Genus Phoma Research Articles

Didymella acutilobae sp. nov. Causing Leaf Spot and Stem Rot in Angelica acutiloba

During disease surveys of Angelica acutiloba plants in Korea, leaf spot symptoms were observed in a field in Andong in July 2019, and stem rot symptoms in vinyl greenhouses in Yangpyeong in April 2020. Incidence of leaf spot and stem rot of the plants ranged from 10 to 20% and 5 to 30%, respectively. Morphological and cultural characteristics of fungal isolates from the leaf spot and stem rot symptoms fitted into those of the genus Phoma. Molecular phylogenetic analyses of two single-spore isolates from the symptoms using concatenated sequences of LSU, ITS, TUB2, and RPB2 genes authenticated an independent cluster from other Didymella (anamorph: Phoma) species. Moreover, the isolates showed different morphological and cultural characteristics in comparison to closely related Didymella species. These discoveries confirmed the novelty of the isolates. Pathogenicity of the novel Didymella species isolates was substantiated on leaves and stems of A. acutiloba through artificial inoculation. Thus, this study reveals that Didymella acutilobae sp. nov. causes leaf spot and stem rot in Angelica acutiloba.

Phoma spp. an untapped treasure of cytotoxic compounds: current status and perspectives.

The genus Phoma has been explored for a wide range of secondary metabolites signifying a huge range of bioactivities. Phoma sensu lato is a major group that secretes several secondary metabolites. The genus Phoma mainly includes Phoma macrostoma, P. multirostrata, P. exigua, P. herbarum, P. betae, P. bellidis, P. medicaginis, P. tropica, and many more species from the genus that are continuously being identified for their potential secondary metabolites. The metabolite spectrum includes bioactive compounds like phomenon, phomin, phomodione, cytochalasins, cercosporamide, phomazines, and phomapyrone reported from various Phoma spp. These secondary metabolites show a broad range of activities including antimicrobial, antiviral, antinematode, and anticancer. The present review is aimed to emphasize the importance of Phoma sensu lato fungi, as a natural source of biologically active secondary metabolites, and their cytotoxic activities. So far, cytotoxic activities of Phoma spp. have not been reviewed; hence, this review will be novel and useful for the readers to develop Phoma-derived anticancer agents. KEY POINTS: • Different Phoma spp. contain a wide variety of bioactive metabolites. • These Phoma spp. also secrete cytotoxic and antitumor compounds. • The secondary metabolites can be used for the development of anticancer agents.

First Report ofPhoma herbarumCausing Leaf Spot on Rhapis humilis in China.

Rhapis humilis Blume is an ornamental plant for landscaping that is widely distributed in China. In February 2020, a leaf spot disease was observed on R. humilis in a nursery shed in Zhanjiang (21.17 N, 110.18 E), Guangdong, China. The disease incidence was more than 90%. The early symptom was small water-soaked lesions, which then turned into black necrotic spots. Eventually, the individual lesions coalesced into larger ones, leading to the death of diseased leaves. Ten diseased leaves were collected from the nursery. The diseased tissues were cut into 2 × 2 mm pieces, surface disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s, and then rinsed three times with sterile water before pathogen isolation. The tissues were plated on potato dextrose agar (PDA) medium and incubated at 28°C in the dark for 4 days. Pure cultures were produced by transferring hyphal tips to new PDA plates. Three isolates(RHPH-1, RHPH-2, and RHPH-3) were obtained. The colonies of the isolates were approximately 5 cm in diameter after 7 days. They were initially whitish and later became grayish white. The NaOH testing on MEA cultures was negative. No sporulation was detected after 30 days. The fertile structures of the specimens collected in the nursery were examined. Pycnidia were globose, measured 68 to 265 × 72 to 360 µm (n = 20), and mostly embedded. Conidia were aseptate, hyaline, and ellipsoid, measuring 3.6 to 6.5 × 2.2 to 2.7 µm (n = 30). Based on the morphological characteristics, the fungus was identified as in genus Phoma(Boerema et al. 2004). For molecular identification, the colony PCR method with MightyAmp DNA Polymerase (Takara-Bio, Dalian, China) (Lu et al. 2012) was used to amplify the internal transcribed spacer (ITS), partial RNA polymerase II largest subunit (RPB2), and beta-tubulin (β-tub) loci of three isolates using primer pairs ITS4/ITS5, RPB2-6F/RPB2-7R, and BT2a/BT2b, respectively (Chen et al, 2015; White et al, 1990). The sequences were deposited in GenBank (ITS, MZ419364-MZ419366; RPB2, MZ562293-MZ562295; and β-tub, MZ562296-MZ562298). Based on BLAST analysis, the sequences of the ITS, RPB2, and β-tub all showed 100% similarity toPhoma herbarumWestend. (CBS 377.92, accession nos. KT389536 for ITS; KT389663 for RPB2; and KT389837 for β-tub).Pathogenicity testing was performed in a greenhouse with 80% relative humidity at 25 to 30°C. Ten healthy plants of R. humilis were grown in pots, with one plant in each pot. The leaves werepinprickedwith sterile needles before inoculation. They were inoculated with mycelial plugs of the isolates or sterile agar plugs (as control), with four plugs for each leaf. Five plants were used in each treatment. Disease symptoms similar to those in the nursery were observed on the inoculated plants 2 weeks after inoculation, whereas the control plants remained healthy. The fungus was reisolated from the symptomatic leaves and confirmed as P. herbarum by morphology and ITS analysis. P. herbarum was reported to cause leaf spot on Atractylodeslancea, Camellia sinensis, Elaeis guineensis, Lilium brownii, and Vetiveria zizanioides in China;Bituminaria bituminosa, Glycine max, Medicago sativa, and Pisum sativumin Australia; andSalvia nemorosain Italy (Li et al. 2011; Li et al. 2012; Thangaraj et al. 2018).To our knowledge, the present study was the first to report P. herbarumcausing leaf spot on R. humilis in China. P. herbarum seriously affects the supply of seedlings in R. humilis, and its epidemiology on R. humilis should be further studied.

Seed-Borne Fungi Associated With Pepper (Capsicum Species) in Some States in Nigeria.

Capsicum (Pepper: common name) species fruits are ground and utilized either fresh or dried as an essential ingredient of sauce/soup in every region of Nigeria. Seed health tests were carried out on thirty-one seed cultivars of Capsicum that is Capsicum frutescens L. and Capsicum annuum L. from Kaduna, Benue and Oyo States in Nigeria in this study. An initial mini-greenhouse project with some of the cultivars resulted in Curly-top Virus symptoms disease. The latter disease which had not been hitherto reported in Nigerian Capsicum cultivars necessitated the grouping of the seeds into two sets of Nigerian/Indigenous Cultivars (in group one) and Exotic plus less exotic cultivars in a second group. The Nigerian set made up of eight cultivars was examined with and without surface-sterilization for mycoflora. The design was completely randomized comprising five (5), replicates per cultivar and 50 seeds in a cultivar replicate. The working sample was 250 seeds per cultivar set up under an alternating cycle of 12hours Near ultra-violet light (NUV light) and 12hours darkness in an incubating room of 27 ± 2oC temperature. Incubation for viability counts and associated fungi was for seven days. The Exotic plus less exotic set had twenty-three cultivars, which were tested as the Nigerian Cultivars, without surface-sterilization. Viability was over 30.00% only in eleven of the twenty-three Exotic plus less exotic Cultivars, whereas there was none (over 30%) in the indigenous or Nigerian Cultivar set. Three reasons adduced for the low turn-out in germination are period of seed storage of six months or over, lack of seed treatment and mixed infections possibly with viruses or nematodes. The genera Phoma, Chaetomium, Penicillium, Rhizopus and Cladosporium with the former two associated with all eight cultivars, were isolated from the un-sterilized indigenous/Nigerian set and are considered to be surface contaminants. Twenty fungi namely Aspergillus flavus, A. niger, A. ochraceus, A. wentii, Cercospora sp., Chaetomium sp., Colletotrichum sp., Curvalaria lunata, C. pallescens, Fusarium equiseti, F. moniliforme, F. solani, Graphuinu sp., Macrophomina sp., Penicillium sp., Phoma sp., Rhizopus sp., Spegazzima sp., Stemphylium sp. and Verticillium sp. were isolated from the un-sterillized Exotic plus less exotic cultivars set. Among the twenty, Aspergillus flavus, Fusarium moniliforme and Phoma sp. were dominant as they were associated with 22, 21 and 19 of the twenty-three cultivars respectively. Overall mean infection of 13.55%, 8.06% and 5.23% were highest by A. flavus, Colletotrichum sp. and Rhizopus sp. respectively and the three highest cultivar replicate infections were 55.60%, 32.80% and 23.20% also by Aspergillus flavus, Rhizopus sp. and Colletotrichum sp. in that order respectively. Seed-borne saprophytes are reported to be economically important as they effect seed rot, seed weight loss or seed germination reduction and ought to be excluded by adequate seed treatment. Twelve fungi were associated and isolated from the eight surface-sterilized Indigenous/Nigerian cultivar set. They are Aspergillus flavus, A. niger, A. tamari, Cochliobolus lunatus, Colletotrichum capsici, Corynespora casiicola, Curunlaria pallescens, Fusarium moniliforme, F. pallidoroseum, Macrophomina phaseolina, Pithomyces chartarum and Thielavia terricola. Aspergillus flavus, Fusarium moniliforme and Aspergillus niger were the three most frequently occurring/dominant fungi as they were isolated from all eight, seven and six cultivars respectively. However, overall mean infection was highest by Aspergillus flavus 11.80%, second is Colletotrichum capsici 6.60% and third is Fusarium moniliforme 3.20%. The two highest infections in any cultivar replicate also were 55.60% by Aspergillus flavus and 23.20% by Colletotrichum capsici, and in third place is 15.20% by Aspergillus niger. Colletotrichum capsici and two other Colletotrichum species gloeosporioides and acutatum are known to be the most important economic fungal pathogens of Capsicum species in Nigeria and globally causing ripe fruit rot and stem die-back. Seed-borne Fusarium species namely moniliforme, solani and oxysporum and Verticillium species also contribute to high pre-harvest losses (by damping-off of seedlings and witling of field plants) on Pepper globally. The Aspergilli cause moulds on above-ground portions of pepper plants and Macrophomina is known to be parasitic on leaves. Pithomyces chartarum and Thielavia terricola have not been reported on Capsicum species and are therefore new records on Capsicum seeds in Nigeria. Seed storage for planting without adequate/appropriate seed treatment is to be discouraged in Nigeria; because of low viability as in this study, and seedling failure/field epidemics/crop failure. Fundings and extensive trials with Plant extracts, Oils and Biocontrol microbes should also be underscored as necessary for seed treatment in place of fungicides for health and environmental safety. Improved Seeds should also be sought for as priority from approved Agencies/Seed Companies by farmers.

Sanity and Germination of Treated with Clove Extract Jurema-Preta and Faveleira Seeds

The Mimosa tenuiflora (jurema-preta) and Cnidoscolus quercifolius (faveleira) are quite common species in the Caatinga biome, being used from forage production to energy generation and in the recovery of degraded areas for reforestation purposes, among other uses. Considering the need and importance of studies related to forest seeds health, especially native seeds and taking into account the scarcity of studies in the literature regarding the association of pathogens to the seeds of the species studied, this work aimed to evaluate the efficiency of the hydroalcoholic extract of clove on germination and incidence of fungi associated with seeds of jurema-preta and faveleira. The experiment was conducted in the Laboratory of Forest Pathology, Center of Health and Rural Technology, Federal University of Campina Grande, Patos, Paraíba, Brasil. For the germination test we performed the dormancy breaking of seeds that were then treated with clove plant extract, and as substrate, washed and sterilized sand was used. Germination percentage and Twinning speed index (SVI) were evaluated. The sanity test was performed using the filter paper method "Blotter Test" for the development of microorganisms. The treatments consisted of: 0%, 25%, 50%, 75% and 100% of clove extract, with 4 repetitions of 25 seeds. The design used was entirely randomized and the means were compared using Tukey's test at 5% probability. The clove extract, in higher concentrations, provided an increase in germination and SVI of the species. It was identified in the seeds of jurema-preta, the fungi Aspergillus niger, Aspergillus flavus, Aspergillus glaucous, Rhizopus sp, the genus Phoma sp. In the seeds of C. quercifolius the microflorea was composed by fungi Aspergillus niger, Aspergillus flavus, Aspergillus glaucous, Rhizopus sp, Aspergillus alutaceous and Aspergillus candidus.

Challenges With Managing Disease Complexes During Application of Different Measures Against Foliar Diseases of Field Pea.

Studies were undertaken across five field locations in Western Australia to determine the relative changes in disease severity and subsequent field pea yield from up to four foliar pathogens associated with a field pea foliar disease complex (viz. genera Didymella, Phoma, Peronospora, and Septoria) across four different pea varieties sown at three different times and at three different densities. Delaying sowing of field pea significantly (P < 0.05) reduced the severity of Ascochyta blight (all five locations) and Septoria blight (one location), increased the severity of downy mildew (four locations), but had no effect on seed yield. In relation to Ascochyta blight severity at 80 days after sowing, at all locations the early time of sowing had significantly (P < 0.05) more severe Ascochyta blight than the mid and late times of sowing. Increasing actual plant density from 20 to 25 plants m-2 to 58 to 78 plants m-2 significantly (P < 0.05) increased the severity of the Ascochyta blight (four locations) and downy mildew (one location), and it increased seed yield at four locations irrespective of sowing date and three locations irrespective of variety. Compared with varieties Dundale, Wirrega, and Pennant, variety Alma showed significantly (P < 0.05) less severe Ascochyta blight, downy mildew, and Septoria blight (one location each). Grain yield was highest for the early time of sowing at three locations. Varieties Alma, Dundale, and Wirrega significantly (P < 0.05) outyielded Pennant at four locations. The percentage of isolations of individual Ascochyta blight pathogens at 80 days after the first time of sowing varied greatly, with genus Didymella ranging from 25 to 93% and genus Phoma ranging from 6 to 23% across the five field locations. This fluctuating nature of individual pathogen types and proportions within the Ascochyta blight complex, along with variation in the occurrence of pathogens Peronospora and Septoria, highlights the challenges to understand and manage the complexities of co-occurring different foliar pathogens of field pea. While the search for more effective host resistance continues, there is a need for and opportunities from further exploring and exploiting cultural management approaches focusing on crop sequence diversification, intercropping, manipulating time of sowing and stand density, and application of improved seed sanitation and residue/inoculum management practices. We discuss the constraints and opportunities toward overcoming the challenges associated with managing foliar disease complexes in field pea.

Fungal pathogens infecting moss green roofs in Finland

Green roofs play an important role for cities in mediating some problems caused by urbanization. Mosses are ecologically important plants and capable of tolerating harsh conditions, and thus their use for greening building surfaces has become more common. There is only a little information concerning moss-associated microbes, especially those found in green roof environments. Moss-associated microbes might have significant role on the welfare of green roofs as they might induce both beneficial as well as adverse effects on mosses. In this study, the occurrence of fungal populations was studied on green roofs in Finland. A total of 94 samples were collected from nine different green roofs, and 64 fungal isolates and one oomycete were obtained from the brown, necrotic parts of the collected green roof mosses. The most general isolated fungal genus was Trichoderma, comprising 25 different fungal isolates. The second most common genus was Fusarium, with 15 fungal isolates. The third most common genus was Mucor, with nine fungal isolates. Most of the Trichoderma isolates were described as T. harzianum, whereas most of the Fusarium isolates were described as F. acuminatium. In addition, the genera Phoma and Mortierella were frequently present. Fifty-two of 65 isolates caused symptoms in the model plant Physcomitrella patens. The most harmful Trichoderma isolates were described as T. atroviride, T. viride, T. koningiopsis and T. hamatum, all of which caused severe damage to the protonema, stem and leaves. The most harmful Fusarium isolates were F. acuminatium, F. avenaceum and F. tricinctum. The genera Mucor and Mortierella were isolated but they did not cause detectable symptoms in P. patens. These results indicate that many fungal isolates belonging to different genera are able to colonize mosses on green roofs and some of them cause severe damage to the mosses.

First report of Boeremia exigua var. exigua causing Black Spot-like symptoms on commercially grown soybean in Germany.

Soybean (Glycine max [L.] Merr.) is economically the most important protein crop grown worldwide. However, Europe largely depends on soybean imported from the Americas (European Commission 2019; Haupt and Schmid 2020). In Germany, soybean production was not formally recorded before 2016, but since then a steady increase along with an expansion of the growing area from the south of Germany to northern states occurred. In 2019 an area of 29,000 hectares was under soybean cultivation (Federal Ministry of Food and Agriculture (Germany) 2019). In the state of North Rhine-Westphalia (NRW, western part of Germany) farmers have started in recent years to cultivate soybean, making it increasingly important to monitor pathogens associated with this new crop. At the beginning of October 2019, shortly before harvest, rows of black spots on pods and stems of soybean plants cv. Viola throughout a field site near Jülich (NRW) were observed. Close observation identified them as pycnidia with similarity to symptoms reported from soybean in Austria in 2015 (Hissek and Bedlan 2016). The collected samples were thoroughly surface sterilized (two washes with 70 % EtOH, a rinse in 0.5 % sodium hypochlorite solution and a final wash in sterile double distilled water) and placed on plates containing potato dextrose agar (PDA) at 22 °C in the dark. Fungal colonies were transferred to malt extract agar plates (MEA) and examined by microscopy. Thus, 34 of 41 isolates looked morphologically similar, producing colonies that appeared dark grey with white aerial mycelium and round to irregular margins. A single spore isolate was generated and designated IPP1903. Spores derived from IPP1903 were unicellular and mostly oblong to cylindrical with a mean width of 2.6±0.3 µm and a mean length of 5.9±0.8 µm (N=50, mean value ± standard deviation). Colonies on MEA were 5.4 to 5.8 cm in diameter after growth for seven days at 20 to 25°C with a photoperiod of 12 h and 3.3 to 3.7 cm in diameter after growth for seven days in the dark at 22°C. These morphological observations led to the conclusion that the isolate may belong to the genus Phoma. To test this hypothesis, we performed a drop test with 5 M NaOH which is used routinely to check for the presence of a genus-specific metabolite. We observed a change in color, indicating a positive test result. The color change was even more pronounced on the plates incubated in the light, further confirming the presence of "metabolite E" (Boerema et al. 2004; Kövics et al. 2014). Next, DNA was extracted and PCR was performed with primers specific for ITS regions (GenBank MT397284), LSU (MT397285), rbb2 (MT414713) or tub2 (MT414712). Sequencing results of PCR products were used to create a combined phylogenetic tree, including sequences published previously (Chen et al. 2015). Our sequencing results together with the morphological observations clearly identified the fungal isolate to be Boeremia exigua var. exigua. The isolate is publicly available in the CBS collection of the Westerdijk Fungal Biodiversity Institute with the accession no. CBS 146730. Koch's postulates were fulfilled by inoculating a spore suspension of the isolate IPP1903 (5x105 ml-1 in 0.05% Tween 20 solution in distilled water) onto healthy primary leaves of twenty 14 days old soybean plants of the cultivar Abelina. While the mock-inoculated plants (inoculated with 0.05% Tween 20 solution in distilled water) stayed healthy, the inoculated plants developed lesions on the leaves after seven days. Six weeks after inoculation the fungus could be reisolated from cuttings of the infected leaves after surface-sterilization. Fungal colonies were confirmed to be B. exigua var. exigua by morphological examination and via NaOH drop test. To our knowledge, this is the first report of B. exigua var. exigua causing disease on commercially grown soybean in Germany.

Phoma diseases: Epidemiology and control

AbstractPhomais the most widely distributed and omnipresent genus of the order Pleosporales and the largest genus with some 3,000 taxa described so far. Of these, approximately 110 species are pathogenic and occupy varied ecological niches. The genusPhomais polyphyletic and is not really delimited, with unclear species boundaries that make it a taxonomically controversial genus. Fungi belonging toPhomacommonly occur on crop plants that are economically important, where they cause devastating plant diseases. Pathogenic members ofPhomasensu lato species attack crop plants with symptoms ranging from leaf blight to root rot, and even wilting of the plant. In infected crop residues and field stubbles, the pathogen produces abundant pycnidia and pseudothecia that serve as the source of primary inoculum, whilst repeated crops of conidia produced inside pycnidia are the main source of secondary infection during the same growing season. After successful infection, the pathogen produces various phytotoxins that alter photosynthetic efficiency and actin cytoskeleton‐based functions, and cause electrolyte leakage from cells. Controlling the diseases caused by members ofPhomasensu lato is challenging and efforts have been made to identify resistant varieties that can be used in various plant breeding programmes. Studies have also been conducted to devise cultural and biological control measures as well as to evaluate the efficacy of fungicides against members ofPhomasensu lato. In this review we aim to discuss the disease epidemiology and control measures that can be practised to protect crops fromPhomadiseases.

Phomous rot is a dangerous disease of potato tubers

Goal. To establish the symptoms of pathogens of fomose rot on potato varieties of different resistance, to isolate pathogens from the genus Phoma, parasitizing on tubers and stems of plants.&#x0D; Methods. Symptoms of phomotic rot were determined visually by the determinant of diseases and the method of microbiological diagnosis was used. Pathogens were isolated from stems and tubers affected by fomose rot.&#x0D; Results. On the basis of psychopathological examination, it was experimentally proved for the first time in Ukraine that fomozna potato rot is widespread in commodity and seed potato plantings. The degree of harmfulness reaches 35%. Pathogens of the genus Phoma (Ph. Solanicola Prill. Et Del Ph tuberosa Malkomcon) affect potato stems and tubers. On the stems, the first symptoms appear as spots during the flowering phase of the plants, and on tubers the gangrene appears as round, depressed and hard spots, light or dark brown in color, on the top of which pycnids form. According to the harmfulness of the pathogen, the Polesye of Ukraine is divided into three zones: 1. The zone of strong development includes the Volyn and Zhytomyr regions, where the number of affected plants with phomosis exceeds 5%, affected tubers — 8—10%; 2. The zone of moderate development, it includes the Rivne and Khmelnitsky regions, where the number of plants affected by phomosis is 2—3%, and tubers during storage of the crop — 5—7%; 3. The zone of insignificant development of the disease includes Kiev and Chernihiv regions, where the number of plants affected by gangrene is up to 2%, and tubers after storage of the crop — up to 4%.&#x0D; Conclusions. According to the results of psychopathological surveys, three zones of development of fomose rot of potatoes (severe, moderate and minor damage to phomosis) were identified and a scheme for the development cycle of the infection of the genus Phoma (Solanicola Prill. et. Del. And Ph. Tuberosa Melh.) was established. Symptoms of fomose rot appear on the stems in the form of elongated blurry spots, on which pycnids form from light brown (Eurostar) to dark brown (Riviera) color. On potato tubers, fomosis appears in the form of round, hard, sunken spots of a dark color. It is proved that during the interaction of potato plants with pathogens of the genus Phoma complex physiological, biochemical and pathological processes occur that significantly reduce productivity, quality, taste and other economically valuable traits.

Community structure, spatial distribution, diversity and functional characterization of culturable endophytic fungi associated with Glycyrrhiza glabra L.

A total of 266 endophytic fungal isolates were recovered from 1019 tissue segments of Glycyrrhiza glabra collected from four different locations in the North-Western Himalayas. The endophytes grouped into 21 genera and 38 different taxa. The host had strong affinity for the genus Phoma, followed by Fusarium. The species richness was highest at the sub-tropical location, followed by the sub-temperate location and the temperate locations, respectively. The tissue specificity of endophytes was also evident. Some endophytes showed potential antimicrobial activity against phyto-pathogens indicating that they may be helpful to the host in evading pathogens. All the endophytic taxa produced the plant growth promoting hormone, indole acetic acid (IAA), though in varying concentrations. None of these endophytes caused any symptoms of disease in co-cultivation with the tissue cultured plants. Further, all the endophytes had a positive influence on the phenolic and flavonoid content of the host. Three endophytes, Stagonosporopsis cucurbitacearum, Bionectria sp. and Aspergillus terreus also increased the host root (rhizome) and shoot growth visibly. Such endophytes are potential candidates for developing endophyte-based technologies for sustainable cultivation and enhanced productivity of G. glabra. This is the first report of community structure and biological properties of fungal endophytes associated with G. glabra.

Occurrence of Phoma Sacc. in the phyllosphere of Neogene Siwalik forest of Arunachal sub-Himalaya and its palaeoecological implications

The present study reports in situ occurrence of two new epiphyllous fungal species of Phomites (comparable to modern genus Phoma Sacc.) on angiospermic leaf remains recovered from the Siwalik sediments (middle Miocene to early Pleistocene) of Arunachal Pradesh, eastern Himalaya. We describe two new species i.e. Phomites siwalicus Vishnu, Khan et Bera S, sp. nov. and Phomites neogenicus Vishnu, Khan et Bera S, sp. nov. on the basis of structural details of pycnidia. The pycnidium is a globose or slightly lens-shaped, ostiolate with a collar layer consisting of thick walled cells, sunken in leaf cuticle, with one-celled conidiospores and short-ampulliform conidiogenous cells. Host leaves resemble to those of extant Dipterocarpus C. F. Gaertn., Shorea Roxb. ex C. F. Gaertn. (Dipterocarpaceae), Dysoxylum Blume (Meliaceae), and Poaceae Barnhart. In situ occurrence of two Phomites morphotypes on the said leaf remains suggests a possible host–parasite interaction in the moist evergreen forest of Arunachal sub-Himalaya during Mio-Pleistocene period. The occurrence of Phomites in appreciable numbers indicates a humid climate favored by high rate of precipitation during Siwalik sedimentation, which is also consistent with our previously published climatic data obtained from the study of the macroscopic plant remains.

Marine-derived Phoma—the gold mine of bioactive compounds

The genus Phoma contains several species ubiquitously present in soil, water, and environment. There are two major groups of Phoma, viz., terrestrial and marine. After 1981 researchers all over the world have focused on marine-derived Phoma for their bioactive compounds. The marine Phoma are very rich sources for novel bioactive secondary metabolites, which could potentially be used as drugs. Recently, a large number of structurally unique metabolites with potential biological and pharmacological activities have been isolated from the marine Phoma species particularly Phoma herbarum, P. sorghina, and P. tropica. These metabolites mainly include diterpenes, enolides, lactones, quinine, phthalate, and anthraquinone. Most of these compounds possess antimicrobial, anticancer, radical scavenging, and cytotoxic properties. The present review has been focused on the general background of Phoma, current approaches used for its identification and their limitations, difference between terrestrial and marine Phoma species. In addition, this review summarizes the novel bioactive compounds derived from marine Phoma and their biological activities.

First Report of Leaf Spot Caused by Phoma multirostrata var. microspora on Dendrobium officinale in Zhejiang Province of China

HomePlant DiseaseVol. 102, No. 8First Report of Leaf Spot Caused by Phoma multirostrata var. microspora on Dendrobium officinale in Zhejiang Province of China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Leaf Spot Caused by Phoma multirostrata var. microspora on Dendrobium officinale in Zhejiang Province of ChinaY. Y. Xie, L. P. Wang, L. Fang, and H. R. WangY. Y. Xiehttp://orcid.org/0000-0003-2057-9307Search for more papers by this author, L. P. WangSearch for more papers by this author, L. FangSearch for more papers by this author, and H. R. Wang†Corresponding author: H. R. Wang; E-mail: E-mail Address: wanghrg@126.comSearch for more papers by this authorAffiliationsAuthors and Affiliations Y. Y. Xie L. P. Wang L. Fang H. R. Wang † , Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, Zhejiang Province, P.R. China. Published Online:25 May 2018https://doi.org/10.1094/PDIS-10-17-1629-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Dendrobium officinale Kimura & Migo is an important Chinese medicinal plant belonging to the family Orchidaceae and is widely cultivated in Zhejiang Province of China. It has broad bioactivities including immunomodulation, antifatigue, antioxidation, digestion promotion, antihyperglycemia, and antihypertension (Gao et al. 2002). During the summer months in 2013 and 2014, plants showing necrotic spots (∼5 mm diameter) on the leaves were observed in a field in Deqing county, Zhejiang Province, China. Over 80% of the plants showed symptoms while infected leaves exhibited circular or irregular, \light brown or dark brown spots, often with a central depression and brown margins. There were no symptoms on adaxial sides of leaves. The pathogen was isolated from different affected tissues individually. Four single-spore isolates were obtained and grown on potato dextrose agar (PDA) at 25°C for 7 days. The colonies on PDA were white, rounded, and with radial margins. Pycnidia were globose, 45 to 95 μm, mostly embedded, and appeared as evenly arranged on the surface of the colony after 7 to 10 days. Conidia were single celled, elliptic or oval, 2.8 to 4.8 × 2.1 to 2.7 μm. Morphological characteristics of the isolates were similar to colonies in the genus Phoma (Boerema et al. 2004). PCR amplification of genomic DNA using the primers ITS1 and ITS4 for ITS region (White et al. 1990), ACT-512 F and ACT-783R for ACT (actin gene), and EF1-728 F and EF1-986R for EF-1α (translation elongation factor 1α) (Carbone and Kohn 1999) was performed. Sequence analysis revealed that the isolate HBtp-003 (GenBank accession nos. KU257610 ITS, KX782333 ACT, KX782332 EF-1α) shared 99 to 100% identity with Phoma multirostrata (FJ839841, FJ426920, EU543986, respectively). This isolate was identified as P. multirostrata var. microspora based on the size of the conidia (Boerema et al. 2004). To conduct a pathogenicity test, conidia were obtained from the crushed pycnidia collected from the surface of the colonies. The conidial suspension of P. multirostrata was diluted into 106 conidia/ml using 0.1% CMC-Na solution (CMC, carboxymethyl cellulose). Twenty healthy D. officinale leaves were wound-inoculated on the abaxial side of the leaves with the conidial suspension, and covered by plastic domes for maintaining humidity and temperature. Twenty plants inoculated with 0.1% CMC served as control. All plants were maintained in greenhouse between 25 and 30°C with natural light. Ten days after inoculation, all treated leaves developed spots similar to those in the field. Control plants remained asymptomatic. P. multirostrata was reisolated from all inoculated plants but not from any of the noninoculated plants. Ten wounding leaves were reinoculated with distilled water in our test, and no symptom was observed. To our knowledge, this is the first report of leaf spot disease caused by P. multirostrata var. microspora on D. officinale in China.

Diversity, Seasonal Variation and Antibacterial Activity of Endophytic Fungi Associated With the Genus Jatropha in Mauritius

Background: Endophytic fungi are important components of the forest community and are significantly diverse from one plant to another as well as from one ecosystem to another. Objective: The current study aimed to characterise, at the molecular level, the diversity and seasonal variation of endophytic fungi from Jatropha plants found in Mauritius and to compare the phytochemicals and the antimicrobial potential of the fungal isolates with the leaves extracts. Materials and methods: Endophytic and saprophytic fungi were isolated from the leaves of Jatropha plants during summer and winter. The isolated fungi were further classified through molecular characterisation. The isolates were grouped into 76 distinct operational taxonomic units based on the sequence of the internal transcribed spacer regions in the rRNA gene. The colonization frequency and the dominant fungi percentage of these endophytic fungi were calculated. The antimicrobial properties of the extracts from the endophytes were compared to that of the extracts obtained from the leaves of the Jatropha plants. Results: The overall colonisation rate for the two seasons was 67.42%. Maximum colonisation (27%) was observed in both J. curcas and J. multifida. There was a diverse array of fungi which included 21 common genera. Colonisation frequency of the other genera recovered during this study varied according to the plant from which the isolation was carried out. J. multifida was richer in the genus Phoma, J. curcas were colonised mainly by Neofusicoccum as compared to J. integerrima and J. podagrica, which were colonised by the Corenespora. Climate was also a primary driver of endophytes and saprophytes community diversity and composition. Moreover, the endophytic fungi from the leaves of J. curcas gave highly significant antimicrobial activities effects (p<0.01) against both the tested Gram (+ve) and Gram (-ve) clinical pathogens. Among the four active isolates, Engyodontium was the genus that showed highest antimicrobial activity. Overall, the endophytic fungi from the Jatropha species were more effective than the crude ethyl acetate extract of the leaves. Conclusion: The antimicrobial activity of these endophytic microorganisms could be further exploited and find application in the pharmaceutical industry.

Paleomycology of the Princeton Chert. III. Dictyosporic microfungi, Monodictysporites princetonensis gen. et sp. nov., associated with decayed rhizomes of an Eocene semi-aquatic fern

This study builds on previous investigations of paleomycological diversity within permineralized plants of a significant Eocene paleobotanical locality, the Princeton Chert. The fungal body fossils described here occur in decayed rhizomes of the extinct semi-aquatic fern Dennstaedtiopsis aerenchymata. Fungi include vegetative hyphae throughout the plant tissue, as well as a dense assemblage of >100 dematiaceous spores. The spores occur in a discrete zone surrounding two extraneous rootlets of other plants, which penetrated the fern tissue post-mortem. Spores are obovoid and muriform, composed of 8–12 cells with constricted septa and produced from hyaline or slightly pigmented hyphae. The spores are morphologically similar to both asexual reproductive dictyospores of phylogenetically disparate microfungi attributed to the morphogenus Monodictys and perennating dictyochlamydospores that occur in the anamorph genus Phoma. In addition to expanding the early Eocene fossil record for Ascomycota, these specimens also provide new insight into the rapidity of initial phases of the fossilization process in this important paleobotanical locality.

Antimicrobial Potential of Thiodiketopiperazine Derivatives Produced by Phoma sp., an Endophyte of Glycyrrhiza glabra Linn.

During the screening of endophytes obtained from Glycyrrhiza glabra Linn., the extract from a fungal culture designated as GG1F1 showed significant antimicrobial activity. The fungus was identified as a species of the genus Phoma and was most closely related to Phoma cucurbitacearum. The chemical investigation of the GG1F1 extract led to the isolation and characterization of two thiodiketopiperazine derivatives. Both the compounds inhibited the growth of several bacterial pathogens especially that of Staphylococcus aureus and Streptococcus pyogenes, with IC50 values of less than 10μM. The compounds strongly inhibited biofilm formation in both the pathogens. In vitro time kill kinetics showed efficient bactericidal activity of these compounds. The compounds were found to act synergistically with streptomycin while producing varying effects in combination with ciprofloxacin and ampicillin. The compounds inhibited bacterial transcription/translation in vitro, and also inhibited staphyloxanthin production in S. aureus. Although similar in structure, they differed significantly in some of their properties, particularly the effect on the expression of pathogenecity related genes in S. aureus at sub-lethal concentrations. Keeping in view the antimicrobial potential of these compounds, it would be needful to scale up the production of these compounds through fermentation technology and further explore their potential as antibiotics using in vivo models.

Genus Phoma according to the newest taxonomic changes

Genus Phoma according to the newest taxonomic changes

Interactive physiological potential of Peyronellaea curtisii (=Phoma narcissi) strains for enzymatic attack and defence capabilities against phytoalexins

Phytopathogenic fungi use a variety of strategies to infect hosts and have a diverse sensitivity to the natural defence mechanisms of the host plant, e.g. synthesis of phytoalexins. Many important pathogens of crops belong to the problematic genus Phoma, including species recently reallocated to Peyronellaea. The work presents: (1) molecular identification of five pathogenic strains of Peyronellaea (syn. Phoma) based on two loci, actin (ACT) and β-tubulin (TUB), and morphological observations; (2) differentiation of these strains based on their enzymatic activity; and (3) their effect on biosynthesis of phytoalexin in Hippeastrum scales. Phylogenetic analysis showed a close relationship between our strains and Peyronellaea curtisii (syn. Phoma narcissi) species. This was also supported by morpho-anatomical analysis although its results were less conclusive. Some phenotypic traits of the strains overlapped with characteristics of other Phoma s.l. species, allowing for misidentification based on morphology alone. Tested cellulolytic, pectolytic and amylolytic activities were strain specific. A high level of amylase activity was positively correlated with cellulase activity but negatively correlated with pectolytic activity. Moreover, some strains suppressed phytoalexin production in Hippeastrum scales and were resistant to various concentrations of phytoalexin added to the culture medium. Based on these results, we suggest that pathogenicity in P. curtisii strains is complex and that it may be associated with their interactive physiological potential for enzymatic attack and defence capabilities against phytoalexin.

FIRST REPORT OF PHOMA ALIENA CAUSING FRUIT ROTS OF POMEGRANATES IN NORTHERN GREECE

Pomegranate fruits rot is a very important disease with a worldwide distribution. In November 2012, pomegranate fruits showing rapidly enlarging brown lesions were observed in Vrontou (Prefecture of Pieria, Greece), from which isolations were made on acidified- PDA (2.5 ml 85% lactic acid per litre of medium). Plates incubated at 23oC for a week yielded colonies with a dark mycelium and abundant black, globose pycnidia 70 to 300 μm in diameter. Hyphae were septate and conidia were hyaline, one-celled, ellipsoid to ovoid (average 5-11x2-4 μm). Pathogen identification was based on morphological characteristics and sequencing of the ITS4/5 region (ca. 700 bp long) which was aligned with comparable fungal sequences using MEGABLAST. The highest homology (99%) was found with Phoma aliena (GenBank accession No. KC311486). For pathogenicity tests 20 mature fruits of cv. Wonderful were disinfected by dipping in 10% sodium hypochlorite for 15 min prior to inoculation, whereby 6 mm wide holes were made on the fruit peel in which an agar disk of the same size, excised from a fungal colony, was placed. Inoculated fruit were enclosed in plastic containers and incubated for a week in a growth chamber at 24-26°C. Control fruits were inoculated with agar discs without mycelium. A fungus identical to that used for inoculation was re-isolated from symptomatic fruits, fulfilling Koch’s postulates. Species of the genus Phoma such P. lycopersici, P. destructive, P. exigua were reported as the agents of fruit rot on tomatoes and eggplants (Kubota et al., 2000; Laundon, 1971). To our knowledge, this is the first report of the occurrence of P. aliena causing fruit rot of pomegranates in Greece and worldwide.