Towards the Selection of Superior Sesame Lines Based on Genetic and Phenotypic Characterisation for Uganda

Walter Okello-Anyanga,Stephan Gaubitzer,Paul T Gibson,Johann Vollmann,Silvia Fluch,Karin Hansel-Hohl,Eva M Sehr,Agnes Burg,Patrick R Rubaihayo

doi:10.5539/jas.v9n9p13

Abstract

Understanding agricultural biodiversity is critical to formulate breeding strategies for crop improvement and it impacts both, conservation and collection activities. Especially germplasm collections serve as valuable resources, thus, their adequate characterisation is of utmost importance. Although Uganda ranks seventh in African sesame production, meagre research was conducted to determine the current genetic diversity among its germplasm. Therefore, in the present study part of the sesame germplasm conserved at the National Semi-Arid Resources Research Institute (NaSARRI) in Uganda focusing on 85 established lines was genetically and phenotypically characterised. Population genetic and structure analyses revealed rather a low extend of genetic diversity (expected heterozygosity [HE], or gene diversity [D]) ranging from 0 to 0.38 per entry, but a high extend of admixture within and between entries. This decrease of heterozygosity is supported by a fixation index (FST) of 0.530, indicating a medium genetic differentiation among entries. The analysis of quantitative and qualitative agromorphological traits revealed a great inter-trait variability among the entries and further indicated a certain conservation of some of the traits reflecting the geographic origin of the analysed entries. Based on both, the genetic and phenotypic characterisation, a selection of 26 superior entries is proposed, which may form a valuable basis both for farmers and breeders.

Highlights

Sesame (Sesamum indicum L.) is a primarily self-pollinated diploid with 2n = 26 chromosomes
In the present study part of the sesame germplasm conserved at the National Semi-Arid Resources Research Institute (NaSARRI) in Uganda focusing on 85 established lines was genetically and phenotypically characterised
That in comparison to intronic SSRs, exonic SSRs contain less allelic variability because they are subjected to stronger selection pressure due to their functional significance (Li et al, 2004), low HE values can further be explained by genetic isolation, historical population bottlenecks, founder effects, inbreeding or selection processes

Summary

Introduction

Sesame (Sesamum indicum L.) is a primarily self-pollinated diploid with 2n = 26 chromosomes. It belongs to the Pedaliaceae (order Lamiales), a small family of 15 genera and 70 species characterised by annual and perennial growth forms. Sesame is an important and ancient crop cultivated in hot, dry climates for its oil and protein-rich seeds (Bedigian et al, 1986). In the last decade, sesame has experienced a worldwide boom increase in its production to 158 per cent from 2004 to 2014 (FAO, 2015). Sesame accounted for 83 per cent of total agricultural sales in 2014 in Uganda (Proctor, 2015), neither its production nor its productivity increased markedly since 2005 (FAO, 2015)

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Conclusion