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Previous issue date: 2008-09-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In the objective of advancing the epidemiologic study of the bacterial stain of the tomato, the
mechanisms of transmission of Xanthomonas vesicatoria from the plant to the seed and from
the seed to the plant have been evaluated. The morphology of seeds and of parts of the
seedlings or saplings (tegument, radicles, hypocotyl and cotyledon leaves, and definitive
leaves) have also been studied by means of electronic scanning microscopy techniques. The
transmission of X. vesicatoria from the plant to the seed has been evaluated upon direct and
indirect isolation of parts of ripe fruit (flesh, placenta, placental liquid, water from the first
washing of the seeds, entire seeds and ground seeds) in a culture of Agar Nutrient (AN). The
fruit were obtained in experimental parcels, conducted at the Horticultural sector of UFRRJ,
and inoculated with the phytobacteria through different methods (atomization and injection)
combined with different regions of inoculation (flower cluster, flesh, and placenta), during the
plant s developing phases (flower, unripened fruit, firm ripe and ripe fruit). The transmission
of the phytobacteria from the seeds to the seedlings and saplings was assessed by means of
isolating in an AN medium parts of the seedling or sapling (root, tegument, radicles,
hypocotyl and cotyledon leaves, and definitive leaves), germinated in different substrata
( germitest paper, sand, and commercialized substrate for saplings). The morphology of
seeds and parts of the seedlings was characterized through observations in electron
microscope scanning by using samples of fresh seeds (extracted from inoculated fruit), of
parts of seedlings or saplings (tegument, radicles, hypocotyl and cotyledon leaves, and
definitive leaves) and of seeds inoculated by vacuum procedure at 7, 14, and 21 days after
sowing. The treatments applied to the unripened fruit (inoculation by atomization, injection in
the placenta and injection in the flesh) were more efficient in the process of transmitting the
phytobacteria than the treatment applied to the firm ripe and ripe fruit. It was also observed
that the X vesicatoria colonizes the tegument and every part of the seedlings and saplings
during the process of germination and emergence. The seed tegument was characterized by an
entanglement of trichomes, with a base in the shape of ring and cavity, which may serve as
sheltering sites for pathogens, including the X vesicatoria. The process of colonization of
tomato seeds by X vesicatoria characterizes itself by the formation of biofilms and fibrils. The
presence of stomata colonized by X vesicatoria has been observed in radicles, of seven day
old seedlings, and in primary roots originated from the radicles of 20 day old saplings. Few
cells of X vesicatoria have been observed on the hypocotyl. The presence of endophytic
bacteria forming aggregates with characteristics of an aggressive growth identified as
Acinetobacter sp. was detected in many samples of seeds. These same bacteria were detected
in many tests of germination and isolation, interfering negatively in the development and
recuperation of X vesicatoria in the in vitro tests. / Com o objetivo de se avan?ar no estudo epidemiol?gico da mancha-bacteriana do tomateiro,
foram avaliados os mecanismos de transmiss?o de Xanthomonas vesicatoria da planta para a
semente e da semente para a planta. Foram feitos, ainda, estudos da morfologia da semente e
partes da pl?ntula ou muda (tegumento, rad?cula, hipoc?tilo e folhas cotiledonares e
definitivas), atrav?s de t?cnicas de microscopia eletr?nica de varredura. A transmiss?o de X.
vesicatoria da planta para a semente foi avaliada a partir de isolamentos diretos e indiretos de
partes de frutos maduros (mesocarpo, placenta, l?quido placent?rio, ?gua proveniente da
primeira lavagem das sementes, sementes inteiras e sementes trituradas) em meio de cultura
Nutriente Agar (NA). Os frutos foram obtidos em parcelas experimentais, conduzidas no setor
de Horticultura da UFRRJ, e inoculados com a fitobact?ria por diferentes m?todos
(atomiza??o e inje??o) combinados com diferentes regi?es de inocula??o (cacho floral,
mesocarpo e placenta), durante as fases de desenvolvimento da planta (flor, frutos verdes,
frutos de vez e frutos maduros). A transmiss?o da fitobact?ria das sementes para as pl?ntulas e
mudas foi avaliada por isolamentos em meio NA a partir de partes da pl?ntula ou muda (raiz,
tegumento, hipoc?tilo, folhas cotiledonares e folhas definitivas), germinadas em diferentes
substratos (papel germitest, areia e substrato comercial para mudas). A morfologia das
sementes e partes das pl?ntulas foi caracterizada por meio de observa??es em microsc?pio
eletr?nico de varredura utilizando-se amostras de sementes frescas (extra?das de frutos
inoculados), de partes de pl?ntulas ou mudas (raiz, hipoc?tilo, folha cotiledonar e folha
definitiva) e de sementes inoculadas pelo procedimento a v?cuo aos 7, 14 e 21 dias ap?s a
semeadura. Os tratamentos aplicados aos frutos verdes (inocula??o por atomiza??o, inje??o na
placenta e inje??o no mesocarpo) foram mais eficientes no processo de transmiss?o da
fitobact?ria que os tratamentos aplicados aos frutos de vez e maduros. Observou-se, ainda,
que X. vesicatoria coloniza o tegumento e todas as partes das pl?ntulas e mudas durante o
processo de germina??o e emerg?ncia. O tegumento da semente foi caracterizado por um
emaranhado de tricomas, com a base em forma de anel e cavidade, que podem servir como
s?tios protetores para pat?genos inclusive X. vesicatoria. O processo de coloniza??o das
sementes de tomate por X. vesicatoria se caracteriza pela forma??o de biofilmes e fibrilas.
Foram observados em rad?culas, de pl?ntulas com sete dias de idade, e em ra?zes prim?rias,
oriundas das rad?culas de mudas com 20 dias de idade, a presen?a de est?matos colonizados
por X. vesicatoria. Sobre o hipoc?tilo, foram observadas poucas c?lulas de X. vesicatoria. Em
v?rias amostras de sementes foi detectada a presen?a de bact?rias endof?ticas, que formavam
agregados com caracter?sticas de crescimento agressivo, identificadas como Acinetobacter sp.
Esta mesma bact?ria foi detectada em v?rios testes de germina??o e isolamento interferindo
negativamente no desenvolvimento e recupera??o de X. vesicatoria nos testes in vitro.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:tede/554 |
| Date | 26 September 2008 |
| Creators | Silva, D?bora Alves Gonzaga da |
| Contributors | Carmo, Margarida Gor?te Ferreira do, Carvalho, Aldir de Oliveira de |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Curso de P?s-Gradua??o em Fitotecnia, UFRRJ, Brasil, Produ??o Vegetal |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
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