International Journal of Plant Breeding and Genetics

International Journal of Plant Breeding and Genetics ISSN 5756-2145 Vol.  2 (1) pp. 062-072, January, 2015. © International Scholars Journals

Full length Research paper

Genetic differing qualities and linkage disequilibrium of two homologous qualities to maize D8: Sorghum SbD8 and pearl millet PgD8

*Heidi Frank, Max D. Deitrich and Karl Johannes

Department for Plant Breeding, Seed Science, and Population Genetics, School of Biological Sciences, University of Hamburg, Hamburg, Germany.

E-mail: [email protected] 

Accepted 27 December, 2014

Abstract 

Yield and yield stability of sorghum [Sorghum bicolor (L.) Moench.] and pearl millet [Pennisetum glaucum (L.) R.Br.] are highly influenced by flowering time and photoperiodic sensitivity in the arid to semi-arid regions of West and Central Africa. Photoperiodic sensitivity is the key adaptation trait of local landraces because it assures flowering at the end of the rainy season, independent of variable dates of planting. Flowering time genes are mainly integrated into four pathways with close interaction among each other: Vernalization, autonomous, GA (gibberellic acid) and photoperiod. In the GA pathway, maize D8, wheat RHT1 and rice SLR have been identified as homologous genes to the Arabidopsis GAI, which is a negative regulator of GA response. We have identified two homologous genes to D8: Sorghum SbD8 and pearl millet PgD8. These genes were expressed in the root and leaves of sorghum and pearl millet as revealed by EST database search and reverse transcription PCR, respectively. The genetic diversity of SbD8 was considerably lower than that of PgD8. The extent of linkage disequilibrium in PgD8 is lower than that of maize D8. SbD8 and PgD8 polymorphisms might be appropriate for dissection of photoperiod sensitivity using association mapping approaches.

Key words: DELLA proteins, GA pathway, flowering time, photoperiod sensitivity, sorghum, pearl millet.