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J. Plant Bio. Res. 2016, 5(2):37-47 Journal of Plant Biology Research 2016 5(2): 37-47 eISSN:2233-0275 pISSN:2233-1980 http://www.inast.org/jpbr.html REGULAR ARTICLE Leaf anatomy of four species and one variety of Datura (Solanoidea, Solanaceae) Olga Lidia Gómez-Nucamendi, Luis Hernández-Sandoval, Mónica Figueroa-Cabañas and Mahinda Martínez* Facultad de Ciencias Naturales. Universidad Autónoma de Querétaro. Avenida de las Ciencias S/N Juriquilla, C.P. 76230. Querétaro, Mexico. ABSTRACT Foliar anatomy of five taxa of the genus Datura is described to identify the anatomic characters that can help distinguish them. Three to five individual leaf samples per taxon were collected and processed using conventional techniques. Foliar characters were measured and analyzed by Kruskal-Wallis and posthoc Dunn tests. To define rules of classification, regression and classification trees (CART) were created. Studied taxa share anatomical characters, such as bifacial leaves with unstratified epidermis, amphistomatic leaves with anisocytic stomata, and the presence of simple and glandular trichomes. Epidermal cells have slightly wavy walls. Mesophyll is composed by an unstratified compact palisade parenchyma, except for D. ceratocaula, that had two strata. Spongy parenchyma was compact, with three to four cell layers and with abundant calcium oxalate druses. Anatomical characters were significantly different between species, except for the length of the glandular trichome stem of the adaxial surface. Anatomical characters of the abaxial surface had the highest discriminating power. Characters with the best discriminating efficiency were the number of simple trichomes. Other relevant differences were the distribution and ornamentation of glandular and simple trichomes. The sum of anatomical differences allows the recognition the Datura taxa studied. Keywords: Anatomy leaf, Datura, Querétaro, Mexico. INTRODUCTION pruinosa Greenm., D. reburra A.S.Barclay and D. The genus Datura L. (Solanaceae) is endemic to arenicola. Datura stramonium var. tatula has been Mexico and adjacent areas of southwestern United classified as a different species but genetic States and the northern region of Central America evidence suggests it is a variety of D. stramonium [1]. It has become naturalized in Asia, Africa and [8, 9]. Australia [2, 3]. The plants grow mainly in dry, Species within the genus are used in traditional mild and subtropical regions [4]. The number of medicine and have economic importance due to recognized species varies from 12 to 14 [5, 6]. their content of amino acids, tannins, Recently, Bye and Sosa [7] described D. arenicola carbohydrates, phytic acid, clorogenic acids, Gentry ex Bye & Luna Baja California. Twelve lectins, albumins, as well as more than 70 alkaloids species have been recorded for Mexico, Datura of pharmaceutical importance [10, 11]. Research ceratocaula Jacq., D. innoxia Mill., D. lanosa has focused a few Datura species, mainly on A.S.Barclay ex Bye, D. metel L., D. wrightii Regel, genetic [12, 13] and biochemical aspects [14]. D. stramonium L. with two varieties stramonium L. Anatomical studies of Datura have focused on and tatula (L.) Torr., D. quercifolia Kunth, D. reproductive structures [15] and roots [16]. kymatocarpa A.S. Barclay, D. discolor Bernh., D. However, there is limited information on foliar *Corresponding author: Mahinda Martínez E-mail: [email protected] J. Plant Bio. Res. 2016, 5(2):37-47 anatomy. Timmerman [17] described D. Processing and Analysis in Java). Stomata number stramonium, D. tatula, D. metel, D. innoxia and D. and glandular trichomes density on the abaxial leaf fastuosa, and pointed out that leaf indumentum can surface of D. ceratocaula was inferred using the help to discriminate species. Not with standing, for blade margin where they exhibited a glabrate D. stramonium and D. tatula, he only reported surface, as the density of simple trichomes in the differences in terms of trichomes size [15]. Thus, central portion of the leaf hindered direct we aimed to describe and compare the leaves of observation. five Datura taxa: D. ceratocaula, D. innoxia, D. Differences among Datura taxa for each variable stramonium var. stramonium, D. stramonium var. were tested by Kruskal-Wallis. Variables with tatula and D. quercifolia, which share a similar significant differences were further tested with a geographic distribution. Dunn test with a Holm correction for multiple comparisons [20, 21], the level of significance was MATERIALS & METHODS set at P< 0.05. Furthermore, an algorithm to build Description order for the five taxa follows the classification and regression trees (CART) was phylogeny of Datura proposed by Bye and Sosa [7] used on data of each leaf surface in order to who propose relationship as follow: Datura identify the variables that best separate the ceratocaula, D. innoxia, D. stramonium var. taxa[22]. To build the classification trees we used stramonium, D. stramonium var. tatula and D. the rpart package [23] in R [24]. quercifolia. Seeds of the five Datura taxa were collected from four sites in Santiago de Queretaro, RESULTS Mexico. Sampling sites were located between 20º Foliar structures of the five Datura taxa shared 31’ 38.91’’ - 20º 49’ 40.29’’ N and 100º 18’42.20’’ many anatomical characters. They presented - 100º 30’23.26’’ W. Site elevation varied from bifacial leaves with unstratified epidermis (Figure 1,814 to 2,156 m. Vegetation type, soil, and 1A), no wax, and amphistomatic leaves with conservation status were similar among sites, anisocytic stomata. Epidermal cells showed namely tropical deciduous forest with pellic evidence of slightly wavy walls, of variable size vertisol [18], and in ruderal areas. All species were among taxa (Table 1). Mesophyll was formed by a terrestrial except for the semiaquatic D. compact and unstratified palisade parenchyma, ceratocaula. except for D. ceratocaula that had two distinct lines Plants were grown in greenhouse conditions and of palisade cells (Figure 1B). Spongy parenchyma three to five leaf samples were sampled per taxon. had three to four cell layers, with abundant calcium Material was fixed overnight in Navashin's fixative, oxalate druses in all taxa (Figures 1A and 1B), dehydrated in ethanol, and embedded in paraffin. either as single prism-shaped crystals or grouped Transverse sections of 12 µm in width were crystals (Figure 1C). obtained with a rotary microtome (Leica, Both surfaces (adaxial and abaxial) of all taxa RM2125), stained with alcian blue and 50% showed two types of indumentum: simple safranin, and mounted with Permount (Fisher trichomes (Figure 1D) and glandular trichomes Chemicals). (Figure 1E). Some of the cells that form the Structures were described following microscopic trichomes exhibited prism-shaped crystals. Simple examination (Olympus, BX43) and scanning trichomes were uniseriate, filiform and electron microscopy (SEM, Carl Zeiss EVO 50). multicellular (from one to seven cells; Figure 1F). Tissue microphotographs were captured with Q- They were distributed throughout the lamina, but Capture Pro 7 software and optimized in Photoshop were most abundant along the nerves, with the (version CC2015) without altering structure highest density over the primary vein and, less information. Structure nomenclature followed Font abundantly, over the secondary veins, except for Quer [19]. Anatomical sections description was the abaxial surface of D. ceratocaula, in which the from the outer to the inner portions of the organs. main vein showed few simple trichomes. Glandular Density, size, distribution and ornamentation of 14 trichomes were multicellular with a secretory head, variables (see tables 1, 2 and 3) related to cell size, formed by six to seven cells, with two to three on stomata, and trichomes in both leaf surfaces were the base and four on the gland (Figures 2a and 2B). assessed under SEM using ImageJ software (Image In addition, D. ceratocaula exhibited trichomes 38 J. Plant Bio. Res. 2016, 5(2):37-47 Table 1. Mean ± standard deviation epidermal cells and stomatic characters (density and size) at the adaxial and abaxial surface of the leaves of five Datura species. D. stramonium var. D. stramonium var. Taxa/Structure D. ceratocaula D. innoxia D. quercifolia stramonium tatula Length μm 46.3 ± 10.4 a 47.9 ±10. 7a 47.5 ± 9.0a 42.7 ± 8.8ab 37.7 ± 9.3b a b bc ac b Adaxial Width μm 29.3 ± 4.8 22.2 ± 3.9 22.5 ± 3.8 25.6 ± 3.6 19.4 ±5.0 Length μm 45.3 ± 8.1 ab 54.8 ± 11.1 c 52.7 ± 9.0 ac 37.0 ± 11.2 b 53.9 ± 8.0 c Epidermal cells ab ac ab c b Abaxial Width μm 26.5 ± 7.7 22.0 ±5.3 24.7 ±5.9 18.5 ± 5.7 31.0 ±8.5 Length μm 25.9 ± 9.2 ab 23.5 ± 2.2 a 29.0 ± 3.2c 26.6 ± 2.8 bc 23.8 ± 2.5a a a b bc ac Width μm 17.8 ± 8.5 15.9 ± 2.1 22.6 ± 2.1 19.9 ± 2.2 18.4 ± 2.7 Pore length μm 12.6 ± 1.8 ab 10.9 ± 1.7ac 18.9 ± 3.1d 12.8 ± 1.9b 11.1 ± 6.8c Adaxial Number/mm2 89.0 ± 8.0a 153.0± 26.0b 122.0 ± 21.0b 35.0 ± 7.0c 94.0 ± 21.0a Stomata Length μm 24.9 ± 3.6 a 32.3 ± 3.9 b 31.3 ± 4.1 b 24.6 ± 2.8 a 24.7 ± 2.8 a Width μm 16.4 ± 2.8 a 24.4 ± 2.2 b 21.1 ± 2.4 c 17.1 ± 2.8 a 20.8 ± 2.7 c a a a b ab Abaxial Pore length μm 13.2 ± 3.5 13.5 ± 2.2 13.1 ± 2.6 12.5 ± 3.4 11.7 ± 2.8 Number/mm2 40.0 ± 6.0 a 58.0 ± 03.0 b 109.0 ± 10.0 c 57.1 ± 25.2 ab 139.0 ± 14.0 c *Anatomical characters that share the same letter (a, b or c) were not significantly different after Kruskal-Wallis and Dunn tests with Holm correction for multiple comparisons 39 J.