See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/292186879 Variation in the tracheary elements in species of Coryphantha (Cacteae- Cactoideae) with contrasting morphology: the bottleneck model Article in Brazilian Journal of Botany · January 2016 DOI: 10.1007/s40415-016-0249-z CITATIONS READS 5 163 3 authors, including: Teresa Terrazas Monserrat Vázquez-Sánchez Universidad Nacional Autónoma de México Colegio de Postgraduados 309 PUBLICATIONS 3,735 CITATIONS 25 PUBLICATIONS 241 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Sistemática de Leiboldiinae (Vernonieae, Asteraceae) View project Pit membrane of selaginella View project All content following this page was uploaded by Monserrat Vázquez-Sánchez on 02 February 2016. The user has requested enhancement of the downloaded file. Variation in the tracheary elements in species of Coryphantha (Cacteae- Cactoideae) with contrasting morphology: the bottleneck model Teresa Terrazas, Rocío Escamilla-Molina & Monserrat Vázquez-Sánchez Brazilian Journal of Botany ISSN 0100-8404 Braz. J. Bot DOI 10.1007/s40415-016-0249-z 1 23 Your article is protected by copyright and all rights are held exclusively by Botanical Society of Sao Paulo. This e-offprint is for personal use only and shall not be self- archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Braz. J. Bot DOI 10.1007/s40415-016-0249-z Variation in the tracheary elements in species of Coryphantha (Cacteae-Cactoideae) with contrasting morphology: the bottleneck model 1 1 2 Teresa Terrazas • Rocı´o Escamilla-Molina • Monserrat Va´zquez-Sa´nchez Received: 21 September 2015 / Accepted: 13 January 2016 Ó Botanical Society of Sao Paulo 2016 Abstract A comparative analysis was conducted of the in the tubercles were two- or threefold wider than those of tracheary elements of the stem and tubercle of six species the vessel elements in the cortical vascular bundles. of Coryphantha. The aims of the study were to identify the Therefore, the results for the species of Coryphantha are micromorphological characters and to determine whether consistent with the bottleneck model observed for the the bottleneck model applied based on the similarity of the diameters of vessel elements for the non-succulent stems of diameters of the tracheary elements in the stem and in the other eudicots. tubercle. We collected individuals of C. bumamma, C. clavata, C. erecta, C. glanduligera, C. ottonis, and C. Keywords Cactaceae Á Helical secondary walls Á radians, which were species with contrasting morphologies Secondary growth Á Vessel elements Á Wide-band tracheids of the stems and tubercles. Sections and macerations were used to prepare the vascular cylinder and the cortical vas- cular bundles of the tubercle for observation. Our results Introduction showed that wide-band tracheids and vessel elements with annular or helical secondary walls predominated in wood. The genus Coryphantha is in the tribe Cacteae of the The cortical vascular bundles had primary or both primary subfamily Cactoideae in the Cactaceae. Species of Co- and secondary growths, and the tracheary elements had ryphantha have globose, depressed-globose, and cylindri- diameters of 10–27 lm, with the pattern and size of the cal stems (Bravo-Hollis and Sanche´z-Mejorada 1991; wide-band tracheids more heterogeneous than those of Va´zquez-Sa´nchez et al. 2012) with tubercles of different wood. These wider and shorter wide-band tracheids are sizes and forms that are rounded, ovoid, or conical and interpreted as analogous to the dilated tracheids in the have a base which is round, square, or rhomboid in shape, veinlets of eudicotyledons. The length and diameter of both with height varying from 8 to 12 mm. The wood anatomy tracheary elements (vessel elements and wide-band tra- of the five species of Coryphantha is similar to that of the cheids) in the tubercles were shorter and narrower than other members of Cacteae (Gibson 1973; Mauseth et al. those of the tracheary elements in the vascular cylinder of 1995;Va´zquez-Sa´nchez and Terrazas 2011), and the wood the stem (P \ 0.05). The diameters of the vessel elements has solitary vessels, abundant wide-band tracheids (WBT), and rarely, fibers. In the other members of Cactoideae, other features are observed in the wood, which include vessel elements with simple perforation plates, septate or & Teresa Terrazas non-septate libriform fibers, scarce paratracheal par- [email protected] enchyma, and the occurrence of stratified elements (Mau- seth and Plemons-Rodriguez 1998). The different cell types 1 Instituto de Biologı´a, Universidad Nacional Auto´noma de Me´xico, Ciudad Universitaria, 04510 Mexico City, Mexico found in the wood of Cactoideae, as in other eudicots, are essential for water movement, mechanical support, and 2 Centro Interdisciplinario de Investigacio´n para el Desarrollo Integral Regional, Unidad Michoaca´n, Jiquilpan de Jua´rez, storage of reserves, which are all required for plant survival 59510 Michoaca´n, Mexico (Va´zquez-Sa´nchez and Terrazas 2011). For example, in 123 Author's personal copy T. Terrazas et al. Cactoideae, fibers help in retaining the living protoplast by diameter and length of tracheary elements of the tubercles providing support and also in storing starch (Gibson 1973; are not available; however, recent studies suggest that the Va´zquez-Sa´nchez and Terrazas 2011), and successful wood of early derived Cacteae has narrow tracheary ele- conduction depends on the number, diameter, and perme- ments in species with different shapes and sizes (Va´zquez- ability of the tracheary elements (Mauseth and Plemons- Sa´nchez and Terrazas 2011). The genus Coryphantha was Rodriguez 1998). selected as the study system because of the wide diversity The leaves in Cactoideae are greatly modified, and the in the form and size of tubercles in different species, as primary photosynthetic organ is the stem (Mauseth 2006). noted previously, and this variability accounts for much of Morphologically, the tubercles in Cactoideae correspond to the diversity of these tubercles within the tuberculate stems a hypertrophied leaf base (Boke 1944; Bravo-Hollis 1978), of the Cacteae. We hypothesized that the bottleneck model and the size and form are important criteria for differen- would apply to the tracheary elements of Coryphantha tiating species (Bravo-Hollis 1978; Dicht and Lu¨thy 2003). tubercles as in other leafy eudicots. The aims of this study The distal part of the areole contains the tectriz leaf, and were to describe and compare the characteristics of the the proximal part contains several lateral meristems and secondary xylem of the stem and the xylem in the cortical produces a number of modified leaves (i.e., spines or bundles of the tubercles in six species of Coryphantha with bristles). The non-photosynthetic leaves are extremely contrasting morphologies and to evaluate whether the small and have little or no vascular tissue, and therefore bottleneck model applied to the genus. photosynthesis occurs in the tuberculate or ribbed stem (Mauseth 2006). Sajeva and Mauseth (1991) and Mauseth (2006) noted that the vascular cylinder of the photosyn- Materials and methods thetic stem connects to the stomata, which occur through- out the stem, through cortical bundles or foliar traces that Seventeen healthy, mature plants of six species of Co- are analogous to the veins in leafy eudicots. ryphantha were collected for the study (Table 1). The In other eudicots, a positive allometric relationship is plants were all collected during the rainy season from observed between leaf size and vascular properties (e.g., natural populations. The height and diameter of each plant vessel diameter in petioles) (Coomes et al. 2008), which were recorded. The spines were removed, and the stems demonstrates the principle that large leaves require an were divided into three sections: basal, middle, and apical extensive conductive system (tracheary elements) to pro- (Fig. 1a). The vascular tissue of the basal stem and of the vide a greater transpiration surface that contributes to cortical bundles of the tubercle was prepared for sections increased hydraulic resistance at the apex (Sack and Hol- (transverse and longitudinal) and macerations (Fig. 1b, c). brook 2006). The hydraulic resistance of the leaves (Rl)isa The segments were fixed in formalin–acetic acid–alcohol bottleneck model (pipe model), which is related to the (FAA, Ruzin 1999) for 48 h and then were washed with structure of the leaf that limits gas exchange and causes running water and stored in a solution of ethyl alcohol, physical damage to the major veins (Sack et al. 2004). water, and glycerin (GAA, 1:1:1) until sectioning. The Zimmermann (1983) notes that the bottleneck model can samples were paraffin-embedded following the technique be applied to all appendices of the stem, including bran- of Loza-Cornejo and Terrazas (1996) and were sectioned to ches, leaves, and inflorescences, because the diameters of a thickness of 12–15 lm with a rotary microtome. The the tracheary elements are narrower primarily at the sections were stained with safranin-fast green and mounted insertions of these appendices. In the Cactoideae with in a synthetic resin. significant reduced leaves, the assumption is that the bot- tleneck model applies between the green stems and the Wood and tubercle bundle maceration cortical bundles (xylem) of the tubercles, which are inter- preted as analogous to leaf veins (Mauseth and Sajeva For the macerations of the vascular cylinder, one or more 1992).