First telomere-to-telomere gapless assembly of the rice blast fungus Pyricularia oryzae.

Rice blast caused by Pyricularia oryzae (syn., Magnaporthe oryzae) was one of the most destructive diseases of rice throughout the world. Genome assembly was fundamental to genetic variation identification and critically impacted the understanding of its ability to overcome host resistance. Here, we report a gapless genome assembly of rice blast fungus P. oryzae strain P131 using PacBio, Illumina and high throughput chromatin conformation capture (Hi-C) sequencing data. This assembly contained seven complete chromosomes (43,237,743 bp) and a circular mitochondrial genome (34,866 bp). Approximately 14.31% of this assembly carried repeat sequences, significantly greater than its previous assembled version. This assembly had a 99.9% complement in BUSCO evaluation. A total of 14,982 genes protein-coding genes were predicted. In summary, we assembled the first telomere-to-telomere gapless genome of P. oryzae, which would be a valuable genome resource for future research on the genome evolution and host adaptation.

MicroRNA Profiling Revealed the Mechanism of Enhanced Cold Resistance by Grafting in Melon (Cucumis melo L.).

Grafting is widely used to improve the resistance to abiotic stresses in cucurbit plants, but the effect and molecular mechanism of grafting on cold stress are still unknown in melon. In this study, phenotypic characteristics, physiological indexes, small-RNA sequencing and expression analyses were performed on grafted plants with pumpkin rootstock (PG) and self-grafted plants (SG) to explore the mechanism of changed cold tolerance by grafting in melon. Compared with SG plants, the cold tolerance was obviously enhanced, the malondialdehyde (MDA) content was significantly decreased and the activities of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD) were significantly increased in PG plants. Depend on differentially expressed miRNA (DEM) identification and expression pattern analyses, cme-miR156b, cme-miR156f and chr07_30026 were thought to play a key role in enhancing low-temperature resistance resulting from grafting. Subsequently, 24, 37 and 17 target genes of cme-miR156b, cme-miR156f and chr07_30026 were respectively predicted, and 21 target genes were co-regulated by cme-miR156b and cme-miR156f. Among these 57 unique target genes, the putative promoter of 13 target genes contained the low-temperature responsive (LTR) cis-acting element. The results of qRT-PCR indicated that six target genes (MELO3C002370, MELO3C009217, MELO3C018972, MELO3C016713, MELO3C012858 and MELO3C000732) displayed the opposite expression pattern to their corresponding miRNAs. Furthermore, MELO3C002370, MELO3C016713 and MELO3C012858 were significantly downregulated in cold-resistant cultivars and upregulated in cold-sensitive varieties after cold stimulus, and they acted as the key negative regulators of low-temperature response in melon. This study revealed three key miRNAs and three putative target genes involved in the cold tolerance of melon and provided a molecular basis underlying how grafting improved the low-temperature resistance of melon plants.

The Molecular Genetics and Genomics of Plant-Pathogen Interactions.

Plants have evolved an intricate immune system to protect themselves from potential pathogens [...].

The effects of different rootstocks on aroma components, activities and genes expression of aroma-related enzymes in oriental melon fruit.

Grafting is widely applied in the cultivation of melon. In this study, 'Qinmi No.1' (Cucumis melo L.(QG)) and 'Ribenxuesong' (Cucurbita maxima Duch. (RG)) were used as rootstocks for 'Qingxin Yangjiaocui' (Cucumis melo L.). The results showed that grafting with muskmelon rootstocks had no significant effect on fruit aroma, but grafting with pumpkin rootstocks significantly reduced the odor intensity and odor preference scores of melon fruits. Compared with the fruits from self-grafted plants (SG), four new aromatic volatiles with a sweet smell were detected, the alcohol dehydrogenase (ADH) activity was significantly decreased at 30 DAP, but unaffected at 42 DAP in QG fruits. There was no difference for alcohol acetyltransferase (AAT) activity between QG and SG fruits. The expression level of CmADH2 was significantly higher at 30 DAP and 42 DAP, but CmAAT2 was significantly lower at 42 DAP in QG fruits compared with SG fruits. In RG fruits, the main aroma compounds including butanoic acid ethyl ester, 2-methyl-2-butene-1-al, and 2-methylheptan-1-al were absent, while the volatile compounds with unpleasant odor characteristics including trans, cis-2,6-nonadien-1-ol, (E,E)-2,4-heptadienal, octanoic acid, and styrene were detected. Compared with SG fruits, 1-nonanol and 1-heptanol with green odor characteristics were significantly increased, but eucalyptol and farnesene with fruity aroma characteristics were significantly decreased in RG fruits. The ADH activity of RG fruits was significantly lower than that of SG fruits at 30 DAP and the AAT activity was significantly lower than that of SG fruits at 42 DAP. In addition, the expression levels of CmADH and CmAAT homologs in RG fruits were significantly lower than those in SG or QG fruits. These results show that grafting with pumpkin rootstocks affected the main aroma components, reduced ADH and AAT activities, and down-regulated the expression levels of CmADHs and CmAATs in the melon fruits. This study reveals the mechanism of different rootstocks on melon fruit aroma quality, and lays a theoretical foundation for the selection of rootstocks in melon production. Future studies using overexpression or CRISPR/CAS system to obtain stable transgenic lines of genes encoding key aromatic volatiles, would be promising to effectively improve the flavor quality of melon.

Speech Acoustic Parameters for Predicting Presbyphagia: A Preliminary Study in the Elderly Shanghainese Population.

PURPOSE: Age is a high-risk factor for dysphagia. Speech and swallowing share the same anatomical and neurophysiological basis. Their functions are closely related; hence, speech assessment can predict the risk of dysphagia. This study aimed to investigate the factors influencing presbyphagia in a normal elderly Shanghainese population by analyzing speech acoustic parameters. METHODS: Relevant speech acoustic parameters were compared between 15 people with dysphagia and 15 without dysphagia. After extracting sensitive speech acoustic parameters related to swallowing, changes in sensitive parameters were compared at different ages to analyze the relevant factors influencing presbyphagia in the normal elderly population. RESULTS: Eight speech acoustic parameters related to swallowing, including maximum phonation time (MPT), max F0, /ʔʌ/Jitter, /ʔʌ/L-DDK, /hʌ/L-DDK, /pataka/DDK, F1/a/, and vowel space area, were extracted after comparing the relevant data between the two groups. Analyzing the changes in each of these parameters between different age groups (age 18-39, 40-64, and 65 and above), we discovered that three speech acoustic parameters, including MPT, /hʌ/L-DDK, and /pataka/DDK, had statistical differences, with a decreasing trend in their mean values with increasing age. CONCLUSIONS: The elderly group had significantly lower MPT, /hʌ/L-DDK, and /pataka/DDK than the young and middle-aged groups. We hypothesized that reduced respiratory support and control, decreased range of mouth movements and coordination, closed control of the vocal cords, and inadequate airflow control in vocal cord abduction are risk factors for presbyphagia in the elderly Shanghainese population.

A gln-tRNA-based CRISPR/Cas9 knockout system enables the functional characterization of genes in the genetically recalcitrant brassica anthracnose fungus Colletotrichum higginsianum.

Colletotrichum higginsianum causes anthracnose disease in brassicas. The availability of the C. higginsianum genome has paved the way for the genome-wide exploration of genes associated with virulence/pathogenicity. However, delimiting the biological functions of these genes remains an arduous task due to the recalcitrance of C. higginsianum to genetic manipulations. Here, we report a CRISPR/Cas9-based system that can knock out the genes in C. higginsianum with a staggering 100% homologous recombination frequency (HRF). The system comprises two vectors: pCas9-Ch_tRp-sgRNA, in which a C. higginsianum glutaminyl-tRNA drives the expression of sgRNA, and pCE-Zero-HPT carrying a donor DNA cassette containing the marker gene HPT flanked by homology arms. Upon co-transformation of the C. higginsianum protoplasts, pCas9-Ch_tRp-sgRNA causes a DNA double-strand break in the targeted gene, followed by homology-directed replacement of the gene with HPT by pCE-Zero-HPT, thereby generating loss-of-function mutants. Using the system, we generated the knockout mutants of two effector candidates (ChBas3 and OBR06881) with a 100% HRF. Interestingly, the ΔChBas3 and ΔOBR06881 mutants did not seem to affect the C. higginsianum infection of Arabidopsis thaliana. Altogether, the CRISPR/Cas9 system developed in the study enables the targeted deletion of genes, including effectors, in C. higginsianum, thus determining their biological functions.

The GRAS protein OsDLA involves in brassinosteroid signalling and positively regulates blast resistance by forming a module with GSK2 and OsWRKY53 in rice.

Brassinosteroids (BRs) play a crucial role in shaping the architecture of rice (Oryza sativa) plants. However, the regulatory mechanism of BR signalling in rice immunity remains largely unexplored. Here we identify a rice mutant dla, which exhibits decreased leaf angles and is insensitive to 24-epiBL (a highly active synthetic BR), resembling the BR-deficient phenotype. The dla mutation caused by a T-DNA insertion in the OsDLA gene leads to downregulation of the causative gene. The OsDLA knockout plants display reduced leaf angles and less sensitivity to 24-epiBL. In addition, both dla mutant and OsDLA knockout plants are more susceptible to rice blast compared to the wild type. OsDLA is a GRAS transcription factor and interacts with the BR signalling core negative regulator, GSK2. GSK2 phosphorylates OsDLA for degradation via the 26S proteasome. The GSK2 RNAi line exhibits enhanced rice blast resistance, while the overexpression lines thereof show susceptibility to rice blast. Furthermore, we show that OsDLA interacts with and stabilizes the WRKY transcription factor OsWRKY53, which has been demonstrated to positively regulate BR signalling and blast resistance. OsWRKY53 directly binds the promoter of PBZ1 and activates its expression, and this activation can be enhanced by OsDLA. Together, our findings unravel a novel mechanism whereby the GSK2-OsDLA-OsWRKY53 module coordinates blast resistance and plant architecture via BR signalling in rice.

Modifying Effect and Mechanism of Polymer Powder on the Properties of Asphalt Binder for Engineering Application.

For achieving the better modifying effect of polyurethane on asphalt pavement materials, the PUA powder modifier was prepared with fine grinding at the glass transition temperature, and polyurethane-modified asphalt (PUA-MA) with different dosages of modifier was prepared. The impact of the PUA on the physical properties of asphalt binder was studied. The modifying mechanism of PUA on asphalt was explored by investigating the thermal performance and chemical composition of asphalt (thermogravimetric analysis, differential scanning calorimetry test, and Fourier transform infrared spectroscopy). The micrograph of the interactive interface was characterized by scanning an electron microscope. Furthermore, the rheological properties of PUA-MA were also investigated and analyzed. The results indicated that the PUA had a dense structure with few pores on the surface. After mixing with asphalt, it altered the asphalt's internal structure via physical fusion and chemical reaction (carbamate formation). PUA improved the thermal stability of asphalt, enhanced the asphalt's thermal decomposition temperature, and further reduced the thermal mass loss while decreasing the glass transition temperature. The addition and dosage increase in the PUA modifier significantly improved the softening point, viscosity, complex shear modulus, and rutting factor of asphalt. Also, the PUA could improve the elastic recovery ability of asphalt and enhance the rutting resistance of asphalt at high temperatures. However, the crack resistance at low temperatures was not effectively improved (ductility and penetration decreased). When the dosage was 6-9%, PUA-MA had the best high-temperature performance, but asphalt showed poor low-temperature performance at this dosage. This study provides a theoretical reference for popularizing and applying polyurethane as an asphalt modifier in road engineering.

Cross-cultural adaptation and validation of vocal fatigue index (VFI) to Chinese language.

Objectives: This study aimed to translate the Vocal Fatigue Index (VFI) into Simplified Chinese and test its reliability and validity in mainland China. Methods: The original English version of the VFI was translated and adapted to a Simplified Chinese version (VFI -SC). Fifty-four participants with voice disorders and 21 healthy controls completed the VFI-SC. Sixteen participants with voice disorders completed it again two weeks later. Reliability, validity, and receiver operating characteristic (ROC) of the VFI-SC were analyzed. Results: The Cronbach's alpha values for the VFI factor scores were found to be 0.930 for tiredness and avoidance of voice use (factor 1), 0.878 for physical discomfort with voice use (factor 2), and 0.915 for improvement of symptoms with voice rest (factor 3). The test-retest reliability was 0.967 for all three factors. There was a significant difference between the total scores of the patient group and the control group (p < 0.01). Factor 1 and factor 2 were positively correlated with the Voice Handicap Index (VHI-30). The ROC curves showed acceptable intrinsic accuracies for factor 1 (AUC = 0.883), factor 2 (AUC = 0.901), and factor 3 (AUC = 0.800), with cutoff scores of 22, 7, and 9, respectively. Conclusions: This study provides preliminary evidence that the VFI-SC has good reliability and validity. It can be used to screen for clinical symptoms of voice fatigue in mainland China.

Computed Tomography-Guided Percutaneous Stylomastoid Foramen Puncture and Radiofrequency Thermocoagulation for Treatment of Hemifacial Spasm via Mandibular Angle Approach.

BACKGROUND: Hemifacial spasm (HFS) is characterized by progressive, paroxysmal, and involuntary convulsions on one side of the face. We have conducted in-depth exploration on the puncture approach through the mandibular angle, which is an important supplement to the first 2 approaches (i.e., premastoid approach and the postmastoid approach), especially for patients who cannot find a suitable way before and after the mastoid process. OBJECTIVES: To investigate the effect of computed tomography (CT)-guided percutaneous mandibular angle radiofrequency thermocoagulation (RFT) of facial nerve through the stylomastoid foramen in treating HFS. STUDY DESIGN: A retrospective, observational study. SETTING: Pain Department, Jiaxing and Hangzhou, China. METHODS: A total of 89 patients with HFS who underwent CT-guided RFT in the Pain Department of Zhejiang Integrated Traditional Chinese and Western Medicine Hospital and the Pain Department of Jiaxing First Hospital, from June 2020 to June 2022, were retrospectively analyzed, including 29 men and 60 women, aged 34~88 (59.8 ± 11.1). They were divided into 3 groups: anterior mastoid approach group (Group A, n = 38), posterior mastoid approach group (Group P, n = 26), and mandibular angle approach group (Group M, n = 25), according to the different puncture approaches. Puncture time, minimum stimulating current triggering facial muscle twitches, temperature at the end of RFT and duration time of RFT at this temperature, and total treatment time, as well as degree of facial paralysis and complications one-day postoperation, were compared among the 3 groups. RESULTS: The puncture times (mean ± SD) of Group A, Group P, and Group M were (30.63 ± 4.88), (31.35 ± 5.89), and (35.08 ± 5.76), respectively, and the differences were statistically significant (P = 0.006). The puncture time of Group M was longer than that of Groups A and P (P < 0.05). The minimum stimulating current triggering facial muscle twitches in the 3 groups were (0.49 ± 0.16), (0.43 ± 0.14), and (0.28 ± 0.09), respectively, with a statistically significant difference (P = 0.000). The minimum stimulation current in Group M was less than that in Groups A and P (P < 0.05). The temperature at the end of RFT of the 3 groups was (78.29 ± 7.91), (76.54 ± 8.10), and (66.60 ± 8.00), respectively, and the differences were statistically significant (P < 0.001). The temperature of Group M was lower than Groups A and P (P < 0.05). There were no significant differences among the 3 groups in the total operation time or the degree of facial paralysis one-day postoperation (P > 0.05). No hematoma, infection, hearing impairment, or other complications were reported in any patients. LIMITATIONS: The nonrandomized nature, small sample size, and retrospective design are limitations of this study. CONCLUSIONS: CT-guided RFT through the stylomastoid foramen is an effective treatment of HFS. Compared to the poster and anterior mastoid approaches, the mandibular angle approach was found to be more effective in terms of reduced minimum stimulating current and reduced-end RFT temperature, which means fewer potential complications to the patient postsurgery. KEY WORDS: Hemifacial spasm, radiofrequency thermocoagulation, stylomastoid foramen, CT-guided.

An ERAD-related ubiquitin-conjugating enzyme boosts broad-spectrum disease resistance and yield in rice.

Rice is a staple crop for over half of the global population. However, blast disease caused by Magnaporthe orzae can result in more than a 30% loss in rice yield in epidemic years. Although some major resistance genes bolstering blast resistance have been identified in rice, their stacking in elite cultivars usually leads to yield penalties. Here we report that OsUBC45, a ubiquitin-conjugating enzyme functioning in the endoplasmic reticulum-associated protein degradation system, promotes broad-spectrum disease resistance and yield in rice. OsUBC45 is induced upon infection by M. oryzae, and its overexpression enhances resistance to blast disease and bacterial leaf blight by elevating pathogen-associated molecular pattern-triggered immunity (PTI) while nullifying the gene-attenuated PTI. The OsUBC45 overexpression also increases grain yield by over 10%. Further, OsUBC45 enhances the degradation of glycogen synthase kinase 3 OsGSK3 and aquaporin OsPIP2;1, which negatively regulate the grain size and PTI, respectively. The OsUBC45 reported in our study has the potential for improving yield and disease resistance for sustainable rice production.

Transcutaneous electrical acupoint stimulation in adult patients receiving gastrectomy/colorectal resection: A randomized controlled trial.

BACKGROUND: Acupuncture promotes the recovery of gastrointestinal function and provides analgesia after major abdominal surgery. The effects of transcutaneous electrical acupoint stimulation (TEAS) remain unclear. AIM: To explore the potential effects of TEAS on the recovery of gastrointestinal function after gastrectomy and colorectal resection. METHODS: Patients scheduled for gastrectomy or colorectal resection were randomized at a 2:3:3:2 ratio to receive: (1) TEAS at maximum tolerable current for 30 min immediately prior to anesthesia induction and for the entire duration of surgery, plus two 30-min daily sessions for 3 consecutive days after surgery (perioperative TEAS group); (2) Preoperative and intraoperative TEAS only; (3) Preoperative and postoperative TEAS only; or (4) Sham stimulation. The primary outcome was the time from the end of surgery to the first bowel sound. RESULTS: In total, 441 patients were randomized; 405 patients (58.4 ± 10.2 years of age; 247 males) received the planned surgery. The time to the first bowel sounds did not differ among the four groups (P = 0.90; log-rank test). On postoperative day 1, the rest pain scores differed significantly among the four groups (P = 0.04; Kruskal-Wallis test). Post hoc comparison using the Bonferroni test showed lower pain scores in the perioperative TEAS group (1.4 ± 1.2) than in the sham stimulation group (1.7 ± 1.1; P = 0.04). Surgical complications did not differ among the four groups. CONCLUSION: TEAS provided analgesic effects in adult patients undergoing major abdominal surgery, and it can be added to clinical practice as a means of accelerating postoperative rehabilitation of these patients.

CRISPR/Cas9-mediated deletion of large chromosomal segments identifies a minichromosome modulating the Colletotrichum graminicola virulence on maize.

Colletotrichum graminicola causes anthracnose on maize, an economically significant disease worldwide. To decipher how the pathogen controls its virulence/pathogenicity on maize at the minichromosomal level, we sequenced the genome and transcriptome of the C. graminicola strain T1-3-3. The 61.91 Mb genome contains three transcriptionally repressed, full-length strain-specific minichromosomes (<1 Mb; Chr11 through Chr13). A CRISPR/Cas9-based system was developed to knock out large chromosomal segments; it involved the generation of multiple simultaneous DNA double-strand breaks across a targeted genomic region, followed by homology-directed replacement thereof with a donor DNA template carrying the selectable marker hygromycin phosphotransferase gene flanked by homologous sequence arms of the targeted region. Using this system, we obtained distinct mutants functionally nullisomic for individual minichromosomes. Only the ΔChr12 mutant lacking the 498.44 Kb genomic region carrying all of the 31 genes of Chr12 exhibited attenuated virulence on maize and was indistinguishable from T1-3-3 in fungal growth and conidiation, indicating that Chr12 is a conditionally dispensable minichromosome and imparts full virulence to C. graminicola on maize. The CRISPR/Cas9-mediated genome editing system developed in this study will enable the determination of the biological functions of minichromosomes or large chromosomal segments in fungal plant pathogens.

Phosphorylation and ubiquitination of OsWRKY31 are integral to OsMKK10-2-mediated defense responses in rice.

Mitogen-activated protein kinase (MPK) cascades play vital roles in plant innate immunity, growth, and development. Here, we report that the rice (Oryza sativa) transcription factor gene OsWRKY31 is a key component in a MPK signaling pathway involved in plant disease resistance in rice. We found that the activation of OsMKK10-2 enhances resistance against the rice blast pathogen Magnaporthe oryzae and suppresses growth through an increase in jasmonic acid and salicylic acid accumulation and a decrease of indole-3-acetic acid levels. Knockout of OsWRKY31 compromises the defense responses mediated by OsMKK10-2. OsMKK10-2 and OsWRKY31 physically interact, and OsWRKY31 is phosphorylated by OsMPK3, OsMPK4, and OsMPK6. Phosphomimetic OsWRKY31 has elevated DNA-binding activity and confers enhanced resistance to M. oryzae. In addition, OsWRKY31 stability is regulated by phosphorylation and ubiquitination via RING-finger E3 ubiquitin ligases interacting with WRKY 1 (OsREIW1). Taken together, our findings indicate that modification of OsWRKY31 by phosphorylation and ubiquitination functions in the OsMKK10-2-mediated defense signaling pathway.

Magnaporthe oryzae endoplasmic reticulum membrane complex regulates the biogenesis of membrane proteins for pathogenicity.

In eukaryotes, the majority of newly synthesized integral membrane proteins are inserted into the endoplasmic reticulum (ER) membrane before transferred to their functional sites. The conserved ER membrane complex (EMC) takes part in the insertion process for tail-anchored membrane proteins. However, the function of EMC in phytopathogenic fungi has not been characterized. Here, we report the identification and functional characterization of two EMC subunits MoEmc5 and MoEmc2 in Magnaporthe oryzae. The knockout mutants ΔMoemc5 and ΔMoemc2 exhibit substantial defect in autophagy, pathogenicity, cell wall integrity, and magnesium ion sensitivity. We demonstrate that the autophagy process was severely impaired in the ΔMoemc5 and ΔMoemc2 mutants because of the low-protein steady-state level of Atg9, the sole membrane-associated autophagy protein. Furthermore, the protein level of membrane proteins Chs4, Fks1, and MoMnr2 is also significantly reduced in the ΔMoemc5 and ΔMoemc2 strains, leading to their supersensitivity to Calcofluor white, Congo red, and magnesium. In addition, MoEmc5, but not MoEmc2, acts as a magnesium transporter independent of its EMC function. Magnaporthe oryzae EMC regulates the biogenesis of membrane proteins for autophagy and virulence; therefore, EMC subunits could be potential targets for fungicide design in the future.

Expression patterns of ABCE model genes during flower development of melon (Cucumis melo L.).

In production, most cultivars of melon are andromonoecious and characterized by carrying both male and bisexual flowers on the same plant. In this study, four A-class genes (CmAP1a, CmAP1b, CmAP2a and CmAP2b), two B-class genes (CmAP3 and CmPI), two C-class genes (CmAGa and CmAGb) and four E-class genes (CmSEP1,2,3,4) were identified in melon. However, no D-class gene of melon was identified. The conserved domains of ABCE function proteins showed relatively high similarity between Arabidopsis and melon. The expression patterns of ABCE homeotic genes in different flower buds of melon suggested that transcripts of CmAP1a, CmPI and CmSEP1 in bisexual buds were significantly lower than that in male flower buds, while the expression levels of CmAGa, CmAGb and CmSEP4 in bisexual flower buds were significantly higher than that in male flower buds. There was no significant difference in expression levels of other ABCE model genes between male buds and bisexual buds. Subsequently, qRT-PCR was performed in different floral organs of bisexual flowers in melon. For A class genes, CmAP1a and CmAP1b showed the highest accumulation in sepals than petals, stamens and pistil, while CmAP2a and CmAP2b revealed the highest expression in pistil than other three floral organs. For B class genes, CmAP3 and CmPI were highly accumulated in petals and stamens though CmAP3 also showed abundant accumulation in pistil. For C class genes, the expression levels of CmAGa and CmAGb were higher in stamens and pistil than that in sepals and petals. For E class genes, CmSEP1 showed higher expression level in sepals and petals than stamens and pistil. CmSEP2, CmSEP3 and CmSEP4 showed the highest accumulation in pistil than other floral organs. These results provided a theoretical basis for studying the function of ABCE homeotic genes in floral organs development of melon.

Editorial for the Special Issue on Advanced Interconnect and Packaging.

Unlike transistors, the continuous downscaling of feature size in CMOS technology leads to a dramatic rise in interconnect resistivity and concomitant performance degradation [...].

Two Species of Stemphylium, S. astragali and S. henanense sp. nov., Causing Leaf and Stem Spot Disease on Astragalus sinicus in China.

Astragalus sinicus is a versatile legume crop, primarily utilized as a green manure in China. During 2020 and 2021, A. sinicus plants exhibiting dark brown or reddish-brown lesions or spots on leaves and stems were collected from fields in the Henan, Sichuan, and Guangxi provinces of China. Sixteen single-spore isolates were isolated from the infected leaf and stem tissue samples. Phylogenetic analyses based on the concatenated internal transcribed spacer, gapdh, and cmdA sequences indicated that 14 of them belong to Stemphylium astragali, whereas two isolates can be well separated from other known species in this genus. Based on the morphological characteristics and nucleotide polymorphisms with sister taxa, the two isolates were identified as a new species named S. henanense. Furthermore, pathogenicity assays showed that the S. astragali and S. henanense isolates caused leaf and stem spot symptoms on A. sinicus. Altogether, we describe a new species of Stemphylium (i.e., S. henanense sp. nov.) causing leaf spot disease of A. sinicus. In addition, this is the first report of S. astragali causing stem spot disease of A. sinicus.

The Hidden Truths of Fungal Virulence and Adaptation on Hosts: Unraveling the Conditional Dispensability of Minichromosomes in the Hemibiotrophic Colletotrichum Pathogens.

Colletotrichum spp. are ascomycete fungi and cause anthracnose disease in numerous crops of economic significance. The genomes of these fungi are distributed among ten core chromosomes and two to three minichromosomes. While the core chromosomes regulate fungal growth, development and virulence, the extent to which the minichromosomes are involved in these processes is still uncertain. Here, we discuss the minichromosomes of three hemibiotrophic Colletotrichum pathogens, i.e., C. graminicola, C. higginsianum and C. lentis. These minichromosomes are typically less than one megabase in length, characterized by containing higher repetitive DNA elements, lower GC content, higher frequency of repeat-induced point mutations (RIPMs) and sparse gene distribution. Molecular genetics and functional analyses have revealed that these pathogens harbor one conditionally dispensable minichromosome, which is dispensable for fungal growth and development but indispensable for fungal virulence on hosts. They appear to be strain-specific innovations and are highly compartmentalized into AT-rich and GC-rich blocks, resulting from RIPMs, which may help protect the conditionally dispensable minichromosomes from erosion of already scarce genes, thereby helping the Colletotrichum pathogens maintain adaptability on hosts. Overall, understanding the mechanisms underlying the conditional dispensability of these minichromosomes could lead to new strategies for controlling anthracnose disease in crops.