In this issue of Mycosystema, twelve papers dealing with plant pathogenic fungi are presented, including five papers concerning floristic investigation, identification and morphological description, two concerning detection and quarantine, and two involving plant pathogen population structure analysis, three summarizing research progress of plant pathogen genomics. These reviews and research papers represent the most updated progress in research of plant pathogenic fungi in China, and provide insights into morphological taxonomy and molecular analysis as well as genomic studies.
Population genomics can reveal the population structures, speciation, evolution and adaptation mechanisms. With the improvement of the next generation high-throughput sequencing technology and cost reduction, large-scale sequencing has become reality. In recent years, the amounts of plant pathogenic fungi with complete genome sequences increased rapidly, promoting greatly the development of population genomics and deepened our understanding of the pathogen origins, genetic diversity, selection, pathogenicity, virulence, fungicide resistance, and host specialization. In this review, the authors briefly introduced the research advance of whole genome sequencing and comparative genomics in plant pathogenic fungi, and presenting a review on the latest research progress of population genomics based on high-throughput sequencing. Population genomics will have been a new field in plant pathogenic fungi.
Sooty blotch and flyspeck fungi colonize on surface of plant tissues, resulting in black colonies on fruit surface due to smudges and blemishes, which usually makes fresh fruits unmarketable. Sooty blotch and flyspeck fungi are ectophytic, not only utilizing fruit leachates, but also degrading epicuticular waxes of fruits. Remarkable progress about sooty blotch and flyspeck fungi has been made during recent ten years. In this paper we briefly summarized recent research progress on biodiversity, mycelial types, taxonomic research techniques, host range, geographic distribution and the research value of sooty blotch and flyspeck fungi.
Rust fungi consist of a huge group of species. Some cause serious yield loss for grain and forest crops, and threaten the global security of food and forestry production. The whole genome sequencing analysis provide powerful tool for the researches of rust gene function identification, virulence variation and evolution mechanism, and consequently provide theoretical support for developing effective strategies of rust control. This article reviews the research advance in the whole genome sequencing analysis, genome structure and genome variation of rust fungi so far. The co-relationship between genome variation and obligate parasitic feature, and the potential effect of genome variation on rust virulence variation are discussed. The rapid research progress in the genomics would undoubtedly facilitate the illumination of genetic bases for the life-style complexity and virulence hyper-variability of rust fungi.
Caeoma taianum sp. nov. and Peridermium falciforme sp. nov. are described; Aecidium wenshanense is a new combination; Aecidium adhatodae, Aecidium ligustici and Aecidium montanum are recorded as new to China. Descriptions and illustrations are provided. Brief taxonomic notes are given for each species. The specimens examined are deposited in Herbarium Mycologicum Academiae Sinicae (HMAS) in Beijing.
Eleven form species of Uredo from China are reported. They are Uredo acaciae-concinnae (new record), Uredo cardiopteridis sp. nov., Uredo costina (new record), Uredo dalbergiae-dyerianae sp. nov., Uredo dumeticola comb. nov., Uredo erigerontis-bonariensis nom. nov., Uredo heteropappi (new record), Uredo ishiuchii (new record), Uredo marisci-trialati sp. nov., Uredo spinulospora comb. nov. and Uredo yunnanensis comb. nov. Descriptions and illustrations based on Chinese collections are provided. Brief taxonomic notes are given for each species. The specimens examined are deposited in Herbarium Mycologicum Academiae Sinicae (HMAS) in Beijing.
Two rust taxa of Uromyces on Fabaceae collected from Inner Mongolia of China are reported. Uromyces punctatus var. dahuricus on Astragalus dahuricus is described as new variety. Uromyces yatsugatakensis on Hedysarum alpinum is recorded as new to China. Morphological descriptions and illustrations are provided based on Inner Mongolian collections. The collections are deposited in the Mycological Herbarium of Chifeng University, Chifeng, Inner Mongolia (CFSZ), and the Herbarium Mycologicum Academiae Sinicae, Beijing (HMAS).
Two rust taxa of Puccinia collected from Inner Mongolia, China are reported. Puccinia miyoshiana var. spodiopogonis on Spodiopogon sibiricus is described as new variety, and Puccinia microsphincta on Carum buriaticum is recorded as new record to China. Morphological descriptions and illustrations are provided based on Inner Mongolian collections. The collections are deposited in the Mycological Herbarium of Chifeng University, Chifeng, Inner Mongolia, China (CFSZ), and the Herbarium Mycologicum Academiae Sinicae, Beijing, China (HMAS).
The pathogens caused apple Valsa canker were investigated morphologically and phylogenetically (ITS and EF1α) based on 78 isolates from 8 apple planting areas in Shanxi Province. The results show that Valsa spp. from Shanxi Province belong to V. mali and V. pyri. V. pyri is dominant and detected in all apple planting areas in Shanxi Province, accounting for 58.97% of the total number of the strains obtained. Relative frequency of Valsa species from the areas investigated was analyzed by SPSS 19.0, and the species were grouped into three clusters at grouping pointing 9 of euclidean distance. ClusterⅠincludes two apple planting area (Xinzhou and Shuozhou) where the pathogen was V. pyri with the relative frequency of 100%. Cluster Ⅱ includes five apple planting area (Jincheng, Changzhi, Linfen, Taiyuan and Yuncheng), where V. pyri is the dominant species. Cluster Ⅲ includes only one planting area (Jinzhong), where V. mali is the dominant species.
The fungal strain 76782-5 isolated from the sunflower seeds mixed in corn grain imported from Ukraine produced aerial mycelia and pycnidia containing β-conidia on PDA medium. Its rDNA ITS and β-tubulin gene sequences were most similar to several sequences of Diaporthe helianthi deposited in GenBank with more than 99% identity. The morphological characteristics and phylogenetic analysis confirmed the fungal strain as D. helianthi. The pathogenicity test showed that it can infect sunflower stem by forming typical symptoms of sunflower stem canker. This is the first interception report of D. helianthi from the Ukraine in China.
Brown rot is an important disease of stone and pome fruit trees. In total, 75 isolates were obtained from the diseased sample collected from wild stone and pome fruit trees in wild forest of Xinjiang Autonomous Region. These isolates were identified base on the morphological characteristics and the phylogenetic analysis of combined sequences including fragment of the internal transcribed spacer (ITS), β-tubulin and elongation factor (EF1α). The results showed that 67 isolates were identified as Monilinia fructigena whereas eight were identified as M. laxa. Both species were distributed in forest of wild pome and stone fruit trees located in north of Xinjiang. M. fructigena was found on fruits of Malus sieversii, Prunus cerasifera, P. armeniaca and P. domestica, while M. laxa was found on fruits of P. cerasifera, M. sieversii and P. pseudocerasus. This is the first report of M. fructigena and M. laxa on wild fruit trees of Xinjiang Autonomous Region. The results not only provide a valuable information of the primary inoculum source of brown rot pathogens for cultivated fruit trees in this region, and also provide the research materials for studying evolution of the brown rot pathogens.
Wheat stem rust is a long distance air-borne disease with high specialization occurring in most wheat growing countries including China, and might cause severe losses in wheat (Triticum aestivum) production in history. The new strong virulent race Ug99 contains association virulence targeting many most useful wheat stem rust resistant genes, esp. Sr31, and imposes a heavy potential threat to wheat production in China. It is necessary to strengthen monitoring and identifying physiological races of Puccinia graminis f. sp. tritici to promote the basic research work, which is beneficial to the disease control. More new approaches are rapidly supplied in studies with modern molecular methods. Molecular marker shows great advantages in detecting the population and the variation of pathogen races. In this paper, the DNA polymorphism of seven prevalent P. graminis f. sp. tritici races is analyzed by using 25 pairs of SSR primers. The results showed that all tested primers were available for amplifying DNA fragments with polymorphism. Additionally, evident differences were found among the tested races. The DNA fragments of a 205bp specific to 21C3CPH with the primer set SSR180 and a 170bp specific to Ug99 with the primer set SSR6 were amplified and isolated, respectively. All those fragments were reproduced. The results indicate that the primers SSR180 and SSR6 could be used for monitoring the physiological races 21C3CPH and Ug99 respectively.
Phytophthora infestans is a heterothallic oomycete, which commonly requires two opposite mating types, A1 and A2 to complete sexual reproduction for producing oospores. Conventional method of mating type determination is through pair-culturing the test isolates with A1 and A2 mating type on medium, which is time-consuming and require the standard cultures. Therefore, a simple and fast method based on difference of nucleotide sequence is highly demanding. So far, three molecular markers closely linked to the mating type locus have been reported. In this study, the mating types of 64 isolates of P. infestans are tested by using the molecular methods base on three reported molecular markers for mating types, and the results are compared with those determined by using conventional method. The comparison indicates that the coincidence rate of mating types determined by the three molecular methods and those determined by the conventional method varied from 61% to 73%, and none of the molecular methods could discriminate the self-fertile isolates. Therefore, the molecular method for mating type determination of P. infestans remained to be investigated.
