Phylogeny and pathogenicity of Lasiodiplodia species associated with dieback of mango in Peru

Phylogenetic and Pathogenic Evidence Reveals Novel Host-Pathogen Interactions between Species of Lasiodiplodia and Citrus latifolia Dieback Disease in Southern Mexico

Mexico ranks second in the world for Persian lime (Citrus latifolia) exports, making it the principal citrus exporter within the national citrus industry, exporting over 600,000 tons per year. However, diseases are the main factor reducing production, resulting in significant economic losses. Among these diseases, fungal diseases like dieback, caused by species of Lasiodiplodia, are an emerging issue in Persian lime. Symptoms include gummosis, twig and branch dieback, cankers, the necrosis of bark and wood, fruit mummification, and tree decline. The aim of this study was to investigate the occurrence and pathogenicity of the fungal species associated with twig and branch dieback, cankers, and decline of Persian lime trees in southern Mexico, and to elucidate the current status of the Lasiodiplodia species causing the disease in Mexico. During June, July, and August of 2023, a total of the 9229 Persian lime trees were inspected across 230 hectares of Persian lime orchards in southern Mexico, and symptoms of the disease were detected in 48.78% of the trees. Branches from 30 of these Persian lime trees were collected. Fungal isolates were obtained, resulting in a collection of 40 strains. The isolates were characterized molecularly and phylogenetically through the partial regions of four loci: the internal transcribed spacer region (ITS), the β-tubulin gene (tub2), the translation elongation factor 1-alpha gene (tef1-α), and the DNA-directed RNA polymerase II second largest subunit (rpb2). Additionally, pathogenicity was assessed, successfully completing Koch's postulates on both detached Persian lime branches and certified 18-month-old Persian lime plants. Through multilocus molecular phylogenetic identification, pathogenicity, and virulence tests, five species were identified as causal agents: L. iraniensis, L. lignicola, L. mexicanensis, L. pseudotheobromae, and L. theobromae. This study demonstrates that in southern Mexico, at least five species of the genus Lasiodiplodia are responsible for dieback in Persian lime. Additionally, this is the first report of L. lignicola and L. mexicanensis as causal agents of the disease in citrus, indicating novel host interactions between species of Lasiodiplodia and C. latifolia.

Keratitis due to Lasiodiplodia theobromae successfully treated with voriconazole: A case series from Assam

Lasiodiplodia theobromae is a dematiaceous fungus which rarely causes keratitis and is mostly resistant to the commonly used antifungal drugs. Here, we report three cases of keratitis caused by L.theobromae from Assam. All the cases were successfully treated with 1% voriconazole and surgical debridement. To the best of our knowledge and literature search, this is the first case series of keratitis caused by L.theobromae reported from eastern India.

Identification of Lasiodiplodia species inciting stem rot of dragon fruit in India through polyphasic approach

Lasiodiplodia species commonly thrive as endophytes, saprobes, and plant pathogens in tropical and subtropical regions. Association of Lasiodiplodia species causing stem rot in dragon fruit in the coastal belt of Odisha, eastern India, has been illustrated here. The stem rot disease was characterized by yellowing of the stem, followed by softening of the stem tissues with fungal fructifications of the pathogen in the affected tissues. On the basis of macro- and micromorphological characteristics, the four fungal isolates recovered from diseased stems were identified initially as Lasiodiplodia species. By comparing DNA sequences within the NCBI GenBank database as well as performing a multigene phylogenetic analysis involving the internal transcribed spacer region (ITS-rDNA), β-tubulin (β-tub), and elongation factor-alpha (EF1-α) genes, the identity of Lasiodiplodia isolates was determined. The isolate CHES-21-DFCA was identified as Lasiodiplodia iraniensis (syn: L. iranensis) and the remaining three isolates, namely CHES-22-DFCA-1, CHES-22-DFCA-2, and CHES-22-DFCA-3, as L. theobromae. Although pathogenicity studies confirmed both L. iraniensis and L. theobromae were responsible for stem rot in dragon fruit, L. iraniensis was more virulent than L. theobromae. This study established the association of Lasiodiplodia species with stem rot in dragon fruit using a polyphasic approach. Further investigations are required, particularly related to on host-pathogen-weather interaction and spatiotemporal distribution across the major dragon fruit-growing areas of the country to formulate prospective disease management strategies. This is the first report on these two species of Lasiodiplodia inflicting stem rot in Hylocereus species in India.

Unveiling Cryptic Species Diversity and Genetic Variation of Lasiodiplodia (Botryosphaeriaceae, Botryosphaeriales) Infecting Fruit Crops in Taiwan

The genus Lasiodiplodia, a member of the family Botryosphaeriaceae, is an important fungal disease genus in agriculture. However, the Lasiodiplodia species survey and genetic diversity in Taiwan remain unclear. This study aimed to investigate the Lasiodiplodia species associated with various fruit species to explore the cryptic Lasiodiplodia species diversity, validate species delimitation, and unveil cryptic genetic diversity. Overall, six Lasiodiplodia species were identified, with several new records of infection identified. Additionally, phylogenetic analyses indicated that the relations of all isolates of L. theobromae might be paraphyletic. They were grouped with L. brasiliense based on Automatic Barcode Gap Discovery (ABGD), Automatic Partitioning (ASAP) and structure-based clustering analyses. These analyses did not provide conclusive evidence for L. brasiliensis as a stable species. It may be necessary to gather more information to clarify the species delineation. The multiple new records of Lasiodiplodia species with high genetic diversity and differentiation revealed that the diversity of Lasiodiplodia in Taiwan was underestimated in the past. We found that L. theobromae has the highest number of haplotypes but the lowest number of haplotype and nucleotide diversities, indicating a recent population expansion. This was supported by the significant negative Tajima's D and Fu and Li's D* tests. The high genetic diversity, low gene flow, and host-associated differentiation of Lasiodiplodia species indicate that they might harbour powerful evolutionary potential in Taiwan. This study provided critical insights into genetic variation, host-associated differentiation, and demography of Lasiodiplodia species, which would be helpful for disease management of related pathogens.

MALDI mass spectrometry-based identification of antifungal molecules from endophytic Bacillus strains with biocontrol potential of Lasiodiplodia theobromae, a grapevine trunk pathogen in Peru

Lasiodiplodia theobromae, a grapevine trunk pathogen, is becoming a significant threat to vineyards worldwide. In Peru, it is responsible for Botryosphaeria dieback in many grapevine-growing areas and it has spread rapidly due to its high transmissibility; hence, control measures are urgent. It is known that some endophytic bacteria are strong inhibitors of phytopathogens because they produce a wide range of antimicrobial molecules. However, studies of antimicrobial features from endophytic bacteria are limited to traditional confrontation methods. In this study, a MALDI mass spectrometry-based approach was performed to identify and characterize the antifungal molecules from Bacillus velezensis M1 and Bacillus amyloliquefaciens M2 grapevine endophytic strains. Solid medium antagonism assays were performed confronting B. velezensis M1 - L. theobromae and B. amyloliquefaciens M2 - L. theobromae for antifungal lipopeptides identification. By a MALDI TOF MS it was possible identify mass spectra for fengycin, iturin and surfactin protoned isoforms. Masses spectrums for mycobacillin and mycosubtilin were also identified. Using MALDI Imaging MS we were able to visualize and relate lipopeptides mass spectra of fengycin (1463.9 m/z) and mycobacillin (1529.6 m/z) in the interaction zone during confrontations. The presence of lipopeptides-synthesis genes was confirmed by PCR. Liquid medium antagonism assays were performed for a proteomic analysis during the confrontation of B. velezensis M1 - L. theobromae. Different peptide sequences corresponding to many antifungal proteins and enzymes were identified by MALDI TOF MS/MS. Oxalate decarboxylase bacisubin and flagellin, reported as antifungal proteins, were identified at 99 % identity through peptide mapping. MALDI mass spectrometry-based identification of antifungal molecules would allow the early selection of endophytic bacteria with antifungal features. This omics tool could lead to measures for prevention of grapevine diseases and other economically important crops in Peru.

Identification of Secondary Metabolites from the Mangrove-Endophyte Lasiodiplodia iranensis F0619 by UPLC-ESI-MS/MS

Lasiodiplodia is a widely distributed fungal genus, frequently found in tropical and subtropical regions where it can cause disease in important crops. It represents a promising source of active secondary metabolites with uses in chemical, pharmaceutical, and agrochemical processes. In this study, the strain Lasiodiplodia iranensis F0619 was isolated from the mangrove Avicennia ger-minans, collected from Sarigua National Park in the Republic of Panama. Fractions of crude extract were analyzed by UPLC-ESI-MS/MS, and five compounds, previously reported from Lasiodiplodia genus were identified, including 11,12-didehydro-7-iso-jasmonic acid (1), 4,5-didehydro-7-iso-jasmonic acid (2), cyclo-(L-Leu-L-Pro) (3), jasmonate-threonine (4), and abscisic acid (5). We describe and analyze their MS/MS fragmentation patterns to confirm the compounds 'chemical structures.

Lasiodiplodia regiae sp. nov.: A New Species Causing Canker and Dieback of Fruit Trees in China

Canker and dieback are serious fungal diseases of woody plants that can cause huge economic losses to orchards. The purpose of this study was to classify and assess the pathogenicity of fungal species associated with canker and dieback on fruit trees growing in Henan Province, China. In total, 150 isolates of Botryosphaeriaceae were obtained from six different fruit trees exhibiting typical symptoms of stem canker, branch dieback, and gummosis. Morphological examinations and phylogenetic analysis of ITS, tef1, tub2, and rpb2 revealed two Botryosphaeriaceae species, which are Botryosphaeria dothidea and a novel species, Lasiodiplodia regiae, respectively. Using Koch's postulates, we confirmed that the different isolates of L. regiae can cause disease in their original hosts. The pathogenicity tests showed that L. regiae can cause canker, dieback, and gummosis symptoms in four different hosts, indicating a relatively wider host range. Moreover, 10 L. regiae isolates exhibited similar symptoms but different levels of virulence on shoots of peach trees under field conditions. This study demonstrated that L. regiae was a new causal agent of canker and dieback of six fruit tree species, which could be a serious risk to the orchard industry in China. Furthermore, the findings provide a foundation for further epidemiological studies and the development of management strategies.

Re-Evaluating Botryosphaeriales: Ancestral State Reconstructions of Selected Characters and Evolution of Nutritional Modes

Botryosphaeriales (Dothideomycetes, Ascomycota) occur in a wide range of habitats as endophytes, saprobes, and pathogens. The order Botryosphaeriales has not been subjected to evaluation since 2019 by Phillips and co-authors using phylogenetic and evolutionary analyses. Subsequently, many studies introduced novel taxa into the order and revised several families separately. In addition, no ancestral character studies have been conducted for this order. Therefore, in this study, we re-evaluated the character evolution and taxonomic placements of Botryosphaeriales species based on ancestral character evolution, divergence time estimation, and phylogenetic relationships, including all the novel taxa that have been introduced so far. Maximum likelihood, maximum parsimony, and Bayesian inference analyses were conducted on a combined LSU and ITS sequence alignment. Ancestral state reconstruction was carried out for conidial colour, septation, and nutritional mode. Divergence times estimates revealed that Botryosphaeriales originated around 109 Mya in the early epoch of the Cretaceous period. All six families in Botryosphaeriales evolved in the late epoch of the Cretaceous period (66-100 Mya), during which Angiosperms also appeared, rapidly diversified and became dominant on land. Families of Botryosphaeriales diversified during the Paleogene and Neogene periods in the Cenozoic era. The order comprises the families Aplosporellaceae, Botryosphaeriaceae, Melanopsaceae, Phyllostictaceae, Planistromellaceae and Saccharataceae. Furthermore, current study assessed two hypotheses; the first one being "All Botryosphaeriales species originated as endophytes and then switched into saprobes when their hosts died or into pathogens when their hosts were under stress"; the second hypothesis states that "There is a link between the conidial colour and nutritional mode in botryosphaerialean taxa". Ancestral state reconstruction and nutritional mode analyses revealed a pathogenic/saprobic nutritional mode as the ancestral character. However, we could not provide strong evidence for the first hypothesis mainly due to the significantly low number of studies reporting the endophytic botryosphaerialean taxa. Results also showed that hyaline and aseptate conidia were ancestral characters in Botryosphaeriales and supported the relationship between conidial pigmentation and the pathogenicity of Botryosphaeriales species.

Pest categorisation of Lasiodiplodia pseudotheobromae

The EFSA Plant Health Panel performed a pest categorisation of Lasiodiplodia pseudotheobromae, a clearly defined fungus of the family Botryosphaeriaceae, which was first described in 2008 as a cryptic species within the L. theobromae complex. The pathogen affects a wide range of woody perennial crops and ornamental plants causing root rot, damping-off, leaf spots, twig blight, cankers, stem-end rot, gummosis, branch dieback and pre- and post-harvest fruit rots. Lasiodiplodia pseudotheobromae is present in Africa, Asia, North and South America and Oceania and has also been reported from Spain with a restricted distribution. However, there is uncertainty on the status of the pathogen worldwide and in the EU because in the past, when molecular tools (particularly multigene phylogenetic analysis) were not available, the pathogen might have been misidentified as L. theobromae. Lasiodiplodia pseudotheobromae is not included in Commission Implementing Regulation (EU) 2019/2072 and there are no interceptions in the EU. Because of the very wide host range of the pathogen, this pest categorisation focused on those hosts for which there is robust evidence that the pathogen was formally identified by a combination of morphology, pathogenicity and multilocus sequence analysis. Plants for planting, including seeds, fresh fruits and bark and wood of host plants as well as soil and other plant-growing media are the main pathways for the further entry of the pathogen into the EU. Host availability and climate suitability factors occurring in parts of the EU are favourable for the further establishment of the pathogen. In the area of its present distribution, including Spain, the pathogen has a direct impact on cultivated hosts. multilocus measures are available to prevent the further introduction and spread of the pathogen into the EU. Lasiodiplodia pseudotheobromae satisfies the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest.

Lasiodiplodia iraniensis, a New Causal Agent of Tuber Rot on Yam (Dioscorea Species) Imported into the United States and Implications for Quarantine Decisions

One negative consequence of international trade of agricultural commodities is the inadvertent global spread of crop diseases. Yam (Dioscorea spp.) is a staple food crop in many countries and is traded globally. Most of the commercially traded yams in the United States are imported. In late 2020, samples of yam tubers from a commercial facility were submitted to the plant diagnostic clinic at the UF/IFAS Tropical Research and Education Center in Homestead, Florida. Samples showed rotten symptoms and were drawn from lots that were marked to be destroyed because the source of the rotting symptoms was unknown. Preliminary isolation showed that a fungus was consistently associated with the symptoms and was confirmed in the subsequent pathogenicity test as the causal agent. The fungus grew profusely on potato dextrose agar (PDA) with highly melanized hyphae. Matured conidia showed longitudinal striations. Based on its growth pattern and morphology, it was suspected that this fungus may be in the genus Lasiodiplodia. DNA-based identification using partial sequences of the internal transcribed spacer (ITS), β-tubulin (TUB2), 28S rDNA (LSU), and elongation factor alpha (EF1-α) genes confirmed the identity of the isolates as Lasiodiplodia iraniensis Abdollahz., Zare & A.J.L. Phillips (synonym: L. iranensis). This is the first report of L. iraniensis affecting yam and has implications for international trade. This finding will provide an important foundation for making quarantine decisions to prevent spread of this disease.

Taxonomy and Phylogeny of Fungi Associated with Mangifera indica from Yunnan, China

During investigations of saprobic fungi associated with mango (Mangifera indica) in Baoshan and Honghe of Yunnan Province (China), fungal taxa belonging to the orders Botryosphaeriales, Calosphaeriales, Chaetothyriales, Diaporthales, and Xylariales were recorded. Morphological examinations coupled with phylogenetic analyses of multigene sequences (ITS, LSU, SSU, tef1-α, rpb1, rpb2, β-tubulin and CAL) were used to identify the fungal taxa. A new genus viz. Mangifericola, four new species viz. Cyphellophora hongheensis, Diaporthe hongheensis, Hypoxylon hongheensis, and Mangifericola hongheensis, four new host and geographical records viz. Aplosporella artocarpi, Hypomontagnella monticulosa, Paraeutypella citricola and Pleurostoma ootheca, and two new collections of Lasiodiplodia are reported.

Metagenomic nanopore sequencing versus conventional diagnosis for identification of the dieback pathogens of mango trees

Dieback is one of the most dangerous fungal diseases affecting mango trees. In this study, nanopore metagenome sequencing of the root-soil samples and infected plant tissues was conducted to identify the fungal pathogens present. Soil analysis of the infected mango trees showed the abundance of the Dikarya subkingdom (59%) including Lasiodiplodia theobromae (15%), Alternaria alternata (6%), Ceratocystis huliohia and Colletotrichum gloeosporioides. Analysis of the infected plant tissues revealed the presence of A. alternata (34%). The data were deposited in the National Center of Biotechnology Information (PRJNA767267). In conclusion, nanopore metagenome sequencing analysis was a valuable tool to rapidly identify dieback-associated fungal pathogens.

Diversity among Lasiodiplodia Species Causing Dieback, Root Rot and Leaf Spot on Fruit Trees in Egypt, and a Description of Lasiodiplodia newvalleyensis sp. nov

Lasiodiplodia (family Botryosphaeriaceae) is a widely distributed fungal genus that causes a variety of diseases in tropical and subtropical regions. During 2020−2021, a routine survey of fruit tree plants was conducted in five Egyptian Governorates, and fresh samples exhibiting dieback, decline, leaf spot and root rot symptoms were collected. Collection from eight different symptomatic leaves, twigs, branches and roots of fruit trees yielded 18 Lasiodiplodia-like isolates. The sequencing data from the internal transcribed spacer region (ITS), partial translation elongation factor 1-alpha (tef1-a) and β-tubulin (tub2) were used to infer phylogenetic relationships with known Lasiodiplodia species. Two isolates obtained from black necrotic lesions on Phoenix dactylifera leaves were identified as a putative novel species, L. newvalleyensis sp. nov., and were thus subjected to further morphological characterization. The results of isolation and molecular characterization revealed that L. theobromae (n = 9) was the most common species on Mangifera indica, Citrus reticulata, C. sinensis, Ficus carica, Prunus persica, Prunus armeniaca and Pyrus communis trees. Lasiodiplodia pseudotheobromae (n = 5) was isolated from M. indica, Prunus persica and C. sinensis. Lasiodiplodia laeliocattleyae (n = 2) was isolated from C. reticulata. Pathogenicity test results suggested that all Lasiodiplodia species were pathogenic to their hosts. The present study is considered the first to characterize and decipher the diversity of Lasiodiplodia species associated with fruit trees in Egypt, using the multi-locus ITS, tef1-a and tub2 sequence data, along with morphological and pathogenic trials. To our knowledge, this is the first report of L. newvalleyensis on Phoenix dactylifera and L. laeliocattleya on C. reticulata in Egypt and worldwide.

Diversity of Endophytes in the Botryosphaeriaceae Differs on Anacardiaceae in Disturbed and Undisturbed Ecosystems in South Africa

Botryosphaeriaceae represents a diverse family of fungi with a cosmopolitan distribution and a wide host range. We studied species diversity and overlap of Botryosphaeriaceae on selected tree species of Anacardiaceae in disturbed (farming or forestry) and undisturbed (isolated and/or protected) ecosystems in the Limpopo and Mpumalanga provinces, South Africa. The disturbed sites resided at Tshikundamalema and Tshipise in Limpopo and the undisturbed sites at Nwanedi and the Mapungubwe National Park in Limpopo and the Kruger National Park in Mpumalanga. Asymptomatic branches were collected from Mangifera indica, Sclerocarya birrea and Lannea schweinfurthii trees in 2017 and 2018. Eleven species were identified using a multi-gene sequencing approach, including Diplodia allocellula, Dothiorella brevicollis, Do. dulcispinae, Do. viticola, Lasiodiplodia crassispora, L. exigua, L. gonubiensis, L. mahajangana, Neofusicoccum parvum, Oblongocollomyces sp. 1 and Oblongocollomyces sp. 2. Ten of the 11 species were identified in undisturbed ecosystems (eight species being unique), while only three species were identified in disturbed ecosystems (one species being unique). Two species were generalists on trees in disturbed and undisturbed ecosystems. Lasiodiplodia mahajangana was the most dominant species as it occurred on the three tree species of Anacardiaceae. Isolates of N. parvum occurred on both S. birrea (a native species) and M. indica (a non-native species) that occurred adjacent to each other in disturbed ecosystems, confirming the ability of this invasive pathogen to cross-infect native and non-native hosts and its abundance in human-disturbed environments. The findings from this study confirm the lack of host specificity for most species of Botryosphaeriaceae. The results also indicate that disturbance through human activity, such as clear-cutting, selective cutting and land-use changes, negatively influences the diversity of the Botryosphaeriaceae.

Morphomolecular and cultural characteristics and host range of Lasiodiplodia theobromae causing stem canker disease in dragon fruit

Dragon fruit (Hylocereus polyrhizus) is an economically promising fruit in Bangladesh. The cultivation of dragon fruit has increased fourfold within a decade due to its popularity. Recently, a new disease known as stem canker was reported in some plantations of dragon fruit in Bangladesh, which forced some farmers to abandon their cultivation. This study aimed to explore the morphological, molecular, and cultural characteristics as well as host range of the causal agent associated with this destructive disease. Morphologically similar eight fungal isolates were recovered from eight canker symptomatic dragon fruit stems. Among them, two isolates (namely BU-DLa 01 and BU-DLa 02) were used for a detailed study. Morphological parameters and phylogeny of sequence data of internal transcribed spacer (ITS1, 5.8S rRNA, and ITS2), β-tubulin, and translation elongation factor 1-α identified the isolates as Lasiodiplodia theobromae. The cultural features were studied hinged on the growth of the two isolates on various media, temperature, and pH. Though the mycelial growth of the fungi was supported by all the media tested, potato dextrose agar was the most suitable one for both isolates. The fungi thrived well at a temperature of 25-35°C and 5.5-6.5 pH. Inoculation trials of dragon fruit stem ascertained Koch's postulate. In host range test, the isolates were found pathogenic toward mango, guava, banana, and the fruits of dragon fruit. These data will contribute not only to understanding the biology of L. theobromae as a newly recognized pathogen of H. polyrhizus but also will help in designing a proper management package against this pathogen.

Medicinal potentialities and pathogenic profile of Lasiodiplodia genus

Considering that current biotechnological advances have been contributing towards improving the well-being of humanity, endophytic fungi, such as Lasiodiplodia, are promising sources of new substances to be used in chemical, pharmaceutical and agrochemical processes. Bioactive secondary metabolites are examples of such substances, although it is widely known that Lasiodiplodia inflicts irreparable damage to several crops of major economic importance. They are often produced as a response against biotic and abiotic factors, thus revealing that they play different roles, such as in signaling and defense mechanisms. Therefore, this review presents a few subtle differences between pathogenicity and mutualistic endophyte-host interactions. Moreover, the main secondary metabolites produced by Lasiodiplodia endophytes have been described with respect to their relevant antimicrobial and cytotoxic activities.

Palm Foliage as Pathways of Pathogenic Botryosphaeriaceae Fungi and Host of New Lasiodiplodia Species from Mexico

Tropical palm foliage is increasingly imported to satisfy the steady growing demand in European floristry. This palm foliage presumably carries along diverse fungi whose taxonomic and functional diversity have not been addressed so far. The present study investigated Botryosphaeriaceae fungi associated with the foliage of palm species Chamaedorea elegans, C. metallica, C. seifrizii, Dypsis lutescens and Lodoicea maldivica imported from Mexico. Five species were identified using combined morphological characterisation and multilocus phylogenetic analyses based on ITS, TEF-1α, TUB2 and RPB2. In addition to Endomelanconiopsis endophytica, Lasiodiplodia brasiliensis and L. euphorbicola, two new species, namely, L. lodoiceae sp. nov. and L. mexicanensis sp. nov, are proposed. Apart from E. endophytica, mostly known as endophyte, L. brasiliensis and L. euphorbicola are responsible for different rot diseases and the dieback of important tropical crop plants. In pathogenicity tests on the temperate pome fruits apple (Malus domestica) and pear (Pyrus communis), all six Botryosphaeriaceae species induced necrotic lesions at different degrees of severity, with highest the aggressiveness from L. euphorbicola and L. mexicanensis on apple and from L. mexicanensis on pear. The results indicate that tropical palm foliage can be a pathway of potentially pathogenic fungi that may give rise to concerns with regard to plant health in the destination countries.

Association of Lasiodiplodia theobromae with die-back and decline of nutmeg as revealed through phenotypic, pathogenicity and phylogenetic analyses

Lasiodiplodia theobromae is a cosmopolitan pathogen geographically widespread in tropics and subtropics inciting economically important diseases on diverse plant genera. In the present study, Lasiodiplodia theobromae associated with nutmeg exhibiting die-back and declining symptoms was identified and characterized by adopting a polyphasic approach. The disease was characterized with the symptoms including general decline, water-soaking patches on branches and tree trunk, die-back of branches, necrotic lesions beneath water-soaked lesions and necrosis of vascular tissues. The isolates representing diverse nutmeg growing tracts were initially identified as Lasiodiplodia species based on macro- and micro-morphological characteristics. Subsequent analyses of internal transcribed spacer (ITS), partial elongation factor 1-alpha (EF1-α) and β-tubulin (β-tub) genes identified the pathogen as Lasiodiplodia theobromae. Pathogenicity studies were proved on nutmeg twigs and branches (in vitro) as well as on saplings (in vivo). The present investigation enunciated the association of Lasiodiplodia theobromae with die-back and decline of nutmeg employing a polyphasic approach which warrants further investigations on its spatio-temporal distribution, pathogen diversity, weather-host-pathogen interaction and formulating prospective disease management strategies.

Multigene Phylogenetics and Morphology Reveal Five Novel Lasiodiplodia Species Associated with Blueberries

Botryosphaeriaceous fungi cause stem blight, canker and dieback in woody plants. During a survey on the fungal pathogens associated with blueberries in China, 135 blighted, cankered or dead blueberry branches were collected from Fujian and Shandong Provinces. Based on the morphological characterization and phylogenetic analyses of a concatenated ITS rDNA, tef1-α, TUB, and RPB2 loci, five new species of Lasiodiplodia, viz., L. clavispora, L. fujianensis, L. henanica, L. nanpingensis and L. paraphysoides were recognized. Detailed descriptions and illustrations, as well as multigene phylogenies, are provided in this paper. The diversity of plant pathogens on agriculturally and economically important plants is higher than anticipated.

Seed Banks as Incidental Fungi Banks: Fungal Endophyte Diversity in Stored Seeds of Banana Wild Relatives

Seed banks were first established to conserve crop genetic diversity, but seed banking has more recently been extended to wild plants, particularly crop wild relatives (CWRs) (e.g., by the Millennium Seed Bank (MSB), Royal Botanic Gardens Kew). CWRs have been recognised as potential reservoirs of beneficial traits for our domesticated crops, and with mounting evidence of the importance of the microbiome to organismal health, it follows that the microbial communities of wild relatives could also be a valuable resource for crop resilience to environmental and pathogenic threats. Endophytic fungi reside asymptomatically inside all plant tissues and have been found to confer advantages to their plant host. Preserving the natural microbial diversity of plants could therefore represent an important secondary conservation role of seed banks. At the same time, species that are reported as endophytes may also be latent pathogens. We explored the potential of the MSB as an incidental fungal endophyte bank by assessing diversity of fungi inside stored seeds. Using banana CWRs in the genus Musa as a case-study, we sequenced an extended ITS-LSU fragment in order to delimit operational taxonomic units (OTUs) and used a similarity and phylogenetics approach for classification. Fungi were successfully detected inside just under one third of the seeds, with a few genera accounting for most of the OTUs-primarily Lasiodiplodia, Fusarium, and Aspergillus-while a large variety of rare OTUs from across the Ascomycota were isolated only once. Fusarium species were notably abundant-of significance in light of Fusarium wilt, a disease threatening global banana crops-and so were targeted for additional sequencing with the marker EF1α in order to delimit species and place them in a phylogeny of the genus. Endophyte community composition, diversity and abundance was significantly different across habitats, and we explored the relationship between community differences and seed germination/viability. Our results show that there is a previously neglected invisible fungal dimension to seed banking that could well have implications for the seed collection and storage procedures, and that collections such as the MSB are indeed a novel source of potentially useful fungal strains.

What Do We Know about Botryosphaeriaceae? An Overview of a Worldwide Cured Dataset

Botryosphaeriaceae-related diseases occur worldwide in a wide variety of plant hosts. The number of studies targeting the distribution, diversity, ecology, and pathogenicity of Botryosphaeriaceae species are consistently increasing. However, with the lack of consistency in species delimitation, the name of hosts, and the locations of studies, it is almost impossible to quantify the presence of these species worldwide, or the number of different host–fungus interactions that occur. In this review, we collected and organized Botryosphaeriaceae occurrences in a single cured dataset, allowing us to obtain for the first time a complete perspective on species’ global diversity, dispersion, host association, ecological niches, pathogenicity, communication efficiency of new occurrences, and new host–fungus associations. This dataset is freely available through an interactive and online application. The current release (version 1.0) contains 14,405 cured isolates and 2989 literature references of 12,121 different host–fungus interactions with 1692 different plant species from 149 countries.

Terroir Is the Main Driver of the Epiphytic Bacterial and Fungal Communities of Mango Carposphere in Reunion Island

The diversity of both bacterial and fungal communities associated with mango surface was explored using a metabarcoding approach targeting fungal ITS2 and bacterial 16S (V3-V4) genomic regions. Fruits were collected in Reunion Island from two different orchards according to a sampling method which allowed the effect of several pre-harvest factors such as geographical location (terroir), cultivars, fruit parts, tree position in the plot, fruit position on the tree (orientation and height), as well as the harvest date to be investigated. A total of 4,266,546 fungal and 2,049,919 bacterial reads were recovered then respectively assigned to 3,153 fungal and 24,087 to bacterial amplicon sequence variants (ASVs). Alpha and beta diversity, as well as differential abundance analyses revealed variations in both bacterial and fungal communities detected on mango surfaces depended upon the studied factor. Results indicated that Burkholderiaceae (58.8%), Enterobacteriaceae (5.2%), Pseudomonadaceae (4.8%), Sphingomonadaceae (4.1%), Beijerinckiaceae (3.5%), and Microbacteriaceae (3.1%) were the dominant bacterial families across all samples. The majority of fungal sequences were assigned to Mycosphaerellaceae (34.5%), Cladosporiaceae (23.21%), Aureobasidiaceae (13.09%), Pleosporaceae (6.92%), Trichosphaeriaceae (5.17%), and Microstromatales_fam_Incertae_sedis (4.67%). For each studied location, mango fruit from each cultivar shared a core microbiome, and fruits of the same cultivar harvested in two different locations shared about 80% fungal and bacterial family taxa. The various factors tested in this study affected bacterial and fungal taxa differently, suggesting that some taxa could act as geographical (terroir) markers and in some cases as cultivar fingerprints. The ranking of the factors investigated in the present study showed that in decreasing order of importance: the plot (terroir), cultivar, fruit parts, harvest date and the position of the fruits are respectively the most impacting factors of the microbial flora, when compared to the orientation and the fruit position (height) on the tree. Overall, these findings provided insights on both bacterial and fungal diversity associated with the mango surface, their patterns from intra-fruit scale to local scale and the potential parameters shaping the mango microbiota.

Variation in Botryosphaeriaceae from Eucalyptus plantations in YunNan Province in southwestern China across a climatic gradient

The Botryosphaeriaceae accommodates many important pathogens of woody plants, including Eucalyptus. Recently, Botryosphaeriaceae were isolated from diseased plant parts from surveys of Eucalyptus plantations in the YunNan Province, China. The aims of this study were to identify these Botryosphaeriaceae isolates and to evaluate their pathogenicity to Eucalyptus. A total of 166 isolates of Botryosphaeriaceae were obtained from six regions in the YunNan Province, of which 76 were from Eucalyptus urophylla × E. grandis hybrids, 49 from E. globulus trees, and 41 isolates were from other unknown Eucalyptus species or hybrids. Isolates were identified by comparing DNA sequences of the internal transcribed spacer ribosomal RNA locus (ITS), partial translation elongation factor 1-alpha (tef1), β-tubulin 2 (tub2) and DNA-directed RNA polymerase II subunit (rpb2) genes, and combined with their morphological characteristics. Eleven species were identified, including Botryosphaeria fusispora, B. wangensis, Lasiodiplodia pseudotheobromae, Neofusicoccum kwambonambiense, N. parvum, and six novel species described as B. puerensis, N. dianense, N. magniconidium, N. ningerense, N. parviconidium and N. yunnanense. The dominant species across the regions were N. yunnanense, N. parvum and B. wangensis, representing 31.3, 25.3 and 19.9% of the total isolates, respectively. Species diversity and composition changed across the different climatic zones, despite their relatively close geographic proximity and the fact that some of the species have a global distribution. All the Botryosphaeriaceae species were pathogenic to one-year-old plants of an E. urophylla × E. grandis clone and E. globulus seed-derived plants, but showed significant inter- and intra-species variation in aggressiveness amongst isolates. The study provides a foundation for monitoring and management of Botryosphaeriaceae through selection and breeding of Eucalyptus in the YunNan Province of southwestern China.

First Report of Dieback Caused by Lasiodiplodia pseudotheobromae on Ormosia pinnata in China

Ormosia pinnata (Lour.) Merr. is an important tree used for landscape and plant recovery of barren slopes in China. During an investigation of plant disease on landscape trees in 2018, a dieback was observed on O. pinnata trees in Guangzhou, Guangdong Province, China. Symptoms were characterized by initial dryness of the twigs and eventual death of the whole branch of the tree. Isolations from symptomatic branches yielded 13 isolates including two main morphotypes. Pathogenicity tests showed that isolate GDOP1 from Type I caused dieback of O. pinnata. Based on morphological characteristics and molecular analysis of the internal transcribed spacer rDNA (ITS1-5.8S-ITS2) and partial sequence of the translation elongation factor 1α (EF1-α), the fungus causing dieback on O. pinnata was identified as Lasiodiplodia pseudotheobromae. This is the first report of L. pseudotheobromae infecting O. pinnata in the world.

First report of Lasiodiplodia pseudotheobromae keratitis susceptible to voriconazole in an Indian mango grower

The family Botriosphaeriacea comprises cosmopolitan endophytic fungi and many of the genera have frequently been implicated in causing human infections, including subcutaneous infection, sinusitis, invasive mycoses and keratitis. Among them, the genus Lasiodiplodia, which contains >30 species, is grouped as coelomycetous fungi with prototype species Lasiodiplodia theobromae as an important cause of keratitis. Several cryptic species morphologically resembling L. theobromae exist, one of which is Lasiodiplodia pseudotheobromae. We present a rare case of mycotic keratitis in an Indian mango grower following penetrating trauma to the left eye. Direct microscopy revealed retractile hyphal elements, and fungal cultures yielded a dematiaceous mould which was confirmed by sequencing as L. pseudotheobromae. Antifungal susceptibility testing revealed low MICs to amphotericin B and voriconazole and increased MICs to itraconazole and posaconazole. This is the first report of phytopathogenic L. pseudotheobromae keratitis, successfully treated with 2 % voriconazole without keratoplasty.

Lasiodiplodia theobromae-induced alteration in ROS metabolism and its relation to gummosis development in Prunus persica

Peach gummosis caused by Lasiodiplodia theobromae is one of the most detrimental diseases to peaches in southern China. Reactive oxygen species (ROS) play major roles in plant-pathogen interactions, however, their roles in the pathogenesis of peach gummosis, especially shoot disease in perennials, are largely unknown. In this study, the effects of L. theobromae on ROS production-scavenging systems and on signalling transduction during L. theobromae-induced gummosis in current-year peach shoots were investigated. The infection by L. theobromae led to a ROS burst and activated the plant antioxidant enzyme-dependent scavenging system. With disease progression, the capacity of the plant antioxidant machinery declined, and allowed for ROS accumulation and eventual malondialdehyde production. As for the fungus L. theobromae, the transcripts of genes related to ROS production were significantly repressed, and concomitantly the expression of genes related to antioxidant systems and oxidative stress resistance was markedly upregulated, perhaps to alleviate oxidative stress for successful colonisation. Moreover, genes involved in phytohormones biosynthesis and pathogenesis-related proteins were all markedly promoted, which could contribute to the restriction of disease development in peach shoots. Overall, the results showed that the ROS production-scavenging system in P. persica might affect disease development during peach-L. theobromae interaction. Our findings lay the foundations for future in-depth investigations of the molecular mechanisms and regulatory networks underlying L. theobromae-mediated shoot diseases in terms of ROS production-scavenging systems.

Lasiodiplodia mitidjana sp. nov. and other Botryosphaeriaceae species causing branch canker and dieback of Citrus sinensis in Algeria

Several Botryosphaeriaceae species are known to occur worldwide, causing dieback, canker and fruit rot on various hosts. Surveys conducted in ten commercial citrus orchards in the northern region of Algeria revealed five species of Botryosphaeriaceae belonging to three genera associated with diseased trees. Morphological and cultural characteristics as well as phylogenetic analyses of the internal transcribed spacer (ITS) region and the translation elongation factor 1-alpha (tef1-α) identified Diplodia mutila, Diplodia seriata, Dothiorella viticola, Lasiodiplodia mediterranea and a novel species which is here described as Lasiodiplodia mithidjana sp. nov.. Of these, L. mithidjana (14.1% of the samples) and L. mediterranea (13% of the samples) were the most widespread and abundant species. Pathogenicity tests revealed that L. mediterranea and D. seriata were the most aggressive species on citrus shoots. This study highlights the importance of Botryosphaeriaceae species as agents of canker and dieback of citrus trees in Algeria.

Botryosphaeriaceae Fungi as Causal Agents of Dieback and Corky Bark in Rambutan and Longan

Fungi in the Botryosphaeriaceae family cause dieback, fruit rots, and stem cankers in many tropical fruit trees. To identify which species of Botryosphaeriaceae were present in tropical fruit in Puerto Rico and the symptoms they cause in rambutan and longan, a disease survey was conducted throughout the island from 2008 to 2016. Diseased organs of rambutan, longan, mango, and tangerine were collected and 39 isolates belonging to the Botryosphaeriaceae family were isolated and identified. Phylogenetic analysis of three nuclear genes identified nine species: six Lasiodiplodia spp. and three Neofusicoccum spp. All 39 isolates were inoculated on healthy 1-year-old rambutan and longan seedlings to confirm their pathogenicity. Dieback on both rambutan and longan was observed at 14 days after inoculation (DAI). Fourteen isolates from seven Botryosphaeriaceae species (Lasiodiplodia brasiliensis, L. hormozganensis, L. iraniensis, L. pseudotheobromae, L. theobromae, Neofusicoccum batangarum, and N. parvum) caused dieback in rambutan. Five of these pathogenic isolates were collected from rambutan, four from longan, two from mango, and three from tangerine. Ten isolates of four Lasiodiplodia spp. caused dieback in longan: L. hormozganensis, L. iraniensis, L. pseudotheobromae and L. theobromae,. Of these, three were collected from rambutan, three from longan, one from mango, and three from tangerine. Abundant development of pycnidia on branches, called corky bark, were observed on both rambutan and longan 60 DAI. Cross-inoculations showed that pathogenicity is wide in spectrum, indicating that different planting alternatives should be considered for better crop management.

Botryosphaeriaceae associated with Acacia heterophylla (La Réunion) and Acacia koa (Hawaii)

Acacia koa and A. heterophylla are commonly occurring native trees on the Hawaiian Islands and La Réunion, respectively. A recent phylogenetic study suggested that A. heterophylla renders A. koa paraphyletic, and that the former likely arose from the Hawaiian Islands around 1.4 million years ago. An intriguing question is whether their microbiota is similar, although they occur naturally in two very distant geographical locations. In this study, we compared the fungi in the Botryosphaeriaceae isolated from natural populations of A. koa and A. heterophylla. These fungi were chosen because they commonly occur on woody plants and some are important pathogens. They are also known to have been moved globally on asymptomatic plant materials. Isolates were identified based on comparisons of DNA sequence data for the rDNA-ITS, TEF1-α and β-tubulin loci. Ten Botryosphaeriaceae species were identified, of which four species were specific to A. koa from the Hawaiian Islands and five to A. heterophylla in La Réunion. Only one species, Neofusicoccumparvum, which is known to have a wide global distribution, was common to both hosts. The overall results of this study suggest that although A. koa and A.heterophylla share a recent evolutionary history, they have established independent microbiota, at least in terms of the Botryosphaeriaceae.

Phylogeny, Distribution, and Pathogenicity of Lasiodiplodia Species Associated With Cankers and Dieback Symptoms of Persian Lime in Mexico

Persian lime (Citrus latifolia Tan.) is an important and widely cultivated fruit crop in several regions of Mexico. In recent years, severe symptoms of gummosis, stem cankers, and dieback were detected in the Persian lime-producing region in the states of Veracruz and Puebla, Mexico. The aims of this study were to identify the species of Lasiodiplodia associated with these symptoms, determine the distribution of these species, and test their pathogenicity and virulence on Persian lime plants. In 2015, symptomatic samples were collected from 12 commercial Persian lime orchards, and 60 Lasiodiplodia isolates were obtained. Fungal identification of 32 representative isolates was performed using a phylogenetic analysis based on DNA sequence data of the internal transcribed spacer region and part of the translation elongation factor 1-α and β-tubulin genes. Sequence analyses were carried out using the Maximum Likelihood and Bayesian Inference methods. Six Lasiodiplodia species were identified as Lasiodiplodia pseudotheobromae, Lasiodiplodia theobromae, Lasiodiplodia brasiliense, Lasiodiplodia subglobosa, Lasiodiplodia citricola, and Lasiodiplodia iraniensis. All Lasiodiplodia species of this study are reported for the first time in association with Persian lime in Mexico and worldwide. L. pseudotheobromae (46.9% of isolates) was the most frequently isolated species followed by L. theobromae (28.1%) and L. brasiliense (12.5%). Pathogenicity on Persian lime young plants using a mycelial plug inoculation method showed that all identified Lasiodiplodia species were able to cause necrotic lesions and gummosis, but L. subglobosa, L. iraniensis, and L. pseudotheobromae were the most virulent.

Characterization of phytotoxin and secreted proteins identifies of Lasiodiplodia theobromae, causes of peach gummosis

Lasiodiplodia theobromae, a phytopathogenic fungus that causes peach gummosis, is considered one of the major constraints to peach production worldwide. Here, we report the characteristics of toxic metabolites and the proteomics investigation of the secreted proteins of L. theobromae from its in vitro culture. The phytotoxins of L. theobromae from the culture filtrate of Richard's liquid medium showed high toxicity on peach current year shoots with large lesion diameter and high gum weight. The toxicity measurement showed that 23.6 and 21.2 mg gum were induced from peach shoots by solvent fractions of ethyl acetate and dichloromethane, respectively, with significant differences from other organic solvents. A total of 23 proteins were identified by liquid chromatography-mass spectrometry from the in vitro secretome of L. theobromae. Sequence analysis indicated that 14 proteins were extracellular proteins based on signal peptides and localization. The expression profiles of the analyzed fungal genes were significantly upregulated from 1 day postinoculation (dpi) to 2 dpi, indicating that the early stage is an important stage for the infection of L. theobromae. The present study has provided insights into the extracellular phytotoxins and secreted proteins that are possibly associated with pathogenicity of the peach gummosis.

Fruit Stem-End Rot

After harvest, the fruit ripens and stem-end rot (SER) starts to develop, leading to significant fruit losses. SER is caused by diverse pathogenic fungi that endophytically colonize the stem during fruit development in the orchard or field and remain quiescent until the onset of fruit ripening. During the endophytic-like stage, the pathogenic fungus colonizes the phloem and xylem of the fruit stem-end; after fruit ripening, the fungus converts to a necrotrophic lifestyle, while colonizing the fruit parenchyma, and causes SER. The fruit stem-end is colonized not only by pathogenic fungi, but also by various nonpathogenic endophytic microorganisms, including fungi, yeast and bacteria. However, little is known about the fruit stem-end endophytic microbiome, which could contain new and existing biocontrol agents. To control fruit SER, treatments such as ripening inhibition, harvesting with the stem, application of chemical or biological fungicides, or physical control such as heat treatments, cold storage, or exposure to light have been suggested. This review focuses on the characterization of SER pathogens, the stem-end microbiome, and different pre- and postharvest practices that could control fruit SER.

Lasiodiplodia theobromae as a Producer of Biotechnologically Relevant Enzymes

Phytopathogenic fungi are known to produce several types of enzymes usually involved in plant cell wall degradation and pathogenesis. The increasing of global temperature may induce fungi, such as Lasiodiplodia theobromae (L. theobromae), to alter its behavior. Nonetheless, there is only limited information regarding the effect of temperature on L. theobromae production of enzymes. The need for new, thermostable enzymes, that are biotechnologically relevant, led us to investigate the effect of temperature on the production of several extracellular enzymatic activities by different L. theobromae strains. Fungi were grown at 25 °C, 30 °C and 37 °C and the enzymatic activities were detected by plate assays, quantified by spectrophotometric methods and characterized by zymography. The thermostability (25–80 °C) of the enzymes produced was also tested. Strains CAA019, CBS339.90, LA-SOL3, LA-SV1 and LA-MA-1 produced amylases, gelatinases, caseinases, cellulases, lipases, laccases, xylanases, pectinases and pectin liases. Temperature modulated the expression of the enzymes, and this effect was more visible when fungi were grown at 37 °C than at lower temperatures. Contrary to proteolytic and endoglucanolytic activities, whose highest activities were detected when fungi were grown at 30 °C, lipolytic activity was not detected at this growth temperature. Profiles of proteases and endoglucanases of fungi grown at different temperatures were characterized by zymography. Enzymes were shown to be more thermostable when fungi were grown at 30 °C. Proteases were active up to 50 °C and endoglucanases up to 70 °C. Lipases were the least stable, with activities detected up to 45 °C. The enzymatic profiles detected for L. theobromae strains tested showed to be temperature and strain-dependent, making this species a good target for biotechnological applications.

Botryosphaeriaceae from Eucalyptus plantations and adjacent plants in China

The Botryosphaeriaceae is a species-rich family that includes pathogens of a wide variety of plants, including species of Eucalyptus. Recently, during disease surveys in China, diseased samples associated with species of Botryosphaeriaceae were collected from plantation Eucalyptus and other plants, including Cunninghamina lanceolata, Dimocarpus longan, Melastoma sanguineum and Phoenix hanceana, which were growing adjacent to Eucalyptus. In addition, few samples from Araucaria cunninghamii and Cedrus deodara in two gardens were also included in this study. Disease symptoms observed mainly included stem canker, shoot and twig blight. In this study, 105 isolates of Botryosphaeriaceae were collected from six provinces, of which 81 isolates were from Eucalyptus trees. These isolates were identified based on comparisons of the DNA sequences of the internal transcribed spacer regions and intervening 5.8S nrRNA gene (ITS), and partial translation elongation factor 1-alpha (tef1), β-tubulin (tub), DNA-directed RNA polymerase II subunit (rpb2) and calmodulin (cmdA) genes, the nuclear ribosomal large subunit (LSU) and the nuclear ribosomal small subunit (SSU), and combined with their morphological characteristics. Results showed that these isolates represent 12 species of Botryosphaeriaceae, including Botryosphaeria fusispora, Cophinforma atrovirens, Lasiodiplodia brasiliense, L. pseudotheobromae, L. theobromae and Neofusicoccum parvum, and six previously undescribed species of Botryosphaeria and Neofusicoccum, namely B. pseudoramosa sp. nov., B. qingyuanensis sp. nov., B. wangensis sp. nov., N. hongkongense sp. nov., N. microconidium sp. nov. and N. sinoeucalypti sp. nov. Aside from B. wangensis, C. atrovirens and N. hongkongense, the other nine Botryosphaeriaceae species were isolated from Eucalyptus trees in South China. Botryosphaeria fusispora (26 % of the isolates from Eucalyptus) is the dominant species, followed by L. pseudotheobromae (23 % of the isolates from Eucalyptus). In addition to species found on Eucalyptus trees, we also found B. pseudoramosa on M. sanguineum; B. wangensis on C. deodara; C. atrovirens on D. longan; L. theobromae on C. lanceolata, D. longan and P. hanceana; and N. hongkongense on A. cunninghamii. Pathogenicity tests showed that the 12 species of Botryosphaeriaceae are pathogenic to three Eucalyptus clones and that Lasiodiplodia species are the most aggressive. The results of our study suggest that many more species of the Botryosphaeriaceae remain to be discovered in China. This study also provides confirmation for the wide host range of Botryosphaeriaceae species on different plants.

Detection and Management of Mango Dieback Disease in the United Arab Emirates

Mango is affected by different decline disorders causing significant losses to mango growers. In the United Arab Emirates (UAE), the pathogen was isolated from all tissues sampled from diseased trees affected by Lasiodiplodia theobromae. Symptoms at early stages of the disease included general wilting appearance of mango trees, and dieback of twigs. In advanced stages, the disease symptoms were also characterized by the curling and drying of leaves, leading to complete defoliation of the tree and discolouration of vascular regions of the stems and branches. To substantially reduce the devastating impact of dieback disease on mango, the fungus was first identified based on its morphological and cultural characteristics. Target regions of 5.8S rRNA (ITS) and elongation factor 1-α (EF1-α) genes of the pathogen were amplified and sequenced. We also found that the systemic chemical fungicides, Score®, Cidely® Top, and Penthiopyrad®, significantly inhibited the mycelial growth of L. theobromae both in vitro and in the greenhouse. Cidely® Top proved to be a highly effective fungicide against L. theobromae dieback disease also under field conditions. Altogether, the morphology of the fruiting structures, molecular identification and pathogenicity tests confirm that the causal agent of the mango dieback disease in the UAE is L. theobromae.

Diversity in the Botryosphaeriales: Looking back, looking forward

The Botryosphaeriales are amongst the most widespread, common and important fungal pathogens of woody plants. Many are also known to exist as endophytes in healthy plant tissues. This special issue highlights a number of key themes in the study of this group of fungi. In particular, there have been dramatic taxonomic changes over the past decade; from one family to nine (including two in this special issue) and from 10 to 33 genera known from culture. It is also clear from many studies that neither morphology nor single locus sequence data are sufficient to define taxa. This problem is exacerbated by the increasing recognition of cryptic species and hybrids (as highlighted for the first time in this special issue). It is futile that management strategies, including quarantine, continue to rely on outdated taxonomic definitions and identification tools. This is especially true in light of growing evidence that many species continue to be moved globally as endophytes in plants and plant products. A well defined natural classification and an extensive collection of tools to study the Botryosphaeriaceae, including a growing number of genomes, now provide a springboard for a much deeper exploration of their biology, biogeography and host associations.

Families, genera, and species of Botryosphaeriales

Members of Botryosphaeriales are ecologically diverse, but most commonly associated with leaf spots, fruit and root rots, die-back or cankers of diverse woody hosts. Based on morphology and DNA sequence data, the Botryosphaeriales have to date been shown to contain eight families, with an additional two, Endomelanconiopsisaceae (Endomelanconiopsis) and Pseudofusicoccumaceae (Pseudofusicoccum) being newly described in this study. Furthermore, Oblongocollomyces is introduced as new genus, while Spencermartinsia is reduced to synonymy under Dothiorella. Novel species include Diplodia pyri (Pyrus sp., the Netherlands), Diplodia citricarpa (Citrus sp., Iran), Lasiodiplodia vitis (Vitis vinifera, Italy), L. sterculiae (Sterculia oblonga, Germany), Neofusicoccum pistaciarum (Pistacia vera, USA), N. buxi (Buxus sempervirens, France), N. stellenboschiana (Vitis vinifera, South Africa), and Saccharata hawaiiensis (Protea laurifolia, Hawaii). New combinations are also proposed for Camarosporium pistaciae (associated with fruit rot of Pistacia vera) in Neofusicoccum, and Sphaeria gallae (associated with galls of Quercus) in Diplodia. The combination of large subunit of the nuclear ribosomal RNA gene (LSU)-rpb2 proved effective at delineating taxa at family and generic level. Furthermore, rpb2 also added additional resolution for species delimitation, in combination with ITS, tef1 and tub2. In this study we analysed 499 isolates, and produce an expanded phylogenetic backbone for Botryosphaeriales, which will help to delimit novelties at species, genus and family level in future.

Endophytic Botryosphaeriaceae, including five new species, associated with mangrove trees in South Africa

Little is known regarding the fungi, especially fungal pathogens, associated with mangroves in Africa. This includes fungi in the Botryosphaeriaceae that comprise numerous opportunistic, stress-associated pathogens often associated with trees affected by environmental and anthropogenically generated stresses, such as those affecting mangroves. We investigated the occurrence of endophytic Botryosphaeriaceae along the entire distribution of mangroves in South Africa. Asymptomatic branches were collected from ten localities and six mangrove species. Isolates resembling species of Botryosphaeriaceae were identified based on multi-gene sequence data of the internal transcribed spacer regions (ITS), including the 5.8S nrRNA, the beta-tubulin (tub2), partial translation elongation factor 1-alpha (tef1-α), and DNA-directed RNA polymerase II second largest subunit (rpb2) gene regions. Inoculation trials were conducted on healthy branches of Avicennia marina and Bruguiera gymnorrhiza to evaluate the potential pathogenicity of the collected species. Fourteen species in the Botryosphaeriaceae belonging to four genera, Botryosphaeria, Diplodia, Lasiodiplodia, and Neofusicoccum were collected, including five new species. Neofusicoccum was the most prevalent genus followed by Lasiodiplodia, with species of Diplodia and Botryosphaeria being the least frequent. The inoculation studies revealed that one of the new species, Lasiodiplodia avicenniae is highly pathogenic to A. marina and could pose a threat to the health of these trees.

Phylogenetic species recognition and hybridisation in Lasiodiplodia: A case study on species from baobabs

Lasiodiplodia species (Botryosphaeriaceae, Ascomycota) infect a wide range of typically woody plants on which they are associated with many different disease symptoms. In this study, we determined the identity of Lasiodiplodia isolates obtained from baobab (Adansonia species) trees in Africa and reviewed the molecular markers used to describe Lasiodiplodia species. Publicly available and newly produced sequence data for some of the type strains of Lasiodiplodia species showed incongruence amongst phylogenies of five nuclear loci. We conclude that several of the previously described Lasiodiplodia species are hybrids of other species. Isolates from baobab trees in Africa included nine species of Lasiodiplodia and two hybrid species. Inoculation trials with the most common Lasiodiplodia species collected from these trees produced significant lesions on young baobab trees. There was also variation in aggressiveness amongst isolates from the same species. The apparently widespread tendency of Lasiodiplodia species to hybridise demands that phylogenies from multiple loci (more than two and preferably four or more) are compared for congruence prior to new species being described. This will avoid hybrids being incorrectly described as new taxa, as has clearly occurred in the past.