Characterization of Alternaria Species Associated with Heart Rot of Pomegranate Fruit.
Ontology highlight
ABSTRACT:
SUBMITTER: Aloi F
PROVIDER: S-EPMC7997272 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Pomegranate (Punica granatum L.) is an emerging crop in Italy and particularly in southern regions, such as Apulia, Basilicata, and Sicily, due to favorable climatic conditions. The crop is affected by several pathogenic fungi, primarily in the field, but also during postharvest phases. The most important postharvest fungal diseases in pomegranate are gray and blue molds, black heart and black spot, anthracnose, dry rot, and various soft rots. The limited number of fungicides allowed for treatment in the field and the lack of postharvest fungicides make it difficult to control latent, quiescent, and incipient fungal infections. Symptomatic pomegranates from southern Italy were sampled and isolated fungi were morphologically and molecularly characterized. The data obtained revealed that various species of Penicillium sensu lato (including Talaromyces genus), Alternaria spp., Coniella granati, and Botrytis cinerea were the principal etiological agents of postharvest pomegranate fruit diseases; other relevant pathogens, although less represented, were ascribable to Aspergillus sect. nigri, Colletotrichum acutatum sensu stricto, and Cytospora punicae. About two thirds of the isolated pathogens were responsible for latent infections. The results obtained may be useful in planning phytosanitary control strategies from the field to storage, so as to reduce yield losses.
| S-EPMC9143415 | biostudies-literature
Project description:A new fungal pathogen was isolated from rotten pomegranates collected from the orchards of different parts of Maharashtra. The pathogen was morphologically identified as Chaetomella raphigera followed by sequencing of ITS and D1/D2 hypervariable region of LSU (28S) of rRNA gene. The pathogen produced pectinase, cellulase, xylanase and protease in liquid medium at a concentration of 71, 13.8, 54.3 and 7 U/ml respectively. Enzyme activity was also determined during pathogenesis in the tissues artificially infected by C. raphigera. Xylanase activity was maximum (25.1 U/g) followed by pectinase (19.2 U/g) and cellulase (1.5 U/g), whereas, protease activity was unnoticed. There was significant correlation (P < 0.05) between disease rating scale and pectinase, xylanase and cellulase activity in infected tissues. This indicates the simultaneous production of hydrolytic enzymes that aids in necrosis of fruit tissues. The elevated levels of these enzymes in infected tissues as compared with control suggest their possible role in pathogenesis. Thus, pectinase, cellulase and xylanase produced by C. raphigera acts as major virulence factors in the development of fruit rot in pomegranates. This is a first report of fungal fruit rot caused by C. raphigera in pomegranate.
| S-EPMC4729742 | biostudies-literature
Project description:During a survey of diseases affecting pomegranate in the southeastern USA we identified a unique species of Diaporthales causing leaf spotting and fruit rot. Objectives of this study were to provide a morphological description of the putative new species, use DNA sequence data of three gene loci (LSU, ITS and rpb2) to accurately place the fungus within the Diaporthales, and to prove Koch's postulates. Morphological and phylogenetic comparisons confirmed the fungus to represent a new species and family, for which the names Dwiroopa punicae sp. nov. and Dwiroopaceae fam. nov. are proposed. This is the first report of a species of Dwiroopa being pathogenic to Punica granatum.
| S-EPMC7241677 | biostudies-literature
Project description:Alternaria brown spot is one of the most important diseases of tangerines and their hybrids worldwide. Recently, outbreaks in Mediterranean areas related to susceptible cultivars, refocused attention on the disease. Twenty representatives were selected from a collection of 180 isolates of Alternaria spp. from citrus leaves and fruit. They were characterized along with reference strains of Alternaria spp. Micro- and macroscopic characteristics separated most Alternaria isolates into six morphotypes referable to A. alternata (5) and A. arborescens (1). Phylogenetic analyses, based on endopolygalacturonase (endopg) and internal transcribed spacer (ITS), confirmed this finding. Moreover, a five-gene phylogeny including two anonymous genomics regions (OPA 1-3 and OPA 2-1), and the beta-tubulin gene (ß-tub), produced a further clustering of A. alternata into three clades. This analysis suggested the existence of intra-species molecular variability. Investigated isolates showed different levels of virulence on leaves and fruit. In particular, the pathogenicity on fruit seemed to be correlated with the tissue of isolation and the clade. The toxigenic behavior of Alternaria isolates was also investigated, with tenuazonic acid (TeA) being the most abundant mycotoxin (0.2-20 mg/L). Isolates also synthesized the mycotoxins alternariol (AOH), its derivate alternariol monomethyl ether (AME), and altenuene (ALT), although to a lesser extent. AME production significantly varied among the six morphotypes. The expression of pksJ/pksH, biosynthetic genes of AOH/AME, was not correlated with actual toxin production, but it was significantly different between the two genotypes and among the four clades. Finally, ten isolates proved to express the biosynthetic genes of ACTT1 phytotoxin, and thus to be included in the Alternaria pathotype tangerine. A significant correlation between pathogenicity on leaves and ACTT1 gene expression was recorded. The latter was significantly dependent on geographical origin. The widespread occurrence of Alternaria spp. on citrus fruit and their ability to produce mycotoxins might represent a serious concern for producers and consumers.
| S-EPMC5026349 | biostudies-literature
Project description:Alternaria is often one on the most abundant fungal genera recovered from a wide array of plant hosts and environmental substrates. Many species within the sub-generic Alternaria section Alternaria are common plant pathogens that cause pre-harvest losses due to reduced productivity and post-harvest losses due to spoilage and contamination with mycotoxins. As certain species of Alternaria may have distinct mycotoxin profiles, and very broad host ranges, understanding the distribution of species by geography and host is critical for disease prediction, toxicological risk assessment, and guiding regulatory decisions. In two previous reports, we performed phylogenomic analyses to identify highly informative molecular markers for Alternaria section Alternaria, and validated their diagnostic ability. Here, we perform molecular characterization of 558 section Alternaria strains, collected from 64 host genera in 12 countries, using two of these section-specific loci (ASA-10 and ASA-19) along with the RNA polymerase II second largest subunit (rpb2) gene. The majority of strains (57.4%) originated from various cereal crops in Canada, which formed the main focus of our study. Phylogenetic analyses were used to classify strains into section Alternaria species/lineages, demonstrating that the most common species on Canadian cereal crops are Alternaria alternata and A. arborescens. Further population genetic analyses were consistent with A. alternata being a widely distributed species with relatively low levels of geographic isolation (i.e., Canadian isolates did not form distinct clades when compared to other regions). Our expanded sampling of A. arborescens has greatly increased the known diversity of this group, with A. arborescens isolates forming at least three distinct phylogenetic lineages. Proportionally, A. arborescens is more prevalent in Eastern Canada than in Western Canada. Sequence analyses, putative hybrids, and mating-type distributions provided some evidence for recombination events, both within and between species. There was little evidence for associations between hosts and genetic haplotypes of A. alternata or A. arborescens.
| S-EPMC10249498 | biostudies-literature
Project description:Decline in the productivity of Eucalyptus hybrid cutting production in the Guangdong Province of China is linked to cutting rot associated with several Calonectria spp. The aim of this study was to identify these fungi using morphological and DNA sequence comparisons. Two previously undescribed Calonectria spp., Ca. pseudoreteaudii sp. nov. and Ca. cerciana sp. nov. were identified together with Ca. pauciramosa. Calonectria pseudoreteaudii resides in the Ca. reteaudii complex and Ca. cerciana is closely related to Ca. morganii. Connected to the discovery of Ca. pseudoreteaudii, species in the Ca. reteaudii complex were re-considered and the group is shown to accommodate two cryptic species. These originate from Australia and are described as Ca. queenslandica sp. nov. and Ca. terrae-reginae sp. nov.
| S-EPMC2890164 | biostudies-literature
Project description:The cosmopolitan fungal genus Alternaria consists of multiple saprophytic and pathogenic species. Based on phylogenetic and morphological studies, the genus is currently divided into 26 sections. Alternaria sect. Alternaria contains most of the small-spored Alternaria species with concatenated conidia, including important plant, human and postharvest pathogens. Species within sect. Alternaria have been mostly described based on morphology and / or host-specificity, yet molecular variation between them is minimal. To investigate whether the described morphospecies within sect. Alternaria are supported by molecular data, whole-genome sequencing of nine Alternaria morphospecies supplemented with transcriptome sequencing of 12 Alternaria morphospecies as well as multi-gene sequencing of 168 Alternaria isolates was performed. The assembled genomes ranged in size from 33.3-35.2 Mb within sect. Alternaria and from 32.0-39.1 Mb for all Alternaria genomes. The number of repetitive sequences differed significantly between the different Alternaria genomes; ranging from 1.4-16.5 %. The repeat content within sect. Alternaria was relatively low with only 1.4-2.7 % of repeats. Whole-genome alignments revealed 96.7-98.2 % genome identity between sect. Alternaria isolates, compared to 85.1-89.3 % genome identity for isolates from other sections to the A. alternata reference genome. Similarly, 1.4-2.8 % and 0.8-1.8 % single nucleotide polymorphisms (SNPs) were observed in genomic and transcriptomic sequences, respectively, between isolates from sect. Alternaria, while the percentage of SNPs found in isolates from different sections compared to the A. alternata reference genome was considerably higher; 8.0-10.3 % and 6.1-8.5 %. The topology of a phylogenetic tree based on the whole-genome and transcriptome reads was congruent with multi-gene phylogenies based on commonly used gene regions. Based on the genome and transcriptome data, a set of core proteins was extracted, and primers were designed on two gene regions with a relatively low degree of conservation within sect. Alternaria (96.8 and 97.3 % conservation). Their potential discriminatory power within sect. Alternaria was tested next to nine commonly used gene regions in sect. Alternaria, namely the SSU, LSU, ITS, gapdh, rpb2, tef1, Alt a 1, endoPG and OPA10-2 gene regions. The phylogenies from the two gene regions with a relatively low conservation, KOG1058 and KOG1077, could not distinguish the described morphospecies within sect. Alternaria more effectively than the phylogenies based on the commonly used gene regions for Alternaria. Based on genome and transcriptome comparisons and molecular phylogenies, Alternaria sect. Alternaria consists of only 11 phylogenetic species and one species complex. Thirty-five morphospecies, which cannot be distinguished based on the multi-gene phylogeny, are synonymised under A. alternata. By providing guidelines for the naming and identification of phylogenetic species in Alternaria sect. Alternaria, this manuscript provides a clear and stable species classification in this section.
| S-EPMC4774270 | biostudies-literature
Project description:Plants of the Iris genus have been widely cultivated because of their medicinal, ornamental, and economic values. It commonly suffers from Alternaria leaf spot or blight disease leading to considerable losses for their commercial values. During an investigation of 14 provinces or municipalities of China from 2014 to 2022, a total of 122 Alternaria strains in section Alternaria were obtained from diseased leaves of Iris spp.. Among them, 12 representative strains were selected and identified based on morphological characterization and multi-locus phylogenetic analysis, which encompassed the internal transcribed spacer of rDNA region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1 alpha (TEF1), RNA polymerase second largest subunit (RPB2), Alternaria major allergen gene (Alt a 1), an anonymous gene region (OPA10-2), and endopolygalacturonase gene (EndoPG). The strains comprised two known species of A. alternata and A. iridicola, and two new species of A. setosae and A. tectorum, which were described and illustrated here. Their pathogenicity evaluated on Iris setosa indicated that all the strains could induce typical Alternaria leaf spot or blight symptoms. The results showed that the virulence was variable among those four species, from which A. tectorum sp. nov. was the most virulent one, followed by A. setosae sp. nov., A. iridicola and A. alternata.
| S-EPMC9635052 | biostudies-literature
Project description:Although large-spored Alternaria species of the section Porri are considered to be the major agents responsible for leaf spot and blight of Solanaceae, small-spored Alternaria species are also frequently isolated from symptomatic tissues. A survey of the north-western regions of Algeria during the 2017-2018 growing seasons revealed that amongst the 623 Alternaria isolates from tomato, potato, pepper, eggplant and black nightshade, 8% could not be morphologically assigned to either section Porri or section Alternaria. In order to more precisely determine the taxonomic position of these isolates, detailed morphological characterizations and multi-locus phylogenetic analyses were performed. Based on these analyses, the isolates were grouped into four main clades: section Ulocladioides, section Infectoriae, including two new species, section Embellisioides, and section Eureka, including one new species. These isolates were also characterized for their virulence under green-house conditions. They were able to produce leaf spot symptoms on tomato plants but with variable levels.
| S-EPMC8704928 | biostudies-literature
Project description:Fruit rot of cucurbits caused by several pathogenic fungi has become an important postharvest disease worldwide. In 2022, fruit rot on watermelon (Citrullus lanatus) and muskmelon (Cucumis melo) was observed during the postharvest storage phase in the Chiang Mai and Phitsanulok Provinces of northern Thailand. These diseases can lead to significant economic losses. This present study was conducted to isolate the causal agent of fungi in lesions of fruit rot. A total of four fungal isolates were obtained, of which two isolates (SDBR-CMU422 and SDBR-CMU423) were obtained from rot lesions of watermelons, while the remaining isolates (SDBR-CMU424 and SDBR-CMU425) were obtained from rot lesions of muskmelons. All fungal isolates were identified using both morphological characteristics and molecular analyses. Morphologically, all isolated fungal isolates were classified into the genus Fusarium. Multi-gene phylogenetic analyses of a combination of the translation elongation factor 1-alpha (tef-1), calmodulin (cam), and RNA polymerase second largest subunit (rpb2) genes reveled that four fungal isolates belonged to the Fusarium incarnatum-equiseti species complex and were distinct from all other known species. Thus, we have described them as two new species, namely F. citrullicola (SDBR-CMU422 and SDBR-CMU423) and F. melonis (SDBR-CMU424 and SDBR-CMU425). A full description, illustrations, and a phylogenetic tree indicating the position of both new species have been provided. Moreover, pathogenicity tests were subsequently performed and the results showed that F. citrullicola and F. melonis caused symptoms of fruit rot on inoculated watermelon and muskmelon fruits, respectively. Notably, this outcome was indicative of the symptoms that appeared during the postharvest storage phase. To our knowledge, two new pathogenic fungi, F. citrullicola and F. melonis, are new causal agents of watermelon and muskmelon fruit rot, respectively. Importantly, these findings provide valuable information for the development of effective strategies for the monitoring and prevention of these diseases.
| S-EPMC9695044 | biostudies-literature