Agave Fourcroydes Research Articles

New cytotaxonomical determinants recognized in six taxa of Agave in the sections Rigidae and Sisalanae

New cytotaxonomical determinants are presented for the following taxa of Agave: (I) section Rigidae: Agave fourcroydes Lemaire (5x = 150), first karyotype; Agave angustifolia Haworth (sensu Gentry), new count (6x = 180), first karyotype; Agave angustifolia Haworth var. marginata Hort. (2x = 60); and Agave tequilana Weber, new count (2x = 60), first karyotype; (II) section Sisalanae: Agave sisalana Perrine (5x = 150), first karyotype; and (III) intersectional hybrid: Agave hybrid 11 648 new count (2x = 60), first karyotype. Chromosomes are classified and arm number, chromatin length, and variability are discussed. These results suggest (i) a speciation process via limited rearrangements and point mutations in the small chromosomes of the complement, within the euploidy level rather than karyotype diversification and (ii) a reconsideration to assign them to the 2C level of Stebbins karyotype classification. Key words: fiber agaves, karyotype analysis.

In vitro propagation of Agave fourcroydes Lem. (Henequen)

In vitro plant regeneration of Agave fourcroydes Lem. (Agavaceae) is described. Results suggest that the NO3 -:NH4 + balance in the culture medium is a key factor controlling callus growth and organogenesis in rhizome cultures. Stem callus showed limited organogenic capacity, but high cytokinin concentrations induced adventitious shoot formation on stem explants. When these shoots were excised and subcultured, new callus formed at their base from which new shoots arose. The shoots from stem explants and rhizome callus formed extensive root systems in vitro and were transferred to pot culture with a 90% survival rate.