First report of Phyllosticta spinarum causing arborvitae foliar blight in Russia

Thuja occidentalis is a popular and widely planted tree in Russia. However, it is susceptible to arborvitae foliar blight, which can compromise the long-term health of trees in the landscape and in nursery production. Leaves with arborvitae needle blight were collected in 2019 in the foothill zone of the Republic of Adygea, and two isolates of Phyllosticta sp. were obtained. Multilocus analyses were performed with sequences of the internal transcribed spacer and 28 S rDNA of the ribosomal DNA, partial actin gene, partial RNA-polymerase II gene, and partial translation elongation factor 1-alpha. Based on phylogenetic analyses combined with morphological features the isolates were identified as Phyllosticta spinarum. Following inoculation of the original host species both isolates produced symptoms similar to those observed in naturally infected leaves. Koch's postulates were then fulfilled by re-isolating P. spinarum from the inoculated leaves. These findings represent the first confirmed detection of P. spinarum causing arborvitae needle blight in Russia.     

Chrysoporthe puriensis causing canker and mortality in Pleroma mutabile in the Atlantic Forest,Brazil

Fungi of the Cryphonectriaceae family are globally known to be tree pathogens. In Brazil, several species of Chrysoporthe have been found causing stem and branch cankers in Pleroma (= Tibouchina) spp. Recently, Chrysoporthe puriensis was described as a new species causing stem and branch cankers in Pleroma granulosum, Pleroma candolleanum, and Pleroma heteromallum, all native species of the Melastomataceae family. During an investigation to collect isolates of the Cryphonectriaceae family in an important Brazilian biome, the Atlantic Forest, in Serra do Mar, structures typical of Chrysoporthe species were found in a different host, Pleroma mutabile. Fruiting bodies present in the bark of these trees were collected and isolated. The isolates were submitted on morphological characterization and phylogenetic analyses of the internal transcribed spacer (ITS) and β-tubulin gene regions using Maximum likelihood, Bayesian inference and Maximum parsimony methods. The isolates collected, for this study, were identified as C. puriensis. Pathogenicity tests on seedlings of Pleroma species and Eucalyptus clones revealed C. puriensis can infect and cause canker in these plant species as mortality. The results demonstrate the importance of delimiting the C. puriensis collection range to track its dissemination in other hosts. No host specificity was observed in the inoculation tests, suggesting this is an important finding, the pathogen causes diseases and mortality in several plants of the Atlantic Forest. Additionally, the pathogen can affect others hosts, such as Eucalyptus clones in commercial plantations.     

The validity of different zokor species and the genus Eospalax inferred from mitochondrial gene sequences

To help resolve the systematic position of Myospalacine (zokors) and to clarify the phylogenetic relationships among zokor species, complete mitochondrial 12S rRNA and cytochrome b gene sequences were determined for seven zokor species from China. Phylogenetic relationships among all extant zokors, except the Siberian zokor (Myospalax myospalax) and Smith's zokor (Eospalax smithi), were reconstructed with the Chinese bamboo rat (Rhizomys sinensis) as an outgroup. Our results support the generic status of Eospalax and also support the validity of the specific status of Eospalax cansus, Eospalax baileyi and Eospalax rufescens.     

基于ITS序列的红山茶组植物系统发育关系的研究

 测定了红山茶组30个物种的ITS序列,利用茶作为外类群,应用PAUP程序中的最大简约法构建了该组植物的系统发育关系。结果表明,大部分红山茶组植物构成一个单系群,这一单系群又分为两个分支。其中一个分支包括了分布在我国中南地区的大花红山茶、多齿红山茶以及分布在华东南的浙江红山茶、山茶等,其自展支持率为79 % (Clade I);另一个分支主要包括分布在我国西南地区的西南红山茶、金沙江红山茶、滇山茶等,自展支持率为92 % (Clade II)。根据ITS系统树并结合物种的形态特征及地理分布探讨了红山茶组植物的种间关系及其系统进化。     

Fusarium rot of melon is caused by several Fusarium species

Fusarium rot of melon, caused by species of the genus Fusarium, has become an important postharvest disease for many Brazilian producers. Due to the delayed onset of symptoms, this disease is often only detected when fruits arrive at the importing country, thus generating economic loss for the exportation of the fruit. This study was developed with the aim of investigating which Fusarium species cause fruit rot in melon and to evaluate any differences in aggressiveness and development of symptoms. Species were identified through phylogenetic analysis of two loci and morphological markers. The 28 isolates obtained from diseased melon fruits of different commercial cultivars were identified as Fusarium falciforme (FSSC), F. sulawesiense, F. pernambucanum (FIESC), and F. kalimantanense (FOSC). Three isolates belong to a new phylogenetic lineage within the F. fujikuroi species complex (FFSC). All isolates were tested for pathogenicity, and first symptoms of rot in Canary melon were observed 2 days after inoculation. Isolates of F. falciforme and F. sulawesiense were shown to be more aggressive. Our results extend information on Fusarium species that cause fruit rot in melon and support the development of management strategies, as there is currently no efficient control for this disease. To our knowledge, this is the first report of the occurrence of species of the FSSC, FOSC, and FFSC from muskmelon fruits in Brazil.     

Phylogeny and Biogeography of Cyanobacteria and Their Produced Toxins

Phylogeny is an evolutionary reconstruction of the past relationships of DNA or protein sequences and it can further be used as a tool to assess population structuring, genetic diversity and biogeographic patterns. In the microbial world, the concept that everything is everywhere is widely accepted. However, it is much debated whether microbes are easily dispersed globally or whether they, like many macro-organisms, have historical biogeographies. Biogeography can be defined as the science that documents the spatial and temporal distribution of a given taxa in the environment at local, regional and continental scales. Speciation, extinction and dispersal are proposed to explain the generation of biogeographic patterns. Cyanobacteria are a diverse group of microorganisms that inhabit a wide range of ecological niches and are well known for their toxic secondary metabolite production. Knowledge of the evolution and dispersal of these microorganisms is still limited, and further research to understand such topics is imperative. Here, we provide a compilation of the most relevant information regarding these issues to better understand the present state of the art as a platform for future studies, and we highlight examples of both phylogenetic and biogeographic studies in non-symbiotic cyanobacteria and cyanotoxins.     

N-Terminal Protease Gene Phylogeny Reveals the Potential for Novel Cyanobactin Diversity in Cyanobacteria

Cyanobactins are a recently recognized group of ribosomal cyclic peptides produced by cyanobacteria, which have been studied because of their interesting biological activities. Here, we have used a PCR-based approach to detect the N-terminal protease (A) gene from cyanobactin synthetase gene clusters, in a set of diverse cyanobacteria from our culture collection (Laboratory of Ecotoxicology, Genomics and Evolution (LEGE) CC). Homologues of this gene were found in Microcystis and Rivularia strains, and for the first time in Cuspidothrix, Phormidium and Sphaerospermopsis strains. Phylogenetic relationships inferred from available A-gene sequences, including those obtained in this work, revealed two new groups of phylotypes, harboring Phormidium, Sphaerospermopsis and Rivularia LEGE isolates. Thus, this study shows that, using underexplored cyanobacterial strains, it is still possible to expand the known genetic diversity of genes involved in cyanobactin biosynthesis.     

Molecular sleuthing: The invader Cynodon case

DNA amplification fingerprinting (DAF) was used to characterize different Cynodon dactylon (L.) Pers. cultivars and accessions and evaluate the genetic diversity among them. DAF analyses of some well known cultivars used in South Africa, i.e. Sahara, Tifway, Tifgreen, Harrismith, Royal Blue, Silverton Blue, Elliott, Tifdwarf, Gulf Green, Magennis, Klip, Florida, Oval, Bayview, Bermuda, X Kweek, Natal Kweek and Tifton 78, as well as 23 unknown Cynodon specimens were done. The unknown Cynodon specimens represent invaders of cultivated lands, with considerable morphological variation. The results were used to determine the genetic distances between the cultivars and unknown accessions, to identify the unknown specimens and to determine the phylogenetic affinities between the cultivars and accessions. The results obtained from the genetic distance matrices confirmed the results obtained from the phylogenetic analyses. In this study DAF analyses was successfully used to distinguish between different C. dactylon cultivars and accessions and could be used to trace the current weed back to its introduction area. This revised version was published online in August 2006 with corrections to the Cover Date.     

苦马豆根瘤中内生细菌遗传多样性分析

苦马豆(Sphaerophysa salsula)是西北荒漠区重要的豆科植物。本研究采用16SrDNA PCR-RFLP和16SrDNA全序列分析方法,对西北部分地区苦马豆根瘤中内生细菌的遗传多样性及系统发育进行分析。结果显示,115株供试菌株产生了28种遗传图谱类型,对每种图谱类型的代表性菌株进行了16SrDNA全序列分析,其中的根瘤菌分别归属于中华根瘤菌属(Sinorhizobium)、根瘤菌属(Rhizobium)、中慢生根瘤菌属(Mesorhizobium);其余的内生菌分别归属于副球菌属(Paracoccus)、鞘脂单胞菌属(Sphingomonas)、固氮螺菌属(Inquilinus)、假单胞菌属(Pseudomonas)、沙雷氏菌属(Serratia)、分枝杆菌属(Mycobacterium)、诺卡氏菌属(Nocardia)、链霉菌属(Streptomyces)、类芽孢杆菌属(Paenibacillus)、短短芽孢杆菌属(Brevibacillus)、Lysinibacillus、葡萄球菌属(Staphylococcus)和芽孢杆菌属(Bacillus),这表明苦马豆根瘤中内生细菌具有丰富的多样性。