The pathways of micro- and megagametophyte development in Agave fourcroydes (henequén) and A. angustifolia were studied. We used histology and light microscopy to observe anther ontogeny and ovary differentiation in relation to flower bud size. Both species have the same sexual reproductive strategies and gametophyte development that may be divided into three phases: (1) premeiotic, which includes the establishment of the megaspore mother cell and the pollen mother cell; (2) meiotic, the formation of mature microspores and functional megaspores; (3) postmeiotic, which encompasses the development of mature pollen grains and the formation of the embryo sac. A successive type microsporogenesis was found in both species with formation of T-shaped tetrads and binuclear pollen grains. In vitro germination tests revealed very low pollen fertility. The female gametophyte is formed from two micropylar megaspore cells after the first meiotic division (bisporic type). Male and female gametogenesis occur asynchronously with microsporogenesis finishing before macrosporogenesis. The results so far show that the formation of male and female gametophytes in henequén is affected at different stages and that these alterations might be responsible for the low fertility shown by this species.

A new type of bioreactor system for plant micropropagation is described that incorporates a number of features specifically designed to simplify its operation and reduce production costs. The BioMINT unit is a mid-sized (1.2 L) reactor that operates on the principle of temporary immersion. It is built of polypropylene and is translucent, autoclavable, and reusable. It consists of two vessels, one for the plant tissues and the other one for the liquid culture media coupled together through a perforated adaptor piece that permits the flow of the liquid media from one vessel to the other. This flux is driven by gravity through a see-saw movement provided by equipment (SyB) consisting of electric motor powered platforms that change position. The structural simplicity and the modular and independent nature of the bioreactors simplify their operation and reduce the amount of hand labor required for transfers, thereby reducing the cost of the whole micropropagation process.

Despite their economic importance, the Agave spp. have not been genetically improved. This is probably owing to the fact that they have very long life cycles and many of them have an inefficient sexual reproduction mechanism. Micropropagation offers an alternative to this problem through the efficient cloning of selected high-yielding "elite" plants. We report here an efficient method to micropropagate agaves and a strategy for the management of large scale production that has been successfully applied to several Agave spp.

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Somatic embryogenesis is a very useful micropropagation technique, due to its high multiplicative capacity that offers the potential for large-scale propagation using temporary immersion bioreactors. The temporary immersion system is mainly based on the contact of plant tissue with culture medium by certain cycles of immersion, avoiding the problems of hyperhydricity, malformed embryos, and low conversion rates, which occur in continuous immersion systems. The automation of some or all of the phases of the process of somatic embryogenesis in a bioreactor could reduce labor and gellant costs and increase micropropagation efficiency, allowing high-quality plantlets to be obtained through more efficient and controlled protocols. This chapter describes the different types of temporary immersion bioreactors that have been used to increase or scale somatic embryogenesis in different plant species.

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