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

Abstract

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.

Diversity of Naturalized Hairy Vetch (Vicia villosa Roth) Populations in Central Argentina as a Source of Potential Adaptive Traits for Breeding

“…To assess relationships between phenotypic traits in 16 and 20 naturalized populations of Argentina (2014 and 2016) and both geographic and environmental distances, six matrices were prepared and examined using the Mantel test (Smouse et al, 1986). The physical distance between naturalized populations was estimated using geographic distance (GGD) for latitude (x)/ longitude (y) values: GGD = ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi (xi − xj) 2 + (yi − yj) 2 p (Peakall and Smouse, 2006;Garayalde et al, 2011). The geographic matrix contained pairwise geographical distances while phenotypic distance was calculated as Euclidean distances between populations.…”

“…Amplifications were initially checked on 1.5% agarose gels. PCR products were analyzed on 6% denaturing polyacrylamide gel, 1×TBE electrophoresis buffer at 60 W for 75 min and the bands were visualized by silver staining and scanned (modified from Tang et al, 2003 andGarayalde et al, 2011). The size of each SSR allele was estimated using a 100 bp molecular weight marker.…”

Handling sunflower (Helianthus annuusL.) populations under heat stress

“…Tang and Knapp (2003) showed that taxon-specific alleles were 35-fold higher among wild species than cultivated species. Moreover, Garayalde et al (2011) noted 60% higher molecular variability in wild germplasm than cultivated species. However, agronomic traits have not evolved in wild species and thus there is the danger of yield loss due to linkage drag, i.e., the introduction of undesirable genes along with a gene of interest.…”

“…Therefore, stress-tolerant genotypes were lost during selection of high-yielding genotypes under non-stress conditions. On the other hand, wild germplasm was continuously acclimatized to harsh conditions and are now considered as sanctuaries of resistant genes (Tang & Knapp 2003;Garayalde et al 2011). Tang and Knapp (2003) showed that taxon-specific alleles were 35-fold higher among wild species than cultivated species.…”

Assessment of RAPD Markers to Analyse the Genetic Diversity among Sunflower (Helianthus annuus L.) Genotypes

“…Few molecular markers like simple sequence repeats (SSRs) (Iqbal et al, 2010;Garayalde et al, 2011), random amplified polymorphic DNA (RAPD) (Isaacs et al, 2003;Wangsomnuk et al, 2011a), target region amplification polymorphism (TRAP) (Yue et al, 2009;Yue et al, 2010), restriction fragment length polymorphism (RFLP) (Carrera et al, 2002), amplified fragment length polymorphism (AFLP) (Rachid et al, 2004;Dong et al, 2007;Vos et al, 1995) and inter simple sequence repeats (ISSRs) (Wangsomnuk et al, 2011b) have widely applied for marker-assisted selection (MAS), genomic evolution and used in some oilseed crops breeding research (SztubaSolińska, 2005). Mostly, genetic studies have separate principles and functions.…”