Abstract

Background: Avocado is an important cash crop in Tanzania, however its genetic diversity is not thoroughly investigated. This study was undertaken to explore the genetic diversity of avocado in the southern highlands using microsatellite markers. A total of 226 local avocado trees originating from seeds were sampled in eight districts of the Mbeya, Njombe and Songwe regions. Each district was considered as a population. The diversity at 10 microsatellite loci was investigated. Results: A total of 167 alleles were detected across the 10 loci with an average of 16.7 ± 1.3 alleles per locus. The average expected and observed heterozygosity were 0.84 ± 0.02 and 0.65 ± 0.04, respectively. All but two loci showed a significant deviation from the Hardy-Weinberg principle. Analysis of molecular variance showed that about 6% of the variation was partitioned among the eight geographic populations. Population FST pairwise comparisons revealed lack of genetic differentiation for the seven of 28 population pairs tested. The principal components analysis (PCA) and hierarchical cluster analysis showed a mixing of avocado trees from different districts. The model-based STRUCTURE subdivided the trees samples into four major genetic clusters. Conclusion: High diversity detected in the analysed avocado germplasm implies that this germplasm is a potentially valuable source of variable alleles that might be harnessed for genetic improvement of this crop in Tanzania. The mixing of avocado trees from different districts observed in the PCA and dendrogram points to strong gene flow among the avocado populations, which led to population admixture revealed in the STRUCTURE analysis. However, there is still significant differentiation among the tree populations from different districts that can be utilized in the avocado breeding program.

Keywords

breeding; genetic admixture; germplasm management; ssr markers; population structure

Published in

Hereditas
2020, Volume: 157, number: 1, article number: 40

SLU Authors

• Juma, Ibrahim

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    
  • University of Dar es Salaam

• Dida, Mulatu Geleta

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Saripella, Ganapathi Varma

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Persson Hovmalm, Helena

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Carlsson, Anders

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Fatih, Moneim

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Ortiz Rios, Rodomiro Octavio

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

End hunger, achieve food security and improved nutrition and promote sustainable agriculture


UKÄ Subject classification

Genetics and Breeding
Horticulture


Publication identifier

DOI: https://doi.org/10.1186/s41065-020-00150-0

Permanent link to this page (URI)

https://res.slu.se/id/publ/107720