Chromosome numbers for the Italian flora: 12

In this contribution, new chromosome data obtained on material collected in Italy are presented. It includes the first counts for Hieracium glanduliferum s.str. and H. tenuiflorum, counts for two Armeria species endemic to Italy, and for Onopordum illyricum subsp. illyricum. We also present here the first chromosome count of Allium permixtum for Italy, where this species is known for few localities.

In vitro induction and identification of polyploid Neolamarckia cadamba plants by colchicine treatment

Polyploidization has played a crucial role in plant breeding and crop improvement. However, studies on the polyploidization of tropical tree species are still very scarce in this region. This paper described the in vitro induction and identification of polyploid plants of Neolamarckia cadamba by colchicine treatment. N. cadamba belongs to the Rubiaceae family is a natural tetraploid plant with 44 chromosomes (2n = 4x = 44). Nodal segments were treated with colchicine (0.1%, 0.3% and 0.5%) for 24 h and 48 h before transferring to shoot regeneration medium. Flow cytometry (FCM) and chromosome count were employed to determine the ploidy level and chromosome number of the regenerants, respectively. Of 180 colchicine-treated nodal segments, 39, 14 and 22 were tetraploids, mixoploids and octoploids, respectively. The highest percentage of polyploidization (20% octoploids; 6.7% mixoploids) was observed after treated with 0.3% colchicine for 48 h. The DNA content of tetraploid (4C) and octoploid (8C) was 2.59 ± 0.09 pg and 5.35 ± 0.24 pg, respectively. Mixoploid plants are made up of mixed tetraploid and octoploid cells. Chromosome count confirmed that tetraploid cell has 44 chromosomes and colchicine-induced octoploid cell has 88 chromosomes. Both octoploids and mixoploids grew slower than tetraploids under in vitro conditions. Morphological characterizations showed that mixoploid and octoploid leaves had thicker leaf blades, thicker midrib, bigger stomata size, lower stomata density, higher SPAD value and smaller pith layer than tetraploids. This indicates that polyploidization has changed and resulted in traits that are predicted to increase photosynthetic capacity of N. cadamba. These novel polyploid plants could be valuable resources for advanced N. cadamba breeding programs to produce improved clones for planted forest development.

Isoetes baodongii (Isoetaceae), a New Basic Diploid Quillwort from China

Isoetes baodongii Y. F. Gu, Y. H. Yan & Yi J. Lu (Isoetaceae) is here described as a newly discovered, rare and endangered species of quillwort from eastern China. It has a basic diploid chromosome count of 2n = 22. Isoetes baodongii is similar to I. sinensis T. C. Palmer in its overall appearance and was previously misidentified as such. It differs from I. sinensis in its chromosome number and in megaspore ornamentation. In I. baodongii, both the proximal surface and distal surface of the megaspore are echinato-cristate, whereas in I. sinensis the proximal surface is echinate and the distal surface echinato-cristate. Microspores of I. baodongii have echinate ornamentation.

Micropropagation of Hibiscus moscheutos L. ‘Luna White’: effect of growth regulators and explants on nuclear DNA content and ploidy stability of regenerants

Hibiscus moscheutos L., also known as hardy hibiscus, is valued for its medicinal and ornamental attributes. It is usually propagated via seeds or cuttings. The purpose of this investigation was to develop a dependable micropropagation for H. moscheutos ‘Luna White’. To that end, the effect of four explant types (leaf, root, node, shoot tip) and two growth regulators 6-benzylaminopurine (BA) and meta-Topolin (mT) (6-(3-hydroxybenzylamino) purine) on in vitro growth of H. moscheutos was investigated. Genetic stability of the in vitro grown plants was assessed using flow cytometry, and chromosome count was investigated. No shoots were obtained from leaf or root explants. An efficient protocol for micropropagation of H. moscheutos using two explant types, 2-node and shoot tip explants, and two cytokinins (BA and mT) capable of producing true-to-type regenerants was established. Both BA and mT can be used at 2 μM or 4 μM using either 2-node or shoot tip explants. No significant difference was found between the nuclear DNA contents of seed-derived and in vitro grown plants (P < 0.05). The mean 2C DNA and monoploid 1Cx-values of seed-derived plants were 3.25 ± 0.08 pg and 1.62 ± 0.04 pg, respectively, compared with 3.26 ± 0.06 pg and 1.63 ± 0.02 pg, respectively, for in vitro grown plants. The chromosome number of both seed-derived plants and regenerants was determined to be 2n = 2x = 38. The mature regenerants obtained were fertile and phenotypically similar to seed-derived plants.

Chromosome Diversity and Evolution in Helicoide a (Gastropoda: Stylommatophora): A Synthesis from Original and Literature Data

We performed a molecular and a comparative cytogenetic analysis on different Helicoidea species and a review of all the available chromosome data on the superfamily to provide an updated assessment of its karyological diversity. Standard karyotyping, banding techniques, and Fluorescence in situ hybridization of Nucleolus Organizer Region loci (NOR-FISH) were performed on fifteen species of three families: two Geomitridae, four Hygromiidae and nine Helicidae. The karyotypes of the studied species varied from 2n = 44 to 2n = 60, highlighting a high karyological diversity. NORs were on a single chromosome pair in Cernuella virgata and on multiple pairs in four Helicidae, representing ancestral and derived conditions, respectively. Heterochromatic C-bands were found on pericentromeric regions of few chromosomes, being Q- and 4′,6-diamidino-2-phenylindole (DAPI) negative. NOR-associated heterochromatin was C-banding and chromomycin A3 (CMA3) positive. Considering the available karyological evidence on Helicoidea and superimposing the chromosome data gathered from different sources on available phylogenetic inferences, we describe a karyotype of 2n = 60 with all biarmed elements as the ancestral state in the superfamily. From this condition, an accumulation of chromosome translocations led to karyotypes with a lower chromosome number (2n = 50–44). This process occurred independently in different lineages, while an augment of the chromosome number was detectable in Polygyridae. Chromosome inversions were also relevant chromosome rearrangements in Helicoidea, leading to the formation of telocentric elements in karyotypes with a relatively low chromosome count.

Cytogenetic, chromosome count optimization and automation of Neolamarckia cadamba (Rubiaceae) root tips derived from in vitro mutagenesis

Chromosome count is the only direct way to determine the number of chromosomes of a species. This study is often considered trivial that seldom described and discussed in detail. Therefore, it is inevitable that the chromosome count protocol should be revised and revisited before it becomes obliterated. In the present study, we encountered challenges in obtaining a clear micrograph for the chromosome count of active mitotic cells of Neolamarckia cadamba (Roxb.) Bosser (Rubiaceae) root tips. Several obstacles were determined through micrograph observation, such as existing unwanted particles in cells, poor chromosome staining and chromosome clumping. To overcome these, root tip types, staining methodologies, squashing methods were among the factors assessed to obtain clear micrographs. The chromosome counts of N. cadamba under optimized procedure showed 2n = 44 chromosomes. We also apply digital technology in chromosome counts, such as online databases and graphic software that are open source and freely accessible to the public. Only basic laboratory equipment and chemicals were used throughout the study, thus making this study economical and applicable in a basic laboratory. The availability of online digital software and databases provide open-source platforms that will ease the efforts in chromosome count.

New Contribution to the Knowledge on the Chromosome Numbers of Turkish Cerambycidae (Coleoptera)

Information on the karyotypes of Turkish species of Cerambycidae is scanty. Our study contributes to the knowledge of the karyological data (chromosomal number and mechanism of sex determination) of five Turkish longicorn beetles; karyotypes of four taxa, one endemic, are described for the first time and for the remaining one, Purpuricenus budensis (Götz, 1783), the previously published chromosome count is confirmed. The chromosome number of Purpuricenus desfontainii inhumeralis Pic, 1891 and Purpuricenus budensis (Götz, 1783) (Cerambycinae, Trachyderini) was found to be 2n = 28 (13 + Xyp); Clytus rhamni Germar, 1817 and Plagionotus floralis (Pallas, 1773) (Cerambycinae, Clytini) 2n = 20 (9 + Xyp); and the endemic Dorcadion triste phrygicum Peks, 1993 (Lamiinae, Dorcadionini) 2n = 24 (11 + Xyp). In view of the paucity of data available until now, our study is important for both to improve the poor karyological knowledge of Turkish Cerambycidae and to provide an incentive for other researchers.

Characterization of Different Arundo donax L. Clones from the Mediterranean Region

The present study assessed the behavior of four clones of Arundo donax L. (giant reed) as a perennial rhizomatous grass of increasing interest due to its high biomass production and great adaptability to stress conditions. In this study, a molecular, physiological, and biomass characterization was performed in greenhouse conditions on four Mediterranean clones. The majority of physiological and biomass parameters were not significantly different between clones. However, it was possible to observe large differences in the chromosome count for the four clones. In this way, we detected different numbers of chromosomes for each clone (98 to 122), but surprisingly, no correlation was observed between their chromosome numbers and their physiological and biomass responses.

Hybridization as a biodiversity driver: The case of Veronica × gundisalvi

Hybridization is an important mechanism in plant evolution, which contributes to the adaptability and biological diversity of species in fundamental ways. Based on morphological data, Veronica × gundisalvi Sennen (Veronica orsiniana × V. tenuifolia subsp. tenuifolia) is an Iberian endemic taxon of presumably polytopic hybrid origin restricted to five localities in Catalonia, where the putative parental species grow in sympatry. In this study, species distribution models were developed for the putative parental species to seek potential new localities where active hybridization could be taking place. As a result, a new location of this nothotaxon in Zaragoza is provided, along with a chromosome count and ploidy level estimations. The data presented here further support Veronica × gundisalvi as a homoploid hybrid taxon that occurs in non-altered habitats. In contrast to the traditional view of hybridization as deleterious for the conservation of biodiversity, it does not always represent a problem in this regard. Hybridization is a complex evolutionary force that requires case-specific evaluation. Given that biodiversity loss is one of the main contemporary challenges, it is important to consider the creative nature of hybridization, a widespread evolutionary mechanism able to produce novel diversity.