Abstract

CHIN-CHAN, T.; ORTIZ-GARCIA, M. M.; RUIZ-GIL, P. J.  and  MARTINEZ-CASTILLO, J.. Genetic diversity of chaya (Cnidoscolus aconitifolius (Mill.) I. M. Johnst. ssp. aconitifolius) in Yucatan, Mexico, its putative domestication center. Polibotánica [online]. 2021, n.51, pp.185-201.  Epub May 06, 2021. ISSN 1405-2768.  https://doi.org/10.18387/polibotanica.51.12.

Chaya (Cnidoscolus aconitifolius ssp. aconitifolius) has great importance as an edible and medicinal plant in the Mayan area. It has been pointed out that Chaya has low genetic diversity since its cultivation occurs clonally, but there are not enough molecular studies to support this. The objective of this work was to provide knowledge about the diversity and genetic structure of the Chaya and its wild relatives in Yucatán, Mexico, its possible area of domestication. One hundred individuals of Chaya, eight wild individuals of C. aconitifolius and nine of C. souzae were characterized using 158 ISSR loci. Analyses carried out with Structure, PCoA, Neighbor-Joining, AMOVA and genetic distances methods, clearly differentiated Chaya from its wild relatives; the first three methods showed the presence of two genetically differentiated landraces of Chaya: Chayamansa (with 98 individuals) and Redonda (with two individuals); PCoA and Neghbor-Joining analyses showed evidence of the presence of only two clones in Chayamansa and two clones in Redonda. Chaya showed low genetic diversity (%P= 5.95; H E= 0.018) compared to C. aconitifolius (%P= 71; H E= 0.26) and C. souzae (%P = 56; H E = 0.21); when the two individuals of the Redonda landrace were eliminated from the analysis, the genetic diversity was much lower (%P= 0.6; H E= 0.008). Our results confirm the existence of very low levels of genetic diversity in Chaya as a result, possibly, of its clonal propagation and/or by a founder effect due to domestication; valuable information was generated on the landrace Redonda and, for the first time, genetic diversity values for C. aconitifolius and C. souzae were provided. The results of this work can be used to generate genetic improvement programs for Chaya and for conservation programs for this plant and its wild relatives.

Keywords : clonal reproduction; Cnidoscolus aconitifolius; Cnidoscolus souzae; genetic structure; ISSR markers; mayas; wild relatives.

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