Bacterial leaf spot of tomato is a worldwide disease, which seriously affects the quality and yield of tomato because of its diverse routes of infestation, rapid spread and difficulty in control. To identify the pathogen of the disease, samples of tomato with leaf spots were collected and prepared for pathogen analysis. Five representative bacterial strains FQ21051401-FQ21051405 strains were isolated and purified from diseased tomato plants. Pathogenicity tests and re-isolation and re-identification of the bacteria were performed to confirm the isolate and fulfill the Koch′ postulates. Based on morphological and biochemical characteristics, phylogenetic analysis, and Koch′s postulates, the bacterial isolates were identified as Erwinia persicina. The aim of this study was to isolate and identify the causal agent of bacterial leaf spot disease of tomato, which will provide a better understanding of pathogenesis of the E. persicina and provided a scientific basis for its control.
Common bean（Phaseolus vulgaris）, also known as the Kidney bean, is widely grown in China for its fresh pod or edible dry seeds, which consumed as vegetable and cereal. In July 2021, severe outbreaks of common bean wilt were observed in several commercial fields in Inner Mongolia. A fungus was isolated from dark brown lesions on diseased stems and roots. The pathogenicity of the isolated fungus was confirmed from inoculation experiments. On the basis of morphological features and EF-1α and β-tubulin sequences, the pathogen was identified as Fusarium oxysporum. This is the first report of F. oxysporum causing Fusarium wilt on common bean in Inner Mongolia. As a destructive plant pathogen, F. oxysporum has a wide host range and is distributed all over China, control measures should be taken in advance.
薄壳山核桃（Carya illinoinensis （Wangenh.） K. Koch）又称美国山核桃，是绿化的优选树种，其果实又称碧根果是世界著名的干果之一。薄壳山核桃原产于美国和墨西哥北部，因其较高的经济价值已被引种到全球20多个国家和地区 [1-2] 。江苏是我国薄壳山核桃引种较早的省份之一 [3] ，江苏句容拥有万亩薄壳山核桃基地，发展势头良好。随着薄壳山核桃种植面积的扩大，病虫害问题突显，褐斑病在江苏句容相继发生，导致叶斑，果腐，落果，经济损失严重。从江苏句容两个薄壳山核桃种植区采集发病样品，进行病原菌的分离与鉴定，结果报道如下。
Verticillium dahliae is a worldwide phytopathogenic fungus which can infect more than 660 plant species, causing serious economic losses annually. Genomic analysis of V. dahlia revealed that different strains contained many strain-specific genes, however, the biological functions of most genes were not clear. In our study, by comparing the genomes of V. dahliae VdLs17 and JR2, a JR2 strain-specific gene Chr6g02370 was identified, which encodes alcohol dehydrogenase and was induced during infection. The enzymatic activity of ethanol dehydrogenase in the knockout mutant decreased significantly, but the utilization of carbon sources such as ethanol was not affected. In addition, the virulence of knockout mutants to tobacco and tomato was significantly reduced. The phenotypic analysis also showed that knockout of this gene reduced melanin synthesis ability, but did not affect mycelial growth and sporulation. In conclusion, our results expand the understanding of the biological functions of strain-specific genes in V. dahlia and provide genetic material for further functional genomics.
In order to understand the resistance risk of Alternaria alternata to mefentrifluconazole, four mutant strains with different resistance levels were obtained by chemical domestication in this study. The resistance risk of A. alternata was evaluated by detecting genetic stability, biological characteristics and cross resistance between mefentrifluconazole and other fungicides. The results showed that the high resistance mutant had high fitness and stable inheritance. Once it appears, it is at risk of becoming a dominant strain in the field. There was no positive cross resistance between the resistance of mefentrifluconazole resistant mutants to mefentrifluconazole and the resistance of other five fungicides, azoxystrobin, kersonxim-methyl, difenoconazole, pyraclostrobin, and hexaconazole. A. alternata can develop mefentrifluconazole-resistant mutants under the fungicide pressure, and there is a risk of fungicide resis-tance. The results of this study provide a scientific basis for the reasonable application of mefentrifluconazole for the control of ginseng Alternaria leaf blight.
