Genetic diversity and population structure of bread wheat genotypes determined via phenotypic and SSR marker analyses under drought-stress conditions

ABSTRACT

Genetic diversity is fundamental for conducting successful crop improvement programs. The objectives of this study were to assess the genetic diversity and to deduce the population structure among bread wheat (Triticum aestivum L.) genotypes using phenotypic traits and simple sequence repeat (SSR) markers to identify divergent and complementary parental genotypes for drought-tolerance breeding. Fifty-two selected bread wheat genotypes were evaluated at five test sites in the 2018/19 cropping season using a 4 × 13 alpha lattice design with two replications. The study was carried out under two sowing dates, i.e., early and late planting, corresponding to non-stress and drought-stress conditions, respectively. The test genotypes were assessed using eight phenotypic traits and 20 SSR markers. Analysis of variance showed significant differences among the genotypes for all phenotypic traits studied. SSR analysis identified a total of 181 alleles, with a mean of 10.1 alleles per locus. Population structure analysis grouped the test genotypes into three main populations. Analysis of molecular variance revealed that 85% of the variance was attributable to intra-population differences. Cluster analysis based on phenotypic and SSR data grouped the test genotypes into three major groups. Three genotypes [10 (ETW17-295), 37 (ETW17-385) and 38 (ETW17-386)] were identified as the most divergent, and were recommended for drought-tolerance breeding. Overall, the SSR markers were useful and provided complementary data for selecting agronomically suitable parental lines for drought-tolerance breeding.

Keywords:

• Bread wheat
• Cluster analysis
• Molecular variance
• Phenotype
• Polymorphism
• Triticum aestivum

Acknowledgments

Thanks are extended to Holetta Agriculture Research Center of the Ethiopian Institute of Agricultural Research (EIAR) for providing leave of absence to the first author and for the overall research support. Kulumsa Agricultural Research Centre/Ethiopia is thanked for the supply of bread wheat genotypes used in the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The study was funded by the Alliance for a Green Revolution in Africa (AGRA) through the African Centre for Crop Improvement of University of KwaZulu-Natal