Utilization of ISSR and SSR markers in wild sunflower conservation

GARAYALDE AF; POVERENE M; CARRERA A

Jornada; I JORNADA ANUAL DE INTERCAMBIO DE BECARIOS Y TESISTAS EN EL CONICET BAHIA BLANCA. Medioambiente y Preservación.; 2013

CCT-CONICET- BBlanca

Populations of wild sunflower Helianthus annuus (ssp. annuus, Asteraceae) have become naturalized in Argentina. This is an annual, diploid specie (x=17) original from North America. The genetic variability of natural populations constitutes an essential parameter for their efficient rationalization and utilization as genetic resources. Several genetic criteria have been used to identify both germplasm accessions and natural populations of high conservation value: i) allele richness or number of alleles per locus, ii) locally common alleles, defined as alleles that are common in one to several populations but not at the species as a whole and iii) number of private or unique alleles. The objectives of this work were: (1) to assess the genetics diversity using SSR and ISSR markers, (2) to compare genetic patterns of cultivated and wild materials, (3) to provide data applicable to wild sunflower conservation and breeding uses. A total of 100 individuals of H. annuus, representing ten natural populations, were sampled throughout its range in Argentina. The locations and their provinces were as follows: A. Alsina (ALS) and Carhue (CAR) from Buenos Aires; J. Celman (JCE), Río Cuarto (RCU) and La Carlota (LCA) from Córdoba; Rancul (RAN) and Colonia Barón (CBA) from La Pampa; Media Agua (MAG) from San Juan; Malvinas (MAL) from Mendoza and Diamante (DIA) from Entre Ríos. Six inbreed lines (HA367, HAR274, HAR2, HAR3, HAR5 and HA89) were include in the analysis. Total genomic DNA was isolated from leaf tissue using a modified CTAB method. Five ISSR (inter-simple sequences repeat) and five microsatellite loci was analyzed. Percentage of polymorphic loci (P), observed heterozygosity (Ho), expected heterozygosity (He), number of alleles per locus; locally common alleles and number of private alleles were calculated using GenAlEx 6 (Genetic Analysis in Excel). None private band/alleles of sunflower cultivated samples were found for ISSRs and SSRs, being a subset of the markers of wild individuals. Wild sunflower showed nine ISSRs private band and 21 SSRs private alleles. Some unique markers were determined in particular crop-wild population comparisons. Based on the presence of private bands in wild populations in comparison to inbred lines, JCE, LCA, CAR and CBA are populations with the highest number of private band/alleles of wild sunflower. This approach attempts to select the most distant populations in comparison to cultivated genotypes. Based in diversity parameters, the genetic criteria used to identify natural populations of high conservation value and also considering the differences between wild and cultivated molecular profiles, the populations JCE, CBA, LCA and CAR constitute interesting targets for more extensive sampling. Molecular data suggest that Argentinean wild sunflower populations constitute an important reservoir of genetic diversity for conservational or breeding programs. Local populations are at present evaluated for variability in cold and drought tolerance, virus resistance, male sterility and functional markers polymorphisms, in order to assess a more detailed germplasm characterization.