Angelo Troia

Population Structure in the Model Grass Brachypodium distachyon Is Highly Correlated with Flowering Differences across Broad Geographic Areas

Genotyping diverse Brachypodium accessions expands research tools for grasses. The B. hybridum genome is a mosaic of B. distachyon‐ and B. stacei‐like sequences. Three distinct, genetically defined populations of B. distachyon were identified. Flowering time, more than geography, distinguishes B. distachyon populations. Results support the feasibility of genome‐wide association studies in a model grass.

The genus Isoëtes L. (Lycophyta, Isoëtaceae): synthesis of karyological data

Summary A synthesis of relevant karyological data regarding the genus Isoëtes is given, with an up-to-date check list of chromosome numbers including 152 records referring to 67 taxa (62 species and 5 infraspecific taxa) and 16 hybrids. Total of different chromosome counts (considering two or more cytotypes for certain taxa, excluding hybrids) is 80. Probable base number is x = 11, even though x = 10 and x = 12 have been proposed for certain species. On the basis of data here summarized, the mean percentage of polyploidy is 61.2%; 31 taxa are diploids (38.8%), 28 are tetraploids (35.0%), 8 are hexaploids (10.0%), with a few species each which are tri-, penta-, octo-, deca- and dodeca-ploids. These data are briefly discussed in the frame of the evolution of the genus: palaeopolyploidy did not play a primary role, autopolyploidy seems rare, allopolyploidy is an active mechanism of speciation especially in aquatic species. Correlation between size of cells (spores and stomata) and ploidy level is also discussed.

Genetic and phytochemical difference between some Indian and Italian plants of Withania somnifera (L.) Dunal

The geographical distribution of Withania somnifera (L.) Dunal is quite wide. However, in Italy, this species is very rare and grows spontaneously only in Sicily and in Sardinia. The PCR–RAPD technique has been utilized in this work to determine the genetic relationship among Sicilian, Sardinian and Indian samples and the HPLC analysis of whitaferin A was used as a marker to evaluate the phytochemical differences. The genetic difference between Indian and Sicilian plants of W. somnifera turned out to be smaller than that between Indian and Sardinian plants of this species. The phytochemical analysis as well showed that the Sardinian specimen strongly differed from the Indian and Sicilian ones in its contents of withaferin A. Our results seem to confirm the hypothesis that the Italian populations of this species may not be indigenous but naturalised. Due to the high withaferin A content of the Sardinian samples, these plants could be used as a source for pharmaceutical purposes.

Isoetes todaroana (Isoetaceae, Lycopodiophyta), a New Species from Sicily (Italy)

Abstract Isoëtes todaroana, a new species from western Sicily (Italy), is described. Morphological, anatomical and ecological characters are given. The main differential characters are the presence of only two leaf air chambers, rather than four as in all other known species of the genus, and the shape of the scales, which have two lateral rounded lobes and one central spine-like lobe, together with its peculiar calcophilic habitat. So far, the species is known from a single locality.

Genetic diversity in Cytisus aeolicus Guss. (Leguminosae), a rare endemite of the Italian flora

ABSTRACT Cytisus aeolicus Guss, is an endemic plant restricted to the isles of Vulcano, Stromboli and Alicudi in the Aeolian archipelago. All known populations were assayed for genetic variability using enzyme polymorphism. Allozyme variation at 16 loci coding for 10 enzyme systems was examined. The great majority of loci turned out to be monomorphic or fixed heterozygous. The observed genetic depauperation is indicative of historical factors, such as the bottleneck effect associated with migration, and the founder effect in population re-establishment. The low genetic diversity is largely partitioned within rather than among populations, indicating that extant populations have not been established long enough for divergence to have occurred. The genetic uniformity, combined with the scattered distribution of small populations, and the negative shift of population size point to a critically endangered species. Strategies for conservation are considered.

A critical conspectus of Italian Isoetes (Isoetaceae)

The work on the Isoetaceae account for the Critical Flora of Italy has resulted in a new, synonymic inventory of Italian Isoetes taxa, based on herbarium studies, observation by scanning electron microscopy and critical re-examination of the previously published works. Ten species are listed. The names I. longissima and I. gymnocarpa are restored as correct, to replace I. velata and I. subinermis, respectively. Eighteen lectotypes, one epitype and one neotype are designated. A dichotomous key to Italian taxa is provided.

Mediterranean island biogeography: Analysis of fern species distribution in the system of islets around Sicily

Abstract The aim of this article was to test the way in which geographical factors influence island floras in the Mediterranean basin, using ferns as target organisms, and the islands surrounding Sicily as location. A matrix with presence/absence data concerning fern taxa in the 16 islands studied was compiled. Cluster analysis, principal co-ordinates analysis (PCoA), principal components analysis (PCA) and a Bayesian analysis were performed. For each island, the total number of fern taxa was regressed against three factors: island area, island elevation and isolation. All the analyses pointed to affinities between islands according to their different geological composition, independently from their geographic position. A clear positive island species/area relationship (ISAR) was shown only for the volcanic islands. The island species/(area×elevation) relationship (ISAER), on the contrary, was unsatisfactory. The main features of interest are the following: (1) the clear division of the islands into two groups, volcanic vs. sedimentary; (2) the floristic richness of the volcanic compared to sedimentary islands and (3) the uniqueness of the pteridophyte flora of Pantelleria. This seems to demonstrate that the lower number of taxa in the islands farthest away from the “mainland” (Sicily, Tunisia) is not due to isolation, but due to another factor, probably habitat availability.

A reassessment of the sections of the genus Cytisus Desf. (Cytiseae, Leguminosae)

Recent morphological and molecular research on Cytisus and allied genera has produced a great deal of new data relevant to systematics, which have not yet been incorporated into a consistent classification system of the genus. We have compared and evaluated recently published cladograms and phenograms based on morphological and molecular (nuclear and plastid DNA) characters. The genus Cytisus sensu lato, including Calicotome, Chamaecytisus, Chronanthus, and Lembotropis, appears to be monophyletic. A subdivision of the genus Cytisus in 13 sections is presented; one species, C. tribracteolatus, remains incertae sedis. A new section (C. sect. Dendrocytisus) and two new combinations for taxa in C. sect. Calicotome are proposed.

Isolation and biodiversity in Cytisus villosus Pourret (Fabaceae, Genisteae): enzyme polymorphism in disjunct populations

ABSTRACT The genetic diversity of isolated populations of Cytisus villosus has been studied by means of enzyme polymorphism analysis. Two types of isolated populations were studied: “terrestrial islands” in Sicily, and “true islands” in the Aeolian archipelago. In the populations of “true islands” the number of alleles and the heterozygosity are lower than in “terrestrial islands”. Isolation amongst Sicilian populations seems to be more recent than isolation of the Aeolian populations, and may be attributed to climatic changes which occurred during the Holocene and/or to human activities. The disjunction of the Aeolian populations seems much more recent than the origin of the isles themselves; the colonization of the archipelago is attributed to a single, recent dispersal event not followed by local evolution. In view of the biological structure of the Aeolian populations, C. villosus must be regarded as a locally endangered species.

Morphological, karyological and taxonomic remarks on Ferulago nodosa (L.) Boiss. (Apiaceae)

Abstract Western (Sicilian) and eastern (Balcan-aegean) populations of the Balcan-tyrrhenian Ferulago nodosa are reported to be different in some morphological characters, and were considered different species by some authors in XIX century. In this work, fruit and pollen morphologies have been compared in Sicilian and Cretan plants; also, the chromosome number of Sicilian plants has been ascertained. Preliminary results highlight a general homogeneity between the two populations, nevertheless showing significant differences in some parameters (fruit form, pollen size). For this reason, and considering the geographic disjunction of the Sicilian plants, the two populations are proposed to be treated as two different subspecies: F. nodosa subsp. nodosa in the east and F. nodosa subsp. rigida (Ten.) Troia & Raimondo comb. & stat. nov. in the west. The names Ferula rigida Ten. and Ferula geniculata Guss. are also typified.