ORIGINAL ARTICLE Effect of polyploidy on the leaf epidermis structure of Cynodon dactylon (L.) Pers. (Poaceae) Ana Luisa A. Chaves 1 & Raquel B. Chiavegatto 1 & Manuel L. Gavilanes 1 & Flávio R. G. Benites 2 & Vânia H. Techio 1 Received: 4 June 2018 /Accepted: 7 August 2018 # Institute of Molecular Biology, Slovak Academy of Sciences 2018 Abstract Cynodon dactylon has different ploidy levels. The ‘gigas effect’ in morphoanatomic traits caused by the increase in the genetic material is poorly studied in the species. Thus, the present research aimed at carrying out a quantitative and descriptive study of the leaf epidermis structure in PI291169–04 (2n = 2× = 18); PI477004–26 (2n = 3× = 27); PI291721–22 (2n = 4× = 36); PI289750–10 (2n = 5× = 45) accessions, in order to investigate the consequences of the polyploidy. Adult leaves were fixed in FAA and the paradermal sections obtained through the scraping technique were stained in 5% safranin. The measurements of the stomata characteristics (polar diameters – PD, equatorial diameters – QD, stomatal density – SD, stomatal functionality – SF, and stomatal index – SI) were taken by means of the software ImageJ. For analysis in scanning electron microscopy, leaf fragments were fixed in Karnovsky, dehydrated in an acetone series, subjected to a critical point and covered with gold. Stomata were classified as paracytic, dumbbell- shaped and partially covered by papillae. Tector trichomes were classified as uniseriate with pointed tips. In general, as ploidy level increased, there was an increase in stomata dimension and a decrease in SD. Diploid and triploid accessions were easily differentiated in relation to PD and QD, which makes it an indirect method for determining the variation in ploidy level. The variables SD and SI were not efficient to discriminate the accessions. Leaf epidermis has characteristics that emphasize the effect of polyploidization process and its analysis may be used to screening of genotypes in breeding programs. Keywords Leaf anatomy . Gigas effect . Stomata . Forage grasses . Ploidy level Abbreviations PD Polar diameters QD Equatorial diameters SD Stomatal density SF Stomatal functionality SI Stomatal index E Stomata P Papillae TT Tector trichome Introduction Cynodon dactylon (L.) Pers. (Poaceae) is a perennial grass with a creeping habit that has a C4 metabolic pathway (Caro and Sanchez 1969; Shi et al. 2012) with different ploidy levels naturally occurring (Dhaliwal and Gupta 2011). The species is widely used as a forage in farming (Wu and Taliaferro 2009) in addition to its phytoremediation potential, demonstrating adaptability to toxicity by heavy metals (Shu et al. 2002; Sekabira et al. 2011; Tan et al. 2017). So far, leaf anatomy studies have been limited to description of major epidermis characteristics such as leaves with the pres- ence of papillae on both epidermal faces (Caro and Sanchez 1969) and dumbbell-shaped, paracytic stomata (Inamdar 1970; Babu and Savithramma 2014). In Cynodon dactylon, the gigas effect caused by the increase in the number of copies of chromo- somes has not been considered in the studies that evaluate the anatomical characteristics. Such a research may support the se- lection of cultivars for formation of pastures especially regarding * Vânia H. Techio vhtechio@gmail.com 1 Department of Biology, Federal University of Lavras – UFLA, Lavras, Minas Gerais State 37200000, Brazil 2 Embrapa Gado de Leite, Juiz de Fora, Minas Gerais State, Brazil Biologia https://doi.org/10.2478/s11756-018-0106-6