Worldwide genotyping of castor bean germplasm (Ricinus communis L.) using AFLPs and SSRs

Abstract

Worldwide genetic diversity in 200 individuals comprising 41 castor bean accessions was assessed using amplified fragment polymorphisms (AFLPs) and simple sequence repeats (SSRs). We found that, despite surveying five continents and 35 countries, genetic diversity in castor bean germplasm is relatively low (overall H e = 0.126 for AFLPs and 0.188 for SSRs) compared to estimates of genetic diversity in other plant species. Our data also show no geographic structuring of genotypes across continents or countries within continents. An assessment of the congruence between AFLP and SSRs indicates a low correlation (R 2 = 0.19) between the two data sets, but each marker class nonetheless shows similar patterns of low-genetic diversity and a lack of geographic structure. Our data do suggest that SSRs yield a higher percentage of polymorphic loci, higher heterozyosity and a greater range of genetic distances, and are therefore more informative than are AFLPs on a locus-by-locus basis. Based on comparisons with numerous other plant species, we suggest that the lower genetic variation in this worldwide collection may be due to one or more factors including: sampling strategies that have not captured the full extent of genetic variation in the species; artifactual variation due to long-term germplasm storage and seed regeneration; or intense selection followed by domestic cultivation of a limited number of castor bean genotypes, which are widely propagated for their horticultural and agro-economic value.

Utilization of in silico EST–SSR markers for diversity studies in castor (Ricinus communis L.)

“…Studies also confirm that Ricinus species does not have a specific genetic pattern or markers that do not allow differentiation based on geographical origin and DNA fragments do not appear to be associated with differentiation of population (Pecina-Quintero et al 2013). The first report which came out with low polymorphism indicated the narrow genetic base (Allan et al 2008). Milani et al (2009) studied diversity structure based on phenotypic traits and RAPD markers.…”

“…PIC values for the tested primers varied from a low of 0.27 (Rc DES 596) to a high of 0.49 (Rc DES 592) with an average value of 0.332. Allan et al (2008) reported 9 genomic SSR markers, 0.403 gene diversity (PIC) with an average of 3.01 alleles per locus. Bajay et al (2009) developed 12 genomic SSR markers with an average of 0.416 gene diversity (He) and 3.3 alleles per locus.…”

Overcoming crossing barriers between jatropha (Jatropha curcas L.) and castor bean (Ricinus communisL.)

“…The lack of adequate genetic variation has limited jatropha improvement (Allan et al 2008, Sun et al 2008, Trebbi et al 2015.One effective way to create genetic variability and incorporate desirable traits is by wide hybridization.The study addressed a combination of desirable traits of the two genera related to seed yield, oil content and quality, and to synchronous maturity. Their segregating progenies, if available, are expected to be an excellent germplasm source for genetic improvement of both crops in the future.…”

Assessment of Rapd Polymorphism in Ricin Genotypes

“…Limited studies have been carried out on the genetic diversity and phylogenetics of castor using molecular markers. Recently, studies have been initiated on assessment of genetic variation in castor germplasm using AFLP and SSR markers (Allan et al, 2008). The aim of this study was to detect genetic variability among the set of 30 castor genotypes using 6 RAPD markers.…”