High variability and disomic segregation of microsatellites in the octoploid Fragaria virginiana Mill. (Rosaceae)

Abstract

The objectives of the present study were to develop microsatellite markers for the wild strawberry, Fragaria virginiana, to evaluate segregation patterns of microsatellite alleles in this octoploid species, and assess genetic variability at microsatellite loci in a wild population. A genomic library was screened for microsatellite repeats and several PCR primers were designed and tested. We also tested the use of heterologous primers and found that F. virginiana primers amplified products in cultivated strawberry, Fragaria x ananassa Duch. and Fragaria chiloensis. Similarly, microsatellite loci developed from cultivated strawberry also successfully amplified F. virginiana loci. We investigated four microsatellite loci in detail, three developed from F. virginiana and one from cultivated strawberry. A survey of 100 individuals from a population of F. virginiana in Pennsylvania demonstrated high heterozygosities (H(e) or gene diversity ranged from 0.80 to 0.88 per locus) and allelic diversity (12-17 alleles per locus), but individual plants had no more than two alleles per locus. Segregation patterns in parents and progeny of two controlled crosses at these four loci were consistent with disomic Mendelian inheritance. Together these findings suggest that the genome of F. virginiana is "highly diploidized" and at least a subset of microsatellite loci can be treated as codominant, diploid markers. Significant heterozygote deficiencies were found at three of the four loci for hermaphroditic individuals but for only one locus among females in this gynodioecious species.

Comparative Genetic Mapping Points to Different Sex Chromosomes in Sibling Species of Wild Strawberry (Fragaria)

“…chiloensis and F. virginiana are allo-allopolyploids (Bringhurst 1990) with disomic inheritance (2n ¼ 8x ¼ 56) (Ashley et al 2003;Lerceteau-Kö hler et al 2003;Rousseau-Gueutin et al 2008). The two species share a very recent common ancestor (RousseauGueutin et al 2009;Njuguna 2010) and are thought to have diverged only after migration across the Bering Strait to northwestern North America from Asia (Staudt 1999), where F. virginiana dispersed eastward and F. chiloensis southward.…”

Inter Simple Sequence Repeat (ISSR) markers to assess genetic diversity and relatedness within strawberry genotypes

“…Each marker system has its own strengths and limitations, making the choice of marker an important decision. Strawberries have been extensively analyzed for clone identification, mapping and diversity studies using randomly amplified polymorphic DNA (RAPD) markers (Hancock et al 1994;Graham et al 1996;Harrison et al 2000;Degani et al 2001;Sugimoto et al 2005), amplified fragment-length polymorphisms (AFLPs) (Degani et al 2001;Tyrka et al 2002) and the simple sequence repeats (SSRs) (Ashley et al 2003;Nourse et al 2002;Cipriani and Testolin 2004;Folta et al 2005;Lewers 2005;Cipriani et al 2006;Lopes et al 2006;Monfort et al 2006;Sargent et al 2006). GilAriza et al (2006) and Keniry et al (2006) described expressed sequence tags (ESTs)-derived microsatellites from cultivated strawberry and their potential use for varietal identification and diversity study.…”

Development and Characterization of Simple Sequence Repeats (SSR) as Markers to Identify Strawberry Cultivars (Fragaria × ananassa Duch.)

“…Although the levels of the other two SSR markers, Fa3C-2 and Fa4A-1, were not high. Ashley et al (2003) developed several SSR markers for the octoploid wild strawberry F. virginiana Duch., and reported that those markers were able to amplify products in the cultivated strawberry, F. × ananassa. The cultivated strawberry F. × ananassa originated from chance hybridizations that occurred in some Europian botanical gardens between two octoploid species, F. virginiana and F. chiloensis Duch.…”

“…A great deal of genetic research on strawberry cultivars has been done concerning fruit bearing, fruit quality, and disease resistance, etc., for breeding new cultivars (Inoue et al, 1997;Matsuda et al, 1988;Monma et al, 1990;Mori, 2000;Mori and Kitamura, 2001;Takahashi et al, 1991). Recently, some molecular scientific research has been reported in the strawberry (Ashley et al, 2003;Folta et al, 2005;James et al, 2003;Lerceteau-Köhler et al, 2003). However, the amount of research is still insufficient compared with other major crops, e.g., rice and wheat.…”

“…Folta et al (2005) reported that the octoploid genome presented a formidable barrier to the efficient study of genome structure and molecular mechanisms that underlie agriculturally relevant traits. It was reported that the development of microsatellite markers for polyploid plant species lagged behind that of diploid species and despite the economic importance of the cultivated strawberry (F. × ananassa) (Ashley et al, 2003).…”