Stress response membrane protein gene OsSMP2 negatively regulates rice tolerance to drought.

In our gene chip analysis, OsSMP2 gene expression was induced under various abiotic stresses, prompting an investigation into its role in drought resistance and ABA signaling. Subsequent experiments, including qRT-PCR and GUS activity detection, affirmed the OsSMP2 gene's predominant induction by drought stress. Subcellular localization experiments indicated the OsSMP2 protein primarily localizes to the cell membrane system. Overexpressing OsSMP2 increased sensitivity to exogenous ABA, reducing drought resistance and leading to reactive oxygen species accumulation under drought stress. Conversely, in simulated drought experiments, OsSMP2-silenced transgenic plants showed significantly longer root lengths compared to the wild-type Nipponbare. These results suggest that OsSMP2 overexpression negatively affects rice drought resistance, offering valuable insights into molecular mechanisms and proposing OsSMP2 as a potential target for enhancing crop resilience to drought stress.

Rice false smut virulence protein subverts host chitin perception and signaling at lemma and palea for floral infection.

The flower-infecting fungus Ustilaginoidea virens causes rice false smut, which is a severe emerging disease threatening rice (Oryza sativa) production worldwide. False smut not only reduces yield, but more importantly produces toxins on grains, posing a great threat to food safety. U. virens invades spikelets via the gap between the two bracts (lemma and palea) enclosing the floret and specifically infects the stamen and pistil. Molecular mechanisms for the U. virens-rice interaction are largely unknown. Here, we demonstrate that rice flowers predominantly employ chitin-triggered immunity against U. virens in the lemma and palea, rather than in the stamen and pistil. We identify a crucial U. virens virulence factor, named UvGH18.1, which carries glycoside hydrolase activity. Mechanistically, UvGH18.1 functions by binding to and hydrolyzing immune elicitor chitin and interacting with the chitin receptor CHITIN ELICITOR BINDING PROTEIN (OsCEBiP) and co-receptor CHITIN ELICITOR RECEPTOR KINASE1 (OsCERK1) to impair their chitin-induced dimerization, suppressing host immunity exerted at the lemma and palea for gaining access to the stamen and pistil. Conversely, pretreatment on spikelets with chitin induces a defense response in the lemma and palea, promoting resistance against U. virens. Collectively, our data uncover a mechanism for a U. virens virulence factor and the critical location of the host-pathogen interaction in flowers and provide a potential strategy to control rice false smut disease.

AP2/EREBP Pathway Plays an Important Role in Chaling Wild Rice Tolerance to Cold Stress.

Cold stress is the main factor limiting rice production and distribution. Chaling wild rice can survive in cold winters. AP2/EREBP is a known transcription factor family associated with abiotic stress. We identified the members of the AP2/EREBP transcription factor family in rice, maize, and Arabidopsis, and conducted collinearity analysis and gene family analysis. We used Affymetrix array technology to analyze the expression of AP2/EREBP family genes in Chaling wild rice and cultivated rice cultivar Pei'ai64S, which is sensitive to cold. According to the GeneChip results, the expression levels of AP2/EREBP genes in Chaling wild rice were different from those in Pei'ai64S; and the increase rate of 36 AP2/EREBP genes in Chaling wild rice was higher than that in Pei'ai64S. Meanwhile, the MYC elements in cultivated rice and Chaling wild rice for the Os01g49830, Os03g08470, and Os03g64260 genes had different promoter sequences, resulting in the high expression of these genes in Chaling wild rice under low-temperature conditions. Furthermore, we analyzed the upstream and downstream genes of the AP2/EREBP transcription factor family and studied the conservation of these genes. We found that the upstream transcription factors were more conserved, indicating that these upstream transcription factors may be more important in regulating cold stress. Meanwhile, we found the expression of AP2/EREBP pathway genes was significantly increased in recombinant inbred lines from Nipponbare crossing with Chaling wild rice, These results suggest that the AP2/EREBP signaling pathway plays an important role in Chaling wild rice tolerance to cold stress.

Molecular understanding of anthocyanin biosynthesis activated by PAP1 and regulated by 2, 4-dichlorophenoxyacetic acid in engineered red Artemisia annua cells.

MAIN CONCLUSION: Eight promoters were cloned, from which AC and G-box cis-elements were identified. PAP1 enhanced the promoter activity. 2,4-D reduced the anthocyanin biosynthesis via downregulating the expression of the PAP1 transgene. Artemisia annua is an effective antimalarial medicinal crop. We have established anthocyanin-producing red cell cultures from this plant with the overexpression of Production of Anthocyanin Pigment 1 (PAP1) encoding a R2R3MYB transcription factor. To understand the molecular mechanism by which PAP1 activated the entire anthocyanin pathway, we mined the genomic sequences of A. annua and obtained eight promoters of the anthocyanin pathway genes. Sequence analysis identified four types of AC cis-elements from six promoters, the MYB response elements (MRE) bound by PAP1. In addition, six promoters were determined to have at least one G-box cis-element. Eight promoters were cloned for activity analysis. Dual luciferase assays showed that PAP1 significantly enhanced the promoting activity of seven promoters, indicating that PAP1 turned on the biosynthesis of anthocyanins via the activation of these pathway gene expression. To understand how 2,4-dichlorophenoxyacetic acid (2,4-D), an auxin, regulates the PAP1-activated anthocyanin biosynthesis, five different concentrations (0, 0.05, 0.5, 2.5, and 5 µM) were tested to characterize anthocyanin production and profiles. The resulting data showed that the concentrations tested decreased the fresh weight of callus growth, anthocyanin levels, and the production of anthocyanins per Petri dish. HPLC-qTOF-MS/MS-based profiling showed that these concentrations did not alter anthocyanin profiles. Real-time RT-PCR was completed to characterize the expression PAP1 and four representative pathway genes. The results showed that the five concentrations reduced the expression levels of the constitutive PAP1 transgene and three pathway genes significantly and eliminated the expression of the chalcone synthase gene either significantly or slightly. These data indicate that the constitutive PAP1 expression depends on gradients added in the medium. Based on these findings, the regulation of 2,4-D is discussed for anthocyanin engineering in red cells of A. annua.

OsWRKY97, an Abiotic Stress-Induced Gene of Rice, Plays a Key Role in Drought Tolerance.

Drought stress is one of the major causes of crop losses. The WRKY families play important roles in the regulation of many plant processes, including drought stress response. However, the function of individual WRKY genes in plants is still under investigation. Here, we identified a new member of the WRKY families, OsWRKY97, and analyzed its role in stress resistance by using a series of transgenic plant lines. OsWRKY97 positively regulates drought tolerance in rice. OsWRKY97 was expressed in all examined tissues and could be induced by various abiotic stresses and abscisic acid (ABA). OsWRKY97-GFP was localized to the nucleus. Various abiotic stress-related cis-acting elements were observed in the promoters of OsWRKY97. The results of OsWRKY97-overexpressing plant analyses revealed that OsWRKY97 plays a positive role in drought stress tolerance. In addition, physiological analyses revealed that OsWRKY97 improves drought stress tolerance by improving the osmotic adjustment ability, oxidative stress tolerance, and water retention capacity of the plant. Furthermore, OsWRKY97-overexpressing plants also showed higher sensitivity to exogenous ABA compared with that of wild-type rice (WT). Overexpression of OsWRKY97 also affected the transcript levels of ABA-responsive genes and the accumulation of ABA. These results indicate that OsWRKY97 plays a crucial role in the response to drought stress and may possess high potential value in improving drought tolerance in rice.

Overexpression of Rice Histone H1 Gene Reduces Tolerance to Cold and Heat Stress.

Temperature stresses, including low- and high-temperature stresses, are the main abiotic stresses affecting rice yield. Due to global climate change, the impact of temperature pressure on rice yield is gradually increasing, which is also a major concern for researchers. In this study, an H1 histone in Oryza sativa (OsHis1.1, LOC_Os04g18090) was cloned, and its role in rice's response to temperature stresses was functionally characterized. The GUS staining analysis of OsHis1.1 promoter-GUS transgenic rice showed that OsHis1.1 was widely expressed in various rice tissues. Transient expression demonstrated that OsHis1.1 was localized in the nucleus. The overexpression of OsHis1.1 reduces the tolerance to temperature stress in rice by inhibiting the expression of genes that are responsive to heat and cold stress. Under stress conditions, the POD activity and chlorophyll and proline contents of OsHis1.1-overexpression rice lines were significantly lower than those of the wild type, while the malondialdehyde content was higher than that of the wild type. Compared with Nip, OsHis1.1-overexpression rice suffered more serious oxidative stress and cell damage under temperature stress. Furthermore, OsHis1.1-overexpression rice showed changes in agronomic traits.

Overexpression of OsHAD3, a Member of HAD Superfamily, Decreases Drought Tolerance of Rice.

Haloacid dehalogenase-like hydrolase (HAD) superfamily have been shown to get involved in plant growth and abiotic stress response. Although the various functions and regulatory mechanism of HAD superfamily have been well demonstrated, we know little about the function of this family in conferring abiotic stress tolerance to rice. Here, we report OsHAD3, a HAD superfamily member, could affect drought tolerance of rice. Under drought stress, overexpression of OsHAD3 increases the accumulation of reactive oxygen species and malondialdehyde than wild type. OsHAD3-overexpression lines decreased but antisense-expression lines increased the roots length under drought stress and the transcription levels of many well-known stress-related genes were also changed in plants with different genotypes. Furthermore, overexpression of OsHAD3 also decreases the oxidative tolerance. Our results suggest that overexpression of OsHAD3 could decrease the drought tolerance of rice and provide a new strategy for improving drought tolerance in rice.

Antifungal mechanisms of the antagonistic bacterium Bacillus mojavensis UTF-33 and its potential as a new biopesticide.

Biological control has gradually become the dominant means of controlling fungal disease over recent years. In this study, an endophytic strain of UTF-33 was isolated from acid mold (Rumex acetosa L.) leaves. Based on 16S rDNA gene sequence comparison, and biochemical and physiological characteristics, this strain was formally identified as Bacillus mojavensis. Bacillus mojavensis UTF-33 was sensitive to most of the antibiotics tested except neomycin. Moreover, the filtrate fermentation solution of Bacillus mojavensis UTF-33 had a significant inhibitory effect on the growth of rice blast and was used in field evaluation tests, which reduced the infestation of rice blast effectively. Rice treated with filtrate fermentation broth exhibited multiple defense mechanisms in response, including the enhanced expression of disease process-related genes and transcription factor genes, and significantly upregulated the gene expression of titin, salicylic acid pathway-related genes, and H2O2 accumulation, in plants; this may directly or indirectly act as an antagonist to pathogenic infestation. Further analysis revealed that the n-butanol crude extract of Bacillus mojavensis UTF-33 could retard or even inhibit conidial germination and prevent the formation of adherent cells both in vitro and in vivo. In addition, the amplification of functional genes for biocontrol using specific primers showed that Bacillus mojavensis UTF-33 expresses genes that can direct the synthesis of bioA, bmyB, fenB, ituD, srfAA and other substances; this information can help us to determine the extraction direction and purification method for inhibitory substances at a later stage. In conclusion, this is the first study to identify Bacillus mojavensis as a potential agent for the control of rice diseases; this strain, and its bioactive substances, have the potential to be developed as biopesticides.

Ectopic Expression of a Maize Gene ZmDUF1645 in Rice Increases Grain Length and Yield, but Reduces Drought Stress Tolerance.

As the human population grows rapidly, food shortages will become an even greater problem; therefore, increasing crop yield has become a focus of rice breeding programs. The maize gene, ZmDUF1645, encoding a putative member of the DUF1645 protein family with an unknown function, was transformed into rice. Phenotypic analysis showed that enhanced ZmDUF1645 expression significantly altered various traits in transgenic rice plants, including increased grain length, width, weight, and number per panicle, resulting in a significant increase in yield, but a decrease in rice tolerance to drought stress. qRT-PCR results showed that the expression of the related genes regulating meristem activity, such as MPKA, CDKA, a novel crop grain filling gene (GIF1), and GS3, was significantly changed in the ZmDUF1645-overexpression lines. Subcellular colocalization showed that ZmDUF1645 was primarily localized on cell membrane systems. Based on these findings, we speculate that ZmDUF1645, like the OsSGL gene in the same protein family, may regulate grain size and affect yield through the cytokinin signaling pathway. This research provides further knowledge and understanding of the unknown functions of the DUF1645 protein family and may serve as a reference for biological breeding engineering to increase maize crop yield.

Isolation of Bacillus siamensis B-612, a Strain That Is Resistant to Rice Blast Disease and an Investigation of the Mechanisms Responsible for Suppressing Rice Blast Fungus.

Rice yield can be significantly impacted by rice blast disease. In this investigation, an endophytic strain of Bacillus siamensis that exhibited a potent inhibitory effect on the growth of rice blast was isolated from healthy cauliflower leaves. 16S rDNA gene sequence analysis showed that it belongs to the genus Bacillus siamensis. Using the rice OsActin gene as an internal control, we analyzed the expression levels of genes related to the defense response of rice. Analysis showed that the expression levels of genes related to the defense response in rice were significantly upregulated 48 h after treatment. In addition, peroxidase (POD) activity gradually increased after treatment with B-612 fermentation solution and peaked 48 h after inoculation. These findings clearly demonstrated that the 1-butanol crude extract of B-612 retarded and inhibited conidial germination as well as the development of appressorium. The results of field experiments showed that treatment with B-612 fermentation solution and B-612 bacterial solution significantly reduced the severity of the disease before the seedling stage of Lijiangxintuan (LTH) was infected with rice blast. Future studies will focus on exploring whether Bacillus siamensis B-612 produces new lipopeptides and will apply proteomic and transcriptomic approaches to investigate the signaling pathways involved in its antimicrobial effects.

Machine learning combined with MALDI-TOF MS has the potential ability to identify serotypes of the avian pathogen Riemerella anatipestifer.

AIM: Combining MALDI-TOF MS and machine learning to establish a new rapid method to identify two important serotypes of Rimerella anatipestifer. METHODS AND RESULTS: MALDI-TOF MS was performed on 115 R. anatipestifer strains (serotype 1, serotype 2, and other serotypes) to explore its ability to identify serotypes of R. anatipestifer. Raw spectral data were generated in diagnostic mode; these data were preprocessed, clustered, and analysed using principal component analysis. The results indicated that MALDI-TOF MS completely differentiated serotype 1 from serotype 2 of R. anatipestifer; the potential serotype-associated m/z loci are listed. Furthermore, Random Forest and Support Vector Machine were used for modelling to identify the two important serotypes, and the results of cross-validation indicated that they had ∼80% confidence to make the right classification. CONCLUSION: We proved that MALDI-TOF MS can differentiate serotype 1 from serotype 2 of R. anatipestifer. Additionally, the identification models established in this study have high confidence to screen out these two important serotypes from other serotypes.

DLUT: Decoupled Learning-Based Unsupervised Tracker.

Unsupervised learning has shown immense potential in object tracking, where accurate classification and regression are crucial for unsupervised trackers. However, the classification and regression branches of most unsupervised trackers calculate object similarities by sharing cross-correlation modules. This leads to high coupling between different branches, thus hindering the network performance. To address the above issue, we propose a Decoupled Learning-based Unsupervised Tracker (DLUT). Specifically, we separate the training pipelines of different branches to unlock their inherent learning potential so that different branches can fully explore the focused feature regions of interest. Furthermore, we design independent adaptive decoupling-correlation modules according to the characteristics of each branch to obtain more discriminative and easily locatable feature response maps. Finally, to suppress the noise interference brought by unsupervised pseudo-label training and highlight the foreground object, we propose a novel suppression-ranking-based unsupervised training strategy. Extensive experiments demonstrate that our DLUT outperforms state-of-the-art unsupervised trackers.

Study on the effect of compound cultivation on the growth feature and active ingredients content of Salvia miltiorrhiza.

We investigated the effects of the complex cultivation of Salvia miltiorrhiza on microbial communities, secretions, yield, and active ingredients, and the mechanism of action between microbial communities, secretions, and S. miltiorrhiza growth and development. Neither maize nor soybean was suitable to grow with S. miltiorrhiza, but sesame significantly increased salvinone content, the active ingredient of S. miltiorrhiza, and Tanshinone IIA, Tanshinone I, and Cryptotanshinone increased by 27.06%, 22.76%, and 26.41%, respectively, which increased the abundance and number of microbial communities in S. miltiorrhiza roots. 16S rRNA results showed that the most abundant bacterial phyla were Proteobacteria and Acidobacteriota, and their number increased with compound planting of sesame and S. miltiorrhiza. Salvia inter-root secretions affected the microbial community and Salvia growth and development, and lipids and lipid-like molecules significantly reduced Salvia yield and active ingredients. Overall, different plant secretions can lead to differences in the natural environment and Salvia root growth and development, and the composite planting of sesame with Salvia can improve inter-root microbial communities, enhance Salvia quality, and make fuller use of land resources.

Overproduction of OsRACK1A, an effector-targeted scaffold protein promoting OsRBOHB-mediated ROS production, confers rice floral resistance to false smut disease without yield penalty.

Grain formation is fundamental for crop yield but is vulnerable to abiotic and biotic stresses. Rice grain production is threatened by the false smut fungus Ustilaginoidea virens, which specifically infects rice floral organs, disrupting fertilization and seed formation. However, little is known about the molecular mechanisms of the U. virens-rice interaction and the genetic basis of floral resistance. Here, we report that U. virens secretes a cytoplasmic effector, UvCBP1, to facilitate infection of rice flowers. Mechanistically, UvCBP1 interacts with the rice scaffold protein OsRACK1A and competes its interaction with the reduced nicotinamide adenine dinucleotide phosphate oxidase OsRBOHB, leading to inhibition of reactive oxygen species (ROS) production. Although the analysis of natural variation revealed no OsRACK1A variants that could avoid being targeted by UvCBP1, expression levels of OsRACK1A are correlated with field resistance against U. virens in rice germplasm. Overproduction of OsRACK1A restores the OsRACK1A-OsRBOHB association and promotes OsRBOHB phosphorylation to enhance ROS production, conferring rice floral resistance to U. virens without yield penalty. Taken together, our findings reveal a new pathogenic mechanism mediated by an essential effector from a flower-specific pathogen and provide a valuable genetic resource for balancing disease resistance and crop yield.

Rice ß-Glucosidase 4 (Os1ßGlu4) Regulates the Hull Pigmentation via Accumulation of Salicylic Acid.

Salicylic acid (SA) is a stress hormone synthesized in phenylalanine ammonia-lyase (PAL) and the branching acid pathway. SA has two interconvertible forms in plants: SAG (SA O-ß-glucoside) and SA (free form). The molecular mechanism of conversion of SA to SAG had been reported previously. However, which genes regulate SAG to SA remained unknown. Here, we report a cytoplasmic ß-glucosidase (ß-Glu) which participates in the SA pathway and is involved in the brown hull pigmentation in rice grain. In the current study, an EMS-generated mutant brown hull 1 (bh1) displayed decreased contents of SA in hulls, a lower photosynthesis rate, and high-temperature sensitivity compared to the wild type (WT). A plaque-like phenotype (brown pigmentation) was present on the hulls of bh1, which causes a significant decrease in the seed setting rate. Genetic analysis revealed a mutation in LOC_Os01g67220, which encodes a cytoplasmic Os1ßGlu4. The knock-out lines displayed the phenotype of brown pigmentation on hulls and decreased seed setting rate comparable with bh1. Overexpression and complementation lines of Os1ßGlu4 restored the phenotype of hulls and normal seed setting rate comparable with WT. Subcellular localization revealed that the protein of Os1ßGlu4 was localized in the cytoplasm. In contrast to WT, bh1 could not hydrolyze SAG into SA in vivo. Together, our results revealed the novel role of Os1ßGlu4 in the accumulation of flavonoids in hulls by regulating the level of free SA in the cellular pool.

Whole-genome analyses of APEC carrying mcr-1 in some coastal areas of China from 2019 to 2020.

OBJECTIVES: Polymyxin is considered as one of the 'last lines of defense' for the treatment of multidrug resistant bacteria. Increased use of polymyxin during recent years poses a risk to public health. The purpose of this study was to investigate the carrying situation of the mcr-1 drug-resistance gene in waterfowl in some coastal areas of China from 2019 to 2020. METHODS: Fifty-seven isolated avian pathogenic Escherichia coli strains were selected from 493 APEC isolates for whole-genome sequencing. The 24 mcr-1-positive APEC strains were tested for conjugation and genome-wide analysis, including sequence type (ST) analysis, serotype analysis, and drug-resistance gene analysis. Numerous mcr-1-positive E. coli were downloaded from the National Center for Biotechnology Information (NCBI) for comparative genomic analysis. RESULTS: Antimicrobial susceptibility test results showed that 57 APEC isolates were highly resistant to gentamicin, cefotaxime, and ofloxacin, and 24 mcr-1-positive APEC isolates were resistant to polymyxin. Fourteen isolates of mcr-1-positive APEC plasmids were successfully conjugated to EC600. Both ST156 and ST10 were found in high proportions in human and avian sources through genome-wide analysis; it is worth noting that these two isolates of APEC were detected to contain the blaNDM-1 and blaNDM-4 genes, respectively. CONCLUSION: In this study, the epidemiological investigation of the mcr-1 gene was carried out on APEC in some coastal areas of China from 2019 to 2020, and our results have enriched the data on the transmission of APEC isolates carrying the mcr-1 gene in waterfowl.

Phytohormones and Transcriptome Analyses Revealed the Dynamics Involved in Spikelet Abortion and Inflorescence Development in Rice.

Panicle degeneration, sometimes known as abortion, causes heavy losses in grain yield. However, the mechanism of naturally occurring panicle abortion is still elusive. In a previous study, we characterized a mutant, apical panicle abortion1331 (apa1331), exhibiting abortion in apical spikelets starting from the 6 cm stage of panicle development. In this study, we have quantified the five phytohormones, gibberellins (GA), auxins (IAA), abscisic acid (ABA), cytokinins (CTK), and brassinosteroids (BR), in the lower, middle, and upper parts of apa1331 and compared these with those exhibited in its wild type (WT). In apa331, the lower and middle parts of the panicle showed contrasting concentrations of all studied phytohormones, but highly significant changes in IAA and ABA, compared to the upper part of the panicle. A comparative transcriptome of apa1331 and WT apical spikelets was performed to explore genes causing the physiological basis of spikelet abortion. The differential expression analysis revealed a significant downregulation and upregulation of 1587 and 978 genes, respectively. Hierarchical clustering of differentially expressed genes (DEGs) revealed the correlation of gene ontology (GO) terms associated with antioxidant activity, peroxidase activity, and oxidoreductase activity. KEGG pathway analysis using parametric gene set enrichment analysis (PGSEA) revealed the downregulation of the biological processes, including cell wall polysaccharides and fatty acids derivatives, in apa1331 compared to its WT. Based on fold change (FC) value and high variation in expression during late inflorescence, early inflorescence, and antherdevelopment, we predicted a list of novel genes, which presumably can be the potential targets of inflorescence development. Our study not only provides novel insights into the role of the physiological dynamics involved in panicle abortion, but also highlights the potential targets involved in reproductive development.

OsMLP423 Is a Positive Regulator of Tolerance to Drought and Salt Stresses in Rice.

Rice (Oryza sativa L.) is one of the main food crops for human survival, and its yield is often restricted by abiotic stresses. Drought and soil salinity are among the most damaging abiotic stresses affecting today's agriculture. Given the importance of abscisic acid (ABA) in plant growth and abiotic stress responses, it is very important to identify new genes involved in ABA signal transduction. We screened a drought-inducing gene containing about 158 amino acid residues from the transcriptome library of rice exposed to drought treatment, and we found ABA-related cis-acting elements and multiple drought-stress-related cis-acting elements in its promoter sequence. The results of real-time PCR showed that OsMLP423 was strongly induced by drought and salt stresses. The physiological and biochemical phenotype analysis of transgenic plants confirmed that overexpression of OsMLP423 enhanced the tolerance to drought and salt stresses in rice. The expression of OsMLP423-GFP fusion protein indicated that OsMLP423 was located in both the cell membrane system and nucleus. Compared with the wild type, the overexpressed OsMLP423 showed enhanced sensitivity to ABA. Physiological analyses showed that the overexpression of OsMLP423 may regulate the water loss efficiency and ABA-responsive gene expression of rice plants under drought and salt stresses, and it reduces membrane damage and the accumulation of reactive oxygen species. These results indicate that OsMLP423 is a positive regulator of drought and salinity tolerance in rice, governing the tolerance of rice to abiotic stresses through an ABA-dependent pathway. Therefore, this study provides a new insight into the physiological and molecular mechanisms of OsMLP423-mediated ABA signal transduction participating in drought and salt stresses.

OsSCL30 overexpression reduces the tolerance of rice seedlings to low temperature, drought and salt.

Rice is one of the main food crops for the world population. Various abiotic stresses, such as low temperature, drought, and high salinity, affect rice during the entire growth period, determining its yield and quality, and even leading to plant death. In this study, by constructing overexpression vectors D-163 + 1300:OsSCL30 and D-163 + 1300-AcGFP:OsSCL30-GFP, the mechanism of action of OsSCL30 in various abiotic stresses was explored. Bioinformatics analysis showed that OsSCL30 was located on the chromosome 12 of rice Nipponbare, belonging to the plant-specific SCL subfamily of the SR protein family. The 1500 bp section upstream of the open reading frame start site contains stress-related cis-acting elements such as ABRE, MYC, and MYB. Under normal conditions, the expression of OsSCL30 was higher in leaves and leaf sheaths. The results of reverse transcription polymerase chain reaction showed that the expression of OsSCL30 decreased after low temperature, drought and salt treatment. In root cells OsSCL30 was localized in the nuclei. The results of the rice seedling tolerance and recovery tests showed that overexpression of OsSCL30 diminished the resistance to low temperature, drought and salt stresses in transgenic rice and resulted in larger accumulation of reactive oxygen species. This study is of great significance for exploring the response mechanisms of SR proteins under abiotic stresses.

Isolation, characterization, and genome analysis of bacteriophage P929 that could specifically lyase the KL19 capsular type of Klebsiella pneumoniae.

In recent years, Klebsiella pneumoniae has caused an increase in the number of serious infections associated with pneumonia, septicemia, urinary tract infections, and pyogenic liver abscess. In this study, a phage P929, isolated from hospital sewage in Jiangsu, could specifically infect K. pneumoniae KL19 capsular type by forming plaques with a translucent halo that expanded over time. Phage P929 with a multiplicity of infection (MOI) of 0.1 produced the highest phage titer. According to a one-step growth curve experiment, the latent time period of phage P929 was 25 min, and the burst size was about 156 phage particles/cell. The sensitivity tests confirmed that P929 was stable at temperatures ranging from 4 to 50 °C and pH 3 to 11. Based on morphological observation and phylogenetic analysis, phage P929 could be assigned to a new species in the genus Drulisvirus of the subfamily Slopekvirinae in the family Autographiviridae. According to genome analysis, phage P929 was 44,764 bp in size with 53.66% G + C content, encoding 57 proteins or coding sequences (117-3699 bp in length). Phage P929 showed potential antibacterial activity on planktonic cells and biofilm. After 120 min, the OD600 values of five phage-treated groups were basically reached zero compared to the untreated group, and the antibacterial activity of P929 was still detectable within 390 min. In anti-biofilm tests, phage P929 at an MOI of 1 significantly reduced the biofilm formation of K. pneumoniae in 48 h. These results suggest that phage P929 may be used to treat carbapenem-resistant and biofilm-forming K. pneumonia in clinical settings.