Stone and pome fruits account for an important part of China’s fruit production. Brown rot caused by several species of the genus Monilinia can result in flower and fruit rot, causing serious economic losses. Some of these species are important quarantine pathogens in certain countries or regions. This article reviews the main research progress related to taxonomy, species identification, omics and pathogenic mechanism of brown rot pathogens and brown rot disease prevention in the past 20 years. The reliability of the reported rapid detection methods of the pathogens are also summarized and discussed. This paper provides references for high-quality fruit production and plant quarantine application in international fruit trade.
Magnaporthe oryzae pathotype Triticum (MoT) is the causal agent of wheat blast, emerging as a global threat. A summarized account of the disease caused by MoT, including taxonomy, distribution, host range, symptoms, morphological characteristics and other aspects is given in this paper. Future directions for efficient detection and managing this destructive disease are prospected. To date, the wheat blast control is still difficult, and fungicides are unsatisfactory. The strong quarantine regulations and measures are the most effective methods in preventing the pathogen spread and these are also discussed within.
Phytopathogenic fungi causing plant diseases can induce disaster to ecosystems, food security and agricultural production. With the recent development of fungal taxonomy, a large number of new taxa are proposed. In the latest International Botanical Congresses held in Melbourne and Shenzhen, based on the initiative of “one fungus, one name”, some revisions and supplementations concerning fungal nomenclature have been made to the International Code of Nomenclature for Algae, Fungi, and Plants. These variations have brought numerous changes in the currently applied names of phytopathogenic fungi. In this list, 590 commonly used names of agricultural phytopathogenic fungi appeared in research papers, monographical works and textbooks in China were selected, involving 370 fungal species belonging to 2 kingdoms, 7 phyla, 15 classes, 47 orders, 84 families and 168 genera. According to the latest nomenclature and taxonomic research progress, the comprehensive check and correction of scientific names, Chinese names, taxonomic status and disease names of these pathogenic fungi are made and provided herein, aiming at providing helpful references for researchers and technicians who are involved with plant pathogenic fungi in China.
China is the largest citrus-producing country in the world, and the citrus industry plays an important role in national agricultural production. Fungal disease is an important factor restricting the benefit of citrus industry. In the past century Chinese phytopathologists and mycologists have been describing and recording a large number of pathogenic fungi on Citrus. However, with the extensive application of molecular phylogeny in the classification and identification of fungi, the taxonomic status and scientific names of some pathogenic fungi have been changed in recent years. In this paper, the species of pathogenic fungi of citrus diseases that have been reported in China are summarized and revised. This list includes 103 pathogenic fungi and 12 pathogenic oomycetes. In addition, five citrus pathogenic fungi listed in entry quarantine list of China are also included. The scientific and Chinese names of pathogenic fungi and disease names are sorted out and revised based on the latest taxonomy system and fungal nomenclature code. This is the latest standardized list of names of citrus pathogenic fungi and diseases found in China for the convenience of researchers and technicians who involved with the control of citrus fungal diseases.
A fungal strain MDD57 was isolated from soybean seeds imported from America by conventional isolation and culture method. Morphological observation showed that the strain produced pycnidia and a lot of α-conidia and β-conidia on PDA medium, but there was no teleomorph stage. ITS and tef1α gene amplification and DNA sequence alignment indicated that the sequences of the strain were the most similar to the two sequences of Diaporthe novem deposited in GenBank with 100% identity, and the strain was clustered with the strain of D. novem. Koch’s rule verification proved that the strain infected soybean stems and leaves, forming typical Diaporthe symptoms. The isolate was identified as D. novem. This is the first interception report of D. novem from American soybean at Tianjin port. The pathogen is similar to D. caulivora, D. aspalathi and D. longicolla, causing stem canker and seed rot of soybean and bring about serious damage.
Fifty-five samples of leaves, petioles, branches and bark of Liquidambar formosana infected with leaf spot were collected from several places of Fujian Province, China. Totally 12 isolates of Pestalotiopsis-like fungi were obtained. Based on phylogenetic analysis of ITS, β-tubulin and tef1 genes in combination with morphological characters, the isolates were identified as Neopestalotiopsis cocoes, N. chrysea, Pestalotiopsis neglecta and P. neolitseae. These species are first reported on Liquidambar formosana, among which N. cocoes is first reported in China. The results of Koch’s postulates showed that N. cocoes could infect the leaves, petioles and branches, N. chrysea could infect the leaves and branches and P. neglecta could infect the petioles and branches, but P. neolitseae appeared to be nonpathogenic.
Endophytic fungi from the leaves, branches, roots and barks of 20-year-old and 1-year-old Cinnamomum cassia plants collected from Luoding city, Guangdong Province were investigated. In total, 90 fungal isolates were obtained and identified as 22 genera, 14 families, 10 orders, 3 classes and 2 phyla by colony characteristics, microscopic observation and ITS sequence analysis. Pestalotiopsis, Nigrospora and Diaporthe were the dominant genera. The distribution of endophytic fungi in C. cassia plants had obvious tissue specificity and preference. Endophytic fungi in leaves showed the highest level in diversity, and 49 isolates obtained were referred to 19 genera, accounting for 54.44% of the total number of isolates. The diversity index of endophytic fungi in leaves, branches, roots and barks were 2.63, 1.86, 1.30 and 1.07, respectively. Endophytic fungi were more abundant in 20-year-old (H'=2.39) plants than in 1-year-old plants (H'=2.00). Based on C. cassia branch blight samples in Luoding City, the suspected pathogens were obtained by tissue isolation method, and the pathogen was identified as Lasiodiplodia pseudotheobromae by morphological observation, Koch's rule verification and ITS, TEF and TUB sequence analysis. This is the first discovery of C. cassia branch blight caused by L. pseudotheobromae. The antagonistic effect against L. pseudotheobromae based on plate confrontation observation showed that 9 isolates of endophytic fungi had significant inhibition activity, and the inhibitory rates were all over 52%. Trichoderma sp. DZR-1-2 had the highest inhibitory rate (68.80%), and Hypoxylon vinosopulvinatum DYR-1-7 had the maximum distance of inhibitory zone (2.5 mm). These strains seem useful for biological control of C. cassia branch blight, which are worthy of further study.
Fruit soft rot is the most serious fungal disease of kiwifruit during storage period. Diaporthe actinidiae is the pathogen with the highest detection rate and the strongest pathogenicity. The pathogen invaded before florescence and showed symptoms until fruit storage. The long infection process can be studied with the help of fluorescent markers. In this study, PEG mediated protoplast transformation of D. actinidiae strain was performed by applying recombinant vector pCAMBgfp carrying GFP and hygromycin gene. The transformants were screened by hygromycin and GFP fluorescence, and then the colony morphology, stability of fluorescence and pathogenicity were analyzed. Three positive transformants showing no significant difference from wild strain in colony morphology, growth rate and pathogenicity were screened out. The transformant KFDA-17 was inoculated to kiwifruit ‘Jinyan’ during storage period. After inoculation, the fruit appeared watery symptoms in 1 d, and soft rot appeared and gradually accelerated. Mycelium showed obviously green fluorescent under fluorescence microscope, and the infection process can be clearly observed. The result proved that the PEG-mediated protoplast transformation of D. actinidiae was successfully constructed, and the obtained fluorescent strains KFDA-17 could be used for the study of infection process.
Fusarium oxysporum f. sp. cubense (Foc) is an important soil-borne pathogenic fungus leading to a serious threat to the production of banana in the world. The Foc race 4 (Foc4) attacking almost all Cavendish cultivars is currently noteworthy in global banana production. The biological roles of the RNA interfering (RNAi) pathway in the pathogenicity of Foc4 remain unknown. The Argonaute protein (AGO) mediated gene silencing plays a critical role in RNA interference (RNAi) pathway. Foc4 have two AGO proteins containing three typical domains. In this study, Δago1, Δago2 and Δago1/2 gene-knockout mutants of Foc4 were obtained by split-marker homologous recombination technique. The biological phenotypes including the vegetative growth, the amount of sporulation, abiotic stress response and pathogenicity of Foc4 and its knockout mutants were tested. The knockout mutants did not affect the vegetative growth, but their sporulation quantity and the virulence to Cavendish banana were significant reduced when AGOs were deleted as compared with wild type Foc4. Meanwhile, hpRNAi-FCC1 is able to induced endogenous FCC1 reporter gene silencing, resulting in clear phenotypes evaluating the AGOs function in RNAi pathway, and the AGO1 played a critical role in the hpRNA mediated gene silencing process in Foc4. sRNA deep sequencing data showed that the sRNA data characterization were markedly changed as compared with Foc4. miRNA could be generated depending on individual, alternative or joint AGOs, indicating the Foc4 AGOs with overlapped and redundant function in small RNA biogenesis. In addition, AGOs-independent miRNA also was identified in the sequencing data. These results indicated that Foc4 AGOs not only play key roles in conidiation, environmental responses and fungal pathogenicity, but also perform a function in generation of sRNAs.
In order to study the role of karyopherin SsKapJ in the sugarcane smut fungus Sporisorium scitamineum, the deletion mutant was generated by using the PEG-mediated protoplast transformation method, and the mutant phenotypes were characterized. The results showed that the putative karyopherin gene deletion mutant SsKapJΔ displayed a significant reduction in sexual mating and filamentation. Transcriptome analysis revealed that SsKapJ was involved in regulation of cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) and mitogen-activated protein kinase (MAPK) signaling pathway. The haploid sporidia of SsKapJΔ mutant was hypersensitive to pyraclostrobin fungicide, but no difference was found in sensitivity towards benomyl fungicide or the tested stressful conditions (osmotic pressure, cell wall, redox and ethanol) as compared with the wild-type. This study suggests that SsKapJ karyopherin may play an important regulatory role in sexual mating and filamentation of S. scitamineum, providing a basis for further study on regulation of fungal dimorphic switch via nuclear transport pathway.
Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is a devastating epidemic disease on wheat. At present, the control of FHB mainly depends on the application of fungicides, such as benzimidazoles, whose targets are β2-tubulin. The aim of this research is to investigate the interaction between β2-tubulin protein of F. graminearum and benzimidazoles. The β2-tubulin structure was obtained by homology modeling method. Structures of β2-tubulin complexed with the small molecular inhibitor, carbendazim, benomyl, thiabendazole and thiophanate-methyl, were built respectively by molecular docking based on β2-tubulin structure. Molecular docking results showed that the amino acid Phe198 and Val236 in F. graminearum β2-tubulin can directly interact through hydrogen bonds with four benzimidazole molecules, and the amino acid residues at position 50, 134, 165, 167, 198, 200, 236, 237, 239, 240, 250, 253, 257, 314 of F. graminearum β2-tubulin can form a drug binding pocket. The binding energy of β2-tubulin/carbendazim is lowest (-5.72 kcal/mol) and the affinity is highest, as compared with the other three complexes. The sensitivity of F. graminearum to four benzimidazole fungicides was tested using mycelium growth rate method, and the results showed that the EC50 value of F. graminearum to carbendazim, benomyl, thiabendazole and thiophanate-methyl was 0.772, 0.862, 1.088, and 13.266 mg/L, respectively, indicating that F. graminearum is more sensitive to carbendazim than to the other three fungicides, and this is consistent with the molecular docking results.
