Abstract Detail


Ramirez, Sarah [1], Fuentes Soriano, Sara [1], Guzman, Ivette [3].

The more the merrier? Bioprospecting the bitterness of cytogenetic variants from creosote bush (Larrea tridentata (DC.) Coville, Zygophyllaceae) in the Sonoran and Chihuahuan desert.

Polyploidy is a common phenomenon among plants in which populations of a single species vary in chromosome counts (cytotypes). On the basis of morphology, polyploid populations of a species are frequently challenging for identification. Creosote bush or Larrea tridentata (DC.) Coville in the Zygophyllaceae is a classic polyploid species complex. Taxonomic and ecological investigations on this species suggest that ploidy levels increase in number among populations of the Mojave (n=6x), Sonoran (n=4x), and Chihuahuan (n=2x) Deserts, respectively. Creosote is a prolific shrub in North American deserts traditionally used as a medicinal herb. This species is rich in bioactive phenolic compounds and essential oils. More than 60 biochemical studies of the species suggest medicinal benefits with various effects. However, the role of ploidy variation on the biochemistry of the species has not been explored. Our hypothesis is that there is a correlation between ploidy and differences in the bioactive compounds present in the species. Information like this is critical from an application perspective because this can guide herbalists and pharmaceutical research to focus on specific populations and cytotypes. The objective of this ongoing study is being accomplished by reviewing literature, studying herbaria specimens and label data, creating species population distribution maps, and conducting biochemical analyses of diploid and tetraploid populations. Study of herbaria species, including +250 vouchers specimens from 9 different herbaria and morphometric analyses of six vegetative and reproductive plant structures have allowed the indirect identification of creosote populations with different ploidy levels. Results from herbarium work indicate that Chihuahuan Desert populations from the Dona Ana Co., NM are diploid whereas those from the Sonoran deserts are tetraploid. These preliminary findings guided field sampling strategies carried on the Chihuahuan and Sonoran Desert localities. In each desert we collected samples from three individuals of three populations for a total of 18 samples. Total phenolics were measured using a spectrophotometric method with gallic acid as a standard. Essential oil extracts were analyzed using gas chromatography mass spectrometry (GC-MS). The results indicated that the Chihuahuan Desert creosote contained the highest amounts of phenolics with 12.6 mg/g total phenolics while the Sonoran Desert creosote contained 11.3 mg/g total phenolics. GC-MS data also confirmed the presence of camphor as a major constituent in creosote essential oils. The results will not only further characterize the native creosote, but also shed light on the variation of medicinally active compounds in cytotypes within a species.

1 -
2 - New Mexico State University, Animal and Range Sciences, Knox Hall, Room 202, Box 30003, MSC 3-I, Las Cruces, NM, 8803
3 - Box 30003 MSC 3Q, Las Cruces, NM, 88003, USA

Chihuahuan Desert
sonoran desert
Morphometric Analysis
Larrea tridentata

Presentation Type: Poster This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PET009
Abstract ID:856
Candidate for Awards:Economic Botany Section best poster

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