Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)

Argentina is the world's largest yerba mate producer; the producing provinces are Misiones and Corrientes. This crop has several drawbacks such as low genetic and physiological seed quality, slow, even and low percentage germination and heterogeneity of plants grown from seed, which led to the...

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Autor principal: Pérez, María Laura
Otros Autores: Mroginski, Luis Amado
Formato: Tesis doctoral
Lenguaje:Español
Publicado: Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias 2020
Materias:
Yerba mate
Micropropagación
Microorganismos contaminantes
Acceso en línea:http://repositorio.unne.edu.ar/handle/123456789/458
Aporte de:
RIUNNE - Repositorio Institucional de la Universidad Nacional del Nordeste (UNNE) de Universidad Nacional del Nordeste
id I48-R184-123456789-458
record_format dspace
institution Universidad Nacional del Nordeste
institution_str I-48
repository_str R-184
collection RIUNNE - Repositorio Institucional de la Universidad Nacional del Nordeste (UNNE)
language Español
topic Yerba mate
Micropropagación
Microorganismos contaminantes
spellingShingle Yerba mate
Micropropagación
Microorganismos contaminantes
Pérez, María Laura
Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)
topic_facet Yerba mate
Micropropagación
Microorganismos contaminantes
description Argentina is the world's largest yerba mate producer; the producing provinces are Misiones and Corrientes. This crop has several drawbacks such as low genetic and physiological seed quality, slow, even and low percentage germination and heterogeneity of plants grown from seed, which led to the necessity of developing micropropagation systems. One of the major difficulties in the yerba mate micropropagation is in vitro contamination by fungi and bacteria. Among the various factors that can influence the contamination of in vitro culture are the time of year, type of explant and the presence of surface and/or endophytic plant-associated microorganisms. Since endophytes live within plant tissues, they are able to survive surface disinfection making them harder to control. The aim of this work was to characterize the microorganisms contaminant of yerba mate micropropagation systems and establish their source. The composition and diversity of the endophytic community associated with aerial organs of yerba mate (Ilex paraguariensis) was investigated using culture-depending methods. Fungal and bacterial endophytes were isolated from young and adult leaves and branches of three yerba mate clones growing under field condition in Corrientes province, Argentina. Besides, in order to establish if most of the contaminants of yerba mate in vitro culture corresponded to endophytes from field or greenhouse growing plants, contaminant microorganisms were isolated from in vitro micropropagated, and greenhouse plants. Fungi were identified based on their micromorphological characteristics and internal transcribed spacer (ITS) rDNA sequence analysis; for bacteria 16S rDNA sequence analysis was used. A total of 156 fungal and 193 bacterial isolates were obtained. Bacteria predominated in stem samples while leaf samples retrieved similar amount of bacterial and fungal isolates. No significant differences were found in isolate quantity nor diversity among seasons or between young and older leaves and stems. The most frequently isolated fungus was Fusarium, followed by Colletotrichum; they were both present in all the sampling seasons and organ types assayed. Other 12 fungus genera were identified including Aspergillus, Cercospora, Clonostachys (Bionectria), Curvularia, Guignardia, Microsphaeropsis, Neofusicoccum, Nigrospora, Paecilomyces, Penicillium, Phomopsis (Diaporthe), and Phyllosticta. Actinobacteria represented 61% of all bacterial isolates. The most dominant bacterial taxa were Curtobacterium and Microbacterium. They were isolated from all the organs assayed, 4 showing that they are ubiquitous endophytes. Other bacteria frequently found throughout the year were Methylobacterium, Sphingomonas, Herbiconiux and Bacillus. The predominant fungi and bacteria detected in yerba mate were similar to those reported in other species in which the same type of technique was used. Fungal genera Curvularia, Fusarium, Penicillium, Setophoma, and bacteria Pantoea and Staphylococcus were isolated as contaminants of in vitro culture and as endophytes in plants grown under greenhouse and field conditions. Alternaria was t isolated as a contaminant of in vitro culture and as endophyte in plants grown in the field, as well as the bacteria Janibacter. Fusarium was the most numerous fungal genus. 8 Fusarium species were identified, and pathogenicity on yerba mate was assayed in three of them (F. oxysporum, F. pseudocircinatum y F. subglutinans), showing that they behave as endophytes when plants are grown under field conditions but are pathogenic to in vitro plants (vitropathogens). The results obtained in this thesis showed that most of the yerba mate in vitro culture contaminants are endophytic microorganisms that occur also in field or greenhouse grown plants without showing any negative effect on ex vitro plants. We have also determined that the number and diversity of fungal and bacterial isolates are affected by the season, being higher during fall and summer, as well as the organ type and age.
author2 Mroginski, Luis Amado
author_facet Mroginski, Luis Amado
Pérez, María Laura
format Tesis doctoral
author Pérez, María Laura
author_sort Pérez, María Laura
title Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)
title_short Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)
title_full Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)
title_fullStr Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)
title_full_unstemmed Caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (Ilex paraguariensis)
title_sort caracterización de microorganismos contaminantes en sistemas de micropropagación de yerba mate (ilex paraguariensis)
publisher Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias
publishDate 2020
url http://repositorio.unne.edu.ar/handle/123456789/458
work_keys_str_mv AT perezmarialaura caracterizaciondemicroorganismoscontaminantesensistemasdemicropropagaciondeyerbamateilexparaguariensis
bdutipo_str Repositorios
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