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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Diversity of endophytic yeasts from sweet orange and their localization by scanning electron microscopy

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Author(s):
Gai, Claudia Santos [1] ; Lacava, Paulo Teixeira [1] ; Maccheroni, Jr., Walter [2] ; Glienke, Chirlei [3] ; Araujo, Wellington Luiz [1] ; Miller, Thomas Albert [4] ; Azevedo, Joao Lucio [1]
Total Authors: 7
Affiliation:
[1] Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, Dept Genet, BR-13400970 Piracicaba, SP - Brazil
[2] Canavialis, Campinas, SP - Brazil
[3] Univ Fed Parana, Dept Genet, BR-80060000 Curitiba, Parana - Brazil
[4] Univ Calif Riverside, Dept Entomol, Riverside, CA 92521 - USA
Total Affiliations: 4
Document type: Journal article
Source: JOURNAL OF BASIC MICROBIOLOGY; v. 49, n. 5, p. 441-451, OCT 2009.
Web of Science Citations: 20
Abstract

Endophytes are microorganisms that colonize plant tissues internally without causing harm to the host. Despite the increasing number of studies on sweet orange pathogens and endophytes, yeast has not been described as a sweet orange endophyte. In the present study, endophytic yeasts were isolated from sweet orange plants and identified by sequencing of internal transcribed spacer (ITS) rRNA. Plants sampled from four different sites in the state of Sao Paulo, Brazil exhibited different levels of CVC (citrus variegated chlorosis) development. Three citrus endophytic yeasts (CEYs), chosen as representative examples of the isolates observed, were identified as Rhodotorula mucilaginosa, Pichia guilliermondii and Cryptococcus flavescens. These strains were inoculated into axenic Citrus sinensis seedlings. After 45 days, endophytes were reisolated in populations ranging from 10(6) to 10(9) CFU/g of plant tissue, but, in spite of the high concentrations of yeast cells, no disease symptoms were observed. Colonized plant material was examined by scanning electron microscopy (SEM), and yeast cells were found mainly in the stomata and xylem of plants, reinforcing their endophytic nature. P. guilliermondii was isolated primarily from plants colonized by the causal agent of CVC, Xylella fastidiosa. The supernatant from a culture of P. guilliermondii increased the in vitro growth of X. fastidiosa, suggesting that the yeast could assist in the establishment of this pathogen in its host plant and, therefore, contribute to the development of disease symptoms. (AU)