Magnaporthe oryzae, the causal agent of rice blast disease, poses a major threat to global rice production. A detailed understanding of its pathogenic mechanisms is important for the development of effective disease management strategies. The mitochondrial cytochrome bc1 complex is a central component of the eukaryotic respiratory chain and plays a critical role in energy metabolism in many plant-pathogenic fungi. The Cob085 gene of M. oryzae encodes a cytochrome b protein that localizes to mitochondrial complex III that is ubiquitous across animals, plants, and fungi. Despite its evolutionary conservation, the functional contribution of the Cob085 gene to fungal virulence remains poorly characterized in plant pathogens, and its role in M. oryzae has yet to be investigated. In this study, Cob085 deletion mutants (ΔCob085) and corresponding complemented strains (ΔCob085-comp) were generated using Agrobacterium tumefaciens-mediated transformation (ATMT). Phenotypic analysis revealed that loss of Cob085 gene significantly impaired conidial germination and appressorium formation. The ΔCob085 mutant altered stress responses, particularly under oxidative, and cell wall stress conditions, and it also contributes to infection related development and pathogenicity in M. oryzae. Moreover, plants infected with the ΔCob085 mutant exhibited altered defense-related enzyme activities. The complementation of Cob085 revealed similar results as the wild-type Guy11, confirming these are gene-specific effects. Overall, these findings demonstrate that Cob085 gene contributes to vegetative growth, appressorium development, stress response and virulence in M. oryzae, highlighting the importance of mitochondrial complex III in fungal pathogenicity and providing new insights into conserved mitochondrial functions in plant-fungus interactions.

Rice sheath blight, caused by Rhizoctonia, is a major threat to global rice production. Hypovirulence-associated mycoviruses offer potential for biocontrol of plant diseases. However, little is known about the diversity of mycoviruses and their effects on the host fungus in Rhizoctonia populations responsible for rice sheath blight in Northeast China. Here, we analyzed 42 strains (39 R. solani AG-1 IA and three R. oryzae-sativae AG-Bb) from this region using metatranscriptomic sequencing, pathogenicity assays, and fungicide sensitivity tests. A total of 67 viral contigs, classified into four families, were identified. From these contigs, eight near‑complete viral genomes were assembled and characterized, including three novel mitoviruses and one novel partitivirus. Pathogenicity assays showed that 21 strains exhibited weak virulence, of which 20 harbored at least one mitovirus, suggesting that mitoviruses are associated with virulence attenuation. In a pot experiment, pre‑inoculation with the hypovirulent strain JMS10, followed by challenge with a highly virulent strain 3 d later, suppressed disease by 53.21%, suggesting a potential protective effect. Fungicide sensitivity analysis showed that virus-infected strains exhibited significantly lower EC50 values for flutolanil compared to virus-free strains, suggesting a possible link between viral infection and enhanced flutolanil sensitivity. This study expands the known mycoviral diversity in Rhizoctonia causing rice sheath blight in Northeast China, establishing a foundation for developing mycovirus-based biocontrol strategies against rice sheath blight.

Abstract Rice bacterial brown leaf spot is a destructive disease caused by the pathogen Pseudomonas syringae pv. syringae. This research evaluated the role of selenium nanoparticles (SeNPs) in plant defense against rice bacterial brown leaf spot disease and compared the effect of SeNPs with sodium selenate. We used 5 different concentrations (10, 20, 30, 40, and 50 mg/L) of both SeNPs and sodium selenate to determine the most effective dosage for maximizing their benefits while minimizing the risk of selenium toxicity. Results showed that plants treated with 30 mg/L SeNPs performed the best, exhibiting the highest relative control effect of 64.16%, followed by plants treated with 30 mg/L of sodium selenate, which showed a relative control effect of 60.67%. Both SeNPs and sodium selenate significantly influenced rice defense mechanisms, but SeNPs performed better in all aspects, resulting in lower disease incidence compared to sodium selenate. SeNPs significantly increased the chlorophyll content, boosted levels of total soluble phenolics (TSP), lignin-thioglycolic acid (LTGA), and defense-related enzymes such as phenylalanine ammonia-lyase (PAL), peroxidase (POD), superoxide dismutase (SOD), polyphenol-oxidase (PPO), catalase (CAT), and β-1,3-glucanase. Furthermore, SeNPs significantly decreased the levels of malondialdehyde (MDA) and reactive oxygen species (ROS), and enhanced the expression of plant defense-related genes such as OsPr1b, PAL, CatA, and POX. These findings suggest that SeNPs enhance the defense responses of rice against bacterial brown leaf spot and could serve as an effective and sustainable tool for crop protection.

Rice seedling blight is a major concern for rice production in China. The disease is primarily caused by Fusarium oxysporum. To effectively control rice seedling blight, it is important to fully understand the pathogenic mechanism of this fungus. 3-Hydroxy-3-methylglutaryl-CoA reductase (HMGR) has been shown to affect the growth and development of Arabidopsis thaliana and the growth and sporulation of Saccharomyces cerevisiae. However, HMGR has not been reported in filamentous fungi. In this study, we constructed FoHmgr gene deletion mutants and complement mutants of F. oxysporum race Fo21 to study the effect of FoHmgr on the growth and pathogenicity of F. oxysporum. We found that deletion of the FoHmgr gene reduced the growth rate of F. oxysporum, altered colony morphology, and reduced spore production by approximately 55

Rice false smut (RFS) is pervasive and has emerged as the primary disease affecting rice productivity. Due to the lack of effective chemical control, disease-resistant varieties are the primary method of managing the disease. This study aimed to investigate the influence of biological characteristics such as hyphal growth rate, spore production and germination ability on the pathogenicity of Ustilaginoidea virens. The genetic diversity of 86 U. virens isolates was analyzed, and the tolerant varieties were identified using Rep-PCR molecular markers. The results indicated that among the U. virens isolates analyzed, about 31, 27 and 28 strains exhibited fast, medium and slow mycelium growth rates, respectively. Among the U. virens isolates analyzed, about 33, 27 and 26 strains exhibited strong, medium and weak sporulation abilities, respectively. In addition, among the U. virens isolates analyzed, about 29, 30 and 27 strains exhibited strong, medium and weak spore germination, respectively. No significant correlation was noted between mycelium growth rate and pathogenicity, but sporulation ability, spore germination ability and liquid culture were positively correlated (p < 0.05). Moreover, the genetic structure of U. virens was diverse and complex. There was a significant correlation between the genetic differentiation and pathogenicity of U. virens in Heilongjiang Province, China, with a maximum coefficient of 0.1786 and a minimum coefficient of 0.0129 between Harbin and Suihua, but no significant correlation was found with gene groups or geographical regions. The study found that genes and geographical population variation were primarily within the population, with 95.63% and 4.37% variation (p > 0.05), respectively, while pathogenicity population variation was mainly within the population, with 86.08% and 13.92% variation (p > 0.05), respectively. Pathogenicity had a significant effect on the differentiation of U. virens. Most rice varieties were susceptible, with 3 resistant, 8 moderately resistant, 9 moderately susceptible, 8 susceptible and 12 highly susceptible to RFS disease. Collectively, these results indicate that the tolerance of rice against U. virens is poor, which merits further investigation.

Xanthomonas euvesicatoria has become a serious problem in Physalis pubescens, leading to substantial crop losses. In our previous investigation, we used rapid molecular detection techniques to identify X. euvesicatoria; however, this pathogen’s diversity and population structure remain poorly understood, despite their importance in disease management. To address this knowledge gap, we analyzed the diversity of X. euvesicatoria using BOX-PCR and ERIC-PCR fingerprinting techniques. A total of 103 isolates were collected from 13 counties across Heilongjiang province during the 2018 and 2019 growing seasons. Our findings revealed 635 unique genetic patterns from ERIC-PCR fingerprinting, compared to 360 patterns from BOX-PCR. BOX-PCR analysis identified 12 distinct genotypic clusters, whereas ERIC-PCR identified 14 clusters through unweighted pair group approach with arithmetic average analysis, demonstrating substantial genetic variability. STRUCTURE analysis further identified five distinct genetic clusters in the BOX-PCR data and two in the ERIC-PCR data. The Hailin isolates showed the highest level of diversification compared to other regional isolates. AMOVA results indicated that 85% of the genetic variation in BOX-PCR was attributable to within-population differences, while 78% of ERIC-PCR variation was due to differences across populations. In addition, a Mantel test demonstrated a tenuous correlation between BOX-PCR and ERIC-PCR genetic markers, indicating distinct genetic profiles. This extensive genetic information enhances our understanding of the epidemiology of bacterial leaf spot and its potential therapeutic prospects. These data can provide insights into Xanthomonas strains’ diversity and geographical dissemination.

Fusarium oxysporum is one of the main pathogens causing rice seedling blight disease. Revealing its pathogenic mechanism is of great significance for formulating prevention and control strategies for rice seedling blight disease. Copper transporting P-type ATPases (Cu-ATPase) is a large class of proteins located on the plasma membrane that utilize the energy provided by ATP hydrolysis phosphorylation to transport substrates across the membrane. It plays a crucial role in signal transduction, the maintenance of cell membrane stability, and material transport. The main function of Cu-ATPase is to maintain the homeostasis of copper in cells, which is essential for the normal growth and development of organisms. This study utilized the ATMT-mediated gene knockout method to obtain the knockout mutant ∆FoCrpA and the complementation strain ∆FoCrpA-C, which are highly homologous to the P-type heavy metal transport ATPase family in F. oxysporum. The results showed that, compared with the wild-type strain, the knockout mutant ∆FoCrpA had a lighter colony color; a reduced tolerance to copper ion, osmotic, and oxidative stress; a weakened ability to penetrate glass paper; and decreased pathogenicity. However, there was no significant difference in pathogenicity and other biological phenotypes between the complementation strain ∆FoCrpA-C and the wild-type strain. In summary, the FoCrpA gene is involved in osmotic and oxidative stress, affecting the invasion and penetration ability and pathogenicity of F. oxysporum, laying a theoretical foundation for understanding the development and pathogenic mechanism of F. oxysporum.

S-adenosylmethionine-dependent methyltransferases use S-adenosylmethionine (SAM) as a methyl donor to catalyze methylation reactions and play a key role in many biological processes. However, studies of their functions in phytopathogenic fungi are still limited. In this study, knockout of the S-adenosyl-L-methionine-dependent methyltransferase FoSAMMT in Fusarium oxysporum affected colony growth, the number of conidia, and spore germination rate. Toxin production was reduced, and the strain's pathogenicity to rice and tolerance to multiple stresses were also decreased. FoSAMMT interacts with Ribosomal protein S7 (FoRPS7), and FoSAMMT may be involved in ribosomal biosynthesis, affecting protein synthesis. Both knockout of FoSAMMT and silencing of FoRPS7 affected protein synthesis and antioxidant defense system. Silencing FoRPS7 up-regulated FoSAMMT expression and weakened its pathogenicity to rice. This provides new insights into the functions of S-adenosyl-L-methionine-dependent methyltransferases in plant pathogenic fungi.

Fusarium oxysporum is one of the most destructive pathogens which causes rice seedling blight. ABA is part of a large signaling system that provides an effective system against microbial and environmental manipulations. The role of ABA in plant defense mechanisms is not clear. In this experiment, we prove the role of abscisic acid (ABA) in boosting rice plant resistance against F. oxysporum and optimizing ABA concentrations against F. oxysporum. This study is divided into two experiments. In the first experiment, we used various ABA concentrations of 0.0, 0.05, 0.1, 0.2, and 0.25 mmol/L under F. oxysporum stress. In the second experiment, we use Fluridone FLD as an ABA inhibitor with the following treatments, (F) is only applied with F. oxysporum (ABA+F), abscisic acid with F. oxysporum (ABAI+F), ABA inhibitor Fluridone with F. oxysporum (ABAI), where only ABA inhibitor Fluridone was applied and CK was used as a control. The results revealed that all the plants treated with ABA exhibit better performance against F. oxysporum, except those treated without ABA. ABA concentrations of 0.2 mmol/L effectively decreased the disease index and disease incidence rate as well as improved the quality of seedlings. ABA effectively increased the activity of defense-related enzymes like PPO, POD, PAL and SOD. ABA also lowers down the MDA content which proves its effectiveness against F. oxysporum. ABA resistance was also proved by plants treated with the abscisic acid inhibitor ABAI (Fluridone FLD). The ABA inhibitor reduced the rice resistance to F. oxysporum, by conforming the expression of defense-related genes PRB1-3, PRBI-2 and Xa39(t). These gene expressions indicate the involvement of ABA in plant defense system.

Rice bacterial leaf brown spot disease caused by Pseudomonas syringae pv. syringae (Pss) is a major disease on rice. In recent years, Pss has emerged worldwide, seriously affecting rice production. It is very important to establish a rapid detection method of Pss for the diagnosis and prevention of this disease. In order to robust and accurately diagnose the rice bacterial leaf brown spot disease in the field and laboratory, an assay system for the Pss was developed in this study, and the specific sequence of hrcN was used as the target, based on loop-mediated isothermal amplification (LAMP). The best detection system was MgSO48 mmol·L-1, Bst DNA polymerase 8 U, dNTP 1.4 mmol·L-1, the ratio of internal and outer primers was 2:1, the reaction temperature was 63℃, the reaction time was 45 min, and the lowest sensitivity was 104 CFU·mL-1. This results provided an accurate and robust method for laboratory and field diagnosis of bacterial leaf brown spot disease of rice.

In recent years,the occurrence of rice false smut has become increasingly serious and the area of damage has expanded year by year,so the false smut has become one of the diseases which have seriously affected rice yield and quality in Heilongjiang Province.However,the genetic diversity research on false smut in Heilongjiang Province was relatively weak.In the current investigation,seven polymorphic SSR markers were taken to analyze the genetic diversity among 89 strains of the pathogens of rice false smut collected from five main rice growing areas in Heilongjiang Province,China.The results showed that the amplified bands of each pair of primers were between 2 and 7.A total of 43 bands were obtained,and each primer was expanded for 4.8 bands.The genetic similarity coefficient(GSC)between strains by using SSR molecular marker analysis showed that the GSC of the strain of Ustilaginoidea virens was 0.613-0.955,with an average of 0.741.According to the results cluster analysis,when the genetic distance was 0.73,89 strains were divided into three groups,and five strains of rice smut strains were distributed in three populations,and strains in Harbin City were mainly distributed in group Ⅲ.In Mudanjiang City,the strains were mainly distributed in groups Ⅰ and Ⅲ,and the strains in Suihua City were mainly distributed in groups Ⅰ and Ⅱ,and the strains in Jiamusi City were evenly distributed in groups Ⅰ,Ⅱ and Ⅲ,and the strains in Qiqihar City were mainly distributed in groups Ⅱ and Ⅲ.The results showed that the genetic background of Ustilaginoidea virens in Heilongjiang Province was relatively low in complexity,and the overall inheritance of the strain was relatively stable.

Rice false smut is a destructive disease that affects rice grain badly.The disease seriously affects the yield and quality of rice in Heilongjiang Province.In this paper,a pair of specific primers was designed to detect the false smut pathogen rapidly and efficiently.The results showed that the pair of primers had strong specificity for false smut pathogen.In addition,the sensitivity of this primer to the genomic DNA of rice false smut pathogen in PCR reaction was 1 pg.By using these primers,the rice false smut pathogen could be detected within 48 h after inoculation,and a PCR reaction system with good specificity and high sensitivity was established.

Ground cherry (Physalis pubescens) is the most prominent species in the Solanaceae family due to its nutritional content, and prospective health advantages. It is grown all over the world, but notably in northern China. In 2019 firstly bacterial leaf spot (BLS) disease was identified on P. pubescens in China that caused by both BLS pathogens Xanthomonas euvesicatoria pv. euvesicatoria resulted in substantial monetary losses. Here, we compared whole genome sequences of X. euvesicatoria to other Xanthomonas species that caused BLS diseases for high similarities and dissimilarities in genomic sequences through average nucleotide identity (ANI) and BLAST comparison. Molecular techniques and phylogenetic trees were adopted to detect X. euvesicatoria on P. pubescens using recQ, hrpB1, and hrpB2 genes for efficient and precise identification. For rapid molecular detection of X. euvesicatoria, loop-mediated isothermal amplification, polymerase chain reaction (PCR), and real-time PCR techniques were used. Whole genome comparison results showed that the genome of X. euvesicatoria was more closely relative to X. perforans than X. vesicatoria, and X. gardneri with 98%, 84%, and 86% ANI, respectively. All infected leaves of P. pubescens found positive amplification, and negative controls did not show amplification. The findings of evolutionary history revealed that isolated strains XeC10RQ, XeH9RQ, XeA10RQ, and XeB10RQ that originated from China were closely relative and highly homologous to the X. euvesicatoria. This research provides information to researchers on genomic variation in BLS pathogens, and further molecular evolution and identification of X. euvesicatoria using the unique target recQ gene through advance molecular approaches.

为深入研究水稻立枯病原菌尖孢镰孢菌(Fusarium oxysporum Schelcht)致病分子机理,利用根癌农杆菌介导遗传转化技术构建尖孢镰孢菌突变体库,筛选致病力降低突变体,检测其T-DNA插入数量和位点.结果表明,691个突变体库构建成功,且突变体可稳定遗传后代.选取34个不同菌落形态变化突变体测定其致病力,筛选到6个致病力降低最严重突变体,分析其菌落形态、菌落生长速率和产孢量.与野生型相比,菌落形态存在差异,其中4个突变体B9、C36、D65、E17生长速率降低,6个突变体产孢数量均降低.通过Southern blot分析发现突变体B92有两个T-DNA插入,其余5个突变体为单个T-DNA插入,利用Hi TAIL-PCR确定6个突变体T-DNA插入位点.结果有助于更好理解尖孢镰孢菌与水稻之间分子相互作用,为进一步确定尖孢镰孢菌致病基因及其功能提供参考.

Rice sheath blight is one of the main diseases in rice production in China, which can make rice unable to absorb and utilize nutrients, and has a serious impact on rice yield and quality. In this study, exogenous ethylene was used to induce rice resistance against rice sheath blight, aiming at exploring a new environment-friendly control method of rice sheath blight. The results showed that within a range of certain concentrations, ethylene had no significant effects on mycelium growth, but it could induce resistance to sheath blight in rice. The optimum concentration was 0.2 mmol · L-1 and the relative control was 86.17％. It was found that ethylene could effectively increase the activities of peroxidase (POD), phenylalanine ammonia-lyase (PAL), β-1, 3-glucanase and reduce the contents of malondialdehyde (MDA), which could enhance the resistance of rice against Rhizoctonia solani. In addition, qRT-PCR detected the expressions of rice defense genes, which indicated that the expressions of the POX, PAL and OsPR1b genes were up-regulated.

In China, rice is one of the most important cereal crops. Rice bacterial brown leaf spot caused by P. s. pv. syringae is among the most damaging rice diseases in the Heilongjiang Province of China and results in substantial yield losses. In this study, a comprehensive analysis of the pathogen, population structure, and genetic diversity within the species was performed. For this purpose, 176 bacterial isolates of P. s. pv. syringae collected from 15 locations were characterized by using biochemical tests such as the LOPAT test, and genetic characterizations such as multilocus sequence analysis (MLSA) and repetitive PCR, using BOX, REP and ERIC primers. Biochemical testing and detection of syrB genes confirm the presence of P. s. pv. syringae, genetic characterization by MLSA and genetic fingerprinting by repetitive PCR confirmed that high genetic heterogeneity exists in the P. s. pv. syringae isolates, and clustering of the tested isolates and reference strains are related with the same genomospecies 1. This work contributes to the physiological classification of the P. s. pv. syringae isolated from Heilongjiang Province, China, and the results present new data concerning the phylogeny and genetic diversity. This type of study about P. s. pv. syringae has been not reported from this region until now.

To date, little attention has been paid to the effects of leaf source reduction on photosynthetic matter production, root function and post-silking N uptake characteristics at different planting densities. In a 2-year field experiment, Xianyu 335, a widely released hybrid in China, was planted at 60 000 plants ha–1 (conventional planting density, CD) and 90 000 plants ha–1 (high planting density, HD), respectively. Until all the filaments protruded from the ear, at which point the plants were subjected to the removal of 1/2 (T1), 1/3 (T2) and 1/4 (T3) each leaf length per plant, no leaf removal served as the control (CK). We evaluated the leaf source reduction on canopy photosynthetic matter production and N accumulation of different planting densities. Under CD, decreasing leaf source markedly decreased photosynthetic rate (Pn), effective quantum yield of photosystem II (ΦPSII) and the maximal efficiency of photosystem II photochemistry (Fv/Fm) at grain filling stage, reduced post-silking dry matter accumulation, harvest index (HI), and the yield. Compared with the CK, the 2-year average yields of T1, T2 and T3 treatments decreased by 35.4, 23.8 and 8.3%, respectively. Meanwhile, decreasing leaf source reduced the root bleeding sap intensity, the content of soluble sugar in the bleeding sap, post-silking N uptake, and N accumulation in grain. The grain N accumulation in T1, T2 and T3 decreased by 26.7, 16.5 and 12.8% compared with CK, respectively. Under HD, compared to other treatments, excising T3 markedly improved the leaf Pn, ΦPSII and Fv/Fm at late-grain filling stage, increased the post-silking dry matter accumulation, HI and the grain yield. The yield of T3 was 9.2, 35.7 and 20.1% higher than that of CK, T1 and T2 on average, respectively. The T3 treatment also increased the root bleeding sap intensity, the content of soluble sugar in the bleeding sap and post-silking N uptake and N accumulation in grain. Compared with CK, T1 and T2 treatments, the grain N accumulation in T3 increased by 13.1, 40.9 and 25.2% on average, respectively. In addition, under the same source reduction treatment, the maize yield of HD was significantly higher than that of CD. Therefore, planting density should be increased in maize production for higher grain yield. Under HD, moderate decreasing leaf source improved photosynthetic performance and increased the post-silking dry matter accumulation and HI, and thus the grain yield. In addition, the improvement of photosynthetic performance improved the root function and promoted post-silking N uptake, which led to the increase of N accumulation in grain.

农业植物病理学是植物保护专业的核心主干课程,在植物保护人才培养中占有重要的地位,在"双一流"建设背景下,东北农业大学农业植物病理学课程构建了具有北方寒地特色的课程知识体系和网络教学资源.以学生为中心,注重科研与教学融合、理论与实践并重,采用启发式与讨论式相结合的互动式教学模式,更新了教学手段,改革了课程考核方式,学生创新能力和实践能力大大提高.