Wild sunflower diversity in Argentina revealed by ISSR and SSR markers: an approach for conservation and breeding programs

ANTONIO GARAYALDE; MONICA POVERENE; MIGUEL A. CANTAMUTTO; ALICIA CARRERA

ANNALS OF APPLIED BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 vol. 158 p. 305 - 317

0003-4746

Wild sunflower Helianthus annuus originates from North America and has naturalised in Argentina where it is considered invasive. The present study attempts to assess the genetic diversity using two different molecular marker systems to study the wild genetic patterns and to provide data applicable to conservation and breeding uses. Ten natural populations sampled throughout the wild range and six inbred lines were studied using inter-simple sequence repeat (ISSR) and simple sequence repeats (SSR) markers. A total of 64 ISSR bands and 29 SSR alleles were produced from 106 wild and cultivated plants. We found 9 ISSR private bands and 21 SSR private alleles in wild accessions, but no private bands/alleles were found in cultivated sunflowers. Molecular variability in wild populations was approximately 60% higher than in inbred lines. Local wild sunflowers kept considerable diversity levels in comparison with populations in the centre of origin (approximately 70%) and therefore they might possess a potential for adaptive evolutionary change. Analysis of molecular variance (AMOVA) indicated population structure with nearly 20% of genetic variability attributable to between-population differentiation. Principal coordinate analyses (PCO) grouped wild populations from different geographic locations, and a Mantel test showed low congruence between genetic distance (GD) and geographic distances (GGD); hence, molecular data could not rule out multiple wild introduction events. Low correlations were found between ISSR and SSR GD at individual and population levels; thus, divergent evolutionary groups were not evident in local wild sunflowers. Several genetic diversity criteria were utilised to assign conservation value and certain wild populations emerged as interesting sites for more extensive sampling. Introduction The wild or common sunflower Helianthus annuus (Asteraceae), an annual, diploid (x = 17) native to North America, is a very variable species, naturalised and invasive in several countries (Dry & Burdon, 1986; Muller et al., 2009). In the central area of Argentina devoted to agriculture, early reports mentioned H. annuus as an unusual species (Cabrera, 1974), but Zuloaga & Morrone (1999) and Poverene et al. (2002, 2008) showed that this species has increased its geographic distribution reaching, at present, seven provinces.Wild sunflower was probably introduced in Argentina as a forage crop (Bauer, 1991) but unintentional introductions as seed impurities or the occurrence of several entries for ornamental or breeding purposes cannot be discarded. The H. annuus species comprises weedy, wild and domesticated forms (Heiser et al., 1969). Wild sunflower populations of H. annuus together with its annual relative Helianthus petiolaris, are undergoing an invasive process Ann Appl Biol 158 (2011) 305–317 © 2011 The Authors 305 Annals of Applied Biology © 2011 Association of Applied Biologists