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Previous issue date: 2014-08-22 / Eucalyptus is an economically important woody species, especially as a raw material in many
industrial sectors. Brazil ranks the second worldwide position in acreage, totalizing
approximately three million hectares. Eucalyptus species are very susceptible to pathogens such
as Botrytis cinerea (gray mold), which leads to mortality of cuttings in rooting phase. Biological
control of plant diseases using soil microorganisms has been considered an alternative to reduce
the use of pesticides and pathogen attack. Plant growth promoting rhizobacteria can act directly
on plant development for production of phytohormones or indirectly as antagonists to
pathogens, as well as promote changes in secondary metabolism, and hence inducing of
systemic resistance. In this study, the direct roleof Streptomyces isolates in plant development
was evaluated through the production of auxin and rhizogenic potential in Eucalyptus grandis
and E. globulus plants, as well as indirectly, by modulation of the secondary metabolism, and
induction of sistemic resistence in plantselicited with Streptomyces sp. and challenged with the
pathogenic fungus B. cinerea. Metabolic responses were evaluated throughactivity of plant
defense enzymes (PPO and POX) and induced secondary compounds (total phenolics and
quercetinic-flavonoids fraction). The incidence and progression of gray mold disease on plants
elicited Streptomyces sp. PM9, and coculture of these microorganisms (Streptomyces and B.
cinerea) were also evaluated. Streptomyces sp. PM5 and PM9 isolates produced more auxin
than the other isolates tested. Streptomyces sp. PM9 showed the highest rhizogenic potential on
Eucalyptus sp. and modulated secondary metabolism of these plants. Antagonism of this
isolated over B. cinerea was evidenced. Plants elicited with Streptomyces sp. PM9 and
challenged with B. cinerea showed changes in PPO and POX enzymes and levels of phenolic
compounds at different time points of analysis, which may be related to initial defense response.
Phenolic compounds chlorogenic acid and gallic acid were, on average, the most abundant, while caffeic acid, benzoic acidand catechin were induced at specific time points. A delay in
the onset of disease was significant in plants of E. grandis elicited with Streptomyces. The
induction of resistance, disease delay and antagonism against B. cinereaindicate the capacity of
Streptomyces sp. PM9 as an inducer of plant systemic resistance, and poses this microorganism
as a potential candidate for biological control programs in nurseries of Eucalyptus. Interaction
of rhizobacteria with eucalyptus plant, as well as the modulation of defense mechanisms may
contribute to the establishment of new biocontrol strategies applied to forestry. / O eucalipto ? uma esp?cie lenhosa economicamente importante, destacando-se como mat?riaprima
em diversos setores industriais. O Brasil ocupa a segunda posi??o mundial em ?rea
plantada, totalizando aproximadamente tr?s milh?es de hectares. As esp?cies de eucalipto s?o
muito suscet?veis a pat?genos como Botrytis cinerea (mofo-cinzento), o qual leva ? mortalidade
de estacas em fase de enraizamento. O controle biol?gico de doen?as em plantas utilizando
microrganismos do solo tem sido considerado uma alternativa para reduzir o uso de
agroqu?micos e o ataque de pat?genos. Rizobact?rias promotoras de crescimento vegetal podem
agir diretamente no desenvolvimento das plantaspela produ??o de fitorm?niosou indiretamente,
como antagonistas a fungos patog?nicos, al?m de causar altera??es no metabolismo secund?rio,
com consequente indu??o de resist?ncia sist?mica. Neste trabalho, avaliou-se a a??o direta no
desenvolvimento vegetal de isolados rizobacterianos do g?nero Streptomyces atrav?s da
produ??o de auxinas e potencial rizog?nico de Eucalyptus grandis e E. globulus, bem como
oefeito modulador no metabolismo secund?rioe a indu??o de resist?ncia sist?mica em plantas
eliciadas com Streptomyces sp. e desafiadas com o fungo patog?nico B. cinerea. As respostas
metab?licas foram avaliadas atrav?s das atividades de enzimas realacionadas ? defesa vegetal
(PPO e POX) e dos compostos secund?rios induzidos (compostos fen?licos totais e fra??o
flavon?ides quercet?nicos). A incid?ncia e progress?o da doen?a mofo cinzento em plantas
eliciadas com Streptomyces sp. PM9, e cocultivo destes microrganismos (Streptomyces e
B.cinerea) tamb?m foram avaliados. Os isolados de Streptomycessp.PM5 e PM9 apresentaram
maior produ??o de auxina que os demais isolados testados. Streptomyces sp.PM9 apresentou o
maior potencial rizog?nico em plantas de Eucalyptus sp. emodulou o metabolismo secund?rio
destas plantas. Oantagonismo deste isolado sobre B. cinerea foi evidenciado.As plantas
eliciadas com Streptomyces sp. PM9 e desafiadas com B. cinereaapresentaram altera??es nas enzimas PPO e POXe nos n?veis de compostos fen?licos totais em diferentes tempos de an?lise,
as quais foram relacionadas ? resposta inicial de defesa.Os compostos fen?licos ?cido g?lico e
clorog?nico foram, em m?dia, os mais abundantes, embora os ?cidos cafeico e benzoico e a
catequina tenham sido induzidos em momentos espec?ficos. O retardo no estabelecimento da
doen?a foi significativo em plantas de E. grandis eliciadas com Streptomyces. Os resultados de
indu??o de resist?ncia, retardo da doen?a eantagonismocontra B.cinerea, demonstram a
capacidade de a??o de Streptomycessp. PM9 como indutor de resist?ncia sist?mica vegetal,
colocando este microrganismo como potencial candidato aos programas de controle biol?gico
em viveiros de mudas de Eucalyptus. A intera??o da planta de eucalipto com a rizobact?ria,
bem como a modula??o dos mecanismos de defesa podem contribuir para o estabelecimento de
novas estrat?giasde biocontrole aplicado ? silvicultura.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/6014 |
| Date | 22 August 2014 |
| Creators | Salla, Tamiris Daros |
| Contributors | Santar?m, Eliane Romanato |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Biologia Celular e Molecular, PUCRS, Brasil, Faculdade de Bioci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 8198246930096637360, 600, 600, 600, 36528317262667714, -1634559385931244697 |
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