Asepsis, defined as the absence of microbial contamination, is one of the most important requirements of plant micropropagation. In long-term micropropagated cultures, there may occasionally occur scattered microorganism growth in the culture medium. These microorganisms are common plant components and are known as latent endophytes. Thus, the aim of this research was to investigate the presence of endophytic bacteria in asymptomatic pineapple and orchid microplants, which were cultivated in three laboratories for 1 year. Isolation and characterization of bacterial isolates, PCR-DGGE from total genomic DNA of microplants and ultrastructural analysis of leaves were performed. In the culture-dependent technique, it was only possible to obtain bacterial isolates from pineapple microplants. In this case, the bacteria genera identified in the isolation technique were Bacillus, Acinetobacter, and Methylobacterium. The scanning electron microscopy and transmission electron microscopy (SEM and TEM) analyses revealed the presence of endophytic bacteria in intracellular spaces in the leaves of pineapple and orchid microplants, independent of the laboratory or cultivation protocol. Our results strongly indicate that there are endophytic bacterial communities inhabiting the microplants before initiation of the in vitro culture and that some of these endophytes persist in their latent form and can also grow in the culture medium even after long-term micropropagation, thus discarding the concept of "truly axenic plants."

1RESUMO -Dos mecanismos com potencial valor adaptativo em resposta ao estresse hídrico merece destaque o apresentado por Eugenia glazioviana Kiaersk cuja perda de turgescência foliar e consequente curvatura do limbo da posição horizontal para a vertical, sem a abscisão das folhas, que estão associados à redução da superfície foliar exposta à luz solar. Dessa forma, o presente trabalho teve por objetivo a caracterização histológica da folha da espécie, visando compreender melhor esse mecanismo de resposta ao estresse hídrico. Para tanto foram realizados cortes transversais e paradérmicos da lâmina foliar, bem como, cortes transversais do pecíolo, sendo estes analisados e as imagens capturadas em microscópio de luz. Os resultados permitem, entre outras coisas, afirmar que E. glazioviania possui características tipicamente xerofíticas, sendo elas: cutícula espessa em ambas as superfícies, folha hipoestomática, com muitos tricomas tectores na face abaxial, além de uma característica que pode ser exclusiva da espécie e que possivelmente justifique tal resposta, a qual relaciona-se a presença de ductos glandulares, que percorrem toda a extensão do pecíolo, em continuidade com a lâmina foliar. ECOLOGICAL ANATOMY OF Eugenia glazioviana KIAERSK LEAF (MYRTACEAE) ABSTRACT -In response to hydrous stress, the adaptive mechanisms with a potential adaptive value presented by

Micropropagation has been applied in the recovery and rejuvenation of adult trees, which is achieved by various subcultures in the multiplication phase. This strategy has brought questions about the endophytic microbiota associated with these plants along its manipulation. Therefore, the aim of this study was to evaluate the composition of the endophytic bacterial communities associated with two explants sources [the canopy branches (CB) and the trunk base of the tree (TB)] under prolonged in vitro cultivation. In addition we analyzed the bacterial community dynamic along the subcultures in different micropropagation phases. Bacterial DNA was extracted from samples of mini-stumps (in vivo) from CB and TB and in micro-stumps produced by in vitro cultivations of these explants sources--both originated from one single matrix plant of Eucalyptus benthamii. In vitro establishment occurred in two dates and the evaluation of endophytic bacterial communities was made in vivo and in vitro samples (on 10th, 13th and 16th subcultures), when elongated shoots and roots were analyzed. Analysis was performed by PCR-DGGE based on the V6 region of ribosomal gene 16S rDNA. Bands profiles showed differences in communities between in vivo and in vitro samples, and also distinctions of communities assessed in the subcultures, elongated and rooted samples. Distinctions in the composition of endophytic bacterial communities were greater in CB micro-stumps. These results indicate a differential colonization of explants by endophytic bacteria, with predominance of common (ever-present) endophytes in TB samples and casual, here named opportunistic, in CB samples.

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