African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12278

Full Length Research Paper

Genetic diversity of stay-green sorghums and their derivatives revealed by microsatellites

Isaac K. A. Galyuon
  • Isaac K. A. Galyuon
  • Department of Molecular Biology and Biotechnology, University of Cape Coast, Cape Coast, Ghana.
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R. Madhusudhana
  • R. Madhusudhana
  • Directorate of Sorghum Research, Hyderabad, India.
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Andrew K. Borrell
  • Andrew K. Borrell
  • Department of Primary and Rural Industries, Queensland, Australia.
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Tom C. Hash
  • Tom C. Hash
  • International Crops Research Institute for the Semi-Arid Tropics, Pantacheru, India.
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Catherine J. Howarth
  • Catherine J. Howarth
  • Institute of Biological, Environmental and Rural Sciences, Plas Gogerddan, Aberystwyth, SY23 3EB, Wales, UK.
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  •  Received: 31 October 2015
  •  Accepted: 23 May 2016
  •  Published: 22 June 2016

Abstract

The genetic variability of 28 sorghum genotypes of known senescence phenotype was investigated using 66 SSR markers well-distributed across the sorghum genome. The genotypes of a number of lines from breeding programmes for stay-green were also determined. This included lines selected phenotypically for stay-green and also RSG 03123, a marker-assisted backcross progeny of R16 (recurrent parent) and B35 (stay-green donor). A total of 419 alleles were detected with a mean of 6.2 per locus. The number of alleles ranged from one for Xtxp94 to 14 for Xtxp88. Chromosome SBI-10 had the highest mean number of alleles (8.33), while SBI-05 had the lowest (4.17). The PIC values obtained ranged from zero to 0.89 in Xtxp94 and Xtxp88, respectively, with a mean of 0.68. On a chromosome basis, mean PIC values were highest in SBI-10 (0.81) and lowest in SBI-05 (0.53). Most of the alleles from B35 in RSG 03123 were found on chromosomes SBI-01, SBI-02 and SBI-03, confirming the successful introgression of quantitative trait loci associated with stay-green from B35 into the senescent background R16. However, the alternative stay-green genetic sources were found to be distinct based on either all the SSRs employed or using only those associated with the stay-green trait in B35. Therefore, the physiological and biochemical basis of each stay-green source should be evaluated in order to enhance the understanding of the functioning of the trait in the various backgrounds. These genetic sources of stay-green could provide a valuable resource for improving this trait in sorghum breeding programmes.

Keywords: Simple sequence repeats, sorghum, stay-green, genetic diversity.