|Osuna-Avila, Pedro - AUTONOMA DE CD JUAREZ, MX|
|Reyes-Vera, Issac - NEW MEXICO STATE UNIV|
Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 29, 2008
Publication Date: March 16, 2008
Citation: Lucero, M.E., Barrow, J.R., Osuna-Avila, P., Reyes-Vera, I. 2008. A cryptic microbial community persists within micropropagated Bouteloua eriopoda (Torr.) Torr. cultures. Plant Science. 174:570-575. Interpretive Summary: Plant colonization by systemic endophytic fungi is often perceived as an exception, rather than a ubiqutous component of plant systems Although plants lacking fungal associations have never been described, and most microbes cannot be cultured in laboratories, plants micropropagated in aseptic laboratory environments are often perceived axenic. In this study, a micropropagated line of the plant species Bouteloua eriopoda (black grama grass) is demonstrated to retain a diverse consortium of systemic ascomycete and basidomycete fungi that persist in micropropagation, only a few of which are occasionaly detected macroscopically. Since the fungi are all retained in regenerated plant lines, it is likely that they are transferred to progeny during cell division, thus both vegetative and seed propagated progeny of plants are likely to contain maternal fungal endophytes. To determine the type and diversity of fungi involved, ribosomal DNA sequences were obtained from plant tissues and from previously isolated endophytes. Sequences obtained from cultured and uncultured endophytes suggest as many as seven fungal species may be present in a single, aseptically propagated plant. Learning the roles these fungi play in plant survival may provide clues to undescribed interactions that influence successful establishment of black grama. Similar interactions are likely to influence other plants species.
Technical Abstract: Higher plants are ubiquitously colonized with fungal endophytes, which often lack readily detectable structures. This study examines the diverse endophyte population within a single line of micropropagated Bouteloua eriopoda (Torr.) Torr., using microscopy and comparison of internal spacer (ITS) gene sequences obtained from both plant and isolated fungal tissues. Sequences amplified from three ascomycete and one basidiomycete fungi isolated from a micropropagated line were compared to seven unique, ITS sequences amplified directly from the fungal-laden micropropagated plant tissue. Clone sequences were also compared to grass ITS sequences. Bayesian analysis placed four of the seven sequences in a tight grass clade. The remaining sequences were placed in a more diverse clade representing both cultured and uncultured endophytes. Results confirm a diverse, cryptic endophyte consortium is retained within this micropropagated plant line. The probability that similar complexity is common among higher plants implies a need to revise commonly held assumptions that aseptically propagated plants are axenic. Genes and natural products derived from such systems could be microbial in origin. Meanwhile, while the development of controlled systems in which to study single plant-fungal interactions presents significant technical challenges, the potential to uncover multi-species interactions that influence plant growth and development is high.