Corresponding author: Huzefa A. Raja ( firstname.lastname@example.org )
Corresponding author: Mario Figueroa ( email@example.com )
Academic editor: Kentaro Hosaka
© 2017 Abraham J. Medina-Ortiz, Teófilo Herrera, Marco A. Vásquez-Dávila, Huzefa A. Raja, Mario Figueroa.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Medina-Ortiz AJ, Herrera T, Vásquez-Dávila MA, Raja HA, Figueroa M (2017) The genus Podaxis in arid regions of Mexico: preliminary ITS phylogeny and ethnomycological use. MycoKeys 20: 17-36. https://doi.org/10.3897/mycokeys.20.11570
Identification of Podaxis species to species-level based on morphology alone is problematic. Thus, species of the genus Podaxis are in dire need of taxonomic and phylogenetic evaluations using molecular data to develop a consensus between morphological taxonomy and more robust molecular analyses. In Mexico, most of the collected specimens of Podaxis have been morphologically identified as Podaxis pistillaris sensu lato and are locally used for its culinary value. In this study, the internal transcribed spacer region of Podaxis specimens from the MEXU fungarium collected between 1948 and 2014 from arid regions of Mexico were sequenced and these collections placed into a molecular phylogenetic framework using Maximum Likelihood analysis. In addition, the ethnomycological use of Podaxis in Mexico (utility, traditional handling, economic importance, etc.) is described by observations, interviews, and sampling of Podaxis species with local people from three areas of the region of the Cañada of Oaxaca, which belongs to the Tehuacán-Cuicatlán Biosphere Reserve. These results indicate that the Mexican Podaxis were divided into two clades. Specimens collected in the northern region showed phylogenetic affinities to clade D, while specimens from the south of Mexico clustered within clade E. Morphological data, such as spore length and width, showed significant differences between the two phylogenetic clades, implying that these clades represent different species. None of the Mexican specimens were found in association with termite mounds, which might indicate an adaptation to desert-like regions. This study provides the first ethnomycological use of Podaxis from Mexico.
Basidiomycota, edible mushroom, Podaxis pistillaris
Podaxis has been collected from numerous arid regions around world; approximately 44 species have been described to date (
In Mexico, Podaxis was reported for the first time in 1893 as P. mexicanus from Agiabampo, Sonora (
Despite the occurrence of Podaxis in arid regions of Mexico, the ethnomycological use of this mushroom in the country is undocumented. This is particularly important since Podaxis spp. have been widely utilized for its culinary value by indigenous people, particularly in the Tehuacán-Cuicatlán Biosphere Reserve (RBTC) in the south of Mexico. In this context, the goals of this study were: 1) to analyze via ITS sequencing newly collected and fungarium specimens of Podaxis from Mexico to better predict their molecular phylogenetic placement and thus establish if one or more phylogenetic species of Podaxis exist in Mexico; and 2) to describe the traditional use, handling and economic importance of Podaxis spp. in the RBTC by observations and interviews with the local people.
Eighteen fungarium and five fresh Podaxis specimens from different arid regions of Mexico were used for the phylogenetic study. The fresh fruiting bodies were obtained from four sites in three communities of the state of Oaxaca (Table
Voucher specimens in the fungi collection of the Herbario Nacional de México (MEXU) at the Instituto de Biología, Universidad Nacional Autónoma de México.
|Voucher (MEXU)||Clade||Locality||Collector and collection date (mm/dd/yyyy)||Location geography||Type of vegetation||Habitat||Native language||GenBank|
|T. Herrera, M. Ruiz-Oronoz (10/16/1948)||San Pedro Chicozapotes, San Juan Bautista Cuicatlán municipality, 633 masl, 17°46.232'N, 96°57.209'W||TrDF||Sandy soil||Cuicatec||KY034680|
|Presa Benito Juárez, Oaxaca-Tehuantepec||--||Limestone soil||--||KY034681|
|12808||D||Oaxaca||O. Téllez, M. Sousa, L. Rico (02/20/1978)||Salina Cruz-Pochutla, Salina Cruz, 20 masl||TrDF||--||--||KY034682|
|7023||D||Oaxaca||T. Herrera (08/04/1979)||Istmo of Tehuantepec||--||Sandy soil||--||KY034683|
|El Brujo, Santa María Tecomavaca municipality, 626 masl, 17°57.501'N, 97°1.266'W||TrDF||Sandy soil, sandy clay in stony, clayey silt, and cultivation soil||Mazatec and Mixtec||KY034684|
|A. Medina-Ortiz, A. de la Cruz-Martínez (10/07/2013)||Santiago Quiotepec, San Juan Bautista Cuicatlán municipality, 626 masl, 17°57.501'N, 97°1.266'W||TrDF and DS||Sandy clay||Cuicatec||KY034686|
|A. Medina-Ortiz, E. Pérez-Silva, A. García-Mendoza (07/12/2014)||Cuicatlán-Concepción Pápalo, San Juan Bautista Cuicatlán municipality. 630 masl, 17°47.727'N, 96°57.530'W||TrDF and DS||Sandy soil||Cuicatec||KY034687|
|Estación Chocolate, Lerdo, Durango-Torreón||DS||--||--||KY034678|
|12338||D||Baja California Sur||E. Pérez-Silva 09/01/ 1978||Econhotel, La Paz||--||--||--||KY034673|
|5015||D||Tamaulipas||A. Gómez-Pompa, E. Nebling (09/03/1967)||Mante-Gonzáles City||ThDF||Clay soil||--||KY034689|
|7212||D||Tamaulipas||A. Marino (03/10/1970)||Abasolo municipality||AZ||Silty soil||--||KY034690|
|22610||E||Sonora||Romo (03/08/1990)||Estación Pesqueira, San Miguel de Horcasitas municipality||--||--||--||KY034688|
|8423||E||Coahuila||R. Hernández, R López, F. Medrano (09/29/1973)||Hidalgo municipality||AZ||Sandy clay||--||KY034674|
|8425||E||Coahuila||R. Hernández, R. López, F. Medrano (09/28/1973)||Hidalgo municipality, 150-200 masl||CV||Sandy clay with some grass||--||KY034675|
|8422||E||Coahuila||R. Hernández, R. López (09/28/1973)||Rancho Palo Blanco, Hidalgo municipality, 147 masl||CV||Sandy clay||--||KY034676|
|8424||E||Coahuila||R. Hernández, R. López, F. Medrano (09/28/1973)||Rancho Palo Blanco, Hidalgo municipality||CV||Sandy clay||--||KY034677|
|8426||E||Nuevo León||R. Hernández, R. López, F. Medrano (09/27/1973)||Rancho San José, Anáhuac municipality, 144 masl||CV||Sandy clay||--||KY034679|
|A. Medina-Ortiz (09/09/2011)||La Sabana, Santa María Tecomavaca municipality 626 masl, 17°57.501'N, 97°1.266'W||TrDF||Sandy soil, sandy clay, in stony, clayey silt, and cultivation soil||Mazatec and Mixtec||KY034685|
|21635||N/A||Oaxaca||A. Calderón (07/11/1988)||Zipolite, Puerto Ángel, San Pedro Pochutla municipality||S||Sandy soil||--||N/A|
|A. Medina-Ortiz, F. Medina-Ruiz (07/13/2013)||Jiotillo redondo, Santa María Tecomavaca municipality
626 masl, 17°57.501'N, 97°1.266'W
|TrDF and DS||Sandy clay||Mazatec and Mixtec||N/A|
|11887||N/A||Oaxaca||O. Téllez (10/24/1977)||San Pedro Totolapam, Oaxaca-Tehuantepec||--||--||--||N/A|
|1148||N/A||Sonora||E. Matuda (11/22/1962)||Sonoyta, 150 masl||AZ||Sandy clay||--||N/A|
|22608||N/A||Sonora||M. Esqueda (08/29/ 1988)||Hermosillo||--||Sandy soil||--||N/A|
|MEXU||Clade||State||Length ± SD||Ranges||Width ± SD||Ranges||L/W ± SD|
|1191||D||Oaxaca||11.56 ± 0.71||10 < L < 13||10.96 ± 0.20||10 < W < 11||1.05 ± 0.06|
|10805||D||Oaxaca||10.92 ± 0.76||10 < L < 13||9.24 ± 0.52||8 < W < 10||1.18 ± 0.06|
|12808||D||Oaxaca||12.52 ± 1.16||11 < L < 15||9.76 ± 0.93||8 < W < 11||1.29 ± 0.09|
|7023||D||Oaxaca||10.64 ± 0.70||10 < L < 12||9.68 ± 0.56||9 < W < 11||1.10 ± 0.06|
|27558||D||Oaxaca||11.28 ± 0.61||10 < L < 12||10.52 ± 0.51||10 < W < 11||1.07 ± 0.05|
|27845||D||Oaxaca||10.44 ± 0.51||10 < L < 11||9.84 ± 0.47||9 < W < 11||1.06 ± 0.06|
|27557||D||Oaxaca||10.04 ± 0.68||9 < L < 11||9.20 ± 0.71||8 < W < 10||1.09 ± 0.07|
|5772||D||Durango||10.80 ± 0.96||9 < L < 13||10.04 ± 0.73||9 < W < 12||1.08 ± 0.06|
|12338||D||Baja California Sur||11.28 ± 0.89||10 < L < 13||10.52 ± 0.65||10 < W < 12||1.07 ± 0.05|
|5015||D||Tamaulipas||10.72 ± 0.89||9 < L < 13||9.76 ± 0.60||9 < W < 11||1.10 ± 0.08|
|7212||D||Tamaulipas||10.32 ± 0.63||9 < L < 12||9.76 ± 0.66||9 < W < 11||1.06 ± 0.06|
|22610||E||Sonora||15.88 ± 0.97||14 < L < 18||14.00 ± 0.82||13 < W < 16||1.14 ± 0.05|
|8423||E||Coahuila||14.72 ± 0.79||13 < L < 16||13.88 ± 0.78||13 < W < 16||1.06 ± 0.05|
|8425||E||Coahuila||14.36 ± 1.22||12 < L < 17||13.28 ± 0.79||12 < W < 15||1.08 ± 0.05|
|8422||E||Coahuila||14.32 ± 1.03||12 < L < 16||12.76 ± 0.97||11 < W < 15||1.13 ± 0.08|
|8424||E||Coahuila||14.76 ± 0.60||14 < L < 16||13.68 ± 0.63||13 < W < 15||1.08 ± 0.04|
|8426||E||Nuevo León||15.36 ± 1.22||13 < L < 18||12.84 ± 0.85||12 < W < 15||1.20 ± 0.08|
|27843||E||Oaxaca||11.16 ± 0.75||10 < L < 13||10.48 ± 0.59||10 < W < 12||1.07 ± 0.05|
|21635||N/A||Oaxaca||10.08 ± 0.40||9 < L < 11||9.12 ± 0.73||8 < W < 10||1.11 ± 0.10|
|27844||N/A||Oaxaca||10.88 ± 0.60||10 < L < 12||10.36 ± 0.49||10 < W < 11||1.05 ± 0.06|
|10887||N/A||Oaxaca||12.32 ± 1.22||11 < L < 15||10.32 ± 0.63||10 < W < 12||1.19 ± 0.08|
|1148||N/A||Sonora||16.44 ± 1.04||15 < L < 19||14.20 ± 1.22||12 < W < 17||1.16 ± 0.06|
|22608||N/A||Sonora||12.28 ± 1.06||11 < L < 15||11.60 ± 1.00||10 < W < 15||1.06 ± 0.06|
DNA was extracted from a powder of dried cap (pileus, fresh samples) and the center of the stipe (fungarium samples) from specimens indicated in Table
The entire ITS region was PCR-amplified on an Applied Biosystems Veriti thermal cycler using PuReTaq Ready-To-Go PCR Beads with ITS5 and ITS4 primers (
Sanger sequencing of the purified PCR products was performed at Eurofins Genomics (http://www.operon.com/default.aspx) using BigDye Terminator v3.1 cycle sequencing. The sequencing was accomplished bidirectionally using both strands with a combination of ITS5 and ITS4 primers. Sequences were generated on an Applied Biosystems 3730XL high-throughput capillary sequencer. For both sequencing reactions, approximately 15 µL of PCR template were used along with 2 µM sequencing primers.
Sequences were assembled with Sequencher 5.3 (Gene Codes), optimized and then manually corrected when necessary; the latter step was to assure that the computer algorithm was properly assigning base calls. Each sequence fragment was subjected to an individual Basic Local Alignment Search Tool (BLAST) (
The newly obtained ITS sequences (Table
All spores were measured using a Carl Zeiss Primo Star microscope (Carl Zeiss, Germany) with a Canon PowerShot G6 camera with a Zeiss universal digital camera adapter d30 M37/52´0.75. For each specimen, 25 spores were measured for spore length and width, and presence or absence of a germ pore (Table
This study was conducted in the RBTC, which is located in the states of Puebla and Oaxaca in central Mexico (between 17°32'24" and -18°52'55"N, and 97°48'43" and -97°48'43"W; Figure
Inhabitants of the region, most 18 years and older, shared their knowledge through the following questionnaire: i) personal information (name, age, sex, ethnicity, place of birth, residence, occupation, and number of family members); ii) knowledge of mushrooms from the locality (traditional name, description of the fruiting body, myths, and uses); iii) how they collect the mushrooms (frequency of collection, if they eat it or buy it); iv) importance of mushrooms in their life; v) how many different mushrooms they see in their locality; vi) if they thought it is important to know the mushrooms; vii) what kind of problems they have when they collect mushrooms in the field; and viii) what information they need to identify the mushrooms.
All specimens studied (Table
The length and width, ranges and standard deviation (SD) of basidiospores are outlined in Table
Mean ± SE spore (A) length and (B) width of MEXU Podaxis specimens from clades D and E. Results of Mann-Whitney U test: D–E, p < 0.001.
Phylogram of the most likely tree (-lnL = 1860.99) from a RAxML analysis of 56 taxa based on ITS rDNA (681 bp). Numbers above the nodes refer to RAxML bootstrap support values ≥ 70% based on 1000 replicates. Clades to the right (A–F) are labeled as per Conlon et al. 2016. The tree is rooted with Leucocoprinus birnbaumii. Symbol (*) next to collections indicates, it was reported from termite mounds. Bar indicates nucleotide substitutions per site.
A Desert scrub B Immature state of Podaxis sp. (MEXU 27843) and C at maturity (the gleba changes from white to dark brown (MEXU 27844); Culinary preparation: D cleaning process of the fruiting body of Podaxis sp. and E mixing ingredients for the typical dish [onions, “epazote" (Dysphania ambrosioides) and green pepper (chile verde)].
Eighteen new ITS sequences from different specimens of Podaxis from Mexico were obtained; these included four from freshly collected specimens, and 14 from samples in the MEXU fungarium (Table
RAxML analysis of the ITS dataset produced a single most likely tree (Figure
Ethnomycological importance lies in the fact that people from this region eat the fruiting body of Podaxis, commonly known as “hongo" (mushroom), “hongo blanco comestible" (white edible mushroom), or “soldadito" (little soldier), almost daily during rainy season (Figure
Through the years, the local people have acquired the necessary knowledge to easily locate, harvest and select this mushroom from the land. Although this mushroom is mainly used for personal consumption, some people collect it and sell it in the community. They have also acquired the knowledge about the phenology and ecology of Podaxis spp., and they relate the “acidity of rain" with the germination of its spores. In addition, most of the people agree on the following: “when there are constant rains, the fungi starts to grow", “small mushrooms show up after it rains, the sun comes out and the sky is clear", “in order for it to grow, the mushroom needs sunlight for one or two days". Concerning the habitat and soil, they indicate that: “mushrooms grow mainly on the river bank or on sandy soil" but also “mushrooms are produced throughout the mountain slopes, even on agricultural production areas". They also say: “if you find one, you will find two" or “they are born in pairs". Finally, when a mushroom fruiting body has “aged", the local people spread the spores in places where they want the fungi to grow next rain season, and they say: “if they don’t grow this season, they’ll grow during the next one".
Podaxis pistillaris sensu lato has been collected and reported from numerous semi-arid regions around the world, fruiting mainly in the rainy seasons. In Mexico, it has widely been collected from north to south (
All the studied specimens from the MEXU fungarium were named as P. pistillaris based on its morphological characteristics (Figure
Interestingly, all specimens in clade E (Figure
Clade E (Figure
We examined the spore sizes and morphology of MEXU specimens from clade E and compared them to the measurements obtained from the type material of P. pistillaris in the LINN fungarium (
Eleven of the eighteen specimens (10805, 5772, 12338, 12808, 5015, 27845, 7217, 27558, 1191, 27557, and 7023) were nested within clade D (sensu
Based on the fruiting body morphology, it was difficult to separate MEXU specimens in clade D and E (Figure
Podaxis species in Mexico are found predominately in open areas, growing solitary in sandy or clay soils of arid and tropical zones (Table
In Mexico, the use of Podaxis species for food consumption has not been reported. Our study includes data from interviews that state the consumption and farming of this mushroom within the RBTC. In this area, the species is greatly valued by the local people, who sell the fungus for 1–1.5 USD per kilogram or consume young fruiting bodies of Podaxis in typical dishes from the region, particularly as “empanadas" (Figure
On the other hand, Podaxis has also been catalogued as a non-edible mushroom (
The names attributed to this species in the three communities of the RBTC are “hongo" (mushroom), “hongo blanco comestible" (white edible mushroom) and “soldadito" (little soldier) (Table
In Yemen and South Africa, Podaxis is used for its medicinal properties and antibacterial activity against Staphylococcus aureus, Micrococcus flavus, Bacillus subtilis, Serratia marcescens, Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis (
Podaxis is considered a very important mushroom in arid regions of the world due to its culinary and medicinal values. Further taxonomic and molecular phylogenetic studies of this genus are urgently required to better understand species boundaries and provide accurate names on specimens of Podaxis, particularly the ones used as food in Mexico and worldwide. Better understanding of Podaxis spp. might be possible when mycologists work closely with local communities in different parts of both the Old and New World. Our study provides preliminary morphological and molecular data from Podaxis specimens collected in Mexico along with its ethnomycolgy use. We anticipate our study will encourage future phylogenetic diversity analyses on this widely distributed yet taxonomically poorly studied genus of Agaricomycetes.
This work was partially supported by grants from CONACyT CB 236564 and DGAPA 205017. We thank to Dr. Evangelina Pérez-Silva for her valuable discussions and comments on this work; to MSc. Elvira Aguirre-Acosta, manager of the mushroom collection at MEXU, for her feedback and comments on this paper; to Biol. Samuel Aguilar Ogarrio for his support on the photographic shooting and editing; and to all the interviewed people in the RBTC for sharing their knowledge. A.J. M-O thanks to SNI-CONACyT for the scholarship. We thank the reviewers for their insightful suggestions that helped improve the manuscript.