Genetic Diversity of Public Inbreds of Sorghum Determined by Mapped AFLP and SSR Markers

Abstract

The objectives of this study were (i) to assess the level of genetic diversity in elite sterility‐maintaining (B) and fertility‐restoring (R) sorghum [Sorghum bicolor (L.) Moench] lines as compared with a group of exotic and converted germplasm (IS) from the World Collection, (ii) to compare the classification of germplasm on the basis of estimates of genetic similarities obtained by means of AFLP and microsatellite (SSR) markers, and (iii) to compare the classification of germplasm obtained by different classes of molecular markers. A set of 100 SSRs, 1318 EcoRI/MseI AFLP, and 496 PstI/MseI AFLP markers with known map positions were utilized to determine the genetic similarity in a group of B, R, and IS public inbreds. Cluster analysis of genetic similarity estimates (GSij) revealed that the classification of sorghum inbreds is based on the sorghum working groups, Zera‐zera, Kafir, Kafir‐Milo, Durra, and Feterita. Cluster analyses failed to give a clear differentiation between B‐ and R‐lines, suggesting that R‐ and B‐lines do not represent well‐defined heterotic groups in this set of public lines. By comparing the different classes of molecular markers (SSRs, AFLPs, combinations of SSRs and AFLPs), we determined that the distribution of the markers and the coverage of the genome by the markers did affect the classification of genotypes. Dendrograms of genetic similarity (GS) based on PstI/MseI AFLP markers, or a set of markers spaced at 1‐ to 2‐cM intervals across the genome, produced clusters that were in better agreement with pedigree information than the analysis based solely on the EcoRI/MseI AFLP or SSR markers used in this study.

Assessment of the genetic diversity and pattern of relationship of West African sorghum accessions using microsatellite markers

“…Cluster I was a mixture of guinea/ caudatum, durra/caudatun and guinea races but the materials were all landraces. Similar results were obtained in sorghum by Menz et al 2004 where the sorghum lines were grouped according to their working groups.…”

“…AMOVA calculated according to weir, (Weir, 1996 morphic in the individuals (except locus mSbCIR 286) and bulks, as seen in previous studies of sorghum germplasm with diverse geographic origins (Grenier et al, 2000b;Casa et al, 2005). The average number of alleles per locus identified in this study was lower in individuals (4.91) and higher in bulks (6.27) than the average of 5.9 previously reported in elite sorghum lines (Smith et al, 2000), though both were lower than obtained in other studies (Menz et al, 2004;Uptmoor et al, 2003;Dje et al, 2000;Grenier et al, 2000). The SSR loci were able to uniquely identify each of our accessions.…”

“…Because of its global socio-economic importance, there has been substantial interest in characterizing the levels of genetic diversity present within sorghum using both phenotypic and molecular markers (Dean et al, 1999;Dje et al, 2000;Ghebru et al, 2002;Grenier et al, 2000a, b;Menz et al, 2004;Casa et al, 2005). These analyses have provided a foundation of genetic data for making informed decisions regarding the management and utilization of genetic resources (Casa et al, 2005).…”

“…Information about genetic diversity also permitted the classification of germplasm into heterotic groups, which are particularly important to hybrid breeding. Even though the genetic mechanisms that explain heterosis are not fully understood, it is well documented that crosses between unrelated and consequently genetically distant parents, show greater hybrid vigor due to an enhanced degree of heterozygosity than crosses between closely related parents (Stuber, 1994;Hallauer, 1999;Menz et al, 2004). Estimates of molecular-marker based genetic distance have been proven to be a useful way to describe existing heterotic groups to identify new heterotic groups and to assign inbreeds of unknown genetic origin to established heterotic groups (Dubreuil et al, 1996;Saghai et al, 1997;Hongtrakul et al, 1997;Pejic et al, 1998;Casa et al, 2002).…”

Transcriptional Profiling of Sorghum Induced by Methyl Jasmonate, Salicylic Acid, and Aminocyclopropane Carboxylic Acid Reveals Cooperative Regulation and Novel Gene Responses

“…Therefore, we initiated work on these pathways in the C4 monocot sorghum (Sorghum bicolor), and have made the resulting data sets publicly accessible. Sorghum is known to synthesize numerous unique cyanogenic glycosides, flavonoids, and other compounds as part of its broad defense response arsenal (Nicholson et al, 1987;Hipskind et al, 1990;Lo et al, 1999), reflective of its significant genetic diversity (Menz et al, 2004) and wide adaptive capabilities. The three-gene pathway for synthesis of the defensive compound dhurrin was recently transferred from sorghum into Arabidopsis, resulting in insect resistant plants (Tattersall et al, 2001).…”