Origen, variación y tendencias evolutivas del Henequén ( Agave fourcroydes Lem.)

Henequen was domesticated by the Maya people, from A. angustifolia, since pre-Hispanic times. It is one of the most important natural hard fibers worldwide because of its good quality and adaptation to ecologically restricted agrohabitats. This cultivar has maintained great economic and cultural value in the state of Yucatan. Ethnobotanical, morphological, and isozyme evidence were compiled to discuss the origin and evolution of henequen by human selection, the germplasm diversity available in the cultivated populations and that of the wild populations from which it could have arisen. Results suggested the occurrence of a drastic erosion of the genetic diversity maintained by the Maya, as a consequence of its cultivation under large plantations established at the beginning of this century for the cordage industry. At present, only three varities are cultivated: Sak ki (SK), Yaax ki (YK) and Kitam ki (KK), these last two in very small populations. SK and YK differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. KK is very similar to the wild types. Isozyme analysis indicated that wild populations have relatively high levels of variation, whereas all individuals of each henequen variety were identical. A parsimony analysis indicated two lineages: that of SK and YK, cultivated cordage plants selected for stronger and longer fibers, whose sister group is the tropical deciduous forest ecotype (SF); and that of ali other wild populations, which also included KK, the cultivated textile plants selected for finer fibers, and nearly extint in Yucatan. These  results support the hypothesis of the yucatecan origin of SK and YK from the SF ecotype, as well as the recent introduction of KK. Methodology used is discussed as well as research perspectives in this theme.