International Journal of Advanced Science and Technology Vol. 29, No. 7, (2020), pp. 1888-1899 Features Of The Reproductive Sphere Of Species Of The Genus Hosta Tratt Irina S. Kazakova1, Anna I. Repetskaya1, Irina G. Savushkina1, Natalya V. Nevkrytaya 2, Vladimir S. Pashtetsky2, Natalia A. Kashirina2 1 V.I. Vernadsky Crimean Federal University, 4 Prospekt Vernadskogo, Simferopol, Republic of Crimea, 295007, Russia 2 FSBSI “Research Institute of Agriculture of Crimea", 150 Kievskaya str., Simferopol, Republic of Crimea, 295493, Russia Abstract Hosta (plantain lily) is a widespread ornamental foliage culture, yet its systematics remains incomplete. The study of the reproductive sphere of five species of hostas (Hosta sieboldii (Paxton) Ingram, H. ventricosa Stearn, H. sieboldiana (Hooker) Engler, H. rectifolia Nakai, H. plantaginea Ascherson) when introduced in the Foothill Crimea is aimed at identifying species-specific traits and selecting promising species for breeding. Morphometric, phenological, cytological methods and electron microscopy were used. Vegetation period in the Foothill Crimea is from April to November; H. rectifolia has the longest blooming period (95 days), and H. ventricosa the shortest (13 days). Flower size in the majority of species is 5-6 cm long to 3-4 cm wide; seed length varies from 8 to 13 mm and is significantly different in all species. Potential seed productivity is 191.2-594.7 ovules per plant; real productivity is 61.3-500.5 seeds. Seed setting comprises 32.1-84.9%, laboratory germination is 14.7-77%. The size of pollen grains on the polar axis ranges from 60.0 to 113.5 μm, on the equatorial axis from 29.5 to 67.1 μm; pollen fertility is 63.6-82.0%. The size and color of seeds are species-specific and can be used as systematic criteria. Three reproductive strategies of species were identified. H. sieboldii, H. sieboldiana, H. plantaginea, and H. ventricosa are recommended for breeding as parental forms. Keywords: Hosta, reproductive sphere, flower, seed, pollen grain. INTRODUCTION Genus Hosta Tratt. comprises more than 40 species (Bakanova, 1988; Kohlein, 1993; Schmid, 1991). At Baker’s initiative in 1870, hostas were assigned to the Hemerocallidaceae family; the researches carried out in the 1930s showed their proximity to such genera as Yucca, Agave, Camassia, Hemerocallis, Hesperocallis, Leucocrinum, and Manfreda. Based on cytological data obtained by a number of researchers (McKelvey, Sax, 1933, Whitaker, 1934, Akemine, 1935, Sato, 1935, 1942, Suto, 1936, Granick, 1944, Cave, 1948, Wunderlich, 1950, Chupov and Kutyavina, 1981), it was suggested the genus should be included in the Agavaceae family, although karyotypic similarities indicated its proximity to the Liliaceae family. In a recent work on the classification of monocots (Dahlgren et al., 1985), daylilies and hostas were separated – Hemerocalllis was placed in the Hemerocallidaceae family, and the genus Hosta, along with Hesperocallis and Leucocrinum, were singled out as the Funkiaceae family in the order of Asparagales. Later, based on Mathew’s research (1987), Leucocrinum was assigned to the Anthericaceae family, and the taxonomically complex and monotypic genus Hesperocallis was assigned to the Hyacinthaceae family. Thus, only the genus Hosta remained in the Funkiaceae family. Mathew suggested renaming the family as Hostaceae (Mathew, 1988); however, the discussion about the systematic position of the genus is not closed. Thus, in a number of topical botanical electronic databases, hosts are placed in the Liliaceae family (Flora of China www.efloras.org) or Asparagaceae (The Plant List http://www.theplantlist.org/; Germplasm Resources Information Network https: //npgsweb.ars -grin.gov/). Questions of the systematics of the genus remain controversial. In particular, some species were described by comparison with cultured specimens, and a number of species clearly are of hybrid origin (Schmid, 1991). ISSN: 2005-4297 IJCA 1888 Copyright ⓒ 2020 SERSC International Journal of Advanced Science and Technology Vol. 29, No. 7, (2020), pp. 1888-1899 The largest review devoted to hostas belongs to Schmid (Schmid, 1991) – the author analyzed studies from 1797 to 1990 and offered the system of the genus Hosta the authors of the present research chose to follow. To solve the issues of systematics, we need to identify ecologically flexible and stable features of individual plants and to single out species-specific characteristics. In this regard, obtaining morphobiological data on plants growing in different soil and climatic conditions and, above all, outside the natural range of the species, is crucial. The natural habitat of the genus is located in the East Asian region of the Holarctic kingdom (Takhtajan, 1987). Most species are common in Japan, some in Korea, China, on Sakhalin and the Kuril Islands (Schmid, 1991; Germplasm Resources Information Network, 2018). Hosta is one of the most popular and widespread decorative leafy plants, widely used in temperate regions to create garden compositions. In the southern regions, it is not so frequent, although landscape decorators take considerable interest in hostas, since they are good for the shaded areas of landscape architecture objects; the cultivation experience of the Foothill Crimea is a vivid example (Kazakova et al., 2011, 2012; Kazakova, Repetskaya, 2017). Obtaining an assortment adapted to the hot arid climate will facilitate the introduction of this very promising culture into southern ornamental horticulture. For introductive and breeding work, complex morphological study of species is important. The main sign of successful plant introduction is their ability to reproduce in new conditions (Kohno, Kurdyuk, 1994). The study of the generative sphere of introduced species is of particular importance for solving problems of selection and use in mass gardening. Erdtman's study of the pollen grains of the Hemerocallidaea family (Erdtman, 1956) gives preliminary information on the hostas' generative sphere. Chung and Jones (Chung, Jones, 1989) conducted a study of pollen of 22 species and subspecies of hostas and of 9 closely related taxa. It confirmed the logic of dividing the genus into three subgenera, first proposed by Bailey (1930) and of singling hostas out into a separate family. Based on a study of the pollen morphology, Chinese researchers (J-X. Liu, C-H. Zhao, X-R. Liu, Y-Z. Xi and Y-L. Zhang, 2011) noted certain features of hostas’ similarity with the Liliaceae family, agaves and yuccas. A number of works by Russian and Ukrainian researchers (Boyko, 2010; Results of the introduction ..., 2007; Davletbaeva, Reut, 2017; Sedelnikova, 2012; Smolinska, 2009; Pavlyuk, 2014) provide certain information about the vegetative and generative sphere of the genus (bush height, leaf blade size, peduncle length and flower size), as well as data on the growth rhythms and development of plants introduced in various soil-climatic zones. In the conditions of the Bashkir Cis-Urals and the Forest-Steppe Zone of Ukraine, laboratory germination of seeds and seed productivity of some species were assessed (Boyko, 2010; Davletbaeva, Reut, 2017). Previously, we gave a characteristic of the vegetative sphere of 7 species, 6 forms and 18 varieties of hostas (Kazakova et al., 2012) and analyzed the anatomical and morphological features of leaf blade of five species on the light gradient (Kazakova et al. 2011). There is no comprehensive description of the generative structures of representatives of this genus under cultivation conditions. The authors’ purpose is a comprehensive study of the reproductive sphere of species of the genus Hosta introduced in the Foothill Crimea, aimed at identifying species- specific traits and selecting promising species for breeding. MATERIALS AND METHODS The work was carried out based on the collection of the N.V. Bagrov Botanical Garden of the Tavricheskaya Academy of V.I. Vernadsky Crimean Federal University (hereinafter BG CFU) in Simferopol. The Botanical Garden is located within the Eastern Foothill agroclimatic region of the northern macroslope of the Crimean Mountains (Vazhov, 1977). The climate is semi-arid, warm, with mild winters. Selyaninov’s hydro-thermal coefficient (HTC) is 0.89, Ivanov's moisture ratio (MR) is 0.56. The average annual temperature is +10.6 °С, the average January temperature is +0.2 °С, the average July temperature is +22.5 °С. The average annual rainfall is 536 mm, 329 mm of which fall during the warm period (April-October) (Agroclimatic reference book, 2011). The BG CFU hostas collection includes 7 species, 49 varieties and 1 form. The objects of research were 5 species: Hosta sieboldii (Paxton) Ingram, Hosta ventricosa Stearn, Hosta sieboldiana ISSN: 2005-4297 IJCA 1889 Copyright ⓒ 2020 SERSC International Journal of Advanced Science and Technology Vol. 29, No. 7, (2020), pp. 1888-1899 (Hooker) Engler, Hosta rectifolia Nakai, Hosta plantaginea Ascherson, introduced in 2007 (Annotated catalog ..., 2014). To identify the possibility of realizing the genetic potential of hostas species in the Foothill Crimea, an assessment of the morphometric parameters of the plant generative organs was made: flower length and width, capsule and seeds size; the sample for each indicator was 100 pieces. Phenological observations were carried out for 5 years according to I.N. Beideman’s method (Beideman, 1974). The following phenological phases were distinguished: the beginning of growth, the beginning of leaf unfolding, the massive unfolding of leaves, budding,