title: Genetic and metabolite diversity of Sardinian populations of Helichrysum italicum.
abstract: BACKGROUND
  Helichrysum italicum (Asteraceae) is a small shrub endemic to the Mediterranean Basin, growing in fragmented and diverse habitats. The species has attracted attention due to its secondary metabolite content, but little effort has as yet been dedicated to assessing the genetic and metabolite diversity present in these populations. Here, we describe the diversity of 50 H. italicum populations collected from a range of habitats in Sardinia.
  
  
  METHODS
  H. italicum plants were AFLP fingerprinted and the composition of their leaf essential oil characterized by GC-MS. The relationships between the genetic structure of the populations, soil, habitat and climatic variables and the essential oil chemotypes present were evaluated using Bayesian clustering, contingency analyses and AMOVA.
  
  
  RESULTS
  The Sardinian germplasm could be partitioned into two AFLP-based clades. Populations collected from the southwestern region constituted a homogeneous group which remained virtually intact even at high levels of K. The second, much larger clade was more diverse. A positive correlation between genetic diversity and elevation suggested the action of natural purifying selection. Four main classes of compounds were identified among the essential oils, namely monoterpenes, oxygenated monoterpenes, sesquiterpenes and oxygenated sesquiterpenes. Oxygenated monoterpene levels were significantly correlated with the AFLP-based clade structure, suggesting a correspondence between gene pool and chemical diversity.
  
  
  CONCLUSIONS
  The results suggest an association between chemotype, genetic diversity and collection location which is relevant for the planning of future collections aimed at identifying valuable sources of essential oil.
authors.affiliation: Dipartimento di Agraria, Università degli Studi di Sassari, Sassari, Italy ; Centro Interdipartimentale per la Conservazione e Valorizzazione della Biodiversità Vegetale, Loc. Surigheddu, Sassari, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Melito
authors.forename: Angela
authors.initials: A
authors.lastname: Sias
authors.forename: Giacomo L
authors.initials: GL
authors.lastname: Petretto
authors.forename: Mario
authors.initials: M
authors.lastname: Chessa
authors.forename: Giorgio
authors.initials: G
authors.lastname: Pintore
authors.forename: Andrea
authors.initials: A
authors.lastname: Porceddu
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D017753:Ecosystem; D005788:Gene Pool; D014644:Genetic Variation; D036562:Helichrysum / Q000235:genetics* / Q000378:metabolism*; D007558:Italy; D009822:Oils, Volatile / Q000378:metabolism*
chemical_list: D009822:Oils, Volatile