JXB Advance Access originally published online on January 19, 2007
Journal of Experimental Botany 2007 58(5):1119-1132; doi:10.1093/jxb/erl271
© 2007 The Author(s).
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RESEARCH PAPER |
Embryogenesis induction, callogenesis, and plant regeneration by in vitro culture of tomato isolated microspores and whole anthers
Instituto para la Conservación y Mejora de la Agrodiversidad Valenciana (COMAV), Universidad Politécnica de Valencia Camino de Vera s/n, edificio I-4, E-46022 Valencia, Spain
* To whom correspondence should be addressed. E-mail: seguisim{at}btc.upv.es
In this work, some of the different in vitro developmental pathways into which tomato microspores or microsporocytes can be deviated experimentally were explored. The two principal ones are direct embryogenesis from isolated microspores and callus formation from meiocyte-containing anthers. By means of light and electron microscopy, the process of early embryogenesis from isolated microspores and the disruption of normal meiotic development and change of developmental fate towards callus proliferation, morphogenesis, and plant regeneration have been shown. From microspores isolated at the vacuolate stage, embryos can be directly induced, thus avoiding non-androgenic products. In contrast, several different morphogenic events can be triggered in cultures of microsporocyte-containing anthers under adequate conditions, including indirect embryogenesis, adventitious organogenesis, and plant regeneration. Both callus and regenerated plants may be haploid, diploid, and mostly mixoploid. The results demonstrate that both gametophytic and sporophytic calli occur in cultured tomato anthers, and point to an in vitro-induced disturbance of cytokinesis and subsequent fusion of daughter nuclei as a putative cause for mixoploidy and genome doubling during both tetrad compartmentalization and callus proliferation. The potential implications of the different alternative pathways are discussed in the context of their application to the production of doubled-haploid plants in tomato, which is still very poorly developed.
Key words: Androgenesis, anther culture, electron microscopy, haploid embryogenesis, Lycopersicon esculentum, microspore culture, morphogenesis, organogenesis, plant regeneration, Solanum lycopersicum
Received 12 September 2006; Revised 15 November 2006 Accepted 16 November 2006