and functional information of SOT family genes in cotton have rarely been reported. RESULTS: According to the results of BLASTP and HMMER, we isolated 46, 46, 76 and 77 SOT genes in the genome G. arboreum, G. raimondii, G. barbadense and G. hirsutum, respectively. A total of 170 in 245 SOTs were further classified into four groups based on the orthologous relationships comparing with Arabidopsis, and tandem replication primarily contributed to the expansion of SOT gene family in G. hirsutum. Expression profiles of the GhSOT showed that most genes exhibited a high level of expression in the stem, leaf, and the initial stage of fiber development. The localization analysis indicated that GhSOT67 expressed in cytoplasm and located in stem and leaf tissue. Additionally, the expression of GhSOT67 were induced and the length of stem and leaf hairs were shortened after gene silencing mediated by Agrobacterium, compared with the blank and negative control plants. CONCLUSIONS: Our findings indicated that SOT genes might be associated with fiber development in cotton and provided valuable information for further studies of SOT genes in Gossypium.

Genome-wide association and differential expression analysis of salt tolerance in Gossypium hirsutum L at the germination stage.

BACKGROUND: Salinity is a major abiotic stress seriously hindering crop yield. Development and utilization of tolerant varieties is the most economical way to address soil salinity. Upland cotton is a major fiber crop and pioneer plant on saline soil and thus its genetic architecture underlying salt tolerance should be extensively explored. RESULTS: In this study, genome-wide association analysis and RNA sequencing were employed to detect salt-tolerant qualitative-trait loci (QTLs) and candidate genes in 196 upland cotton genotypes at the germination stage. Using comprehensive evaluation values of salt tolerance in four environments, we identified 33 significant single-nucleotide polymorphisms (SNPs), including 17 and 7 SNPs under at least two and four environments, respectively. The 17 stable SNPs were located within or near 98 candidate genes in 13 QTLs, including 35 genes that were functionally annotated to be involved in salt stress responses. RNA-seq analysis indicated that among the 98 candidate genes, 13 were stably differentially expressed. Furthermore, 12 of the 13 candidate genes were verified by qRT-PCR. RNA-seq analysis detected 6640, 3878, and 6462 differentially expressed genes at three sampling time points, of which 869 were shared. CONCLUSIONS: These results, including the elite cotton accessions with accurate salt tolerance evaluation, the significant SNP markers, the candidate genes, and the salt-tolerant pathways, could improve our understanding of the molecular regulatory mechanisms under salt stress tolerance and genetic manipulation for cotton improvement.

Overdominance is the major genetic basis of lint yield heterosis in interspecific hybrids between G. hirsutum and G. barbadense.

The genetic basis of heterosis has not been resolved for approximately a century, although the role of loci with overdominant (ODO) effects has continued to be discussed by biologists. In the present investigation, a proposed model was studied in Gossypium hirsutum L. introgression lines (ILs) harbouring a segment of G. barbadense. These introgressions were confirmed by a single marker of G. barbadense. These ILs contained 396 quantitative trait loci (QTLs) for 11 yield and non-yield traits that were recorded in the field on homozygous and heterozygous plants for 5 years. After comparing the different types of QTLs between the yield group and the non-yield group, it was found that the yield group had significantly higher ODO QTL ratios. Moreover, 16 ODO QTLs identified for 5 yield-related traits were consistently detected during 5 cotton growing seasons (2010-2011 and 2013-2015): 6 of 7 for boll weight, 3 of 11 for seed-cotton yield per plant, 4 of 17 for boll number, 2 of 13 for lint yield per plant and 1 of 11 for lint percentage. Therefore, we propose that overdominance is the major genetic basis of lint yield heterosis in interspecific hybrids between G. barbadense and G. hirsutum. These findings have important implications in cotton breeding in that the boll weight can be improved by utilizing ODO QTLs via heterosis; thus, the stagnant yield barrier can be smashed to achieve sustainable increases in cotton production. Additionally, this concept can be translated to other field crops for improving their yield potential.

Construction of nanoscale liposomes loaded with melatonin via supercritical fluid technology.

Melatonin-loaded liposomes (MLL) were successfully prepared using rapid expansion of supercritical solution technology. The effects of supercritical pressure on encapsulation efficiency (EE) and average particle size were then analysed. Meanwhile, temperature, formation time and ethanol concentration in the products were studied and optimised based on the response surface methodology (RSM). An in vitro simulated digestion model was also established to evaluate the release performance of MLL. The results showed that 140 bar was the best pressure for maximising the EE value using RSM optimisation, reaching up to 82.2%. MLL characterisations were performed using analytic techniques including infrared spectroscopy, transmission electron microscopy, a laser scattering particle size analyser and gas chromatograph-mass spectrometer. The size distribution was uniform, with an average diameter of 66 nm. Stability tests proved that MLL maintained good preservation duration, and residual solvent experiments indicated that only 1.03% (mass ratio) of ethanol remained in the products. Simulated release experiments indicated the slow release feature in early digestive stages and more thorough characteristics in later stages of simulated digestion.

Preparation of cathode catalysts for efficient direct lignin fuel cells by nitrogen doping reduction of oxidized graphene with phthalocyanine iron and Kraft lignin.

Direct lignin fuel cells (DLFC) are one of the important forms of high value-added utilization of lignin. In this study, lignin was studied not only as a fuel but also as a catalyst. Specifically, Kraft lignin was modified with ZnCl2, KOH and THF (Tetrahydrofuran) respectively, and added to the catalyst after activation. The results of scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), Brunauer - Emmett - Teller (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR) and Raman spectra shown that AL/FePc-NrGO (activated lignin/iron phthalocyanine/nitrogen-doped reduction of graphene oxide) three-dimensional composite catalyst has been synthesized. The results showed that KOH-activated Kraft lignin had the best performance as an oxygen reduction reaction (ORR) catalyst, with a half-wave potential (E1/2) of 0.73 V and a limiting diffusion current density of 4.3 mA cm-1. The THF-modified catalyst showed similar stability and methanol resistance to 20 % Pt/C at ORR. The ORR catalyst applied to the DLFC has the best electrical performance with an open circuit voltage (OCV) was 0.53 V and the maximum power density it could reach 95.29 mW m-2 when the catalyst was modified with THF. It is encouraging that the AL/FePc-NrGO catalyst has better-generated electricity performance than 20 % Pt/C. This work has provided a new idea for developing non-noble metal catalysts and studying direct biomass liquid fuel cells.

Inhibition of Salmonella typhimurium and Listeria monocytogenes in coconut juice by graphene-doped photocatalyst rGO/TiO2.

This research used the photocatalyst rGO/TiO2 prepared by hydrothermal method to inhibit the growth of these microorganisms in water and coconut juice. In coconut juice, the initial count of Salmonella typhimurium decreased from 3 × 105 CFU /mL to 6.3 × 104 CFU /mL, and the initial count of L. monocytogenes was reduced from 3 × 105 CFU/mL to 1.2 × 105 CFU/mL. Moreover, the chemical structure characterization rGO/TiO2 showed that the doping of rGO formed a compact composite, enhanced the transfer of photogenerated electrons, and improved the photocatalytic efficiency of TiO2. The active substances ·OH and ·O2- produced by photocatalysis directly destroyed the integrity of bacteria cells, led to leakage of protein and DNA in the cells, and resulted in inactivation of the microorganisms, although Salmonella typhimurium and Listeria monocytogenes have different cell structures. These results would provide a good candidate photocatalyst to resist Salmonella typhimurium and Listeria monocytogenes and promote the development of photocatalysis applications.

Selective regulation of products for guaiacol hydrodeoxygenation by adjusting type and acidity of supports.

Upgrading lignin-oil into advanced fuels or chemicals has been widely studied in recent years. To understand the effect of support type and acidity on the hydrodeoxygenation (HDO) of guaiacol (lignin-oil model compound), Ni-based catalysts were prepared with SiO2, Al2O3 and ZSM-5 as supports, respectively. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption desorption, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Pyridine adsorption Fourier-transform infrared (Py-IR). The research results indicate that selective regulation of guaiacol hydrogenation products can be achieved by changing the type and acidity of support. Cyclohexanol is the main product over Ni/SiO2, while cyclohexane is the main product over Ni/ZSM-5 series catalysts. Moreover, as the Si/Al ratio increases, the catalytic activity of Ni/ZSM-5 slightly decreases, and the yield of cyclohexane also decreases. The Brønsted acidity of the support is the key to promoting the conversion of cyclohexanol to cyclohexane. The formation of NiAl2O4 is the main reason for the relatively low activity of Ni/Al2O3. The conversion of guaiacol is as high as 99.2 %, and the yield of cyclohexane is as high as 86.6 % over Ni/ZSM-5(Si/Al = 27). In addition, complete conversion of guaiacol and 92.6 % yield of cyclohexanol were achieved over Ni/SiO2. More importantly, Ni/SiO2 and Ni/ZSM-5(27) are suitable for aromatic substrates with different substituents, respectively.

Efficient adsorption of short-chain perfluoroalkyl substances by pristine and Fe/Cu-loaded reed straw biochars.

As the substitutes of legacy long-chain per-/polyfluoroalkyl substances (PFASs), short-chain PFASs have been widely detected in the environment. Compared to long-chain PFASs, short-chain PFASs have smaller molecules and are more hydrophilic. Therefore, they are more likely to experience long-distance transport and pose lasting environmental impacts. In this study, Fe-doped (R-Fe) and Cu-doped biochars (R-Cu) were prepared using reed straw biochar (R). The results showed that the PFBA and PFPeA sorption capacities of R-Fe were 25.81 and 43.59 mg g-1, 1.65 and 1.55 times higher than those of R, respectively. The PFBA and PFPeA sorption capacities of R-Cu were 19.34 and 33.69 mg g-1, 1.24 and 1.20 times higher than those of R, respectively. In addition, R, R-Fe, and R-Cu exhibited higher PFBA and PFPeA sorption capacities than the biochars previously reported. The excellent PFAS sorption performances of the biochars were attributed to the highly porous structure of R, which provided rich adsorption sites. Ion-pair sorption, pore filling, electrostatic interaction between the Fe/Cu and cationic groups on biochar and the anionic groups of PFASs, and hydrophobic interaction between the hydrophobic surface of biochar and the fluorinated tails of PFASs were the underlying sorption mechanisms. The biochars presented high removal rates (>86 %) of multiple PFASs (∑PFAS: 350 µg L-1) from synthetic wastewaters, including legacy and emerging PFASs of different chain lengths and with different functional groups. The biochars reported in this study are promising candidate adsorbents for treating waters contaminated with short-chain PFASs.

Mapping heterotic loci for yield and agronomic traits using chromosome segment introgression lines in cotton.

In the present study, a set of chromosome segment introgression lines (CSILs) using Gossypium hirsutum L. TM-1 as the recipient parent and G. barbadense Hai7124 as the donor parent were used to explore the genetic basis of heterosis for interspecific hybrids. Two sets of F1 populations individually derived from CSILs crossing with both parents were configured to investigate heterotic loci (HL) and substitution effect loci (SL). A total of 58 HL and 39 SL were identified in 3 years. One stable HL, hLP-A4-3, could be detected in all 3 years. Three HLs, hBS-A8-1, hLP-D6-1, and hSI-D7-11, could be detected in 2 years. Four SLs, sBS-D7-1, sLP-A8-1, sLP-D7-1, and sLP-D12-1, could be detected in 2 years. HL and SL tended to be distributed in some HL-rich chromosome segments with close positions. Compared with QTL detected in a former study, HL showed little overlap with QTL, indicating that trait phenotype and heterosis might be controlled by different sets of loci. All three forms of genetic effects (partial-, full-, over-dominant) were identified, while the over-dominant effect made the main contribution to heterosis. These results may help lay the foundation for clarifying the heredity mechanism of heterosis in cotton.

A simple nanocomposite photocatalyst HT-rGO/TiO2 for deoxynivalenol degradation in liquid food.

A simple nanocomposite photocatalyst HT-rGO/TiO2 for deoxynivalenol (DON) degradation was synthesized by hydrothermal method to maintain the quality of cereal grains and byproducts. The characterization of HT-rGO/TiO2 was analyzed by XRD, FTIR, Raman spectroscopy, and XPS. Moreover, according to UV-vis DRS analysis, HT-rGO/TiO2 had a smaller band gap, indicating a wider response range to light and a higher utilized rate of quantum photons. Additionally, the results of LC-MS showed that the hydroxyl group at the C3 position, and the unsaturated bond between C9 and C10, and the epoxy group at C12 and C13 positions of DON molecule were destroyed step by step by photocatalytic degradation. These groups have active effects on the DON toxicity, which means it is successful to degrade DON in liquid-food by HT-rGO/TiO2 photocatalyst.

Free-standing reduced graphene oxide/carboxymethylcellulose-polyaniline (RGO/CMC-PANI) hybrid film electrode for high-performance asymmetric supercapacitor device.

This work demonstrates a facile and effective strategy for the preparation of a reduced graphene oxide/carboxymethylcellulose-polyaniline (RGO/CMC-PANI) hybrid film electrode. Specifically, through the hydrogen bonding interaction between -OH of CMC molecules and -NH2 of aniline monomer, PANI grows in an ordered manner on the surface of CMC, which effectively alleviates the structural collapse of PANI during the continuous charge/discharge process. After compounding with RGO, CMC-PANI bridges adjacent RGO sheets to form a complete conductive path, and opens the gap between RGO sheet layers to obtain fast ion channels. As a result, the RGO/CMC-PANI electrode exhibits excellent electrochemical performance. Moreover, an asymmetric supercapacitor was fabricated using RGO/CMC-PANI as the anode and Ti3C2Tx as the cathode. The results show that the device has a large specific capacitance of 450 mF cm-2 (81.8 F g-1) at 1 mA cm-2 and a high energy density of 140.6 µWh cm-2 at a power density of 749.9 µW cm-2. Besides, 87.3 % initial capacitance and 100 % good coulombic efficiency can be maintained even after 20,000 GCD cycles. Therefore, the device has a broad application prospect in the field of new-generation microelectronic energy storage.

Evolution and natural selection of ribosome-inactivating proteins in bacteria, fungi, and plants.

Ribosome-inactivating proteins (RIPs) are found in bacteria, fungi, and plants, with a wide range of biological resistances such as anti-fungal, anti-viral, anti-insect, and anti-tumor. They can be roughly divided into proactive defense bacterial or fungal types and passive defense plant types. We identified 1592 RIP genes in bacteria, fungi, and plants. Approximately 88 % of the 764 bacterial RIPs were Shiga or Shiga-like toxins which were exotoxins and could rapidly enter cells to possess strong biotoxicity, and about 98 % of fungal RIPs were predicted as secreted proteins. RIPs were not detected in non-seed plants such as algae, bryophytes, and ferns. However, we found RIPs in some flowering and non-flowering seed plants. The existence of plant RIPs might be related to the structure of seeds or fruits, which might be associated with whether seeds are easy to survive and spread. The evolutionary characteristics of RIPs were different between dicotyledons and monocotyledons. In addition, we also found that RIP2 genes might emerge very early and be plant-specific. Some plant RIP1 genes might evolve from RIP2 genes. This study provides new insights into the evolution of RIPs.

Degradation mechanism and pathway of tetracycline in milk by heterojunction N-TiO2-Bi2WO6 film under visible light.

N-doped TiO2-Bi2WO6 (NTB) three-component photocatalyst was prepared using a glycol solvothermal method. The photocatalysts and films were characterized, and applied to the degradation of tetracycline (TC) in milk and its effect on the quality of milk. The results show that the NTB photocatalyst exhibits good photocatalytic activity under visible light, and its TC degradation rate is increased by 1.76, 1.49, 1.42, 1.16, and 1.13 times higher than that of TiO2, Bi2WO6, N-TiO2, N-Bi2WO6 and TiO2-Bi2WO6, respectively. Due to the N doping, the photogenerated electron-hole pair recombination rate of photocatalyst is greatly reduced, which improving its photocatalytic performance. Additionally, the absorption wavelength threshold is enlarged by 459 nm, the gap width is reduced to 2.69 eV, and the degradation rate of TC is still 83.24 % after 5 repetitions. HPLC-MS revealed the active species, intermediates and photodegradation pathways in the photocatalytic process.

Interaction mechanism of carotenoids and polyphenols in mango peels.

In this study, carotenoids and polyphenols were demonstrated to be the major active substances in the crude pigment extracts (CPE) of mango peels, accounting for 0.26 mg/g and 0.15 mg/g, respectively. The interactions between carotenoids and polyphenols in CPE was observed, as evidenced by that polyphenols significantly improved the antioxidant activity and storage stability of carotenoids in the CPE. Meanwhile, scanning electron microscopy showed that polyphenols are tightly bound to carotenoids. To further elucidate the interaction mechanism, the monomers of carotenoids and polyphenols were identified by HPLC and LC-MS analysis. Lutein (203.85 µg/g), ß-carotene (41.40 µg/g), zeaxanthin (4.20 µg/g) and α-carotene (1.50 µg/g) were authenticated as the primary monomers of carotenoids. Polyphenols were mainly consisted of gallic acid (95.10 µg/g), quercetin-3-ß-glucoside (29.10 µg/g), catechin (11.85 µg/g) and quercetin (11.55 µg/g). The interaction indexes between carotenoid and polyphenol monomer of CPE were calculated. The result indicated that lutein and gallic acid showed the greatest synergistic effect on the scavenging of DPPH and ABTS radical, suggesting the interaction between carotenoids and polyphenols in CPE was mainly caused by lutein and gallic acid. Molecular dynamics simulations and thermodynamic parameters analysis demonstrated that hydrogen bonding, electrostatic interactions, and van der Waals forces played dominant roles in the interaction between lutein and gallic acid, which was confirmed by Raman and X-ray diffraction. These results provided a new perspective on the interaction mechanism between carotenoids and polyphenols, which offered a novel strategy for the enhancement of the activities and stability of bioactive substances.

Genome-wide identification and expression analysis of the HVA22 gene family in cotton and functional analysis of GhHVA22E1D in drought and salt tolerance.

The HVA22 family of genes, induced by abscisic acid and stress, encodes a class of stress response proteins with a conserved TB2/DP1/HVA22 domain that are unique among eukaryotes. Previous studies have shown that HVA22s play an important role in plant responses to abiotic stresses. In the present study, 34, 32, 16, and 17 HVA22s were identified in G. barbadense, G. hirsutum, G. arboreum, and G. raimondii, respectively. These HVA22 genes were classified into nine subgroups, randomly distributed on the chromosomes. Synteny analysis showed that the amplification of the HVA22s were mainly due to segmental duplication or whole genome replication (WGD). Most HVA22s promoter sequences contain a large number of drought response elements (MYB), defense and stress response elements (TC-rich repeats), and hormone response elements (ABRE, ERE, SARE, etc.), suggesting that HVA22s may respond to adversity stresses. Expression profiling demonstrated that most GhHVA22s showed a constitutive expression pattern in G. hirsutum and could respond to abiotic stresses such as salt, drought, and low temperature. Overexpression of GhHVA22E1D (GH_D07G0564) in Arabidopsis thaliana enhances salt and drought tolerance in Arabidopsis. Virus-induced gene silencing of GhHVA22E1D reduced salt and drought tolerance in cotton. This indicates that GhHVA22E1D plays an active role in the plant response to salt stress and drought stress. GhHVA22E1D may act in plant response to adversity by altering the antioxidant capacity of plants. This study provides valuable information for the functional genomic study of the HVA22 gene family in cotton. It also provides a reference for further elucidation of the functional studies of HVA22 in plant resistance to abiotic stress response.