Genomic evidence for evolutionary history and local adaptation of two endemic apricots: Prunus hongpingensis and P. zhengheensis.

Apricot, belonging to the Armeniaca section of Rosaceae, is one of the economically important crop fruits that has been extensively cultivated. The natural wild apricots offer valuable genetic resources for crop improvement. However, some of them are endemic, with small populations, and are even at risk of extinction. In this study we unveil chromosome-level genome assemblies for two southern China endemic apricots, Prunus hongpingensis (PHP) and P. zhengheensis (PZH). We also characterize their evolutionary history and the genomic basis of their local adaptation using whole-genome resequencing data. Our findings reveal that PHP and PZH are closely related to Prunus armeniaca and form a distinct lineage. Both species experienced a decline in effective population size following the Last Glacial Maximum (LGM), which likely contributed to their current small population sizes. Despite the observed decrease in genetic diversity and heterozygosity, we do not observe an increased accumulation of deleterious mutations in these two endemic apricots. This is likely due to the combined effects of a low inbreeding coefficient and strong purifying selection. Furthermore, we identify a set of genes that have undergone positive selection and are associated with local environmental adaptation in PHP and PZH, respectively. These candidate genes can serve as valuable genetic resources for targeted breeding and improvement of cultivated apricots. Overall, our study not only enriches our comprehension of the evolutionary history of apricot species but also offers crucial insights for the conservation and future breeding of other endemic species amidst rapid climate changes.

Multilayer regulatory landscape and new regulators identification for bud dormancy release and bud break in Populus.

For trees originating from boreal and temperate regions, the dormancy-to-active transition, also known as bud dormancy release and bud break, are crucial processes that allow trees to reactive growth in the spring. The molecular mechanisms underlying these two processes remain poorly understood. Here, through integrative multiomics analysis of the transcriptome, DNA methylome, and proteome, we gained insights into the reprogrammed cellular processes associated with bud dormancy release and bud break. Our findings revealed multilayer regulatory landscapes governing bud dormancy release and bud break regulation, providing a valuable reference framework for future functional studies. Based on the multiomics analysis, we have determined a novel long intergenic noncoding RNA named Phenology Responsive Intergenic lncRNA 1 (PRIR1) plays a role in the activation of bud break. that the molecular mechanism of PRIR1 has been preliminary explored, and it may partially promote bud break by activating its neighbouring gene, EXORDIUM LIKE 5 (PtEXL5), which has also been genetically confirmed as an activator for bud break. This study has revealed a lncRNA-mediated regulatory mechanism for the control of bud break in Populus, operating independently of known regulatory pathways.

In-situ observation of silk nanofibril assembly via graphene plasmonic infrared sensor.

Silk nanofibrils (SNFs), the fundamental building blocks of silk fibers, endow them with exceptional properties. However, the intricate mechanism governing SNF assembly, a process involving both protein conformational transitions and protein molecule conjunctions, remains elusive. This lack of understanding has hindered the development of artificial silk spinning techniques. In this study, we address this challenge by employing a graphene plasmonic infrared sensor in conjunction with multi-scale molecular dynamics (MD). This unique approach allows us to probe the secondary structure of nanoscale assembly intermediates (0.8-6.2 nm) and their morphological evolution. It also provides insights into the dynamics of silk fibroin (SF) over extended molecular timeframes. Our novel findings reveal that amorphous SFs undergo a conformational transition towards ß-sheet-rich oligomers on graphene. These oligomers then connect to evolve into SNFs. These insights provide a comprehensive picture of SNF assembly, paving the way for advancements in biomimetic silk spinning.

Difluoromethylated Difunctionalization of Alkenes under Visible Light.

Difluoromethylated compounds usually act as bioisosteres for alcohol functional groups and show unique physicochemical and biological properties. The cyano-difluoromethylation of alkenes using 5-((difluoromethyl)sulfonyl)-1-phenyl-1H-tetrazole as a CF2H radical difluoromethyl precursor was developed to afford nitriles including a CF2H group. A low-cost, stable, easily handled 5-((difluoromethyl)sulfonyl)-1-methyl-1H-tetrazole (DFSMT) was synthesized and applied as the radical CF2H reagent. Using DFSMT as the radical CF2H precursor, the oxyl-difluoromethylation of alkenes was developed to obtain difluoromethylated ether products. All of the reactions showed good functional group tolerability. Initial mechanistic experiments indicated that the CF2H radical was involved as the key active intermediate.

Leaf spot of Alnus cremastogyne Caused by Colletotrichum gloeosporioides in Sichuan, China.

Alnus cremastogyne Burk, a broad-leaved tree endemic to south-western China, has both ecological and economic value. The tree is widely used in furniture, timber, windbreaks and sand fixation, and soil and water conservation (Tariq et al. 2018). In December 2020, a new leaf spot disease was discovered on A. cremastogyne in two plant nurseries in Bazhong City (31°15' to 32°45N, 106°21' to 107°45'E), with 77.53% disease incidence. Among the infected trees, 69.54% of the leaves were covered with symptoms of the disease. The typical symptoms initially appeared as irregular brown necrotic lesions, while some lesions were surrounded by a light yellow halo. As the disease progressed, the number of necrotic lesions increased, and lesions gradually expanded and coalesced (Fig. 1). Finally, the disease caused the leaves of A. cremastogyne to wither, curl, die, and fall off. Ten symptomatic leaves were collected from 5 different trees in the two plant nurseries. The leaves with symptoms of leaf spot disease were collected and cut from the junction between the diseased and the healthy tissues. The infected tissues from 10 samples were cut into small 2.5 × 2.5 mm pieces. Infected tissues was sterilized in 3% NaClO solution for 60 s followed by 75% ethanol for 90 s, rinsed three times in sterile water, blot-dried with autoclaved paper towels, and then cultured on potato dextrose agar (PDA) at 25℃ for 4 to 8 days in 12 h/12 h light/dark conditions. After 8 days, the colony diameter reached 71.2 to 79.8 mm. The colonies were initially light pink, and then turned white with pale orange beneath. The conidia were single-celled, aseptate, colorless, cylindrical, straight, bluntly rounded at both ends, and measured 11.6 to 15.9 × 4.3 to 6.1 µm (n = 100). These morphological characteristics were consistent with the description of Colletotrichum gloeosporioides (Pan et al. 2021). For molecular identification, the genomic DNA of a representative isolate, QM202012, was extracted using a fungal genomic DNA extraction kit (Solarbio, Beijing). The internal transcribed spacer (ITS), actin (ACT), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified with primers ITS1/ITS4 (White et al. 1990), ACT-512F/ACT-783R (Carbone & Kohn, 1999) and GDF/GDR (Templeton et al. 1992), respectively. Sequences were deposited in GenBank (ITS: OL744612, ACT: OL763390, and GAPDH: OL799166). BLAST results indicated that the ITS, ACT, and GAPDH sequences showed >99% identity with C. gloeosporioides sequences in NCBI (GenBank NR160754, MG561657, and KP145407). Identification was confirmed by Bayesian inference using Mr Bayer (Fig 2) A conidial suspension (1 × 106 conidia/ml) was used to test pathogenicity on the leaves of 4-year-old A. cremastogyne plants (10 plants). Fifteen leaves of each plant (10 pots in total) were inoculated with the spore suspension on the leaves. The same number of control leaves was sprayed with sterilized distilled water as a control. Finally, all potted plants were placed in a greenhouse at 25°C under 16 h/8 h photoperiod and 67 to 78% relative humidity. The symptoms observed on the inoculated plants were similar to those of the original diseased plants, with 100% of the inoculated plants being infested with brown leaf spots, but the controls remained symptom-free. C. gloeosporioides was re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated three times, showing similar results each time, confirming Koch's postulates. To our knowledge, this is the first report of leaf spot on A. cremastogyne caused by C. gloeosporioides in China. This finding indicates that C. gloeosporioides may become a serious threat to A. cremastogyne production in Bazhong City and helps to further examine and prevent leaf spot disease in A. cremastogyne growing areas in Bazhong City.

Mid-infrared analogue polaritonic reversed Cherenkov radiation in natural anisotropic crystals.

Cherenkov radiation (CR) excited by fast charges can serve as on-chip light sources with a nanoscale footprint and broad frequency range. The reversed CR, which usually occurs in media with the negative refractive index or negative group-velocity dispersion, is highly desired because it can effectively separate the radiated light from fast charges thanks to the obtuse radiation angle. However, reversed CR at the mid-infrared remains challenging due to the significant loss of conventional artificial structures. Here we observe mid-infrared analogue polaritonic reversed CR in a natural van der Waals (vdW) material (i.e., α-MoO3), whose hyperbolic phonon polaritons exhibit negative group velocity. Further, the real-space image results of analogue polaritonic reversed CR indicate that the radiation distributions and angles are closely related to the in-plane isofrequency contours of α-MoO3, which can be further tuned in the heterostructures based on α-MoO3. This work demonstrates that natural vdW heterostructures can be used as a promising platform of reversed CR to design on-chip mid-infrared nano-light sources.

Pollinator Proboscis Length Plays a Key Role in Floral Integration of Honeysuckle Flowers (Lonicera spp.).

Pollinator-mediated selection is supposed to influence floral integration. However, the potential pathway through which pollinators drive floral integration needs further investigations. We propose that pollinator proboscis length may play a key role in the evolution of floral integration. We first assessed the divergence of floral traits in 11 Lonicera species. Further, we detected the influence of pollinator proboscis length and eight floral traits on floral integration. We then used phylogenetic structural equation models (PSEMs) to illustrate the pathway through which pollinators drive the divergence of floral integration. Results of PCA indicated that species significantly differed in floral traits. Floral integration increased along with corolla tube length, stigma height, lip length, and the main pollinators' proboscis length. PSEMs revealed a potential pathway by which pollinator proboscis length directly selected on corolla tube length and stigma height, while lip length co-varied with stigma height. Compared to species with short corolla tubes, long-tube flowers may experience more intense pollinator-mediated selection due to more specialized pollination systems and thus reduce variation in the floral traits. Along elongation of corolla tube and stigma height, the covariation of other relevant traits might help to maintain pollination success. The direct and indirect pollinator-mediation selection collectively enhances floral integration.

Brown leaf spot of Cunninghamia lanceolata Caused by Colletotrichum kahawae in Sichuan province, China.

Chinese fir (Cunninghamia lanceolata) is an important timber species that has been widely cultivated in southern China. It is extensively applied in medicine, environmental monitoring, furniture, urban (e.g., street trees) and rural landscaping, windbreak forest, soil and water conservation. In January 2022, distinct leaf spot symptoms were observed in Chinese fir in Hongya Forestry (29°45'N, 103°11'E) Meishan City, Sichuan Province, China. Field surveys showed that the disease was widespread, with around 70% disease incidence. The typical symptoms initially appeared as yellowish-brown necrotic lesions on the margin of the leaves. Subsequently, lesions gradually expanded and developed into larger necrotic areas with red-brown irregular shape. The lesions later expanded throughout the leaf. Infected leaves turned dark brown and wilted, leading to seeding's death. Diseased leaves with typical symptoms were collected for pathogen isolation and identification. Infected tissues from ten samples were cut into small pieces of 2 × 2 mm. Infected tissues were surface disinfected with 3% sodium hypochlorite and 75% ethanol for 30s and 60s, respectively, and rinsed with sterile water 3 times. They were blotted dry with autoclaved paper towels and incubated on potato dextrose agar (PDA) with streptomycin sulfate (50 µg/mL) for 5 ~ 8 days at 25°C. and 12 h light/dark period. The diameter of the colonies reached 65.7 to 75.9 mm, with a gray to black center, and white edges while the reverse sides were gray to orange. Conidia were single-celled, colorless, straight, cylindrical, bluntly rounded at both ends, Conidia dimensions varied from, 7.3 µm to 15.7 µm in length and 3.3 µm to 6.1 µm in width (n = 100). For molecular identification, the genomic DNA of isolate SM2290708, SM229070801 and SM229070802 were extracted using a fungal genomic DNA extraction kit (Beijing Solarbio Science & Technology Co., Ltd., City, China). The internal transcribed spacers of the ribosomal RNA (ITS) [ITS1/ITS4 (White et al., 1990), calmodulin (CAL) (Weir et al., 2012), ß-tubulin (TUB2) (O'Donnell et al., 1997), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Templeton et al. 1992) were amplified. Sequences were deposited in GenBank (ITS: ON564877, OQ535027 and OQ535028; CAL: ON583827, OQ538101 and OQ538102; TUB2: ON583830, OQ538104 and OQ538105; and GAPDH: ON583831, OQ538108 and OQ538109). BLAST results showed that our ITS, CAL, TUB2 and GAPDH sequences were >99% identical to the corresponding sequences of Colletotrichum kahawae deposited at NCBI (GenBank JX010231, JX009642, JX010444, and JX010012). Identification was confirmed by Bayesian inference using MrBayes (Fig 2). The conidial suspension (1 × 106 conidia/ml) was used for inoculation by spraying leaves of ten 3-year-old Chinese fir plants for pathogenicity test. Fifteen leaves of each plant were inoculated. An equal number of control leaves was sprayed with sterilized distilled water as a control. Finally, all potted plants were placed in a greenhouse at 28°C under a 16 h/8 h photoperiod and in 73% to 79% relative humidity. After fifteen days, the symptoms observed on the inoculated plants were similar to those of the original diseased plants, but the controls remained asymptomatic. Colletotrichum kahawae was re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated three times, which showed similar results, confirming Koch's postulates. To our knowledge, this is the first report of brown leaf spot on C. lanceolata caused by C. kahawae in China. The results of this study provide basic information for diagnosis of the pathogen and developing prevention strategies to manage C. lanceolata leaf spot disease.

Natural annual transcriptome dynamics of Eucalyptus reveal seasonal adaptation of tropical/sub-tropical trees.

Seasonal environment cues are primary factors that influence a plant's growth and adaptation. The molecular basis of seasonal phenology has been well studied in trees growing in boreal and temperate ecosystems. However, little is known about the molecular phenology of trees belonging to tropical/sub-tropical regions. Here, we characterize the annual transcriptome dynamics of Eucalyptus dunnii, one of the world's most widely planted tropical/sub-tropical hardwoods, in natural environments. Our transcriptome analysis combined with the geographical distribution, environmental cues, microscopic observations and heterologous transformation analyses provides a molecular timetable of seasonal regulatory events of E. dunnii and its planting prospects in China. We further investigated the molecular mechanisms of the flowering phenology of E. dunnii. Our results suggest that low temperature is one of environment triggers for its seasonal flowering. In addition, a comparative transcriptome and cell ultrastructure analysis between Eucalyptus and Populus reveals the molecular bases of different shoot apex growth habits of trees originating from tropical/sub-tropical and boreal/temperate regions. Our study will provide cues for further investigating the molecular mechanisms underlying the seasonal phenology of trees from tropical/sub-tropical regions.

The genome of Dioscorea zingiberensis sheds light on the biosynthesis, origin and evolution of the medicinally important diosgenin saponins.

Diosgenin saponins isolated from Dioscorea species such as D. zingiberensis exhibit a broad spectrum of pharmacological activities. Diosgenin, the aglycone of diosgenin saponins, is an important starting material for the production of steroidal drugs. However, how plants produce diosgenin saponins and the origin and evolution of the diosgenin saponin biosynthetic pathway remain a mystery. Here we report a high-quality, 629-Mb genome of D. zingiberensis anchored on 10 chromosomes with 30 322 protein-coding genes. We reveal that diosgenin is synthesized in leaves ('source'), then converted into diosgenin saponins, and finally transported to rhizomes ('sink') for storage in plants. By evaluating the distribution and evolutionary patterns of diosgenin saponins in Dioscorea species, we find that diosgenin saponin-containing may be an ancestral trait in Dioscorea and is selectively retained. The results of comparative genomic analysis indicate that tandem duplication coupled with a whole-genome duplication event provided key evolutionary resources for the diosgenin saponin biosynthetic pathway in the D. zingiberensis genome. Furthermore, comparative transcriptome and metabolite analysis among 13 Dioscorea species suggests that specific gene expression patterns of pathway genes promote the differential evolution of the diosgenin saponin biosynthetic pathway in Dioscorea species. Our study provides important insights and valuable resources for further understanding the biosynthesis, evolution, and utilization of plant specialized metabolites such as diosgenin saponins.

First report of Leaf spot Caused by Colletotrichum siamense on Pharbitis purpurea in Sichuan, China.

The Pharbitis purpurea (L.) Voisgt, a member of the Convolvulaceae, is a graceful plant with an air purifying function and ornamental values. It is often cultivated in parks and roadsides. In April 2021, leaf spots (with approximately 67.9% disease incidence) were observed on P. purpurea grown in Xichang city (27°49'N; 102°16'E). More than 1000 square meters of planting area were investigated. Initially, yellowish-brown spots were of different sizes with a yellow irregular border, and slightly sunken necrotic lesions. Gradually, the necrotic lesions expanded and developed into brown spots that often coalesced and expanded to cover the entire leaves. Finally, the leaves wilted, died and fell off. For fungal isolation, infected tissues from ten samples were cut into small pieces of (2.5 × 2.5 mm) sterilized with 3% NaOCl for 30 s and 75% ethanol for 60 s, rinsed three times with sterilized water, blot-dried and cultured on potato dextrose agar (PDA) at 25°C in dark for 8 days. After culturing for 8 days, the colony diameter reached 75.2 to 79.7 mm. The pure colonies were grayish-white with pale yellowish borders and grayish black and pale yellowish borders on the reverse side. The conidia were hyaline, single-celled, cylindrical, smooth-walled, subcylindrical with obtuse to slightly rounded ends, measuring 11.6 to 17.9 × 3.7 to 5.8 µm (n = 100; average=14.7 × 4.9µm). These morphological characteristics were consistent with the description of Colletotricum siamense (Zhang et al. 2021). For molecular identification, the genomic DNA of the representative isolate LBH202104 was extracted using a fungal genomic DNA extraction kit (Solarbio, Beijing). Partial of internal transcribed spacer (ITS) regions, actin (ACT), calmodulin (CAL), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified using the primers ITS1/ITS4, ACT-512F/ACT-783R, CL1C/CL2C, and GDF/GDR, respectively (Weir et al. 2012). BLAST results of obtained sequences (ITS: OM948680, ACT: OM959361, CAL: OM959366, and GAPDH: OM959364), showed >99% identity with C. siamense sequences (MN305712, MZ461478, MK141754, and MK361203) in GenBank. Based on morphology and phylogenetic analysis, the representative isolate was identified as Colletotrichum siamense (Fig. S1&S2). For pathogenicity test, the conidial suspension (1 × 106 conidia/ml) was sprayed on the leaves of 4-year-old eight potted P. purpurea plants. Fifteen leaves of each plant were inoculated. For negative controls, 8 plants were sprayed with sterilized distilled water. Finally, all pots were kept in a greenhouse at 26°C under a 16 h/8 h photoperiod and 68 to 75% relative humidity. The inoculated plants showed symptoms similar to those of the original diseased plants, while controls remained asymptomatic. C. siamense cultures were re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated thrice, which showed similar results, confirming Koch's postulates. To our knowledge, this is the first report of leaf spot caused by C. siamense on P. purpurea worldwide. The identification of this pathogen provides a foundation for the management of Leaf spot in P. purpurea.

Brown leaf spot of Prunus serrulata Caused by Colletotrichum fioriniae in Sichuan, China.

Prunus serrulate Lindl is widely cultivated in urban areas of China. It is mainly used for wood cultivation and urban landscaping. In May 2021, new leaf spot disease was observed in Chengdu city (30°42' to 30°45'N, 103°51' to 104°7'E), with 69.3% disease incidence, which could inhibit leaf growth and reduce their biomass. A planting area of more than 1000 square meters was investigated. The diseased leaves were mostly concentrated in the lower position of plants, where the humidity was higher. The disease infected P. serrulata leaves and occurred in the field from March to October, with the highest incidence in early May. The typical symptoms initially appeared as brown necrotic lesions on the margin of the leaves. The lesions then enlarged gradually and developed into reddish brown spots, eventually coalescing into large irregular, necrotic lesions with dark brown margins. Finally, the diseased leaves withered and died. Conidiomata were not formed on the diseased tissue. Ten symptomatic leaves were collected from 5 different trees in the planting area. Infected tissues from ten samples were cut into small pieces of 3 × 3 mm. The infected tissues were surface-sterilized by 3% sodium hypochlorite and 75% ethanol respectively for 30s and 60s, and rinsed three times in sterile water. Then they were blot-dried with autoclaved paper towels and cultured on potato dextrose agar (PDA) amended with streptomycin sulfate (50 µg/mL), and incubated at 25°C for 4 to 8 days. After culturing for 8 days at 25℃ and 12 h/12 h light/dark on PDA, the colony diameter reached 67.5 to 78.6 mm. The colonies were initially white, cottony, then became light pink to misty rose at the center, and the reverse side of the colony turned dark red to red and had pale yellowish borders. The conidia were straight, smooth-walled, colorless, fusiform with acute ends, measuring 8.2 to 16.7 × 3.1 to 5.9 µm in size (n = 100). For molecular identification, the genomic DNA of the representative isolate RBWY202105 was extracted using a fungal genomic DNA extraction kit (Solarbio, Beijing). The internal transcribed spacer (ITS) [ITS1/ITS4 (White et al., 1990)], histone3 (HIS3) [CYLH3F/CYLH3R (Crous et al. 2004)], chitin synthase (CHS-1) [CHS-79F/CHS-345R (Carbone & Kohn, 1999)], actin (ACT) [ACT512F/ACT (Carbone & Kohn, 1999)], ß-tubulin (TUB2) [BT2A/BT2B (O'Donnell et al., 1997)], and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) [GDF/GDR (Templeton et al. 1992)] were amplified. Sequences were deposited in GenBank (ITS: ON000436, HIS3: ON014581, CHS-1: ON014579, ACT: ON014583, TUB2: ON014582, and GAPDH: ON014580). BLAST results indicated that the ITS, HIS3, CHS-1, ACT, TUB2 and GAPDH sequences showed >99% identity with Colletotrichum fioriniae (Marcelino & Gouli) R.G. Shivas & Y.P sequences at NCBI (GenBank MW497230 (561/582), MT740312 (415/415), KU736865 (258/258), MK680659 (246/246), MK967342 (757/757), and MW656269 (263/263)). The conidial suspension (1 × 106 conidia/ml) was used for inoculation by spraying leaves of ten 4-year-old P. serrulata plants for pathogenicity test. Fifteen leaves of each plant were inoculated with spore suspensions on the leaves (600 µl per leaf). The same amount of control leaves was sprayed with sterilized distilled water as a control. Finally, all potted plants were placed in a greenhouse at 25°C under a 16 h/8 h photoperiod and 67 to 78% relative humidity. After ten days, the symptoms observed on the inoculated plants were similar to those of the original diseased plants, but the controls remained asymptomatic. Colletotrichum fioriniae was re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis (The ITS, HIS3, TUB2, CHS-1, GAPDH and ACT genes). The pathogenicity test was repeated thrice, which showed similar results, confirming Koch's postulates. To our knowledge, this is the first report of brown leaf spot on P. serrulata caused by C. fioriniae in China. The identification of C. fioriniae could provide relevant information for taking management strategies and further research on the Prunus serrulata disease.

Neutrophils inhibit CD8+ T cells immune response by arginase-1 signaling in patients with sepsis.

BACKGROUND: Patients with sepsis often exhibit an acute inflammatory response, followed by an immunosuppressive phase with a poor immune response. However, the underlying mechanisms have not been fully elucidated. METHODS: We sought to comprehensively characterize the transcriptional changes in neutrophils of patients with sepsis by transcriptome sequencing. Additionally, we conducted a series of experiments, including real-time quantitative polymerase chain reaction (RT-qPCR) and flow cytometry to investigate the role of arginase-1 signaling in sepsis. RESULTS: Through the analysis of gene expression profiles, we identified that the negative regulation of T cell activation signaling was enriched, and the expression of arginase-1 was high in neutrophils from patients with sepsis. Furthermore, we conducted flow cytometry and found that the function of CD8+ T cells in septic patients was impaired. Moreover, neutrophils from septic patients inhibited the percentage of polyfunctional effector CD8+ T cells through arginase-1. Additionally, the proportions of granzyme B+IFN-γ+CD8+ T and TNF-α+IFN-γ+CD8+ T cells increased after inhibition of arginase-1 signaling. CONCLUSION: The impaired effector function of CD8+ T cells could be restored by blocking arginase-1 signaling in patients with sepsis.

Studying Plasmon Dispersion of MXene for Enhanced Electromagnetic Absorption.

2D metal carbides and nitrides (MXene) are promising candidates for electromagnetic (EM) shielding, saturable absorption, thermal therapy, and photocatalysis owing to their excellent EM absorption. The plasmon resonances in metallic MXene micro/nanostructures may play an important role in enhancing the EM absorption; however, their contribution has not been determined due to the lack of a precise understanding of its plasmon behavior. Here, the use of high-spatial-resolution electron energy-loss spectroscopy to measure the plasmon dispersion of MXene films with different thicknesses is reported, enabling accurate analysis of the EM absorption of complex MXene structures in a wide frequency range via a theoretical model. The EM absorption of MXene can be excited at the desired frequency by controlling the momentum (e.g., the sizes of the nanoflakes for EM excitation) as the strength can be enhanced by increasing the layer number and the interlayer distance in MXene. For example, a 3 nm interlayer distance can nearly double the plasmon-enhanced EM absorption in MXene nanostructures. These findings can guide the design of advanced ultrathin EM absorption materials for a broad range of applications.

Brown leaf spot of Jacaranda mimosifolia Caused by Colletotrichum karstii in Sichuan, China.

Jacaranda mimosifolia D. Don is widely cultivated in southwest China (Yunnan, Sichuan, and other regions). It is widely applied in papermaking, medicine, environmental monitoring, timber, urban and rural afforestation, and soil and water conservation. In October 2020, a new brown leaf spot disease of J. mimosifolia was discovered in Xichang City (27°49' to 27°56'N, 102°16' to 102°11'E), with approximately 66.23% disease incidence. Firstly, the typical symptoms showed deep yellow necrotic lesions in the center or on the margin of the leaves. Gradually, the necrotic lesions expanded and developed into brown spots. Under humid conditions, the edges of necrotic lesions turned dark brown progressively. Finally, the leaves withered, died, and fell off. Infected tissues from ten samples were cut into small pieces of 2.5 × 2.5 mm. The surfaces of infected tissues were sterilized for 30 s in 3% sodium hypochlorite, 60 s in 75% ethanol, and rinsed three times in sterile water. They were then blot-dried with autoclaved paper towels and cultured on potato dextrose agar (PDA) at 25℃ for 3 to 8 days. After culturing for 8 days at 25℃ and 12 h/12 h light/dark on PDA, the colony diameter reached 78.2 to 82.7 mm. The colonies were light orange, turned pale pink with light orange beneath. The conidia were single-celled, aseptate, cylindrical, smooth-walled, straight, hyaline with both ends bluntly rounded, measuring 12.3 to 16.8 × 4.3 to 5.6 µm (n = 100; average=14.5 × 5.1µm). These morphological characteristics were consistent with the description of C. karstii (Zhao et al. 2021). For molecular identification, the genomic DNA of the representative isolate JM202010 was extracted using a fungal genomic DNA extraction kit (Solarbio, Beijing). The internal transcribed spacer (ITS) [ITS1/ITS4 (White et al., 1990)], calmodulin (CAL) [CL1C/CL2C (Weir et al., 2012)], actin (ACT) [ACT512F/ACT-783R (Carbone & Kohn, 1999)], chitin synthase (CHS-1) [CHS-79F/CHS-345R (Carbone & Kohn, 1999)], ß-tubulin (TUB2) [BT2A/BT2B (O'Donnell et al., 1997)], and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) [GDF/GDR (Templeton et al. 1992)] were amplified. Sequences were deposited in GenBank (ITS: OL454787, CAL: OL518966, ACT: OL518967, CHS-1: OL518968, TUB2: OL518969, and GAPDH: OL518970). BLAST results indicated that the ITS, CAL, ACT, CHS-1, TUB2 and GAPDH sequences showed >99% identity with Colletotrichum karstii sequences at NCBI (GenBank MW494453.1, MW495036.1, MG387951.1, MW495038.1, MW495042.1, and MG602034.1). The conidial suspension (1 × 106 conidia/ml) was sprayed on the leaves of 4-year-old J. mimosifolia plants (10 plants) and inoculated for pathogenicity test. Fifteen leaves of each plant (10 pots in total) were inoculated with spore suspensions on both sides of the leaves. An equal number of control leaves was sprayed with sterilized distilled water as a control. Finally, all pots were kept in a greenhouse at 26°C under a 16 h/8 h photoperiod and 60 to 68% relative humidity. The inoculated plants showed symptoms similar to those of the original diseased plants, but the controls remained asymptomatic. Colletotrichum karstii was re-isolated from the infected leaves and identified by both morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated thrice, which showed similar results, confirming Koch's postulates. To our knowledge, this is the first report of brown leaf spot on J. mimosifolia caused by C. karstii in China. C. karstii was previously reported as the causal agent of anthracnose on Fatsia japonica (Xu et al. 2020) and Nandina domestica (Li et al. 2017) in China. This finding provides an important basis for further research on the control of this disease.

The speciation and adaptation of the polyploids: a case study of the Chinese Isoetes L. diploid-polyploid complex.

BACKGROUND: The Chinese Isoetes L. are distributed in a stairway pattern: diploids in the high altitude and polyploids in the low altitude. The allopolyploid I. sinensis and its diploid parents I. yunguiensis and I. taiwanensis is an ideal system with which to investigate the relationships between polyploid speciation and the ecological niches preferences. RESULTS: There were two major clades in the nuclear phylogenetic tree, all of the populations of polyploid were simultaneously located in both clades. The chloroplast phylogenetic tree included two clades with different populations of the polyploid clustered with the diploids separately: I. yunguiensis with partial populations of the I. sinensis and I. taiwanensis with the rest populations of the I. sinensis. The crow node of the I. sinensis allopolyploid system was 4.43 Ma (95% HPD: 2.77-6.97 Ma). The divergence time between I. sinensis and I. taiwanensis was estimated to 0.65 Ma (95% HPD: 0.26-1.91 Ma). The narrower niche breadth in I.sinensis than those of its diploid progenitors and less niche overlap in the pairwise comparisons between the polyploid and its progenitors. CONCLUSIONS: Our results elucidate that I. yunguinensis and I. taiwanensis contribute to the speciation of I. sinensis, the diploid parents are the female parents of different populations. The change of altitude might have played an important role in allopolyploid speciation and the pattern of distribution of I. sinensis. Additionally, niche novelty of the allopolyploid population of I. sinensis has been detected, in accordance with the hypothesis that niche shift between the polyploids and its diploid progenitors is important for the establishment and persistence of the polyploids.

Nonlinear optical response of a two-dimensional semi-Dirac system in the terahertz regime.

We demonstrate a strong nonlinear optical response in a two-dimensional semi-Dirac system in the terahertz regime. By applying the Boltzmann transport theory for the intra-band process and a quantum mechanics method for the inter band process, we obtained the three-photon current response. It is found that both the intra- and inter-band excitations make significant contributions to the nonlinear response. The third order conductivities (TOCs) [Formula: see text] are about two magnitudes higher than that of [Formula: see text]. Interestingly, for the inter-band TOCs, there is a sign change when the chemical potential varies across the saddle point in the conduction band in [Formula: see text] direction (that is parabolic), due to the competition between the two opposite nonlinear current contributed by the electrons at states [Formula: see text] and [Formula: see text], respectively. Finally, we show that the nonlinear response in the terahertz regime is significant at experimentally accessible field strengths. Our results suggest that this system could be of potential applications in photonic device for frequency up-conversion.

Residues of persistent organic pollutants in frequently-consumed vegetables and assessment of human health risk based on consumption of vegetables in Huizhou, South China.

Concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), 16 phthalate esters (PAEs), eight organochlorine pesticides (OCPs) and seven polychlorinated biphenyls (PCBs) in 17 frequently-consumed varieties of vegetables collected from 48 sites in Huizhou were measured. Concentrations of PAHs and PAEs of leafy vegetables were higher than those of gourd and fruit vegetables but it was the opposite for OCPs and PCBs. A questionnaire of 450 local residents on vegetable consumption showed that the total vegetable ingested rates of females and males were 278.80 g person(-1)d(-1) and 282.92 g person(-1)d(-1), respectively. The weight-specific daily intakes of pollutants by females were higher than those by males because of differences in body weight. Twenty-seven pollutants were used to assess the potential risk to human health by calculating target hazard quotient (THQ) values. Results showed that the risk to females was higher than for males. OCPs were the major contributors to the risk for both females and males. The main risks were from consumption of eggplant, Chinese lettuce and luffa and were significantly related to the contents of di-nonyl phthalate, ß-hexachlorocyclohexane, γ-hexachlorocyclohexane, p,p-dichlorodiphenyltrichloroethane and p,p-dichlorodiphenyl dichloroethane in vegetables. Although the THQ values induced by individual pollutants were relatively low, the total THQ values induced by 27 pollutants were above 1 in some administrative regions of Huizhou, which might give cause for concern.

Toxicity of the xenoestrogen nonylphenol and its biodegradation by the alga Cyclotella caspia.

Alkylphenols (APs), the breakdown products of alkylphenol polyethoxylates that are widely used as surfactants, have been proven to exert estrogenic effects. With industrial development, higher concentrations of APs are discharged into aquatic environments. Nonylphenol (NP), the most noxious AP, is included in the blacklist of several countries. The toxicity of NP to the alga Cyclotella caspia and the biodegradation of NP by C. caspia were studied in the laboratory. The median effective concentration at 96 hr (96 hr EC50) of NP for C. caspia was found to be 0.18 mg/L. Five toxicity and three degradation indices were selected for toxicity and biodegradation experiments, respectively, in five or three concentrations of NP set by the 96 hr EC50 of NP. The algal growth rate and chlorophyll a contents decreased as NP concentration increased. The main manifestations of morphological deformity of the cells included volume expansion and the presence of cytoplasmic inclusions (lipid droplets). The abnormality rate of the cells increased with NP concentration and time, and was 100% at 0.22 and 0.26 mg/L of NP after 192 hr of culture. Superoxide dismutase activity initially increased and then declined at a higher NP toxicity of greater than 0.18 mg/L. After 192 hr of culture, the biodegradation rates of NP by C. caspia with initial concentrations of 0.14, 0.18, and 0.22 mg/L were 37.7%, 31.7%, and 6.5%, respectively. The kinetic equation of C. caspia biodegradation on NP was correlated with algal growth rate and initial NP concentration.