In order to understand the pathogenicity differentiation of rice blast fungus (Pyricularia oryzae Cavara), a total of 206 isolates of P. oryzae were collected from three Japonica rice regions in Jilin Province, northeast China. Pathogenicity test showed that the reaction pattern of 25 monogenic differential varieties (MDVs) of rice (Oryza sativa L.) demonstrated a wide pathogenic diversity among the isolates. Those MDVs harbor 23 resistance (R) genes with the susceptible variety Lijiangxintuanheigu (LTH) as control. Virulent isolates of MDVs harboring R genes Pish, Pit, Pia, Pii, Pik-s, Pik, Pita (two lines), and Pita-2 (two lines) had high frequencies ranging from 80 to 100%, to MDVs harboring R genes Pib, Pi5(t), Pik-m, Pi1, Pik-h, Pik-p, Pi7(t), Piz, Piz-5, and Piz-t showed intermediate frequencies ranging from 40 to 80%, and to MDVs with R genes Pi3, Pi9(t), Pi12(t), Pi19(t) and Pi20(t) presented low frequencies ranging only from 0 to 40%. The U-i-k-z-ta pattern of race-named criteria categorized the 206 isolates into 175 races. Sub-unit U73 for Pib, i7 for Pi3 and Pi5(t), k177 for Pik-m/Pik-h/Pik-p, z17 for Pi9(t), and ta332 for Pi20(t) were crucial on pathogenic differences in regions. Twenty-seven standard differential blast isolates (SDBIs) were selected to characterize resistance in rice accessions. This study could help to build a durable identification system against blast in the Japonica rice area of northeast China and enhance our understanding of the differentiation and diversity of blast races in the world.
Helicobacter pylori is a human pathogen competent for natural transformation. Intrinsic and acquired antibiotic resistance contribute to the survival and multiplication of H. pylori under antibiotics. While drug-resistance dissemination by natural transformation (NT)-mediated horizontal gene transfer remains poorly understood in H. pylori. The purpose of the study was to investigate the role of H. pylori porins (HopA, HopB, HopC, HopD, and HopE) in the intrinsic antibiotic resistance and to preliminarily reveal the potential effect of HopE and HopD porins in streptomycin resistance acquisition after NT in the presence of antibiotics. Using traditional antibiotic susceptibility tests and growth curve analysis, we found the MIC values of metronidazole, clarithromycin, levofloxacin, tetracycline, rifampin, and streptomycin in mutants lacking HopE and/or HopD were significantly elevated compare to those in wild-type strain. The quantitative analysis of the tetramethyl rhodamine isothiocyanate (TRITC)-labeled streptomycin accumulation at the single-cell level showed reduced streptomycin intracellular fluorescence in ΔhopE and ΔhopD mutant cells. Furthermore, in the presence of translation-inhibiting antibiotic streptomycin, the resistance acquisition frequency was decreased in the wild-type strain, which could be reversed by mutants lacking HopE and HopD that restored relatively high resistance acquisition frequencies. By transforming a pUC19-rpsLmut-sfgfp linear plasmid carrying a streptomycin conferring mutation, we observed that the impaired ability of rpsLmut synthesis in the wild-type strain was restored in the ΔhopE and ΔhopD mutant transformants. Our study revealed that in the presence of streptomycin, resistance acquisition at least partially relied on the deletion of the hopE and hopD genes, because their loss reduced streptomycin concentration in the cell and thus restored the expression of the resistance-conferring gene, which was inhibited by streptomycin in wild-type strain. The loss of HopE and HopD influx activity may also preserve resistance acquisition by transformation in the presence of antibiotics with other modes of action. IMPORTANCE Helicobacter pylori is constitutively competent for natural transformation (NT) and possesses an efficient system for homologous recombination, which could be utilized to study the NT-mediated horizontal gene transfer induced antibiotic resistance acquisition. Bacterial porins have drawn renewed attention because of their crucial role in antibiotic susceptibility. From the perspective of porin-mediated influx in H. pylori, our study preliminarily revealed the important role of HopE and HopD porins not only in preserving the intrinsic susceptibility to specific antibiotic but also in evading acquired antibiotic resistance by NT in the presence of translation-inhibiting antimicrobial. Therefore, the loss of HopE or HopD porin in H. pylori genomes, combined with the large number of secreted or cell-free genetic elements carrying mutations conferring antibiotic resistance, may raise the possibility that this mechanism plays a potential role in the propagation of antibiotic resistance within H. pylori communities.
Abstract Coping with stressful conditions and maintaining reproduction are two key biological processes that affect insect population dynamics. Small heat shock proteins (sHSPs) are involved in the stress response and the development of insects. The sHsp gene Laodelphax striatellus (Hemiptera: Delphacidae) sHsp 21.5 ( LsHsp21.5 ) showed constitutive, stage‐ and organ‐specific expression in L. striatellus , a pest that damages cultivated rice in east Asia. The expression of LsHsp21.5 was highest in the ovary, with 43.60, 12.99 and 1.45 time higher expression here than in the head, gut and female fat bodies, respectively. The expression of this gene was weakly affected by heat or cold shock. The gene provided in vitro protection against heat damage to malate dehydrogenase and in vivo protection against heat stress in Escherichia coli (Enterobacteriales: Enterobacteriaceae) BL21(DE3) and L. striatellus . Moreover, L. striatellus reproduction decreased by 1.85 times when the expression of LsHsp21.5 was inhibited by RNA interference. The expression of some genes related to reproduction, such as the homologous gene of chorion protein, also declined. These results suggest that LsHsp21.5 expression not only protects other proteins against stress but also helps maintain the stable expression of some reproduction‐related genes under non‐stressful conditions, with impacts on L. striatellus fecundity.
Antibiotic resistance genes (ARGs) are emerging contaminants that pose a health risk to humans worldwide. Little information on ARGs in bee honey is available. This study profiles ARGs in bee honey samples produced in China, the biggest producer in the world. Of 317 known ARGs encoding resistance to 8 classes of antibiotics, 212 were found in collected honey samples by a real-time quantitative polymerase chain reaction approach. Occurrence frequencies of genes providing resistance to FCA (fluoroquinolone, quinolone, florfenicol, chloramphenicol, and amphenicol) and aminoglycosides were 21.0% and 18.5%, respectively. Frequencies of genes encoding efflux pumps were 42.5% and those of destructase genes 36.6%, indicating that these two mechanisms were predominant for resistance. Nine plasmid-mediated quinolone resistance genes were detected. Of the nine transposase genes known to be involved in antibiotic resistance, eight were found in the samples examined, with tnpA-4, tnpA-5, and tnpA-6 being more abundant. The abundance of the transposase genes was associated with genes conferring resistance to tetracyclines (r = 0.648, p < 0.01), macrolide-lincosamide-streptogramin B (r = 0.642, p < 0.01), FCA (r = 0.517, p < 0.01), and aminoglycosides (r = 0.401, 0.01 < p < 0.05). This is the first study on the abundance and diversity of ARGs in Chinese bee honey products. These findings suggest that bee honey may be a significant source of ARGs that might pose threat to public health. Further research is required to collect more samples in diverse geographic regions in China to make a more comprehensive judgment of ARG in bee honey.
Abstract Baoying Pumping Station as the first station built in the East Route of the S-to-N Water Diversion Project in China, due to the importance of water source project and its 5000 hours yearly operating time, a serial of model tests and other measures were taken to secure its safety and high efficiency operation. Through the comparative model tests in the preliminary design stage, it was made clear that mixed-flow pump was the right direction of pump selection. The acceptance model test indicated that all performance requirements were satisfied and the head-weighted efficiency of the pumping system reached 80.5%, which was about 7 percentages higher than that obtained in the preliminary research and a good foundation for its efficient and economical operation was laid. The optimization design of inlet and outlet flow passages was not significant for improve the efficiency of pumping system. The verification test results were very close to the acceptance test results, and have been confirmed each other. The international bidding and mechanism of joint venture in purchasing main equipment for Baoying pumping station proved to be a success in introducing advanced foreign technology, and its construction experience can provide a useful reference for similar pumping stations.
Aphelenchoides oryzae Yokoo caused a large reduction in rice yields in Japan (1948). It was later synonymised with A. besseyi by Allen (1952), but Subbotin et al. (2021) considered it a valid species. In the main foxtail millet (Setaria italica (L.) P. Beauv.) production area of western Jilin Province, China, many plants were stunted, with thin spikes and open, smooth, shiny glumes. Severely affected spikes were noticeably shorter, fluffy at the top, and erect. In August 2023, 10 foxtail millet samples were collected and nematodes were isolated from 9 of them. A population from Songyuan City, Jilin Province (E:123.64, N:44.86) was studied. The average number of nematodes isolated per gram of ear was 510.7 ± 15.17. Female body slender, lip region rounded, lateral fields with 4 or 6 incisures, vulva located at 71.6% of the body length, post vulvar uterine sac (PUS) 3.7 times anal body width long but less than quarter distance from vulva to anus (VA), tail conical with 3 or 4 terminal spikes. The body length (L), maximum body width (W) and tail length of the female (mean, n=25) were 648 μm, 15.9 μm and 36.7 μm, respectively. PUS length / (VA)% = 23.5, L/W = 41.1, L/ tail length = 17.8. Male body tail curves like a sickle, lacks bursa and shows three pairs of copulatory papillae. Spicules typical of the genus except that the proximal end lacks a dorsal process and has only a moderately developed rostrum. Male measured (mean, n = 25): L = 525.8 μm, W = 14.8 μm, tail length = 34.0 ± 0.7 μm, spicule length = 16.4 μm; L/W = 35.6; L/tail length = 15.6 μm. Amplification of the D2-D3 expansion segments of the 28S ribosomal RNA and the cytochrome oxidase subunit I (COI) gene of mitochondrial DNA (mtDNA) with primers the forward D2A (5’-ACAAGTACCGTGAGGGAAAGTTG-3’) and the reverse D3B (5’-TCGGAAGGAACCAGCTACTA-3’) (Subbotin et al. 2006), and forward COI-F1 (5’-CCTACTATGATTGGTGGTTTTGGTAATTG-3’) and the reverse COI-R2 (5’-GTAGCAGCAGTAAAATAAGCACG-3’) (Kanzaki and Futai 2002). PCR conditions were as described by Ye et al. (2007). The sequences of 28S D2-D3 region (726 bp, PP573753- PP573761) of rDNA were 100% identical to A. oryzae (KY123700, KY123694) and COI region (698-700 bp, PP733171-PP733179), were 98.88% identical to A. oryzae (GU367867). Bayesian inference was used to construct phylogenetic tree of 28S D2-D3 region and COI gene, which showed that the Jilin populations clustered together with A. oryzae, which was a sister branch of A. besseyi. Pathogenicity was established via the infection of foxtail millet (cv. Jiyou 2). The germinated foxtail millet seeds were planted in pots containing 350 ml of sterile soil mixture. On the 15th day, every 10 seedlings were inoculated with 100 A. oryzae at the leaf sheet wounds and 3 plants were noninoculated as control. Three independent replicates were performed on different dates. Forty days post-inoculation, an average of 88.3 ± 2.26 A. oryzae were extracted from each nematode-inoculated plant, and the plants were yellowed and necrotic, uninoculated plants grew normally. The molecular and morphological identification of the nematodes obtained by re-isolation from the plants was identical to that of A. oryzae. Our findings clarify the pathogen species, which can be targeted to develop prevention and control strategies, which are important for ensuring safe grain production and helping promote sustainable local agricultural production. To our knowledge, this is the first record of A. oryzae on foxtail millet in Jilin, China.
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