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Open Access Research article

Association analysis of photoperiodic flowering time genes in west and central African sorghum [Sorghum bicolor (L.) Moench]

Sankalp U Bhosale1, Benjamin Stich2, H Frederick W Rattunde3, Eva Weltzien3, Bettina IG Haussmann14*, C Thomas Hash45, Punna Ramu5, Hugo E Cuevas67, Andrew H Paterson6, Albrecht E Melchinger1 and Heiko K Parzies1

Author Affiliations

1 Institute of Plant Breeding, Seed Science, and Population Genetics, University of Hohenheim, 70593 Stuttgart, Germany

2 Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany

3 International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) - Bamako, BP 320 Bamako, Mali

4 ICRISAT - Sadoré, BP 12404 Niamey, Niger

5 ICRISAT - Patancheru, Hyderabad 502324, Andhra Pradesh, India

6 Plant Genome Mapping Laboratory, University of Georgia, Athens GA 30602, USA

7 U.S. Dept. of Agriculture, Agricultural Research Service, Tropical Agriculture Research Station, 2200 P.A. Campos Ave., Mayaguez P.R. 00680, Puerto Rico

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BMC Plant Biology 2012, 12:32  doi:10.1186/1471-2229-12-32

Published: 7 March 2012

Abstract

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.