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First Report of Boeremia exigua var. exigua (syn. Phoma exigua var. exigua ) Causing Black Root Rot on Industrial Chicory ( Cichorium intybus var. sativum ) in Chile

2016; American Phytopathological Society; Volume: 100; Issue: 11 Linguagem: Catalão

10.1094/pdis-05-16-0591-pdn

1943-7692

D. Grinbergs, A. France, Mark Varrelmann,

Plant Disease Resistance and Genetics

HomePlant DiseaseVol. 100, No. 11First Report of Boeremia exigua var. exigua (syn. Phoma exigua var. exigua) Causing Black Root Rot on Industrial Chicory (Cichorium intybus var. sativum) in Chile PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Boeremia exigua var. exigua (syn. Phoma exigua var. exigua) Causing Black Root Rot on Industrial Chicory (Cichorium intybus var. sativum) in ChileD. Grinbergs, A. France, and M. VarrelmannD. GrinbergsSearch for more papers by this author, A. FranceSearch for more papers by this author, and M. VarrelmannSearch for more papers by this authorAffiliationsAuthors and Affiliations D. Grinbergs A. France , Instituto de Investigaciones Agropecuarias, INIA Quilamapu, Chillán, Chile M. Varrelmann , Institut für Zuckerrübenforschung, 37079 Göttingen, Germany. Published Online:16 Aug 2016https://doi.org/10.1094/PDIS-05-16-0591-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Cichorium intybus var. sativum is an Astereacae plant grown for its fleshy roots, which are rich in inulin, oligofructose, and other fructans, and are used as functional food. It was introduced to Chile in 2006, where climate conditions allowed high yields. However, during crop adaptation period, a severe crown rot was observed, with yield losses of up to 31% and reduced efficiency in inulin extraction process. Field collections of rotted plants from all cultivated areas were performed between 2009 and 2013. Root symptoms started as dark, small, sunken lesions on the crown, turning to firm, black colored cavities as the crop developed. Signs were not visible. Sections of tissue were aseptically excised from the margins of necrotic lesions and placed into petri plates, containing either water agar or acidified 25% potato dextrose agar. Pure cultures were obtained through hyphal tips. Isolates were identified on the basis of their morphological characteristics on oatmeal agar (OA) and malt agar (MEA), the metabolite ‘E’ test (Aveskamp et al. 2010), and molecular features. DNA was extracted from pure cultures and multilocus sequence typing was performed (Aveskamp et al. 2009). The internal transcribed spacer (ITS) sequence, actin, and β-tubulin genes were amplified and sequenced. Primers ITS1 and ITS4 were used for ITS region, Act-512F and Act-783R for actin, and Bt2a and Bt2b for β-tubulin. Acquired sequences were subjected to NCBI BLAST search. Bootstrap analyses were performed on each dataset using neighbor-joining with 1,000 replicates. After 7 days, colonies grew 39 to 70 mm in diameter on OA and 47 to 82 mm on MEA. Colonies on MEA were olivaceous gray with irregularly scalloped margins, floccose, white to pale olivaceous-gray aerial mycelium, and olivaceous-gray to black reverse. Pycnidia were dark, submerse, globose to subglobose, glabrous, solitary or confluent, with a yellowish conidial matrix and a nonpapillated ostiole. Conidia were hyaline and unicellular, ellipsoidal to oblong (n = 100), ranging from 1.9 to 3.2 µm wide (2.8 ± 0.9 µm) × 4.2 to 6.8 µm long (5.7 ± 4.2 µm), with bipolar guttules. Swollen cells were olivaceous and constricted at the septa. Chlamydospores were absent (Boerema et al. 2004). All isolates were E+. Multilocus sequence alignment and tree construction assigned the isolates to Boeremia exigua var. exigua. Pathogenicity tests were performed with four different inoculation methods. Mycelium plugs 70 mm diameter, from colonies on PDA, were inoculated on surface sterilized root discs 50 to 70 mm diameter and incubated in a humid chamber, at 22°C in the dark. Plugs were also inoculated on surface sterilized entire roots and incubated both in a humid chamber and in pasteurized soil in the greenhouse for 20 days. Controls were inoculated with sterile agar plugs. Subsequently, the fungus was massified in sterile millet grains and mixed with pasteurized soil (0.1% v/v), where healthy plants were transplanted. The pathogen was able to colonize the root, either with or without injuries to the crown, reproducing black root rot symptoms in all the inoculations. For all the tests, the pathogen was reisolated on PDA, fulfilling Koch’s postulates. Consequently, this is the first report of B. exigua var. exigua on industrial chicory in Chile.References:Aveskamp, M. M., et al. 2009. Mycologia 101:363. https://doi.org/10.3852/08-199 Crossref, ISI, Google ScholarAveskamp, M. M., et al. 2010. Stud. Mycol. 65:1. https://doi.org/10.3114/sim.2010.65.01 Crossref, ISI, Google ScholarBoerema, G. H., et al. 2004. Phoma Identification Manual. CABI Publishing, Wallingford, UK. Google ScholarDetailsFiguresLiterature CitedRelated Vol. 100, No. 11 November 2016SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 7 Oct 2016Published: 16 Aug 2016First Look: 13 Jun 2016Accepted: 4 Jun 2016 Page: 2328 Information© 2016 The American Phytopathological SocietyCited byCharacterization of Boeremia exigua causing stem necrotic lesions on Luobuma in northwest China14 December 2022 | Scientific Reports, Vol. 12, No. 1Spatiotemporal Attributes and Crop Loss Associated with Tan Spot Epidemics in Baby Lima Bean in New YorkSarah J. Pethybridge, Frank S. Hay, Adrienne Gorny, and Julie R. Kikkert14 December 2017 | Plant Disease, Vol. 102, No. 2