Morphological variation, management and domestication of ‘maguey alto’ (Agave inaequidens) and ‘maguey manso’ (A. hookeri) in Michoacán, México

Abstract

BackgroundAgave inaequidens and A. hookeri are anciently used species for producing the fermented beverage ‘pulque’, food and fiber in central Mexico. A. inaequidens is wild and cultivated and A. hookeri only cultivated, A. inaequidens being its putative wild relative. We analysed purposes and mechanisms of artificial selection and phenotypic divergences between wild and managed populations of A. inaequidens and between them and A. hookeri, hypothesizing phenotypic divergence between wild and domesticated populations of A. inaequidens in characters associated to domestication, and that A. hookeri would be phenotypically similar to cultivated A. inaequidens.MethodsWe studied five wild and five cultivated populations of A. inaequidens, and three cultivated populations of A. hookeri. We interviewed agave managers documenting mechanisms of artificial selection, and measured 25 morphological characters. Morphological similarity and differentiation among plants and populations were analysed through multivariate methods and ANOVAs.ResultsPeople recognized 2–8 variants of A. inaequidens; for cultivation they select young plants collected in wild areas recognized as producing the best quality mescal agaves. Also, they collect seeds of the largest and most vigorous plants, sowing seeds in plant beds and then transplanting the most vigorous plantlets into plantations. Multivariate methods classified separately the wild and cultivated populations of A. inaequidens and these from A. hookeri, mainly because of characters related with plant and teeth size. The cultivated plants of A. inaequidens are significantly bigger with larger teeth than wild plants. A. hookeri are also significatly bigger plants with larger leaves but lower teeth density and size than A. inaequidens. Some cultivated plants of A. inaequidens were classified as A. hookeri, and nearly 10% of A. hookeri as cultivated A. inaequidens. Wild and cultivated populations of A. inaequidens differed in 13 characters, whereas A. hookeri differed in 23 characters with wild populations and only in 6 characters with cultivated populations of A. inaequidens.ConclusionsDivergence between wild and cultivated populations of A. inaequidens reflect artificial selection. A. hookeri is similar to the cultivated A. inaequidens, which supports the hypothesis that A. hookeri could be the extreme of a domestication gradient of a species complex.

TEK, local perceptions of risk, and diversity of management practices of Agave inaequidens in Michoacán, Mexico

“…This process, according to the handlers’ testimony, has led to a historical decrease in the size of mature agaves in wild populations as has been evaluated and reported by Figueredo et al . [ 34 ]. The most common perception of people is a testimony that in general the populations are declining in both quantity and quality.…”

Caracterización morfológica de Agave angustifolia y su conservación en Guerrero, México

“…Lineño, obteniendo una variabilidad total 79% semejante a la obtenida en este estudio empleando la misma técnica, pero con A. angustifolia 'sacatoro' y 'espadín'. Figueredo et al (2014) a través de métodos multivariables, con base en caracteres morfológicos, diferenciaron poblaciones de maguey silvestre y cultivado reflejando la selección artificial; mostrando que A. hookeri pudiera ser el extremo de un gradiente de domesticación en un complejo de especies, debido a la similitud que presenta con A. inaequidens cultivado. Por el contrario, los magueyes silvestres como A. macroculmis son plantas pequeñas y con espinas grandes.…”

“…Es por eso que, cuando se caracteriza una población de especímenes de manera morfológica y se trabaja con variables cuantitativas y cualitativas es importante la reclasificación de variables basada en la correlación o pruebas de normalidad multivariadas, aplicando el teorema del límite central, se entiende que las muestras comprenden una población 'normal' (Castañón-Nájera et al, 2008). La distribución y agrupamiento de los especímenes fue compleja; por lo tanto, se optó por considerar un análisis multidimensional para formar clases o grupos definidos tanto por similitudes como por disimilitudes morfológicas (Figueredo et al, 2014;Avendaño-Arrazate et al, 2015).…”

Review and in silico analysis of fermentation, bioenergy, fiber, and biopolymer genes of biotechnological interest inAgaveL. for genetic improvement and biocatalysis

“…Unfortunately, until now, only a handful of species have been studied aimed at obtaining evidence of their domestication and management processes. Domesticated Agave plants are larger than their wild relatives, have fewer and smaller spines, and because of their cultivation in plantations have limited genetic variation . However, the few studies made in cultivated polyploid species of Agave in rDNA, NBS‐LRR, and LEA genes, have revealed that A. tequilana “Azul” (2 n = 2 x = 60)—used for production of tequila—and A. fourcroydes “Kitam ki” (2 n = 3 x = 90)—used for fiber production—have variants of these genes that could be involved in gene evolution, rRNA functionality, and activity of proteins participating in defense responses.…”

“…Domesticated Agave plants are larger than their wild relatives, have fewer and smaller spines, and because of their cultivation in plantations have limited genetic variation. 56,87,88 However, the few studies made in cultivated polyploid species of Agave in rDNA, NBS-LRR, and LEA genes, have revealed that A. tequilana "Azul" (2n = 2x = 60)-used for production of tequila-and A. fourcroydes "Kitam ki" (2n = 3x = 90)-used for fiber production-have variants of these genes that could be involved in gene evolution, rRNA functionality, and activity of proteins participating in defense responses. This strongly suggests that anthropic pressure might have had negative effects on their variability, genetic diversity, and response to abiotic and biotic stress.…”