Grana ISSN: 0017-3134 (Print) 1651-2049 (Online) Journal homepage: http://www.tandfonline.com/loi/sgra20 Pollen morphology and its relation with meiotic irregularities in ten species of Campuloclinium (Eupatorieae, Asteraceae) Gabriela Elizabeth Farco & Massimiliano Dematteis To cite this article: Gabriela Elizabeth Farco & Massimiliano Dematteis (2017) Pollen morphology and its relation with meiotic irregularities in ten species of Campuloclinium (Eupatorieae, Asteraceae), Grana, 56:5, 339-350, DOI: 10.1080/00173134.2016.1249514 To link to this article: http://dx.doi.org/10.1080/00173134.2016.1249514 Published online: 07 Dec 2016. Submit your article to this journal Article views: 34 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=sgra20 Download by: [190.191.253.20] Date: 22 May 2017, At: 19:25 Grana, 2017 Vol. 56, No. 5, 339–350, https://doi.org/10.1080/00173134.2016.1249514 Pollen morphology and its relation with meiotic irregularities in ten species of Campuloclinium (Eupatorieae, Asteraceae) GABRIELA ELIZABETH FARCO1 & MASSIMILIANO DEMATTEIS1,2 1Instituto de Botánica del Nordeste (UNNE-CONICET), Corrientes, Argentina, 2Facultad de Ciencias Exactas y Naturales y Agrimensura (UNNE), Corrientes, Argentina Abstract Pollen grains of ten species of Campuloclinium (Eupatorieae, Asteraceae) are described and illustrated using light and scanning electron microscopy. The species included in this study are C. burchelli, C. campuloclinioides, C. chlorolepis, C. hirsutum, C. irwinii, C. macrocephalum, C. megacephalum, C. parvulum, C. purpurascens and C. riedelli. Pollen grains of Campuloclinium are typically radially symmetric, echinate, tectate, oblate-spheroidal to prolate-spheroidal (P/E ratio: 0.94– 1.10). Pollen is mostly triaperturate, but tetraaperturate or biaperturate pollen also occurs in some species. The pollen diameter was highly variable ranging from 10.54 µm to 36.18 μm. The significance of the variation in type and size of pollen is discussed in relation to diverse meiotic abnormalities and possible reproductive apomictic processes within the polyploid species. Keywords: exine, 2-colporate, 3-colporate, 4-colporate, polyploidy The genus Campuloclinium (Eupatorieae, Asteraceae) Asteraceae show some of the most complex and is derived from the taxonomic reorganisation of diverse pollen grains among the flowering plants Eupatorium s.l. It comprises 15 species distributed (Skvarla & Turner 1966). The pollen is typically in North and South America (Robinson 2006). isopolar and radially symmetric, with compound Most of the species occur in various Brazilian apertures (Stix 1960). Pollen ornamentation is psi- biomes, 11 of which are endemic (Nakajima et al. late, echinate or lophate (Wodehouse 1926, 1929). 2014). Campuloclinium macrocephalum has the widest Three main patterns of exine stratification, anthe- geographical distribution occurring in Mexico, Hon- moid, helianthoid, and senecioid, were established duras, Guatemala, Venezuela, Colombia, Brazil, by Skvarla and Larson (1965) and Skvarla and Paraguay, Uruguay and Argentina (King & Robin- Turner (1966). Based on the exine structure, Stix son 1987; McConnachie et al. 2011). In contrast, C. (1960) described several pollen types for the Aster- parvulum is in danger of extinction and has been aceae using light microscopy (LM) and transmission included in the Red List of Brazilian plants (Naka- electron microscopy (TEM). Pollen grains of the jima et al. 2013). The importance of palynology as a tribe Eupatorieae were described as the Eupatorium subsidy to the systematics of major groups of plants type characterised by the presence of a large cavity is evident in the contributions of The Angiosperm between two layers of the exine (Blackmore 1984). Phylogeny Group II, III and IV (APG II 2003; APG Subsequently Skvarla et al. (1977) analysed pollen III 2009; APG IV 2016). In the Asteraceae, the use grains of other species of the tribe Eupatorieae and of pollen features is recognised due to its importance described these grains as the Helianthoid type. This for taxonomy hierarchical levels and, more recently, latter type is characterised by a caveate exine with to establish the phylogenetic position of genera, sub- internal foramina. In recent years, studies on pollen families and tribes (Funk et al. 2009). morphology in some species of the tribe Eupatorieae Correspondence: Gabriela Elizabeth Farco, Instituto de Botanica del Nordeste, Corrientes, Sargento Cabral 2131, Corrientes 3400, Argentina. E-mail: [email protected] (Received 7 March 2016; 29 October 2016) © 2016 Collegium Palynologicum Scandinavicum 340 G. E. Farco and M. Dematteis Figure 1. Pollen morphology in Campuloclinium (SEM micrographs). A. Campuloclinium chlorolepis, polar view, apocolpium. B, C. Campuloclinium macrocephalum, detail of the spines with perforations of different sizes on the basis (B), equatorial view, colpus (C). D–F. Campuloclinium megacephalum, polar view, spines covering the folded colpi (D), detail of colpore (E), equatorial view (F). G–I. Campulo- clinium purpurascens, polar view, apocolpium (G), equatorial view, colporus (H), inner structure (I). Abbreviations: bc, basal region of columellae; cv, cavea; ec, ectoaperture; ed, endoaperture; en, endexine. Scale bars – 2 µm (A, C, D, F, G, H), 1 μm (E), 500 nm (B, I). were performed by Salgado Labouriau (1973), Men- recent years (Wortley et al. 2012). This lack of inter- donça and Gonçalves- Esteves (2000), Esteves est perhaps reflects the relatively homogenous nature (2001), Cancelli et al. (2005, 2010) and Cancelli of pollen morphology within the most derived sub- et al. (2007). families of Asteraceae (Wortley et al. 2009). For The evolution of the pollen grains in the Eupator- pollen of Campuloclinium, there are only a few mor- ieae has been poorly studied and currently, evolu- phological and ultrastructural studies and pollen wall tionary trends are known only for five groups of the architecture was not previously investigated using Asteraceae: Cardueae, Arctotideae, Cichorieae, Ver- scanning electron microscopy (SEM). nonieae and Inuleae (Funk et al. 2009). Studies of Pollen features are often claimed as important in pollen grains in this big group show that, in general, elucidating taxonomic problems. In the Asteraceae the Eupatorieae pollen is the most elaborate in the pollen morphology appears to be useful in taxonomic family. The Eupatorieae pollen is spheroidal with discussions and has resulted in certain changes at the acute colpus ends, foramina, uniform distribution generic and subgeneric level. In Campuloclinium, of columellae, caveate and ornamentation echinate palynological data are only available for the species (Funk et al. 2005). The pollen morphology of several C. macrocephalum (Ines et al. 1981; Cancelli et al. tribes does not appear to have been studied at all in 2010). The aim of this work is, therefore, to contri- Pollen morphology of Campuloclinium 341 bute to our knowledge of this genus by performing a Surface sculpture comparative study on pollen morphology including Mean length of the spines ranges from 2.78 µm to most Campuloclinium species. Furthermore, the 5.18 μm(Table I). Spine perforations can be homo- study also investigates possible correlation between geneous or heterogeneous, circular, elliptical or pollen morphology and the meiotic irregularities of amorphous and these continue around the spine polyploid cytotypes. base. The spines possess channels or projections formed by the layers of columellae at their base, Material and methods with the width of the base of the spines being major than the area between spines (Figure 1I). The per- Pollen samples from 33 populations belonging to ten forations are wide in the lower half of the spine and species of Campuloclinium were obtained from herbar- decrease in number around of it. In equatorial view, ium specimens of the Instituto de Botánica del Nor- a row with four to five pairs of spines can be seen deste (CTES), Corrientes, Argentina, the New York bordering the aperture. Campuloclinium megacepha- Botanical Garden (NY), New York, USA, the Univer- lum is unique by having folded spines that cover the sity of Uberlândia (HUFU), Uberlândia, Brazil and the aperture (Figure 1D). Botanical Garden of Rio de Janeiro (RB), Brazil. See the ‘Specimens investigated’ list for details. Pollen material was obtained from flowers at Exine structure fl anthesis and/or from preanthetic buds. The ower The exine structure in Campuloclinium pollen grains buds were processed using the acetolysis method of is caveate, tectate and columellate, with a mean Erdtman (1960). Random measurements included exine thickness from 2.56 µm to 5.32 μm (including – 15 30 pollen grains for each sample. For LM, pollen cavea). The tectum is continuous, with numerous grains were mounted on glass slides using glycerin microperforations (lesser than 1 μm) and usually jelly and were subsequently examined with an oil echinate microperforated in SEM. Perforations are immersion objective (100×) of a Zeiss Axioplan either elliptical or circular. The infratectum is sepa- light microscope. For SEM analyses, the acetolysed rated by a caveate region and supported by columel- fi pollen grains were rst washed in alcohol 96% and lae (Figure 1I). absolute alcohol, then coated with gold-palladium and examined with a JEOL 5800 LV scanning elec- tron microscope. Apertures The following characters were considered: