Plumele Soft Rot Caused by Fusarium equiseti, F. oxysporum, and F. pallidoroseum on Soybean Seedlings in Argentina

Soybean (Glycine max) is an important crop in the northern area of the province of Buenos Aires, Argentina. Phomopsis spp. and Fusarium spp. are the prevalent pathogens in soybean seeds. Infection levels for both pathogens can be greater than 50%. In seedlings growing in sand or soil, both pathogens produce rotten lesions on cotyledons and hypocotyls, but over the past 2 years a plumele soft rot has also been observed associated with detached teguments that was previously demonstrated to be caused by Fusarium spp. (1). In 1996, seeds with a germination level lower than 82% were selected from an assay including 22 cultivars, and examined for the presence of Fusarium spp. The infection level ranged from 2 to 16%, and the Fusarium spp. present were identified as F. equiseti, F. oxysporum, and F. pallidoroseum. After each Fusarium sp. was cultured on potato dextrose agar, a conidial suspension was prepared and adjusted to 1.8 × 106 conidia per ml. This inoculum was sprayed on water-soaked paper, in petri dishes, and good quality soybean seeds were placed on the paper, with 400 seed for each Fusarium sp. The petri dishes were maintained at 26°C for 24 h. Control seeds were plated on water-soaked paper. Inoculated seeds were sown in sand with a water content of 16% wt/wt, covered with polyethylene bags, and incubated for 7 days in a growth chamber at 26°C and a 12-h light period. All the samples inoculated with the three Fusarium spp. exhibited seed rot, seedlings with cotyledon and hypocotyl lesions as described previously (2), but also plumele soft rot. Control seedlings remained symptomless. This is the first report confirming that the characteristic plumele soft rot of soybean seedlings is a nonspecific symptom associated with F. equiseti, F. oxysporum, and F. pallidoroseum. References: (1) B. González et al. ISTA-PDC Symp., 2nd. 1996. (2) G. S. Saharan and V. K. Gupta. Plant Dis. Rep. 56:693, 1972.

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Proteomic Analysis of Irradiation with Millimeter Waves on Soybean Growth under Flooding Conditions

International Journal of Molecular Sciences ◽

10.3390/ijms21020486 ◽

2020 ◽

Vol 21 (2) ◽

pp. 486 ◽

Cited By ~ 3

Author(s):

Zhuoheng Zhong ◽

Takashi Furuya ◽

Kimitaka Ueno ◽

Hisateru Yamaguchi ◽

Keisuke Hitachi ◽

...

Keyword(s):

Oxidative Stress ◽

Proteomic Analysis ◽

Millimeter Waves ◽

Sugar Metabolism ◽

Immunoblot Analysis ◽

Glutathione Metabolism ◽

Soybean Seeds ◽

Soybean Seedlings ◽

Promotive Effect ◽

Trehalose Synthesis

Improving soybean growth and tolerance under environmental stress is crucial for sustainable development. Millimeter waves are a radio-frequency band with a wavelength range of 1–10 mm that has dynamic effects on organisms. To investigate the potential effects of millimeter-waves irradiation on soybean seedlings, morphological and proteomic analyses were performed. Millimeter-waves irradiation improved the growth of roots/hypocotyl and the tolerance of soybean to flooding stress. Proteomic analysis indicated that the irradiated soybean seedlings recovered under oxidative stress during growth, whereas proteins related to glycolysis and ascorbate/glutathione metabolism were not affected. Immunoblot analysis confirmed the promotive effect of millimeter waves to glycolysis- and redox-related pathways under flooding conditions. Sugar metabolism was suppressed under flooding in unirradiated soybean seedlings, whereas it was activated in the irradiated ones, especially trehalose synthesis. These results suggest that millimeter-waves irradiation on soybean seeds promotes the recovery of soybean seedlings under oxidative stress, which positively regulates soybean growth through the regulation of glycolysis and redox related pathways.

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Fusarium Root and Crown Rot: A Disease of Container-Grown Hostas

Plant Disease ◽

10.1094/pdis.2000.84.9.980 ◽

2000 ◽

Vol 84 (9) ◽

pp. 980-988 ◽

Cited By ~ 15

Author(s):

B. Wang ◽

S. N. Jeffers

Keyword(s):

South Carolina ◽

Crown Rot ◽

Undescribed Species ◽

Fresh Weight ◽

Fusarium Spp ◽

Disease Symptoms ◽

Leaf Yellowing ◽

Oat Seeds ◽

Root And Crown Rot ◽

Fusarium Sp

A previously unreported disease was observed on 11 cultivars of container-grown hosta plants at five wholesale nurseries in South Carolina between 1997 and 1999. Symptoms included leaf yellowing, plant stunting, rotting of and vascular discoloration in roots, and necrosis in the crowns. Fusarium spp. consistently were isolated from symptomatic hosta plants. Four species were recovered: F. solani, F. oxysporum, F. proliferatum, and an undescribed species designated Fusarium sp.; F. solani and Fusarium sp. were recovered most frequently. To demonstrate pathogenicity, four methods were used to inoculate hosta plants with representative isolates of F. solani, F. oxysporum, and Fusarium sp. Two types of inoculum, colonized oat seeds and conidium suspensions, were used to inoculate wounded and nonwounded plants. Disease symptoms occurred consistently only on hosta plants inoculated by dipping wounded roots and crowns into suspensions of conidia. Symptoms were most severe on plants inoculated with Fusarium sp. and much less severe on plants inoculated with F. solani or F. oxysporum. Disease severity increased and fresh weight of inoculated plants decreased when the concentration of inoculum of Fusarium sp. was increased over the range of 1 × 103 to 1 × 107 conidia per ml. Isolates of Fusarium sp., F. solani, and F. oxysporum varied in virulence when Hosta ‘Francee’ plants were inoculated. This study demonstrated that Fusarium root and crown rot of container-grown hostas is caused primarily by Fusarium sp. but that it also can be caused by F. solani and F. oxysporum. Fusarium sp. appears to be taxonomically distinct from other species, and its identity currently is under investigation.

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The Effect of Macroalgal Extracts and Near Infrared Radiation on Germination of Soybean Seedlings: Preliminary Research Results

Open Chemistry ◽

10.1515/chem-2018-0115 ◽

2018 ◽

Vol 16 (1) ◽

pp. 1066-1076 ◽

Cited By ~ 3

Author(s):

Izabela Michalak ◽

Sylwia Lewandowska ◽

Jerzy Detyna ◽

Sylwia Olsztyńska-Janus ◽

Henryk Bujak ◽

...

Keyword(s):

Infrared Radiation ◽

Near Infrared ◽

Synergistic Effects ◽

Biologically Active ◽

Growth And Yield ◽

Soybean Seeds ◽

Near Infrared Radiation ◽

Soybean Seedlings ◽

Wide Range ◽

Stimulate Plant Growth

AbstractIn the present study, synergistic effects between the application of near-infrared radiation (NIR) and macroalgal extracts on the germination of soybean seeds were searched for. NIR is captured by special photoreceptors (i.e. phytochromes, cryptochromes and phototropins) and next plants generate a wide range of specific physiological responses through these receptors. For the study, a special system of NIR was applied to irradiate soybean seeds. To our knowledge, this is the first time this kind of radiation was used for the biostimulation of soybean seeds. Previously, the effect of other ranges of light (e.g. green, red, blue) was analysed in terms of photosynthetic activity, growth and yield of different plants, except seeds. NIR for 3 and 5 minutes was also combined with the application of macroalgal extracts used for seeds soaking. They are known as a rich source of biologically active compounds that can stimulate plant growth. These preliminary studies show that the examined factors can stimulate plant’s growth and their quality.

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Fusarium Species Associated with Tall Fescue Seed Production in Oregon

Plant Health Progress ◽

10.1094/php-2004-0319-01-rs ◽

2004 ◽

Vol 5 (1) ◽

pp. 7 ◽

Cited By ~ 1

Author(s):

Cynthia M. Ocamb ◽

Stephen C. Alderman

Keyword(s):

Hydrogen Peroxide ◽

Seed Germination ◽

Seed Production ◽

Tall Fescue ◽

Fusarium Species ◽

Fusarium Spp ◽

Fusarium Sp

Seed samples were collected from 15 commercial tall fescue seed production fields and examined for Fusarium spp. The percentage of seeds from which Fusarium spp. were recovered ranged from 0 to 32%, while disinfesting seeds with 3% hydrogen peroxide reduced the recovery of Fusarium to 7% or less. The predominant Fusarium spp. isolated from the tall fescue seeds included F. avenaceum, F. culmorum, F. pseudograminearum, and F. sambucinum. Greenhouse inoculations of tall fescue panicles with F. avenaceum, F. culmorum, and F. pseudograminearum resulted in higher seedborne rates of each respective Fusarium sp. than that recovered from noninoculated plants. Seeds recovered from panicles treated with F. avenaceum or F. pseudograminearum had significantly lower germination rates relative to panicles sprayed with water or a suspension of F. culmorum. Our work confirms that Fusarium spp. decrease seed germination and expands the pathogen list to include F. avenaceum and F. pseudograminearum. Accepted for publication 17 February 2004. Published 19 March 2004.

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First Report of Fusarium Blight on Majesty Palm Caused by Fusarium proliferatum in Italy

Plant Disease ◽

10.1094/pdis.2003.87.9.1149a ◽

2003 ◽

Vol 87 (9) ◽

pp. 1149-1149 ◽

Cited By ~ 6

Author(s):

G. Polizzi ◽

A. Vitale

Keyword(s):

Fusarium Proliferatum ◽

Conidial Suspension ◽

First Report ◽

Leaf Spots ◽

Initial Symptoms ◽

Mt Etna ◽

Young Leaves ◽

Pure Cultures ◽

Severe Infections ◽

Fusarium Sp

During spring 2002, a new disease of majesty palm (Ravenea rivularis Jumelle & H. Perrier) was observed on young, container-grown plants (3 to 4 years old with five to seven expanded leaves) in a nursery in eastern Sicily. Initial symptoms on the youngest, expanded leaves and especially on the unopened, spear leaves were small, reddish-brown necrotic lesions (2 to 4 mm in diameter) with a yellow halo. In high humidity, lesions increased in size and number, coalescing into large, irregular dead areas. These symptoms developed into blights of the youngest, unopened leaves. As a consequence, infected leaves would dieback and only a few plants recovered from these severe infections. On the surviving plants, reddish-brown necrotic lesions appeared on the rachis. From these lesions, 30 pieces of tissue were cut, surface sterilized (30 s in 1.2% wt/vol of NaOCl), washed with sterile water, and plated on potato dextrose agar supplemented with 1.1 μl/ml of lactic acid (stock 88 to 92%) (A-PDA). Conidia and conidiophores were collected directly from the tissue with a flamed needle and placed on A-PDA. Fusarium sp. was consistently isolated from the necrotic tissue, and after 3 days, single hyphal tips were transferred to pure cultures from which were obtained two single, conidial isolates. These fungal isolates were forwarded to the CABI Bioscience U.K. Centre, Bakeham Lane (Egham), Surrey, U.K., where both isolates were identified as Fusarium proliferatum (T. Matsushima) Nirenberg. A morpho-biometrical characterization was performed on carnation leaf agar with a photoperiod of 10 h. Macroconidia were slender, lightly falcate to almost straight, 3- to 5-septate, and ranged from 37 to 53 × 2.5 to 3 μm (average 44.1 × 2.8 μm). Microconidia, clavate or oval with a truncated base, were formed in chains from mono- or polyphialides. Chlamydospores were absent. Eight 2-year-old seedlings (three to five expanded leaves) of majesty palm had the unopened spear leaves needle-wounded and another eight were unwounded. All were sprayed with a conidial suspension (1.5 × 106 CFU/ml). An equal number of noninoculated plants were used as a control. All plants were covered with polyethylene bags and incubated in a greenhouse at 25 ± 2°C for 72 h. All wounded majesty palms showed brown areas on unopened spear leaves. When natural injures were present, reddish leaf spots appeared as early as 4 days after inoculation. Macroscopic observations revealed the presence of white mycelium on the necrotic areas and reddish spots. Koch's postulates were satisfied by reisolation of the fungus on A-PDA from artificially infected tissues. On the basis of 3 months of field observations in Sicily, spread of Fusarium blight on majesty palm was always greater when plants were injured on the tender and unopened leaves by volcanic cinders from Mt. Etna, which caused bruises on young leaves. The disease does not represent a major threat to nurseries, but it could cause loss in the cultivation of the majesty palm. F. proliferatum was previously recorded in Saudi Arabia as the causal agent of wilt and dieback of date palm (1). To our knowledge, this is the first report of F. proliferatum on palms in Italy and the first outbreak of the disease on majesty palm. Reference: (1)M. Y. Abdalla et al. Plant Dis. 84:321, 2000.

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First Report of Fusarium Wilt of Babaco (Carica × heilbornii var. pentagona) in Ecuador

Plant Disease ◽

10.1094/pdis.2000.84.2.199a ◽

2000 ◽

Vol 84 (2) ◽

pp. 199-199 ◽

Cited By ~ 4

Author(s):

J. Ochoa ◽

G. Fonseca ◽

M. A. Ellis

Keyword(s):

Sodium Hypochlorite ◽

Crop Production ◽

Infected Plant ◽

Soft Rot ◽

Local Market ◽

Market Demand ◽

Sterile Water ◽

Tissue Sections ◽

Pathogenicity Tests ◽

Petri Dishes

Babaco, Carica × heilbornii V.M. Badillo var. pentagona (Heilborn) V.M. Badillo, is a fruit native to Ecuador that has great potential as a cultivated crop. Local market demand and strong potential as an export crop have greatly increased interest in babaco production in Ecuador. Although the crop can be produced in open fields, the majority of crop production is in plastic greenhouses. In 1996, a serious wilt disease developed on babaco in several greenhouses, resulting in up to 100% loss of plants. Symptoms first appeared as chlorosis of the lower leaves, followed by defoliation progressing up the stem until the entire plant was defoliated. When cut in cross section, vascular discoloration was observed in the stem. Eventually necrosis and soft rot of the stem occurred and entire plants collapsed. Fungal isolations were conducted from fine feeder roots of diseased plants by soaking root pieces (2 cm long) in a 0.5% solution of sodium hypochlorite for 3 min. Root pieces were cut into smaller sections and placed on potato dextrose (PDA) or corn meal (CMA) agar in petri dishes. Isolations from larger roots, crowns, stems and fruits were made by soaking tissue sections of each plant part in a 2.87% solution of sodium hypochlorite for 3 min. Tissue sections were rinsed three times in sterile distilled water. Smaller tissue sections (≈0.125 cm3) were cut from surface-disinfested pieces and placed on PDA and CMA in petri dishes. Cultures were incubated at 20°C. A fungus resembling Fusarium sp. was isolated consistently from infected tissues from all infected plant parts. Based on the morphology of the fungal colony and conidia from monosporic isolations, the fungus was identified as Fusarium oxysporum Schlechtend:Fr. (1). Pathogenicity tests were conducted by growing babaco plants in pots containing an equal mixture of sterilized soil, compost, and sand in the greenhouse. Eight 7-month-old plants were inoculated by placing 40 ml of a suspension (106 conidia per ml) of F. oxysporum in four plastic straws placed in the soil (5 cm depth) at equal distances (5 cm) from the base of each plant. Straws around noninoculated control plants received sterile water. Plants were watered with 400 ml of sterile water daily. Pathogenicity tests were repeated once as described. All inoculated plants developed typical wilt symptoms within 45 days after inoculation. No symptoms developed on uninoculated control plants. F. oxysporum was successfully reisolated from infected stem tissues of inoculated plants. Incidence of Fusarium vascular wilt of babaco has continued to increase since 1996 and is currently the major constraint to production. References: (1) P. E. Nelson et al. 1981. Fusarium: Diseases, Biology, and Taxonomy. The Pennsylvania State University Press, University Park.

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First report of Fusarium commune causing root and crown rot on maize in Italy

Plant Disease ◽

10.1094/pdis-01-21-0075-pdn ◽

2021 ◽

Author(s):

Monica Mezzalama ◽

Vladimiro Guarnaccia ◽

Ilaria Martino ◽

Giulia Tabome ◽

Maria Lodovica GULLINO

Keyword(s):

Plant Disease ◽

Tap Water ◽

Morphological Characteristics ◽

Plant Diseases ◽

Crown Rot ◽

Conidial Suspension ◽

Fusarium Spp ◽

First Report ◽

Root And Crown Rot ◽

Pathogenicity Tests

Maize (Zea mays L.) is a cereal crop of great economic importance in Italy; production is currently of 62,587,469 t, with an area that covers 628,801 ha, concentrated in northern Italy (ISTAT 2020). Fusarium species are associated with root and crown rot causing failures in crop establishment under high soil moisture. In 2019 maize seedlings collected in a farm located in San Zenone degli Ezzelini (VI, Italy) showed root and crown rot symptoms with browning of the stem tissues, wilting of the seedling, and collapsing due to the rotting tissues at the base of the stem. The incidence of diseased plants was approximately 15%. Seedlings were cleaned thoroughly from soil residues under tap water. Portions (about 3-5 mm) of tissue from roots and crowns of the diseased plants were cut and surface disinfected with a water solution of NaClO at 0.5% for 2 minutes and rinsed in sterile H20. The tissue fragments were plated on Potato Dextrose Agar (PDA) amended with 50 mg/l of streptomycin sulfate and incubated for 48-72 hours at 25oC. Over the 80 tissue fragments plated, 5% were identified as Fusarium verticillioides, 60% as Fusarium spp., 35% developed saprophytes. Fusarium spp. isolates that showed morphological characteristics not belonging to known pathogenic species on maize were selected and used for further investigation while species belonging to F. oxysporum were discarded. Single conidia of the Fusarium spp. colonies were cultured on PDA and Carnation Leaf Agar (CLA) for pathogenicity tests, morphological and molecular identification. The colonies showed white to pink, abundant, densely floccose to fluffy aerial mycelium. Colony reverse showed light violet pigmentation, in rings on PDA. On CLA the isolates produced slightly curved macronidia with 3 septa 28.1 - 65.5 µm long and 2.8-6.3 µm wide (n=50). Microconidia were cylindrical, aseptate, 4.5 -14.0 µm long and 1.5-3.9 µm wide (n=50). Spherical clamydospores were 8.8 ± 2.5 µm size (n=30), produced singly or in pairs on the mycelium, according to the description by Skovgaard et al. (2003) for F. commune. The identity of two single-conidia strains was confirmed by sequence comparison of the translation elongation factor-1α (tef-1α), and RNA polymerase II subunit (rpb2) gene fragments (O’Donnell et al. 2010). BLASTn searches of GenBank, and Fusarium-ID database, using the partial tef-1α (MW419921, MW419922) and rpb2 (MW419923, MW419924) sequences of representative isolate DB19lug07 and DB19lug20, revealed 99% identity for tef-1α and 100% identity to F. commune NRRL 28387(AF246832, AF250560). Pathogenicity tests were carried out by suspending conidia from a 10-days old culture on PDA in sterile H2O to 5×104 CFU/ml. Fifty seeds were immersed in 50 ml of the conidial suspension of each isolate for 24 hours and in sterile water (Koch et al. 2020). The seeds were drained, dried at room temperature, and sown in trays filled with a steamed mix of white peat and perlite, 80:20 v/v, and maintained at 25°C and RH of 80-85% for 14 days with 12 hours photoperiod. Seedlings were extracted from the substrate, washed under tap water, and observed for the presence of root and crown rots like the symptoms observed on the seedlings collected in the field. Control seedlings were healthy and F. commune was reisolated from the symptomatic ones and identified by resequencing of tef-1α gene. F. commune has been already reported on maize (Xi et al. 2019) and other plant species, like soybean (Ellis et al. 2013), sugarcane (Wang et al. 2018), potato (Osawa et al. 2020), indicating that some attention must be paid in crop rotation and residue management strategies. To our knowledge this is the first report of F. commune as a pathogen of maize in Italy. References Ellis M L et al. 2013. Plant Disease, 97, doi: 10.1094/PDIS-07-12-0644-PDN. ISTAT. 2020. http://dati.istat.it/Index.aspx?QueryId=33702. Accessed December 28, 2020. Koch, E. et al. 2020. Journal of Plant Diseases and Protection. 127, 883–893 doi: 10.1007/s41348-020-00350-w O’Donnell K et al. 2010. J. Clin. Microbiol. 48:3708. https://doi.org/10.1128/JCM.00989-10 Osawa H et al. 2020. Journal of General Plant Pathology, doi.org/10.1007/s10327-020-00969-5. Skovgaard K 2003. Mycologia, 95:4, 630-636, DOI: 10.1080/15572536.2004.11833067. Wang J et al. 2018. Plant Disease, 102, doi/10.1094/PDIS-07-17-1011-PDN Xi K et al. 2019. Plant Disease, 103, doi/10.1094/PDIS-09-18-1674-PDN

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Seed priming with sodium nitroprusside attenuates the effects of water deficit on soybean seedlings

Comunicata Scientiae ◽

10.14295/cs.v10i1.2842 ◽

2019 ◽

Vol 10 (1) ◽

pp. 176-184

Author(s):

Marina Alves Gavassi ◽

Lucas Aparecido Gaion ◽

Carolina Cristina Monteiro ◽

Joel Cabral Santos ◽

Rogério Falleiros Carvalho

Keyword(s):

Nitric Oxide ◽

Sodium Nitroprusside ◽

Water Deficit ◽

Field Capacity ◽

Seed Priming ◽

Carotenoid Biosynthesis ◽

Soybean Seeds ◽

Initial Development ◽

Soybean Seedlings ◽

Fundamental Part

Considering that water deficit is one of the main environmental factors responsible for low soybean yield and that nitric oxide (NO) has been shown to be a fundamental part of plant defense signaling during stress, the aim of the present study was to evaluate the effect of seed priming with nitric oxide on the induction of water deficit tolerance during the initial development of soybean. Thus, seeds were treated with 0 (water only), 50, 100 or 250 μmol.L-1 sodium nitroprusside for 6 hours. Additionally, untreated seeds were used. After drying, the seeds were placed in containers filled with a commercial substrate mixture and vermiculite and irrigated to 100% and 50% field capacity. Biometric and biochemical evaluations (pigment and proline contents) were performed after 14 days. It was concluded that pretreatment of soybean seeds with 50 to 250 μmol.L-1 SNP attenuated the effects of water deficit on stem growth, leaf area, and shoot dry matter and induced carotenoid biosynthesis. The accumulation of proline in the leaves was pronounced in the treatments with 100 and 250 μmol.L-1 SNP, while 100 μmol.L-1 SNP induced proline accumulation in the roots.

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Potensi Trichoderma spp. sebagai Agens Pengendali Fusarium spp. Penyebab Penyakit Layu pada Tanaman Stroberi

Jurnal Hortikultura ◽

10.21082/jhort.v25n4.2015.p331-339 ◽

2016 ◽

Vol 25 (4) ◽

pp. 331 ◽

Cited By ~ 1

Author(s):

Mutia Erti Dwiastuti ◽

Melisa N Fajri ◽

Yunimar Yunimar

Keyword(s):

Fragaria X Ananassa ◽

Dual Culture ◽

Fusarium Spp ◽

Trichoderma Spp ◽

Trichoderma Sp ◽

Fusarium Sp

Layu yang disebabkan oleh Fusarium spp. merupakan salah satu penyakit penting tanaman stroberi (Fragaria x ananassa Dutch.) di daerah subtropika, yang dapat menggagalkan panen. Penelitian bertujuan untuk mempelajari potensi Trichoderma spp. dalam mengendalikan Fusarium spp. Isolat Trichoderma spp. diisolasi dari rizosfer tanaman stroberi dan Fusarium spp. diisolasi dari tanaman stroberi yang mengalami layu fusarium. Isolat cendawan dimurnikan, dikarakterisasi, dan dibandingkan dengan isolat cendawan acuan. Uji antagonis dilakukan secara in vitro dan in vivo. Uji in vitro dilakukan dengan metode dual culture dan slide culture. Uji in vivo dilakukan di rumah kasa menggunakan dua varietas stroberi, yaitu Santung serta California. Hasil penelitian in vitro memperoleh dua jenis isolat cendawan antagonis, yaitu Trichoderma sp.1 dan Trichoderma sp.2, dan dua jenis cendawan patogen Fusarium, yaitu Fusarium sp.1 dan Fusarium sp.2. Isolat Trichoderma sp.1 memiliki kemampuan antagonisme lebih tinggi dibandingkan dengan isolat Trichoderma sp.2. Isolat Trichoderma sp.1 mampu menghambat pertumbuhan Fusarium sp.1 dan Fusarium sp.2 secara berturut- turut, yaitu 49,7% dan 49,6%. Isolat Trichoderma sp.2 mampu menghambat pertumbuhan Fusarium sp.1 dan Fusarium sp.2 lebih rendah, yaitu sebesar 45,8% dan 43,4%. Mekanisme antagonis yang terjadi antara cendawan antagonis dan patogen pada uji in vitro, yaitu pembelitan dan intervensi hifa. Hasil pada uji in vivo pada perlakuan Trichoderma sebelum Fusarium menunjukkan keefektifan pengendalian paling baik (41,72%) dibanding perlakuan lain. Varietas Santung lebih tahan terhadap serangan patogen dibandingkan varietas California. Implikasi dari hasil penelitian ini adalah, agens hayati Trichoderma spp. lebih optimal digunakan sebagai pencegahan (preventif) tanpa menunggu tanaman terinfeksi penyakit layu fusarium.

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First Report of Diaporthe novem Causing Postharvest Rot of Kiwifruit During Controlled Atmosphere Storage in Chile

Plant Disease ◽

10.1094/pdis-02-14-0183-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1274-1274 ◽

Cited By ~ 5

Author(s):

G. A. Díaz ◽

B. A. Latorre ◽

S. Jara ◽

E. Ferrada ◽

P. Naranjo ◽

...

Keyword(s):

Aerial Mycelium ◽

Soft Rot ◽

Storage Conditions ◽

Negative Control ◽

Its2 Region ◽

Conidial Suspension ◽

Controlled Atmosphere ◽

First Report ◽

Postharvest Rot ◽

Negative Controls

Chile is considered the third major exporter of kiwifruits (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferguson) worldwide after Italy and New Zealand (1). The genus Diaporthe Nitschke (anamorph: genus Phomopsis) has been reported as causing postharvest rot in kiwifruit (4). During the current study, 1,400 fruits arbitrarily collected from seven controlled atmosphere (CA) rooms after 90 days of storage conditions (2% O2, 5% CO2) determined that 21.5% of the fruit were affected by decay and 0.86% developed symptoms different than those caused by Botrytis cinerea, the main postharvest pathogen associated to kiwifruit. Symptoms were soft rot with brown skin that started at the stem-end and in severe cases affected the entire fruit. Internally, affected fruit showed browning and watery tissues. Twelve affected fruits were surface disinfested (75% ethanol) and small pieces of internal rotten tissues were placed on acidified potato dextrose agar (APDA) for 7 days at 20°C. Twelve isolates were obtained, and four of them were identified morphologically and molecularly as Diaporthe ambigua, a species that has been previously described causing rot in stored kiwifruits in Chile (2). However, eight other flat, white to grayish colonies with sparse dirty-white aerial mycelium at the edge of the dish were obtained (3). Black pycnidia contained unicellular, hyaline, biguttulate, oval to cylindrical alpha conidia, with obtuse ends of (7.9) 6.7 (5.3) × (2.9) 2.5 (2.1) μm (n = 30). These isolates were tentatively identified as a Diaporthe sp. The species identification was determined by sequencing comparison of the internal transcribed spacer (ITS1-5.8S-ITS2) region of the rDNA (GenBank Accession Nos. KJ210020 to 24, KJ210027, and KJ210033) and a portion of beta-tubulin (BT) (KJ210034 to 38, KJ210041, and KJ210047) using primers ITS4-ITS5 and Bt2a-Bt2b, respectively. BLAST analyses showed 99 to 100% identity with D. novem J.M. Santos, Vrandecic & A.J.L Phillips reference ex-type (KC343156 and KC344124 for ITS and BT, respectively) (3). Eighteen mature kiwifruits cv. Hayward were inoculated using a sterile cork borer on the surface of the fruit and placing 5-mm agar plugs with mycelial of D. novem (DN-1-KF). An equal number of fruits treated with sterile agar plugs were used as negative controls. After 30 days at 0°C under CA, all inoculated fruit showed rot symptoms with lesions 7.8 to 16.4 mm in diameter. The same D. novem isolate was inoculated with 30 μl of a conidial suspension (106 conidia/ml) on the surface of 18 ripe kiwifruits that were previously wounded and non-wounded as described above. An equal number of wounded and non-wounded fruits, treated with 30 μl sterile water, were used as negative controls. All inoculated wounded fruits developed rot symptoms with necrotic lesions of 14.1 to 20.2 mm of diameter after 14 days at 25°C. Inoculated non-wounded and negative control fruits remained symptomless. Koch's postulates were fulfilled by re-isolating D. novem only from the symptomatic fruits. To our knowledge, this is the first report of rot caused by D. novem on kiwifruit during cold storage in Chile and worldwide. Therefore, both Diaporthe species appears to be associated to Diaporthe rot of kiwifruit in Chile. References: (1) Belrose, Inc. World Kiwifruit Review. Belrose, Inc. Publishers, Pullman, WA, 2012. (2) J. Auger et al. Plant Dis. 97:843, 2013. (3) R. Gomes et al. Persoonia 31:1, 2013. (4) L. Luongo et al. J. Plant Pathol. 93:205, 2011.

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