DNA marker analysis of flowering time, semi-dwarf, fertility restorer, and brown midrib genes in sorghum (Sorghum bicolor [L.] Moench)

Abstract

DNA markers for the genes for flowering time (Ma1/SbPRR37, Ma2/SbEHD1, Ma3/SbPhyB, Ma4/SbCO, Ma5/SbPhyC, and Ma6/SbGHD7), semi-dwarfism (dw1 and dw2), fertility restorers (Rf1, Rf2, Rf5, and partial A1 mitochondrial sequence) and cytoplasmic–nuclear male sterile (CMS), and brown midrib (bmr-2, bmr-6, and bmr-18) were developed in this study. These markers and previously published DNA markers for dw3 were used to analyze sorghum cultivars used in breeding programs in Japan and traditional landraces from the National Institute of Agricultural Sciences (NIAS) sorghum core collection. Agronomically useful mutations were effectively detected in the cultivars by the DNA markers. Most of the mutation types for flowering and semi-dwarfism were detected in sorghum cultivars, but only the dominant-type allele of SbEHD1 and SbPhyB for flowering was detected in the NIAS collection. Fertility restorers and CMS were rarely detected in NIAS collection. Agronomically useful traits such as early flowering and semi-dwarfism became combined in the modern cultivars by phenotypic evaluation for the adaptation of harvesting to the temperate zones. Fertility restorers and CMS were introduced for F₁ hybrid breeding. These phenotypes are often recessive, so information on the alleles responsible would be helpful for sorghum breeding. We expect these DNA markers to facilitate and improve the efficiency of F₁ sorghum breeding programs.