First Report of Nigrospora hainanensis Causing Leaf Blight on Brachiaria Griseb in China.

Brachiaria Griseb is an important gramineous forage grown in tropical regions, and also a main grass species uses to restore grasslands in tropical and subtropical regions of China. In August 2022, symptoms of leaf blight were observed on nearly 30% of the Brachiaria forage grass in the base of the Chinese Academy of Tropical Agricultural Sciences, Hainan, China. Symptomatic leaves initially exhibited small, reddish-brown, round or oval spots on their tips, subsequently expanding in size along the leaf margin, and gradually becoming wilted and dry. Twenty leaves showing typical symptoms were randomly collected and pieces (5×5 mm) from the junction of diseased and healthy region were cut, sterilized with 75% alcohol for 30 s, followed by 5% sodium hypochlorite for 30 s. Rinsed three times with sterile water and dried with sterile filter paper. Leaf pieces were placed on potato dextrose agar (PDA) and incubated at 28℃. The colonies were white on the surface and gray on the reverse side. The conidiogenous cells were monoblastic, hyaline, globose or ampulliform, and 6 to 8.7(13.1) ×5 to 7.2 (9) m (n=200). Conidia is single celled, smooth, black, spherical, or ellipsoidal, and (11)13 to 16.5 × (8.2) 10.3 to16.1 m (n=100). Setae were not observed. The morphological characteristics of the isolates were consistent with Nigrospora species. A representative isolate (LNH-5) was selected for genomic DNA extraction. Sequences of the transcribed spacer region of rDNA (ITS), partial translation elongation factor (TEF1), and beta-tubulin fragment (TUB) were amplified using primer pairs ITS1/ITS4(White et al. 1990), EF-728F and EF-986R (Carbone et al. 1999) and Bt2a and Bt2b (Glass et al. 1995), respectively. The sequences of ITS (OQ473493), TEF1 (OQ506059) and TUB gene (OQ506055) were submitted to GenBank. They were 99 to 100% identical to the Nigrospora hainanensis ITS(OM283581.1)(538 out of 519 bp),TEF1(YK019415.1)(274 out of 276 bp),and TUB (OK086377.1)(405 out of 405 bp) sequences. The phylogenetic maximum likelihood analysis using the combined ITS, TEF1 and TUB sequences indicated that the isolate was part of the N. hainanensis clade (100% bootstrap value) that also contained the type isolate LC6979 of this species. Pathogenicity was tested on 15 healthy Brachiaria plants. Fungal conidia were harvested by flooding two-week-old single conidial cultures with sterile water, centrifuging, and adjusting the concentration to 107 spores/mL. Then 10 µL of conidial suspension was dropped onto the surfaces of leaves wounded with a sterile needle. Sterile distilled water was used for control treatment. The test was repeated three times. After inoculation, the plants were kept at 90~100% relative humidity at 25 to 28°C in a greenhouse for two weeks, and monitored daily for lesion development. Seven days post inoculation, all the inoculated leaves presented symptoms similar to those observed under natural conditions, while the control leaves showed no symptoms. The fungus was re-isolated from the diseased tissues by the single spore isolation method (Choi et al. 1999) to complete Koch's postulates. This pathogen has been reported on sugarcane in China (Raza et al., 2019; Zheng et al., 2022). To our knowledge, this is the first report of N. hainanensis causing leaf blight on Brachiaria plants in China.

Development of a Specific Nested PCR Assay for the Detection of 16SrI Group Phytoplasmas Associated with Sisal Purple Leafroll Disease in Sisal Plants and Mealybugs.

Sisal purple leafroll disease (SPLD) is currently the most destructive disease affecting sisal in China, yet its aetiology remains unclear. In our previous research, it was verified to be associated with phytoplasmas, and nested PCR based on the 16S rRNA gene using universal primers R16mF2/R16mR1 followed by R16F2n/R16R2 was confirmed as the most effective molecular method for the detection of phytoplasmas associated with SPLD (SPLDaP). However, the method has a shortcoming of inaccuracy, for it could produce false positive results. To further manage the disease, accurate detection is needed. In this study, we developed a specific nested PCR assay using universal primers R16F2n/R16R2, followed by a set of primers designed on 16Sr gene sequences amplified from SPLDaP, nontarget bacteria from sisal plants, and other phytoplasma subgroups or groups. This established method is accurate, specific, and effective for detection of 16SrI group phytoplasma in sisal, and its sensitivity is up to 10 fg/µL of total DNA. It also minimized the false positive problem of nested PCR using universal primers R16mF2/R16mR1 followed by R16F2n/R16R2. This method was further used to verify the presence of phytoplasma in Dysmicoccusneobrevipes, and the results showed that D. neobrevipes could be infected by SPLDaP and thus could be a candidate for vector transmission assays.

Phylogeny and Expression Atlas of the NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY in Agave.

Agave species are widely cultivated crassulacean acid metabolism (CAM) plants for alcoholic beverages, food and fiber production. Among these, the Agave hybrid H11648 ((A. amaniensis × A. angustifolia) × A. amaniensis) is the main cultivar for sisal fiber in the tropical areas of Brazil, China, and African countries. The plants of Agave hybrid H11648 have a long life cycle and large leaves, which require a huge amount of nitrogen nutrient. However, the molecular basis of nitrogen transport and allocation has not been well understood in agave. In this study, we identified 19 NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY(NPF) genes (called AhNPFs) with full-length coding sequences in Agave hybrid H11648. Our analysis of gene expression in various types of tissues revealed the tissue-specific expression pattern of AhNPFs. We further examined their expression patterns at different leaf developmental stages, under abiotic/biotic stresses and nutrient deficiency. The results reveal several candidate regulators in the agave NPF family, including AhNPF4.3/5.2/7.1. We first characterized the NPF genes in agave based on published leaf transcriptome datasets and emphasized their potential functions. The study will benefit future studies related to nitrogen nutrient in agave.

First Report of Paramyrothecium breviseta Causing Leaf Spot Disease of Coffea canephora in China.

Coffee is a tropical plant with two widely cultivated species, namely Coffea arabica and Coffea canephora. A leaf spot disease causing brownish and necrotic lesions was broken out on the C. canephora coffee seedlings in a nursery in Ruili County, Yunnan Province, China, during 2018 to 2019. The incidence of the disease was 15% ~ 20%. Ten diseased leaf samples from five diseased plants were collected for pathogen isolation by tissue separation method. Leaf pieces were cut from the margin of the necrotic lesions (4 × 6 mm), surface-sterilized for 30 s in 75% ethanol, followed by 0.1% arsenic mercury solution for 15 s, then washed 3~4 times with sterilized distilled water and transferred onto potato dextrose agar (PDA) medium in petri plates. Four morphologically similar isolates were obtained from lesions and cultivated on PDA at 25°C. Initial colonies of isolates were round, neat edge, white, floccose mycelium and developed dark green-to-black concentric rings that were sporodochia bearing viscid spore masses after 5~7 days. Conidia were acetates, hyaline and cylindrical with both rounded ends and 4.8 to 6.4 µm long × 1.6 to 2.6 µm wide. Koch's test were conducted on three healthy plants leaves of original source variety C. canephora No.2 and C.arabica Catimor CIFC7963 (control plants) with spore suspension (1 × 106/mL), respectively. Meanwhile, equal numbers of healthy plants were inoculated with water as controls. After inoculation, the plants were transferred into an incubator at 25℃ with saturated humidity. After 10 days of inoculation, all the tested plants presented similar typical symptoms with the diseased leaves under natural conditions; whereas the controls remained healthy. Koch's postulates were performed by re-isolating the fungus from the inoculated leaves and verifying its colony and morphological characters. Two single spore isolates cultured on PDA medium were selected for DNA extraction. The ribosomal internal transcribed spacer (ITS) was PCR amplified by using primers ITS1 and ITS4 (White et al., 1990), ß-tubulin gene by Bt2a and Bt2b (Glass and Donaldson, 1995), the RNA polymerase II second largest subunit (rpb2) by RPB2-5F2 and RPB2-7cR (O'Donnell et al, 2007), calmodulin (cmda) gene by CAL-228F and CAL2Rd (Groenewald et al., 2013). The sequences of ITS (MT853067 ~ MT853068), ß-tubulin (MT897899 ~ MT897900), rpb2 (MW256264~ MW286265) and cmda (MT897897~ MT897898) were deposited in GenBank databases. BLAST analysis revealed that the representative isolates sequences shared 99.31%~99.65% similarities to the ITS sequence of Paramyrothecium breviseta (Accession Nos. NR_155670.1), 99.43% similarities to the ß-tubulin sequence of P. breviseta (Accession Nos. KU846406.1), 98.98% similarities to the rpb2 sequence of P. breviseta (Accession Nos. KU846351.1), and 98.54%~98.71% similarities to the cmda sequence of P. breviseta (Accession Nos. KU846262.1). As it shown in the phylogenetic tree derived from combined ITS, ß-tubulin, rpb2, and cmda gene sequences, the two representative isolates were clustered together with P. breviseta CBS 544.75 with 98% strong bootstrap support, which confirmed that P. breviseta is the causal agent of leaf spot of Coffea canephora. To our knowledge, this is the first report of a leaf spot disease caused by P. breviseta on C. canephora in China, which raised the caution that P. breviseta is also pathogenic to Coffea Arabica.

De Novo Transcriptome Assembly of Agave H11648 by Illumina Sequencing and Identification of Cellulose Synthase Genes in Agave Species.

Agave plants are important crassulacean acid metabolism (CAM) plants with multiple agricultural uses, such as being used in tequila and fiber production. Agave hybrid H11648 ((A. amaniensis Trel. and Nowell × A. angustifolia Haw.) × A. amaniensis) is the main cultivated Agave species for fiber production in large tropical areas around the world. In this study, we conducted a transcriptome analysis of A. H11648. About 49.25 million clean reads were obtained by Illumina paired-end sequencing. De novo assembly produced 148,046 unigenes with more than 40% annotated in public databases, or matched homologs in model plants. More homologous gene pairs were found in Asparagus genome than in Arabidopsis or rice, which indicated a close evolutionary relationship between Asparagus and A. H11648. CAM-related gene families were also characterized as previously reported in A.americana. We further identified 12 cellulose synthase genes (CesA) in Asparagus genome and 38 CesA sequences from A. H11648, A.americana, A.deserti and A.tequilana. The full-length CesA genes were used as references for the cloning and assembly of their homologs in other Agave species. As a result, we obtained CesA1/3/4/5/7 genes with full-length coding region in the four Agave species. Phylogenetic and expression analysis revealed a conserved evolutionary pattern, which could not explain the distinct fiber traits in different Agave species. We inferred that transcriptional regulation might be responsible for Agave fiber development. This study represents the transcriptome of A. H11648, which would expand the number of Agave genes and benefit relevant studies of Agave fiber development.

Transcriptome Comparison Reveals Distinct Selection Patterns in Domesticated and Wild Agave Species, the Important CAM Plants.

Agave species are an important family of crassulacean acid metabolism (CAM) plants with remarkable tolerance to heat and drought stresses (Agave deserti) in arid regions and multiple agricultural applications, such as spirit (Agave tequilana) and fiber (Agave sisalana) production. The agave genomes are commonly too large to sequence, which has significantly restricted our understanding to the molecular basis of stress tolerance and economic traits in agaves. In this study, we collected three transcriptome databases for comparison to reveal the phylogenic relationships and evolution patterns of the three agave species. The results indicated the close but distinctly domesticated relations between A. tequilana and A. sisalana. Natural abiotic and biotic selections are very important factors that have contributed to distinct economic traits in agave domestication together with artificial selection. Besides, a series of candidate unigenes regulating fructan, fiber, and stress response-related traits were identified in A. tequilana, A. sisalana, and A. deserti, respectively. This study represents the first transcriptome comparison within domesticated and wild agaves, which would serve as a guidance for further studies on agave evolution, environmental adaptation, and improvement of economically important traits.

[Analysis of risk factors of ventilator-associated pneumonia in an intensive care unit].

OBJECTIVE: To explore the risk factors of ventilator-associated pneumonia (VAP) in patients admitted in an intensive care unit (ICU) for pulmonary tuberculosis (TB). METHODS: The clinical data of 143 patients admitted in the ICU at our center between January, 2014 and June, 2015 were reviewed. The patients with VAP and those without VAP were analyzed for risk factors of VAP in the setting of an ICU for pulmonary TB and compared for the duration of ventilation and hospital stay. RESULTS: The patients with pulmonary TB showed a significantly higher incidence of VAP in the ICU than those without TB. Univariate analysis suggested that the occurrence of VAP was significantly correlated with the duration of mechanical ventilation, invasive examination, pulmonary tuberculosis, lung structure changes, use of multiple antibiotics, diabetes, tracheal incision, indwelling gastric tube, APACHE II score, and coma (P<0.05). Multivariate logistic regression analysis showed that pulmonary TB, duration of mechanical ventilation, APACHE II score, invasive operation, and use of multiple antibiotics were independent risk factors for VAP (P<0.05). The patients who developed VAP had a prolonged duration of mechanical ventilation and ICU stay (P<0.05). CONCLUSION: Patients admitted in tuberculosis ICU are exposed to a high risk of VAP with a high mortality rate as the result of multiple interacting risk factors. Pulmonary TB, prolonged mechanical ventilation, an APACHE II score >15, invasive operation, and use of multiple antibiotics are all independent risk factors for VAP in tuberculosis ICU.

[Structural and functional changes of the carotid artery and their relationship with subclinical inflammation in patients with H-type hypertension].

OBJECTIVE: To investigate the changes in the structure and function of the carotid artery and their relationship with subclinical inflammation in patients with H-type hypertension. METHODS: Sixty patients with H-type hypertension and 49 with non-H-type hypertension were enrolled in this study, with 20 healthy volunteers as the control group. All the subjects underwent color Doppler ultrasound examination of the carotid artery, and their blood levels of hyper-sensitive C-reactive protein (hs-CRP), fibrinogen (FIB), and tumor necrosis factor-α (TNF-α) were measured to investigate the correlation between the structural and functional changes of the carotid artery and the inflammatory factors. RESULTS: No significant difference was found in the blood pressure level between the H-type and non-H-type hypertension groups (136.0∓10.1 vs 131.9∓7.0 mmHg for systolic blood pressure, P>0.05; 80.9∓8.9 vs 73.2∓7.9 mmHg for diastolic pressure, P>0.05). The intima-media thickness, distensibility of the common carotid artery, carotid artery stiffness, and blood homocysteine level all showed significant differences between patients with H-type and non-H-type hypertension (1.52∓0.08 vs 1.09∓0.06 mm, 0.23∓0.14 mmHg(-1)×100 vs 0.46∓0.14 mmHg(-1)×100, and 15.37∓5.89 vs 8.19∓4.53 µmol/L, respectively, P<0.05). The H-type hypertensive patients showed significantly higher hs-CRP, FIB, and TNF-α levels than the non-H-type hypertensive patients, and these inflammatory factors were positively correlated with the structural and functional changes of the carotid artery. CONCLUSION: The patients with H-type hypertension are more likely to have carotid artery structure and function impairments, which closely correlate with the subclinical inflammatory factors. These changes might be attributed to the synergism of subclinical inflammation and hyperhomocysteinemia, for which active intervention may prove beneficial.

[A retrospective study of one case of X-linked agammaglobulinemia].

OBJECTIVE: To investigate the clinical manifestations, diagnostic methods and treatment of X-linked agammaglobulinemia (XLA). METHODS: Flow cytometric analysis of the peripheral monocytes using the anti-BTK antibody was used to characterize the expression of BTK in a 21 year old male patient and his mother. The patient suffered from frequent pneumonia, and was found to be complicated with lymphocytopenia in the B cell populations, hypogammaglobulinemia (IgG 1.38 g/L, IgA 0.25 g/L, IgM 0.17 g/L) and angiotelectasis (which had not been reported in XLA patients). Sequencing of the BTK cDNA obtained from the peripheral monocytes of the patient and his mother was performed to confirm the genetic defect. RESULTS: The BTK expressions in peripheral monocytes of the patient and his mother were 96.9% and 97.8% respectively. Sequencing of the BTK gene revealed a missense mutation of R525Q in exon 16, and his mother was confirmed to be an XLA carrier. The patient was treated with immunoglobulin replacement therapy (2 g/kg). One month later, the serum IgG level of the patient was elevated to 5.79 g/L, and the clinical symptoms (included angiotelectasis), lung function and the CT scan results significantly improved. CONCLUSION: Genetic diagnosis was made for one Chinese XLA adult patient complicated with angiotelectasis. This case suggests that some XLA cases may present angiotelectasis. High dose intravenous immunoglobulin given at 2 g/kg may be of efficacy in severe XLA cases. More attention should be paid to the disease in China.