Geographic and Altitudinal Allozyme Variation in Sorghum (Sorghum Bicolor (L.) Moench) Landraces from Ethiopia and Eritrea

Abstract

The amount and distribution of genetic variation was investigated in 48 sorghum landrace accessions, representing 13 regions of origin and three adaptation zones (lowland, intermediate and highland elevation) in Ethiopia and Eritrea. Assaying 11 enzymes systems, 23 putative loci were scored for a total of 27 alleles. Nineteen loci were monomorphic and fixed for the same allele, while the remaining 4 loci, each with 2 alleles, were polymorphic across the 48 accessions. The results show significant differences in allele frequencies among the accessions, regions of origin and the adaptation zones. However, all measures of genetic variation used show that the accessions maintained much lower levels of variation than the corresponding mean values for self-pollinating crop plants, confirming previous conclusions that sorghum is depauperated in allozymic variation. The total gene diversity was 0.25, which partitioned 59% within and 41% among accessions. The latter was largely due to variation among accessions within the adaptation zones (38%), while only 3% was due to variation among accessions between the adaptation zones. Similarly, most of the total gene diversity was found within the regions of origin (80%) and within the adaptation zones (97%). Both the dendrogram constructed from NEI's unbiased genetic distance and the plot of the first two principal components distinguished three groups of regions. The level of gene flow was low among accessions, regions of origin and among accessions within adaptation zones, but high among adaptation zones. The results are discussed with emphasis on genetic resources conservation and utilization.

Development of SSR-based sorghum (Sorghum bicolor (L.) Moench) diversity research set of germplasm and its evaluation by morphological traits

“…It could be because of our large population size and greater number of SSR markers. While Ayana et al (2000) showed no genetic relationship (allozyme plus RAPD) with quantitative agro-morphological traits, which shows no correlation between molecular markers and morphological traits. Similarly Dahlberg et al (2002) reported insufficient relationship between RAPD markers and agronomic descriptors.…”

“…Many researchers have used different kinds of molecular markers e.g. Restriction Fragment Length Polymorphisms (RFLPs) (Ahnert et al 1996;Deu et al 1994;Tao et al 1993), Randomly Amplified Polymorphic DNA (RAPDs) (Ayana et al 2000;Tao et al 1993;Uptmoor et al 2003), microsatellites (SSRs) (Ali et al 2007;Casa et al 2005;Anas and Yoshida 2004;Folkertsma et al 2005;Menz et al 2004;Smith et al 2000;Uptmoor et al 2003) and Amplified Fragment Length Polymorphisms (AFLPs) (Menz et al 2004;Uptmoor et al 2003) have all been successfully used to estimate the genetic diversity in sorghums germplasm. Morphological traits or pedigree are important estimates of genetic diversity in crops but such information is usually found unrealistic and mostly influenced by environmental factors (Fufa et al 2005;Alamnza-Pinzon et al 2003).…”

Genetic structure and relationships within and between cultivated and wild sorghum (Sorghum bicolor (L.) Moench) in Kenya as revealed by microsatellite markers

“…This is especially needed for Africa, the center of origin and primary diversification of sorghum. Attempts have been made to use in situ collected samples but such studies have been limited to separate investigations of genetic diversity and structure in either cultivated sorghum (Djè et al 1998;Djè et al 1999;Ayana et al 2000b;Ayana et al 2001;Ghebru et al 2002;Barnaud et al 2007;Deu et al 2008;Sagnard et al 2008;Barro-Kondombo et al 2010) or its closest wild relatives (Ayana et al 2000a). Our study applied microsatellite markers to analyse cultivated sorghum and its closest wild relatives sampled from different growing regions in Kenya, in order to elucidate patterns of diversity within and among the two congeners, and to shed more light on their genetic and evolutionary relationships.…”

Karyomorphological and Phylogenetic Studies in Different Species of Sorghum L. Moench

“…S. intrans with lower chromosome number may be more primitive. Increase in number of chromosomes in the other species studied is attributed to polyploidy (Ayana et al 1992, Gu et al 1984, Nurul Islam Faridi et al 2002, which increases the diversity and adoptability besides enabling combination of the characteristics of the parental species. Allopolyploidy seems to have played a prominent role in the evolution of species in Sorghum.…”