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Plant Disease Apr 2024, native of Mexico (Reyes et al. 2011), holds economic importance as it is marketed as a potted plant and cut flower due to its drought-tolerant capabilities and...
, native of Mexico (Reyes et al. 2011), holds economic importance as it is marketed as a potted plant and cut flower due to its drought-tolerant capabilities and aesthetic appeal. In September 2023, a field sampling was conducted at the Research Center in Horticulture and Native Plants (18°55'56.6" N, 98°24'01.5" W) of UPAEP University. cv. Quilpalli plants with white mold symptoms were found in an area of 0.5 ha, with an incidence of 40% and severity of 50% on severely affected stems. The symptoms included chlorosis of older foliage, necrosis at the base of the stem, and soft rot with abundant white to gray mycelium and abundant production of irregular sclerotia resulting in wilted plants. The fungus was isolated from 30 symptomatic plants. Sclerotia were collected, sterilized in 3% NaOCl, rinsed with sterile distilled water (SDW), and plated on Potato Dextrose Agar (PDA) with sterile forceps. Subsequently, a dissecting needle was used to place fragments of mycelium directly on PDA. Plates were incubated at 23 °C in darkness. A total of 30 isolates were obtained using the hyphal-tip method, one from each diseased plant (15 isolates from sclerotia and 15 from mycelium). After 6 days, colonies had fast-growing, dense, cottony-white aerial mycelium forming irregular sclerotia of 3.67 ± 1.13 mm (=100). Each Petri dish produced 32.47 ± 7.5 sclerotia (=30), after 12 days. The sclerotia were initially white and gradually turned black. The isolates were tentatively identified as based on morphological characteristics (Saharan and Mehta 2008). Two isolates were selected for molecular identification. Genomic DNA was extracted using the CTAB protocol. The ITS region and the glyceraldehyde 3-phosphate dehydrogenase (G3PDH) gene were sequenced for two randomly selected isolates (White et al. 1990; Staats et al. 2005). The ITS and G3PDH sequences of the SsEg9 isolate were deposited in GenBank (ITS-OR816006; G3PDH-OR879212). BLAST analysis of the partial ITS (510 bp) and G3PDH (915 bp) sequences showed 100% and 99.78% similarity to S. sclerotiorum isolates (GenBank: MT101751 and MW082601). Pathogenicity was confirmed by inoculating 30 120-day-old cv. Quilpalli plants grown in pots with sterile soil. Ten sclerotia were deposited at the base of the stem, 10 mm below the soil surface. As control treatment, SDW was applied to 10 plants. The plants were placed in a greenhouse at 23 °C and 90% relative humidity. After 16 days, all inoculated plants displayed symptoms similar to those observed in the field. Control plants did not display any symptoms. The fungus was reisolated from the inoculated stems, fulfilling Koch's postulates. The pathogenicity tests were repeated three times. Recently has been reported causing white mold on cabbage in the state of Puebla, Mexico (Terrones-Salgado et al. 2023). To the best of our knowledge, this is the first report of causing white mold on in Mexico. Information about diseases affecting this plant is very limited, so this research is crucial for designing integrated management strategies and preventing spread to other production areas.
PubMed: 38568786
DOI: 10.1094/PDIS-01-24-0196-PDN -
Foods (Basel, Switzerland) Sep 2023This study aims to evaluate the antifungal effects of volatile organic compounds (VOCs) produced by a marine biocontrol yeast, W9. The results showed that the VOCs from...
This study aims to evaluate the antifungal effects of volatile organic compounds (VOCs) produced by a marine biocontrol yeast, W9. The results showed that the VOCs from the yeast inhibited the growth of mycelium and spore germination by 77.8% and 58.3%, respectively. Additionally, it reduced the disease incidence and lesion diameter of gray mold on the strawberry fruit surface by 20.7% and 67.4%, respectively. Electronic micrographs showed that VOCs caused damage to the morphology and ultrastructure of the hyphae. Based on headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS), W9 emitted 18 main VOCs, and the pure substance of VOCs, such as 3-methyl-1-butanol, 2-methyl-1-butanol, 2-phenylethanol, and isoamyl acetate, showed antifungal effects against mycelium growth. Among them, 2-phenylethanol exhibited the strongest antifungal activity. It has been concluded that VOCs are the key antifungal mechanism of W9, and a promising strategy for controlling gray mold on strawberry fruit.
PubMed: 37835272
DOI: 10.3390/foods12193619 -
Journal of Fungi (Basel, Switzerland) Sep 2023White-rot fungi are the most important group of lignin biodegraders. YK-624 has higher ligninolytic activity than that of model white-rot fungi. However, the underlying...
White-rot fungi are the most important group of lignin biodegraders. YK-624 has higher ligninolytic activity than that of model white-rot fungi. However, the underlying mechanism responsible for lignin degradation by white-rot fungi remains unknown, and the induced compounds isolated from white-rot fungi for lignin degradation have never been studied. In the present study, we tried to screen ligninolytic-inducing compounds produced by YK-624. After large-scale incubation of YK-624, the culture and mycelium were separated by filtration. After the separation and purification, purified compounds were analyzed by high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance. The sterilized unbleached hardwood kraft pulp was used for the initial evaluation of ligninolytic activity. Ergosterol was isolated and identified and it induced the lignin-degrading activity of this fungus. Moreover, we investigated ergosterol metabolites from YK-624, and the ergosterol metabolites ergosta-4,7,22-triene-3,6-dione and ergosta-4,6,8(14),22-tetraen-3-one were identified and then chemically synthesized. These compounds significantly improved the lignin-degrading activity of the fungus. This is the first report on the ligninolytic-inducing compounds produced by white-rot fungi.
PubMed: 37755059
DOI: 10.3390/jof9090951 -
Plants (Basel, Switzerland) Aug 2023Oxidative stress in soybean plants infected with isolates was evaluated in order to select (1) the least aggressive inoculation method, (2) to determine the most...
Oxidative stress in soybean plants infected with isolates was evaluated in order to select (1) the least aggressive inoculation method, (2) to determine the most aggressive isolate, and (3) to determine the most tolerant soybean cultivar to this isolate. Based on the present malondialdehyde (MDA) content, the main end product of the lipid peroxidation process, and the biomarker for oxidative stress, the mycelium contact method was chosen as the least aggressive inoculation method, compared to the toothpick method and plug method. The activity of the antioxidant enzymes (superoxide-dismutase (SOD), catalase (CAT), and peroxidase (PX)), the reduced glutathione (GSH) content, and the level of lipid peroxidation (LP) were measured in soybean cv. Sava infected by five different species (DPM1F-, DPC/KR19-, DPC004NY15-, 18-DIA-SOY-14-, and PL157A-). The most pathogenic species to cv. Sava was . The screening of the antioxidant enzymes activity in the leaves of 12 different soybean cultivars (Altona, Atlas, Capital, Chico, CX134, Favorit, Lakota, McCall, Morsoy, Strain, Rubin, and Victoria) infected with by the mycelium contact inoculation method showed that Capital, McCall, and Morsoy were the cultivars with the highest tolerance to , followed by Chico, Favorit, Lakota, and Rubin. The most sensitive cultivars were Atlas, CX134, Victoria, and Strain.
PubMed: 37631108
DOI: 10.3390/plants12162896 -
Microbial Cell Factories Jul 2023Triterpenoids have shown a wide range of biological activities including antitumor and antiviral effects. Typically, triterpenes are synthesized through the mevalonate...
BACKGROUND
Triterpenoids have shown a wide range of biological activities including antitumor and antiviral effects. Typically, triterpenes are synthesized through the mevalonate pathway and are extracted from natural plants and fungi. In this work, triterpenoids, ganoderic acids (GAs) were discovered to be produced via biotransformation of a diterpene, 15,16-dihydrotanshinone I (DHT) in the liquid cultured Ganoderma sessile mycelium.
RESULTS
Firstly, the biotransformation products, two rare GAs were isolated and purified by column chromatography, and characterized using HR-ESI-MS spectrometry and NMR spectrometry. The two compounds were Lanosta-7,9(11),24-trien-15α,22,β-diacetoxy-3β-hydroxy-26-oic acid (LTHA) and Lanosta-7,9(11),24-trien-15α,22,β-diacetoxy-3β-carbonyl-26-oic acid (LTCA). Then, transcriptome and proteome technologies were employed to measure the expression of mRNA and protein, which further confirmed that triterpenoid GAs could be transformed from exogenous diterpenoid DHT. At the molecular level, we proposed a hypothesis of the mechanism by which DHT converted to GAs in G. sessile mycelium, and the possible genes involved in biotransformation were verified by RT-qPCR.
CONCLUSIONS
Two rare GAs were obtained and characterized. A biosynthetic pathway of GAs from DHT was proposed. Although the synthetic route was not confirmed, this study provided important insights into omics resources and candidate genes for studying the biotransformation of diterpenes into triterpenes.
Topics: Trientine; Triterpenes; Biotransformation
PubMed: 37507727
DOI: 10.1186/s12934-023-02156-5 -
Plant Disease Jul 2023Indian jujube (Ziziphus mauritiana Lamarck), is one of the most popular fruit crops in South China. In March 2023, a fruit rot of indian jujube with about 5% disease...
Indian jujube (Ziziphus mauritiana Lamarck), is one of the most popular fruit crops in South China. In March 2023, a fruit rot of indian jujube with about 5% disease incidence was observed in two supermarkets of Nanchang City, Jiangxi Province, China. Initially, the symptoms appeared as slightly brown spots on the fruit surface, with disease progression, the lesions gradually expanded and covered with a layer of hyphae. Small pieces (3 to 4 mm2) from the periphery of 15 diseased fruit were surface disinfected using 1% sodium hypochlorite for 30 s, rinsed three times in sterilized distilled water, air dried, and then aseptically placed onto potato dextrose agar (PDA) media and incubated at 25°C for three days. A total of ten single spore isolates with similar morphology were obtained. Colonies of these consisted of initially white, gradually turning gray and eventually becoming black, and aerial hyphae were dense and fluffy. Conidiogenous cells were smooth, hyaline, cylinder-shaped, and holoblastic. Conidia were ellipsoidal, top and base-rounded, and thick-walled, immature conidia were colorless, hyaline, and aseptate, compared with dark brown color of the mature conidia, which were one-septate with longitudinal striations, ranging in size from 22.8 to 31.8 (mean 27.6) µm in length and 12.2 to 20 (mean 14.6) µm in width. The morphological characteristics were consistent with the characteristics of the Lasiodiplodia species (Phillips et al. 2013). To accurately identify the strain, three representative isolates, namely JFRL 03-1147, JFRL 03-1148, and JFRL 03-1149, were selected for further identification. The internal transcribed spacers (ITS), translation elongation factor 1-alpha (TEF1-α), and beta-tubulin (TUB2) genes/regions were amplified and sequenced using primers ITS1/ITS4, EF1-688F/EF1-1251R, and Bt2a/Bt2b, respectively (Chen et al. 2021). These nucleotide sequences were deposited in GenBank with accession numbers OQ804425-OQ804427 (ITS), OQ818097-OQ818099 (TEF1-α), and OQ818100-OQ818102 (TUB2). A BLASTn homology search for these nucleotides showed 99-100% identity to ITS (EF622077, 487 nt/487 nt), TEF1-α (EF622057, 306 nt/307 nt) and TUB2 (EU673111, 434 nt/434 nt) sequences of Lasiodiplodia pseudotheobromae CBS 116459 (ex-type). The maximum likelihood analyses were performed for the combined ITS, TEF1-α and TUB2 data set using IQtree web server (Trifinopoulos et al. 2016). The phylogenetic tree showed that the three isolates clustered with Lasiodiplodia pseudotheobromae in a clade with 99% bootstrap support. Therefore, the fungus was identified as L. pseudotheobromae based on morphological and molecular characteristics. To evaluate pathogenicity, 4 healthy fruits of indian jujube were surface sterilized with 75% ethanol and wounded by sterile needle, and a 5-mm-diameter agar with 5-days-old mycelium of the isolate JFRL 03-1148 cultured on PDA at 25°C was put on the wound. Another set of 4 fruits was inoculated with sterile agar plugs as controls. The fruits were cultured at 25℃ and 85% relative humidity, and the test was repeated twice. These fruits inoculated with L. pseudotheobromae showed similar rot symptoms after 3 days, while the control group remained asymptomatic. To fulfill Koch's postulates, the pathogen was re-isolated from the inoculated fruits and confirmed as L. pseudotheobromae by morphological and molecular analysis. L. pseudotheobromae has previously been reported causing fruit rot on citrus, mango and papaya (Alam et al. 2021; Chen et al. 2021; Netto et al. 2014). But to our knowledge, this is the first report of L. pseudotheobromae caused postharvest fruit rot on indian jujube in China. Therefore, managers should pay more attention to postharvest fruit rot disease caused by L. pseudotheobromae, and formulate appropriate disease control measures to reduce its losses.
PubMed: 37467135
DOI: 10.1094/PDIS-05-23-0984-PDN -
Plant Disease Apr 2024Hosta longipes (Franch. & Sav.) Matsum. (Asparagaceae) is a perennial, herbaceous plant, native to Japan and Korea (Lee et al. 2021). In Korea, the plant is used as an...
Hosta longipes (Franch. & Sav.) Matsum. (Asparagaceae) is a perennial, herbaceous plant, native to Japan and Korea (Lee et al. 2021). In Korea, the plant is used as an edible vegetable and ornamental (Kang and Ju 2015). During 2021-2022, anthracnose symptoms were observed on leaves of H. longipes with over 70% disease incidence in Wanju-gun (35°38'47''N; 127°31'16''E) and Jangsu-gun (35°35'31''N; 127°30'03''E) in Jeollabuk-do, Korea. The disease initially appeared on old leaves, gradually spreading to young ones. The symptoms were characterized as yellow to white discoloration on the upper leaf surface with black necrotic tissue in the center of the lesion. Three H. longipes samples with anthracnose symptoms were collected. From each, a monoconidial isolate was obtained and then deposited in the Korea Agricultural Culture Collection (accession Nos. KACC 410038, 410391, and 410443). The dried specimens were housed at the herbarium of Jeonbuk National University (JBNU0129, 0137) and Korea University (KUS-F33379). Conidiomata was acervular, 65 to 80 × 56 to 70 µm in diam. Setae were dark brown, 2 to 4-septate, 63 to 161 µm long, being formed on a pale brown cushion. Conidia were hyaline, smooth-walled, aseptate, slightly curved, base truncate, 3.9 to 5.1 × 17 to 23 µm. The appressoria were solitary, olivaceous-brown, ovoid or irregularly shaped. Two-week-old colonies grown on PDA at 25 ℃ were 20-25 mm in diameter, initially white, then turned gray with age, with cottony aerial mycelium. The morphological and cultural characteristics of the fungus were consistent with those of Colletotrichum spaethianum (Allesch.) Damm, P.F. Cannon & Crous (Damm et al. 2012). To confirm morphology-based identification, the nucleotide sequences of the internal transcribed spacer (ITS) rDNA region, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), actin (actA), chitin synthase (CHS1), histone (HIS3) and tubulin (TUB2) genes were determined for KACC410443, as outlined by Cannon et al. (2012) and Damm et al. (2009). The resulting sequences were submitted into GenBank (PP000829 for ITS, PP133094 for GAPDH, PP083418 for actA, PP133091 for CHS1, PP133097 for HIS3, and PP133099 for TUB2) and compared with reference sequences in GenBank using BLASTn search tool. The results showed a 100% match with C. spaethianum (MT611068), C. incanum (MN880260) and C. truncatum (EF016303) for ITS, and 100% with C. spaethianum for GAPDH (MH370513), actA (MH045677), CHS1 (MH370520), HIS3 (MH985161), and TUB (MH456884). Pathogenicity was tested by inoculating conidial suspension (1 ×104 cfu/ml) of three-week-old fungal colonies of the isolate KACC410443 onto leaves of three healthy potted plants. Prior to inoculation, leaves were deliberately wounded by pinpricking with a sterilized needle. Two wounded but non-inoculated plants served as controls. Plants were maintained in a greenhouse at 25 to 30 °C. Inoculated plants developed anthracnose symptoms after eight days, while the control plants remained symptomless. The fungus isolated from the inoculated plants was morphologically identical to that observed initially, fulfilling Koch's postulates. To our knowledge, there is no previous record of C. spaethianum on H. longipes, although C. spaethianum has been reported to infect another species, H. plantaginea (Cheon and Jeon 2016). This is the first report of this fungus on H. longipes in Korea (KSPP 2024) and globally (Farr and Rossman 2024). The anthracnose on this ornamental plant can be considered a new severe threat to planting strategies in gardens.
PubMed: 38595059
DOI: 10.1094/PDIS-02-24-0340-PDN -
Analytical and Bioanalytical Chemistry May 2024Mushrooms are considered a valuable food source due to their high protein and fibre and low fat content, among the other health benefits of their consumption. Selenium...
Mushrooms are considered a valuable food source due to their high protein and fibre and low fat content, among the other health benefits of their consumption. Selenium is an essential nutrient and is renowned for its chemo-preventative properties. In this study, batches of selenium-enriched Lingzhi mushrooms were prepared by growing mycelium and fruit in substrates containing various concentrations of sodium selenite. The mushroom fruit accumulated low levels of selenium with selenomethionine being the most abundant form in all enriched samples. Conversely, the mycelium showed significant selenium accumulation but relatively low proportions of selenomethionine. The red colour of the selenium-enriched mycelia indicated the probable presence of selenium nanoparticles, which was confirmed by single-particle inductively coupled plasma-mass spectrometry. Mean particle diameters of 90-120 nm were observed, with size distributions of 60-250 nm. Additional analysis with transmission electron microscopy confirmed this size distribution and showed that the biogenic selenium nanoparticles were roughly spherical in shape and contained elemental selenium.
Topics: Selenium; Selenomethionine; Agaricales; Reishi; Nanoparticles
PubMed: 37987766
DOI: 10.1007/s00216-023-05031-9 -
Plant Disease Oct 2023is a native tree that produces fruit that can be consumed fresh or used by industry (Donadio et al., 2002). In February 2022, in the experimental area of the...
is a native tree that produces fruit that can be consumed fresh or used by industry (Donadio et al., 2002). In February 2022, in the experimental area of the Universidade Tecnológica Federal do Paraná - Brazil, disease was observed in 22 trees, with 50% to 80% severity in crown leaves. Symptoms were small, irregular, or circular-shaped, dark-brown lesions with yellow halos (Figure S1). As the disease progressed, the lesions increased in size, without distinction between mature and young tissues, causing complete leaf wilting. Twenty symptomatic leaves from 11 trees grown in the same orchard line were collected. For fungal isolation, the leaf surfaces were disinfected with 0.5% NaOCl solution for 1 min, rinsed in sterile distilled water, and dried on sterile filter paper. Five fragments of diseased leaf tissue were placed on a potato dextrose agar medium. The morphological characteristics of the colony, such as filamentous mycelium and golden yellow on the upper part, with the presence of circular to ovoid and multicellular conidia (mean 21.00 µm x 24.45 µm, n = 30) of the nine isolates, coincided with the description of the fungus of the genus (Valenzuela-Lopez et al., 2018). Further identification of one of these nine isolates was confirmed by amplifying and sequencing three loci (ITS, β-tubulin, and RPB2) using the ITS1/ITS4, Bt2a/Bt2b, and 5F2/7cR primer pairs, respectively (White et al., 1990, Glass and Donaldson, 1995, O'Donnell et al., 2007). A single representative isolate (Cgen01) was analyzed and submitted to GenBank (OR020968, OR079879, and OR079878). The Bayesian Inference was used to reconstruct the phylogenetic trees (Figure S2), starting from random trees for 5,000,000 generations, using MrBayes v. 3.2.1 (Ronquist et al., 2012). The isolate clustered together with the isolate of (Chen et al., 2017) with a high posterior probability (0.98). For the pathogenicity tests, four young, healthy branches containing 20 leaves were spray-inoculated with 1.5 mL of conidia suspension of Cgen01 (10 conidia mL-1), covered with perforated transparent plastic bags, and moistened with distilled water in the orchard. The air temperature ranged from 14ºC to 25ºC. Sterile distilled water was used as a control. Three replicates (pathogen and control) on different trees were evaluated. After five days, the fungus was re-isolated from the symptomatic lesion, showing morphological characteristics similar to those of Cgen01. Control branches did not show fungal growth. The inoculation test was conducted twice and similar symptoms were observed. This is the first report of leaf spots caused by on C. guazumifolia in Brazil. , an endophytic fungus described as a mycoparasite, showed phytopathogenic behavior in this study, causing spots and loss of leaves in drastically reducing the production of photoassimilates and affecting the quality of the fruits.
PubMed: 37858973
DOI: 10.1094/PDIS-06-23-1236-PDN -
Plant Disease Jul 2023Dinteranthus vanzylii is a low-growing species in the family Aizoaceae, native to southern Africa, with a pair of thick grey leaves covered with dark red spots and...
Dinteranthus vanzylii is a low-growing species in the family Aizoaceae, native to southern Africa, with a pair of thick grey leaves covered with dark red spots and stripes. This stone-like succulent grows near the ground, which may protect it from water evaporation and herbivores. Dinteranthus vanzylii has become popular in China due to its attractive appearance and easy indoor cultivation. In September 2021, 7% of D. vanzylii (approximately 140 pots) showed leaf wilt symptoms in a commercial greenhouse located in Ningde (119°35'39.696″E, 27°23'30.556″N), Fujian Province, China. The diseased plants were shrivelling and eventually underwent necrosis. Their leaf tissues were rotting and carpeted with white mycelium. The leaf tissues of 10 symptomatic plants were cut into 0.5 cm2 pieces, surface-sterilized and placed on PDA medium. According to the colony morphology after 7 days of culture, 20 fungal isolates with abundant whitish aerial mycelium were divided into two types: 8 isolates produced lilac pigment whereas 12 did not. Both produced unicellular ovoid microconidia, sickled-shaped macroconidia with 3 - 4 septa and single or paired smooth, thick-walled chlamydospores on carnation leaf agar (CLA). Molecular identification based on DNA sequences from EF1-α (O'Donnell et al. 1998), RPB1 and RPB2 (O'Donnell et al. 2010) revealed 100% identity among isolates within each group; however, there were several base differences between two types. Sequences of representative isolates KMDV1 and KMDV2 were deposited in GenBank (acc. nos.: OP910243, OP910244, OR030448, OR030449, OR030450 and OR030451), which showed 99.10% - 99.74% identity with different F. oxysporum strains (GenBank acc. nos.: KU738441, LN828039, MN457050, MN457049, ON316742 and ON316741). Phylogenetic tree inferred from the concatenated EF1-α, RPB1 and RPB2 revealed that these isolates clustered with F. oxysporum. Thus, these isolates were identified as F. oxysporum. Using a root-drenching method, 10 one-year-old healthy D. vanzylii were inoculated in conidial suspensions (1*106 conidia/mL) of isolates KMDV1 and KMDV2 for 60 min, respectively. They were transplanted into pots with sterilized soil and incubated in a plant-growth chamber at 25°C and 60% relative humidity. Control plants were treated with sterilized water. The pathogenicity test was repeated three times. All plants inoculated with each isolate developed leaf wilt symptoms after 15 days and were dead after 20 - 30 days. However, no symptoms were observed in the control plants. Fusarium oxysporum was reisolated and confirmed based on morphology and EF1-α sequence analysis. No pathogens were isolated from the control plants. This is the first report of F. oxysporum causing leaf wilt disease on D. vanzylii in China. To date, several diseases have been reported on members of the Aizoaceae. For instance, collar and stem rot on Lampranthus sp. caused by Pythium aphanidermatum (Garibaldi et al. 2009), wilt on Lampranthus sp. and Tetragonia tetragonioides caused by Verticillium dahliae (Garibaldi et al. 2010; Garibaldi et al. 2013), and leaf spot on Sesuvium portulacastrum caused by Gibbago trianthemae (Chen et al., 2022). Our research could provide insight into fungal diseases on members of the Aizoaceae and contribute to their cultivation and management.
PubMed: 37436212
DOI: 10.1094/PDIS-05-23-0983-PDN