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Bhosale S.U.,University of Hohenheim | Stich B.,Max Planck Institute for Plant Breeding Research | Rattunde H.F.W.,International Crops Research Institute for the Semi Arid Tropics ICRISAT Bamako | Weltzien E.,International Crops Research Institute for the Semi Arid Tropics ICRISAT Bamako | And 4 more authors.
Genetica | Year: 2011

Accounting for population structure to minimize spurious associations in association analyses is of crucial importance. With sorghum genomic sequence information being available, there is a growing interest in performing such association studies for a number of important agronomic traits using a candidate gene approach. The aims of our study were to conduct a systematic survey of molecular genetic diversity and analyze the population structure in cultivated sorghum [Sorghum bicolor (L.) Moench] accessions from West Africa. Our analysis included 219 West African cultivated sorghum accessions with differing maturity intended for a marker-trait association study. A total of 27 SSRs were used, which resulted in detection of 513 alleles. Genetic diversity estimates for the accessions were found to be high. The accessions were divided into two subgroups using a model-based approach. Our findings partly agree with previous studies in that the guinea race accessions could be distinguished clearly from other accessions included in the analysis. Race and geographical origin of the accessions may be responsible for the structure we observed in our material. The extent of linkage disequilibrium for all combinations of SSRs was in agreement with expectations based on the mating system. © 2011 Springer Science+Business Media B.V.


Bhosale S.U.,University of Hohenheim | Stich B.,Max Planck Institute for Plant Breeding Research | Rattunde H.F.W.,International Crops Research Institute for the Semi Arid Tropics ICRISAT Bamako | Weltzien E.,International Crops Research Institute for the Semi Arid Tropics ICRISAT Bamako | And 10 more authors.
BMC Plant Biology | Year: 2012

Background: Photoperiod-sensitive flowering is a key adaptive trait for sorghum (Sorghum bicolor) in West and Central Africa. In this study we performed an association analysis to investigate the effect of polymorphisms within the genes putatively related to variation in flowering time on photoperiod-sensitive flowering in sorghum. For this purpose a genetically characterized panel of 219 sorghum accessions from West and Central Africa was evaluated for their photoperiod response index (PRI) based on two sowing dates under field conditions.Results: Sorghum accessions used in our study were genotyped for single nucleotide polymorphisms (SNPs) in six genes putatively involved in the photoperiodic control of flowering time. Applying a mixed model approach and previously-determined population structure parameters to these candidate genes, we found significant associations between several SNPs with PRI for the genes CRYPTOCHROME 1 (CRY1-b1) and GIGANTEA (GI).Conclusions: The negative values of Tajima's D, found for the genes of our study, suggested that purifying selection has acted on genes involved in photoperiodic control of flowering time in sorghum. The SNP markers of our study that showed significant associations with PRI can be used to create functional markers to serve as important tools for marker-assisted selection of photoperiod-sensitive cultivars in sorghum. © 2012 Bhosale et al; licensee BioMed Central Ltd.


Mutegi E.,Kenya Agricultural Research Institute | Mutegi E.,International Crops Research Institute for the Semi Arid Tropics ICRISAT Nairobi | Mutegi E.,Ohio State University | Sagnard F.,International Crops Research Institute for the Semi Arid Tropics ICRISAT Nairobi | And 10 more authors.
Conservation Genetics | Year: 2012

Little information is available on the extent and patterns of gene flow and genetic diversity between cultivated sorghum and its wild related taxa under local agricultural conditions in Africa. As well as expanding knowledge on the evolutionary and domestication processes for sorghum, such information also has importance in biosafety, conservation and breeding programmes. Here, we examined the magnitude and dynamics of crop-wild gene flow and genetic variability in a crop-wild-weedy complex of sorghum under traditional farming in Meru South district, Kenya. We genotyped 110 cultivated sorghum, and 373 wild sorghum individuals using a panel of ten polymorphic microsatellite loci. We combined traditional measures of genetic diversity and differentiation with admixture analysis, population assignment, and analyses of spatial genetic structure to assess the extent and patterns of gene flow and diversity between cultivated and wild sorghum. Our results indicate that gene flow is asymmetric with higher rates from crop to wild forms than vice versa. Surprisingly, our data suggests that the two congeners have retained substantial genetic distinctness in the face of gene flow. Nevertheless, we found no significant differences in genetic diversity measures between them. Our study also did not find evidence of isolation by distance in cultivated or wild sorghum, which suggests that gene dispersal in the two conspecifics is not limited by geographic distance. Overall our study highlights likely escape and dispersal of transgenes within the sorghum crop-wild-weedy complex if genetically engineered varieties were to be introduced in Africa's traditional farming systems. © 2012 Springer Science+Business Media B.V.

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